From Project to Production

Also by PETER E . M . S H A R P :

Sound and Vision, a Design Centre Publication, Macdonald & Co. (Publishers) Ltd., 1967

FROM PROJECT TO P R O D U C T I O N

BY

A. M. BRICHTA, C.Eng., M.I.Mech.E., M.I.Prod.E.

A N D

PETER Å. M. S H A R P , A .C.G.I . , B.SC . (Eng.), F.I.E.E.

P E R G A M O N P R E S S Sfe

Oxford ' London ' Edinburgh ' New York *?rtr Toronto ' Sydney ' Paris ' Braunschweig

1966

PERGAMON PRESS LTD., Headington Hill Hall, Oxford 4 & 5 Fitzroy Square, London W.l PERGAMON PRESS (SCOTLAND) LTD., 2 & 3 Teviot Place, Edinburgh 1 PERGAMON PRESS INC., Maxwell House, Fairview Park, Elmsford, New York 10523 PERGAMON OF CANADA LTD., 207 Queen's Quay West, Toronto 1 PERGAMON PRESS (AUST.) PTY. LTD., 19a Boundary Street, Rushcutters Bay, N.S.W. 2011, Australia PERGAMON PRESS S.A.R.L.,

•24 rue des Écoles, Paris 5e

VIEWEG & SOHN GMBH, Burgplatz 1, Braunschweig

Copyright © 1970 Pergamon Press Ltd. First edition 1970 All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of Pergamon Press Ltd.

Library of Congress Catalog Card No. 79-97830

Printed in Great Britain by A. Wheaton & Co., Exeter

This book is sold subject to the condition that it shall not, by way of trade, be lent, resold, hired out, or otherwise disposed of without the publisher's consent, in any form of binding or cover other than that in which it is published.

08 006639 9 (flexicover) 08 006638 0 (hard cover)

LIST OF TABLES, PLATES AND ILLUSTRATIONS

T A B L E S

1. U.D.C.—Example of Subdivision of Main Tables. (By courtesy of the British Standard Institution, 2 Park Lane, London W.l.) 90/91

2. Rotary Knife of Slip Inserter. (By courtesy of P. J. Booker, and the Engineering Designer.) 128

3. Car Windscreen Material. (By courtesy of R. Bauerfeind and Maschinenbau Technik.) 143

4. Structural Criteria of Design. (By courtesy of G. B. R. Feilden, Bulleid Memorial Lecture.) 159

5. General Tolerances. 206/207 6. Tool Limits and Finish. 207 7. Implications of the Queueing Problems—Methods of Reducing

Delays. (By courtesy of K. J. Shone and Time & Motion Study.) 268

PLATES

1. Magic lantern late nineteenth century. (By courtesy of Science Museum, London.) 103

2. Aldis Star slide projector. (By courtesy of the makers.) 104 3. Aldis '303* slide projector. (By courtesy of the makers.) 104 4. Aldis 'XT434' slide projector. (By courtesy of the makers.) 105 5. Old type overhead crane cabin. (By courtesy of B.I.S.R.A.,

London.) 109 6. Modernised cabin. (By courtesy of B.I.S.R.A., London.) 110 7. Modern version currently being supplied. (By courtesy of

Siemens-Schuckertwerke A.G., Germany.) 111 8. Model of a shaver. (By courtesy of K. Grange, R.D.I., F.S.I.A.,

Industrial Designer, London.) 118 9. Electric shaver. Duke of Edinburgh's Award 1963. (By courtesy

of the Council of Industrial Design, London.) 119 10. Leitz Pradovit slide projector. (By courtesy of the makers.) 136 11. Kodak Carousel slide projector. (By courtesy of the makers.) 137 12. Sawyers Rototray slide projector. (By courtesy of the makers.) 138 13. Electric typewriter IBM 72. (By courtesy of the makers.) 139 14. Heavy-duty routing machine older type. (By courtesy of the

makers and Knapp Design Associates.) 140

ix

X LIST OF T A B L E S , PLATES A N D I L L U S T R A T I O N S

15. Heavy-duty routing machine redesigned. (By courtesy of the makers and Knapp Design Associates.) 141

16. Shipyard crane. (By courtesy of Krupp-Ardelt.) 166 17. Theodolite. (By courtesy of Theiss & Co. K.G.) 167 18. Radial drill with pillar detail. (By courtesy of Raboma Maschin-

enfabrik, Hermann Schoening.) 168 19. Turret lathe. (By courtesy of Werkzeugmaschinen-Fabrik

Gildemeister & Co., A.G.) 169 20. Reflector telescope. ( By courtesy of Carl Zeiss, Oberkochen. 170 21. Guillotine. By courtesy of Vereinigte Drehbank-Fabriken

V.D.F., H. Wohlenberg K.G.) 171 22. Telephone apparatus. (By courtesy of Standard Telephones

and Cables Ltd.) 171 23. Ringmaster communication unit. (By courtesy of Gustav A.

Ring, A.S., Oslo.) 172 24. Twin-screw kneader. (By courtesy of Werner & Pfleiderer

Machinenfabrik und Ofenbau.) 172 25. Piano-Miller. (By courtesy of Werkzeugmaschinen-Fabrik

Gildemeister & Co., A.G.) 173 26. I.B.M. Executive typewriter. (By courtesy of the makers.) 174 27. 'Mondiale gallic' lathe. (By courtesy of Soag Machine Tools

Ltd.) 174 28. Internal communication unit. (By courtesy of Siemens & Halske,

A.G.) 175 29. Instrument console of a power station. (By courtesy of Siemens

& Halske, A.G.) 175 30. Stress distribution in the vicinity of surface forces in bodies of

small volume and large loaded surface. (By courtesy of J. B. Hartman, R. E. Benner and Machine Design.) 222

31. Three silicon rubber models of a main bearing support of a Diesel engine. (By courtesy of G. B. R. Feilden and Ruston & Hornsby Ltd.) 225

32. Time-exposure of the left-hand rubber model in Plate 31 marked with black spots. 225

33. Typical fatigue crack. (By courtesy of G. A. Cottel and the Institution of Mechanical Engineers.) 228

34. Fractured landing gear pivot shaft. (By courtesy of J. A. Bennett and the Institution of Mechanical Engineers.) 229

35. Fatigue crack opposite where fracture originated. (By courtesy of J. A. Bennett and the Institution of Mechanical Engineers.) 229

36. Failure in T-headed bolt. (By courtesy of G. A. Cottel and the Institution of Mechanical Engineers.) 232

37. Typical cracks in rotating shafts. (By courtesy of G. A. Cottel and the Institution of Mechanical Engineers.) 233

38. Fatigue failure in the section of a keyed shaft. (By courtesy of R. Cazaud and the Institution of Mechanical Engineers.) 235

39. Fatigue cracks revealed by dye penetrant method. (By courtesy of R. Cazaud and the Institution of Mechanical Engineers.) 235

LIST OF TABLES, PLATES AND ILLUSTRATIONS XI

40. Fatigue by peeling in a key way. (By courtesy of R. Cazaud and the Institution of Mechanical Engineers.) 236

41. Failure in crankshaft initiated at oil hole. (By courtesy of R. Cazaud and the Institution of Mechanical Engineers.) 236

42. Fatigue crack in forward steering arm of a car. (By courtesy of G. A. Cottel and the Institution of Mechanical Engineers.) 237

43. Crack due to badly cut thread on stud. (By courtesy of G. A. Cottel and the Institution of Mechanical Engineers.) 237

44. Torsional fatigue fracture at the fillet radius of a crankshaft. (By courtesy of R. Cazaud and the Institution of Mechanical Engineers.) 238

45. Typical corrosion fatigue cracks. (By courtesy of G. A. Cottel and the Institution of Mechanical Engineers.) 238

46-61. Steel micrographs. (By courtesy of J. T. Greaves and Chapman & Hall.) 241

62. Finishing the outside of a plaster model. (By courtesy of R. R. Knoblaugh and McGraw-Hill.) 252

63. Vertical lines being added to the plaster model. (By courtesy of R. R. Knoblaugh and McGraw-Hill.) 252

64. Gouging out a cavity in plaster. (By courtesy of R. R. Knob-laugh and McGraw-Hill.) 253

I L L U S T R A T I O N S

1. The organisation chart of a small or medium engineering firm. 6 2. A chart of a horizontally integrated mixed production organisa-

tion with an engineering division. 6/7 3. Company performance chart. (By courtesy of P. R. Marvin

and Machine Design.) 11 4. Graph as basis for company development policy. (By courtesy

of L. A. Williams, R. J. Finlayson and the Institution of Mechani-cal Engineers.) 13

5. Product survey. (Based on E. L. G. Robbins and Industrial Administration Ltd.) 19

6. Marketing research. (By courtesy of E. L. G. Robbins and Industrial Administration Ltd.) 20

7. Market evaluation and kWh disposal graph. (By courtesy of L. A. Williams, R. J. Finlayson and the Institute of Mechanical Engineers.) 23

8. Research expenditure and growth of industries chart. (By courtesy of C. Freeman and Economic Review.) 29

9. Law of expenditure graph. 31 10. Development activity and functional relationships diagram.

(Based on Torward product planning' by courtesy of E. L. G. Robbins and The Production Engineer.) 36

X U L I S T O F T A B L E S , P L A T E S A N D I L L U S T R A T I O N S

11. Product development, initial phase—Feasibility study and speci-fication chart. (Based on E. L. G. Robbins and Industrial Ad-ministration Ltd.)

12. Project proposal form. (By courtesy of J. Hodge and the Insti-tution of Mechanical Engineers.)

13. Budgeting form. (By courtesy of J. Hodge and the Institution of Mechanical Engineers.)

14. Generalised model of an engineering project. (By courtesy of P. J. Booker and the Engineering Designer.)

15. Feasibility study—duct restraint unit. (By courtesy of P. J. Booker and the Engineering Designer.)

16. Final product. Frusto-conical restraint unit. (By courtesy of P. J. Booker and the Engineering Designer.)

17. Product profitability and variety reduction graph. (By courtesy of E. L. G. Robbins and Industrial Administration Ltd.)

18. Manufacturing costs and variety reduction graph. (By courtesy of E. L. G. Robbins and Industrial Administration Ltd.)

19. Functional relationship of R. & D. (By courtesy of P. R. Marvin and Machine Design.)

20. Product development programme bar graph. (By courtesy of E. L. G. Robbins and Industrial Administration Ltd.)

21. C.P.M. diagram with bar graph. (By courtesy of H. Berman and The Constructor and Building Research Fiation, D.S.I.R.)

22. M.O.S.T. Management Operation System. (Based on A. L. Iannone and the Chart. Mech. Engineer.)

23. P.E.R.T. network and printouts. (By courtesy of International Computors and Tabulators.)

24. Slip inserter history tree. (By courtesy of P. J. Booker, J. Prince and the Engineering Designer.)

25. Slip inserter. Completed project. (By courtesy of P. J. Booker, J. Prince and the Engineering Designer.)

26. Symmetry of units. (By courtesy of A.E.I. (Manchester) Ltd.) 27. Symmetry of controls (By courtesy of A.E.I. (Manchester)

Ltd.) 28. Unity in functional interdependence. (By courtesy of A.E.I.

(Manchester) Ltd.) 29. House symbol (By courtesy of A.E.I. (Manchester) Ltd.) 30. Machine tool control panel. (By courtesy of R. S. M. Kay

and A.E.I. (Manchester) Ltd.) 31. Electronic circuit control panel. (By courtesy of A.E.I. (Man-

chester) Ltd.) 32. Design task: provision of a rotating net platform. (By

courtesy of R. Bauerfeind and Maschinenbau Technik.) 33. Effects of torsion and shear on frusto-conical bellow restraint

unit. (By courtesy of P. J. Booker and the Engineering De-signer.)

34. Compression spring design. Load-length curves. (By courtesy of F. A. Votta and Machine Design.)

37

40

42/43

44

48

49

51

51

53

56

60

62

62/63

71

72 99

100

100 107

112

113

125

126

130

LIST OF T A B L E S , P L A T E S A N D I L L U S T R A T I O N S

35. Compression spring design. Effect of wire diameter on final stress, all other factors remaining constant. (By courtesy of F. A. Votta and Machine Design.)

36. Compression spring design. Allowable stress curves super-imposed on actual working stress curves. (By courtesy of F. A. Votta and Machine Design.)

37. Screw jack design. Variations and combinations. (By courtesy of R. Bauerfeind and Maschinenbau Technik.)

38. Family of Gildermeister piano-millers. (By courtesy of the makers.)

39. Compression spring design. Comparison. (By courtesy of F. A. Votta and Machine Design.)

40. Absolute and percentage costs for a turned component in aluminium alloy. (By courtesy of V.D.i.-Verlag G.m.b.H., Düsseldorf, Germany.)

41. Percentage cost distribution for a wagon and precision wrist watch. (By courtesy of V.D.I.-Verlag G.m.b.H., Düsseldorf, Germany.)

42. Percentage cost distribution for prototypes of a small automatic switch. (By courtesy of V.D.I.-Verlag G.m.b.H., Düsseldorf, Germany.)

43. Percentage of material costs by product. (By courtesy of V.D.I.-Verlag G.m.b.H., Düsseldorf, Germany.)

44. Engineering value of three successive designs. (By courtesy of V.D.I.-Verlag G.m.b.H., Düsseldorf, Germany.)

45. Schematic version of an early prototype. (By courtesy of P. J. Booker, J. Prince and the Engineering Designer.)

46. Principal design concept. Cantilever type inserter. (By courtesy of P. J. Booker, J. Prince and the Engineering Designer.)

47. Principal design concepts of duct restraint units. (By courtesy of P. J. Booker and the Engineering Designer.)

48. Principal problem of fishing net platform and design concepts. (By courtesy of R. Bauerfeind and Maschinenbau Technik.)

49. Design concepts for net platform problem and principal solu-tions of element 'a'—runner. (By courtesy of R. Bauerfeind and Maschinenbau Technik.)

50. Design concepts for net platform problem and solutions of element *b'—height adjustment of strut. (By courtesy of R. Bauerfeind and Maschinenbau Technik.)

51. Design concepts for a net platform and solutions of element *c' —strut anchorage. (By courtesy of R. Bauerfeind and Maschin-enbau Technik.)

52. Roller support proposal for a net platform problem. (By courtesy of R. Bauerfeind and Maschinenbau Technik.)

53. Design scheme tree for a fishing net platform. 54. Sub-problem analysis for a kinematic scheme of a pushrod cup

cam. Slip inserter. (By courtesy of P. J. Booker, J. Prince and the Engineering Designer.)

xiii

131

131

132

133

134

145

146

147

147/8

148

149

150

151

152

153

154

155

156 157

158

X i v LIST O F T A B L E S , P L A T E S A N D I L L U S T R A T I O N S

55. Cycle of operations of grippers. Slip inserter. (By courtesy of P. J. Booker, J. Prince and the Engineering Designer.) 163

56. Gripper unit of slip inserter. (By courtesy of P. J. Booker, J. Prince and the Engineering Designer.) 164

57. The significance of lack of new product development. (By courtesy of P. R. Marvin and Machine Design.) 181

58. Newcomen's steam engine. Sample specification. (By courtesy of R. Bauerfeind and Maschinenbau Technik.) 186

59. Alternatives to avoid infringement. (By courtesy of G. V. Woodling and Machine Design.) 188

60. Design realisation. (By courtesy of E. L. G. Robbins and In-dustrial Administration Ltd.) 196

61. Soderberg-Goodman diagram. 226 62. Stress concentration nomograph. 234 63. Prototype completion and acceptance. (Based on E. L. G.

Robbins and Industrial Administration Ltd.) 254 64. Lock design simplification. (By courtesy of E. L. G. Robbins

and Industrial Administration Ltd.) 260 65. Pulley and fan cost reduction. (By courtesy of E. L. G. Robbins

and Industrial Administration Ltd.) 260 66. Oil pump improvements. (By courtesy of E. L. G. Robbins and

Industrial Administration Ltd.) 261 67. Manufacturing functions. (By courtesy of E. L. G. Robbins and

Industrial Administration Ltd.) 263 68. Launching of Product. (Based on E. L. G. Robbins and In-

dustrial Administration Ltd.) 264 69. Tooling and production costs. (Based on E. L. G. Robbins and

Industrial Administration Ltd.) 265 70. The effect of increasing size of batch on process time. (By

courtesy of K. J. Shone and Time & Motion Study.) 271 71. Variation of process time with reciprocal of batch size. (By

courtesy of K. J. Shone and Time & Motion Study.) 272

PREFACE

T H E prosperity of a commercial concern depends to a large extent on its ability to introduce new products, or at least revised designs of the same products as required. The success of these products, and thus the growth of the company, will depend mainly on their function, cost and appearance, in other words, their design com-petence. Too often in industry the progress of an idea for a new product to its ultimate production is haphazard and wasteful. To ensure successful operation in a competitive environment, a thorough investigation of the whole development process is essen-tial. Successful design as generally practised today is still a largely creative, intuitive process growing up around a central theme or an original idea and ranging in execution from the bare, func-tional solution to the purely artistic, depending on the type of product. In order to obtain maximum financial return, project evaluation is essential before and during development. Attempts have been made to rationalise this process, but the literature so far available does not cover the whole field, nor have many of the aspects of the problem been discussed in this context. Although reference to the bibliographies in each chapter might indicate how some aspects of design can be tackled, it is felt that a broader, more independent approach is required, rather than a synthesis of the various opinions expressed so far.

The book sets out to provide the uninitiated with details of engineering project development in any industry which produces or uses engineering plant of any kind. Management is frequently unaware of actual progress and is therefore unable to give the necessary guidance, or take vital decisions. Communications be-tween factories, or even departments involved, are often non-existent or tenuous, and the result is wasteful duplication or

XV

XVi P R E F A C E

inadequate performance. New materials, components and applica-tions are often not considered until too late in the design of the product, if at all. A system such as is envisaged in this book details the administrative procedure along which creative effort should be channelled. It enables management to evaluate and check development at all stages. It also explains the necessity for, and the use of the industrial designer. It is hoped that the book will go a long way towards preparing a syllabus for teaching engineering design by pointing out where the machine element analysis and synthesis, circuit calculations, design and drafting fit into the general industrial pattern. Too often the student leaves university without the faintest idea of how industry is organised or what part he will play in it. The student attending a technical college may be somewhat better off, though not always so far as the details of design and drawing-office procedure are concerned.

Because this book covers entirely new ground in places, it presents a number of new ideas in management and organisation. Many of these will prove provocative. In writing the book there were areas in which the authors themselves did not agree. As these were mainly matters of priority and presentation rather than matters of policy, Mr. Sharp has suggested that the final editing should be in the hands of Mr. Brichta.

ACKNOWLEDGEMENTS

P. J . Booker, A . M . i . E .D . ; J . E. Bowler, B.SC. (ECON.) , A.M.I.

MECH.E., R. M. Kay, B.SC. TECH.; M. Rowlands, F.S.I .A.; L. J .

Thiselton; G. V. Woodling, Attorney and Counsellor at Law.

The following companies gave encouragement as well as pro-viding tables, illustrations or plates.

A.E.I. (Manchester) Ltd. Council of Industrial Design. Department of Scientific and Industrial Research (Ministry of

Technology). International Computors and Tabulators Ltd. Industrial Administration Ltd. Northampton Public Library and Reference Library.. Brent Public Library.

The forbearance and patience of the authors ' families, whose homes were not the best evidence of the approach recommended in this book for setting out a project, is given due acknow-ledgement.

xvii

C H A P T E R 1

INTRODUCTION

1.1. Definitions and Scope

An industrial engineering product, as other goods and services, has primarily to satisfy a demand. In selecting the right product to develop, these facts should be considered; ideally the product should not only give satisfaction to the customer, but also perform directly or indirectly a useful function hitherto not adequately catered for. It will then have much better marketing prospects as well. When it has been decided at some stage that there is a market for it, a product still has to be designed and detailed before it can be produced. A contribution to the rationalisation of this activity will help, it is hoped, to persuade all concerned of its importance. Engineering project development work (divorced from specific products) may be described as a continuous en-deavour to implement a development programme. A design will then be seen as the master plan for providing a step towards the project realisation, of which the prototype is the end product. Factory and workshop organisation and management are not considered in this book mainly because this subject already has and possibly still is receiving attention in the books of various authors.

The functional division of work envisaged between develop-ment, project and design engineering does not exclude the possi-bility of combining one or more functions in one person; it is merely used as a device to facilitate the analysis of design and pro-cess phases. Further, it will be quite obvious to those who have had some experience in project development work and given the matter some thought, that in small firms with limited resources

1

2 FROM P R O J E C T T O P R O D U C T I O N

it is difficult to prepare thoroughly for the initial stages of project work. Also in a non-engineering or even small engineering firm which may lack balanced distribution of engineering talent, the management may have difficulty in appreciating the less obvious parts of the design effort or even the nature of project work as a whole. For example, there is very little to show for the first 10 days of a machine design project in actual drawing work, which may take eventually at least 6 weeks and sometimes much more to complete. Likewise, the electronic engineer may still be reading literature and seeking appropriate parts to assemble before making measurements and drawing up a completed circuit diagram.

Perhaps this book will clarify matters by showing how planning during the first few days can make the difference between an ill-considered and hurried attempt to produce drawings, which virtually amount to little more than a mutation, and the carefully considered inception of a well-thought-out scheme. One could say that what appears to be needed is just sufficient fundamental calculation and analysis at the outset to point the direction which the design work should take, and the economic gain to be ex-pected from it. Of course, as the project grows the process be-comes more exacting and time-consuming.

The main obstacle to presenting a balanced analysis of design and development, which would be applicable to the whole field of design, is the long and tedious process of becoming a designer. The difficulty is increased with the ever-widening variety of materials and manufacturing techniques. The second difficulty is relating experience and knowledge to form a hypothesis which would be generally valid over the whole range of mechanical engineering design and development.

It is frequently a characteristic of the design engineer, even at an early stage of his training, that he shows not only inventive-ness and originality of approach but he also demonstrates the tendency to look for fundamentals. Accordingly, instead of leaving matters to a natural evolution of the engineer's designing ability, this book seeks to enhance it by fully conscious effort and

INTRODUCTION 3

hence increase its effectiveness. It is hoped that the analysis provided will enable both the graduate engineer and the apprentice to become acquainted before going into the drawing office, with the factors involved in design, so that each can relate his sub-sequent practical experience to an acceptable pattern. Both the professional and graduate engineer can also use this information whilst they are training and especially once they are delegated specific design tasks.

Finally it is hoped that the design draughtsman will benefit as this book shows how he can set out his work and where and when he should seek specialist advice. The difficulties in producing a satisfactory guide to design and development work have been touched upon at the beginning of this chapter. Whilst hoping that the book will be of some value, it should not be used as a stick in the hands of management to beat out whatever creative talent there is by unimaginative application.

1.2. Engineering Training

Anyone approaching this subject for the first time has first of all to master the language of the designer and to learn how to draw, i.e. acquire knowledge of

1. Drawing symbols, methods of projection, sectioning and dimensioning, limits and fits, including geometric tolerances and surface finish.

2. The appreciation of characteristics of an engineering drawing as a graphical representation of an object but presented with the utmost economy of expression consistent with clarity.

It is highly desirable for the student to gain sound workshop experience before he enters university, and if the university does not provide adequate instruction in engineering drawing and design it is better that he gets this experience too. After that it is very much a question of guidance and information, such as this book sets out to give. Whether in fact it is at all desirable to produce engineers who have no previous workshop experience


and who are not well versed in engineering drawing and apprecia-tion of design is something which some universities in particular may do well to consider. The 'part time' Higher National Certifi-cate Mechanical Engineer, or a graduate who has spent alternate periods in industry and college, have at least some practical knowledge, but not as much as an architect has design exper-ience. The answer may lie in a much greater integration and organisation of training courses between potential employers, technical colleges and universities. Such an integration is taking place under the supervision of the Council of National Academic Awards in Britain and could be of particular relevance to tech-nological research for higher degrees.

1.3· The Chain of Command

Jt would prove rather difficult to conceive, even theoretically, an organisation which has direct relevance to every case in which engineering development is involved. Accordingly, two organisa-tional charts are shown; Fig. 1, a small to medium-sized engineer-ing firm, and Fig. 2, a large non-engineering organisation with adequate engineering facilities of its own. Most firms, no doubt, would fit somewhere in between, thus giving a hypothetical but necessary background for the process analysis detailed.

It can readily be appreciated that production should be con-trolled by production scheduling, whether it be by charts, day sheets or job cards with recorded time. In turn management will have the benefit of reports by cost accountants who make up charts of cost and income regarding the percentage of utilisation of plant. The same information, related to manpower, will indi-cate a trend in productivity. However, when considering the utilisation of personnel, it is perhaps not altogether out of place to voice the belief that, even when an organisation is modified to fit the personalities concerned, it is desirable to define their responsi-bilities and their authority with reference to the functions to be discharged within the whole structure of command. Let us begin with the premise that the maximum number of relationships,

INTRODUCTION 5

spread over a suitable interval of time, may well be twenty-eight direct group, twelve cross and five direct single relationships (Graicunas). As most direct single, and for that matter cross rela-tionships, in development are functional rather than 'line' (e.g. chief development engineer to chief designer or chief draughts-man) and would not as a rule go beyond the third supervisory level, an increase in the number of both these relationships is possible without entailing a correspondingly larger increase in the number of direct group relationships. Some of the direct group relationships (e.g. between chief engineer and drawing office personnel) cannot be avoided unless the responsibility for the D.O. as a whole is delegated, in which case such group relationships can be practised less frequently. It is important to remember that although the nature of the problems and the work involved in development changes continuously, the number of relationships should not be allowed to exceed the agreed maxi-mum.

'Staff' relationships resulting from the appointment of assistants may be excluded as they do not constitute a 'link', for assistants may be appointed to advise their superior if he lacks special knowledge or experience. This should be a temporary arrange-ment, and the position filled by someone who has been brought out of retirement or seconded from another department. More complicated still are liaison appointments. It is suggested that these also have no permanent place in any organisation as they create an additional link and even inhibit rather than assist com-munications. Instead, it should be accepted that the established and recognised chain could have 'links' with specially added liaison responsibilities and thus effectively prevent 'empire build-ing'. A supplementary direct communicating information link can be created with a person who may be functionally involved at a higher supervisory level. A b o , as and when required, a 'bridge' (Fayol) can be effected to someone on the same level in another department and possibly to someone below (e.g. chief develop-ment engineer to cost accountant), thus bringing the number of direct single relationships up to possibly eight at any one time.

MANAGING DIRECTOR General Manager

Chief Engineer

Design and Development Engineer

Product Drawing & Design

Works Manager

Secretary Accountant

Commercial Manager

Chief Draughtsman

Chief Inspector

Production Production Engineer Control

(Scheduling and Progress)

Works Superintendent

Buyer

Special Purpose M/C Des.

Tool Design

Operation Planning Estimating

Sales Superintendent

Tool Departmental Machine Light S he e t Room lnsp~ectors ProdTfction Engineering Meial

and Welding

Stores

KEY TO COMMAND AND COMMUNICATION CHAIN L I N K S Y M B O L N A T U R E D I R E C T I O N

Direct and

L ine

Policy

Directives

Decisions

Reports

Recommendations

Down Direct and

L ine

Policy

Directives

Decisions

Reports

Recommendations Up

A u x i l i a r y Supplementary or Br idge

Adv ice

In format ion

Suggest ions

Down A u x i l i a r y Supplementary or Br idge

Adv ice

In format ion

Suggest ions Up

FIG. I . The organisation of a small or medium engineering firm.

CHAIRMAN

LEGAL ADVISOR

MANAGING DIRECTOR

T R E A S U R E R and

SECRETARY 1 S

. 1 1 1

Engineering Manufacture A Manufacture Β Director Director Director (Plant ) ! L <

1 1 /

1 ? I l Technical Director ; Commercial Director Personnel

(Materials and Processes) 1 \ Director ν A. , ! j •\ Γ\ , Ι ι 1 "Γ 1 1 .

ν . ^ . . . > > !> J !

Chief Engineer Chief Buyer

or Managing Director Subsidiary

Engineering Works

Manager

Chief Inspector Buyer Engineering

General Manager Chief

Buyer General

Sundries t

Accountant I

1 Marketing Manager

Buyer Laboratory Mangr. Raw Materials (Product Quali ty)

Chief Chemist

Plant Engineering Eng ineer Superintendent

Building 1

[_ E lect r ica l Power Machine Maintenance

Machine Overhaul Plant Store

Engineering Superintendent

Building 2

Γ Engineering Product ion

Control

y * _ _ _

Production Engineer

Scheduling

Cost

Foreman (Sheet metal and Verd ing ) "

\

Foreman Tool ( M / C Production) S tock

Accounting

4- Progressing ^

Τ Charge C h a r g e Hand Hand

(Machining) (Assembly )

Departmental Inspectors

Room

[Compounding

Analys is

Chief Physicist

L

Chief Design Engineer

Chief Development Engineer

Φ

Physical Testing

ι ' 1 Materials Products

». - Quality Control ~*

I • . Γ

! Inspector Inspector

Production Ά ' Manager

1 , . Production Β

Manager

t

A.___

Engineering Laboratory

M e t a l . _ . T e s t i n g

Personnel Manager

j

[_ Sales (Home) Superintendent

[_ Sales (Export) Superintendent Publicity Officer

[_ Service Superintendent

A r e a 1

Employment 'Of f icer

I Safety *" Of f icer

.Securi ty Of f icer

L Welfare Of f icer

A r e a 2

Merchandise Superintendent

r. r-t Stock Foreman

Despatch Foreman

Transport Foreman

Work Study • Superintendent

Engineering Stores

Tool and Gauge Inspection

.Steels Castings-

•Engineering Sundries

Electrical Equipment

Production Contro l Superintendent

[_Operat ion pianning

[_ Sampling

Pilot production

Method Study

.Time and Motion

[ -Schedul ing

Cost Account ing

Progressing -

Superintendent F loor 1, or Building 1

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Superintendent Floor 2, or

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Planning Tool Chief Design Stress Design Draughtsman Engineer Engineer

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KEY TO COMMAND AND COMMUNICATION CHAIN L I N K S Y M B O L N A T U R E D I R E C T I O N

Direct and

L i n e

Policy

Directives

Decisions

Reports

R e c o m m e n d a t i o n

Down Direct and

L i n e

Policy

Directives

Decisions

Reports

R e c o m m e n d a t i o n Up

Auxi l ia ry Acivir Ρ

INTRODUCTION 7

The command structure will be used to issue policy directives and decisions downwards; and to feed reports, recommendations and suggestions upwards. The supplementary chain, being auxil-iary in character and less formal, would transmit information and advice downwards and technical specialised reports and technical queries upwards, whereas requests for assistance are likely to be approximately at the same level. To make this system workable it is presupposed that appointments are normally made and terminated on the concurrence of the immediate superior with the supervisor at a higher level, or at the other end of the supplementary link (see Figs. 1 and 2).

The suggestion scheme should be the only formal manner for transmitting ideas outside the established lines of communication (see Section 2.6, under Project origins).

1.4. Bibliography and Further Reading

ALFORD, J. P. and BANK, J. R.: Production Handbook, Ronald (1957). Anon. : The Practical Training of Professional Mechanical Engineers. Inst, of

Mech. Engrs., (1960). Anon.: Professional training in mechanical engineering practice, Chart.

Mech. Eng. (July 1965). Anon. '.Professional Training in Mechanical Engineering for Chartered Engineers.

A guide. Inst, of Mech. Engrs, July (1965). BISHOP, R. E . D. : On the teaching of design in universities, Proc. Inst. Mech.

Engrs. 1 7 7 , 27, 719 (1963). BURNS, T . and STALKER, G . M . : The Management of Innovation, Tavistock

Publication (1961). CENTRAL YOUTH EMPLOYMENT EXECUTIVE: Engineering. CONF. ORGANISING COMMITTEE: Conference on the Teaching of Engineering

Design. Inst, of Eng. Designers, London (1964). D.S.I.R.: Engineering Design, H . M . S . O . (1963); Draughtsman, H.M.S.O.,

Nov. 1954. EWEN M'EWEN: An interview with Prof. S . Timoshenko, Chart. Mech. Eng.

466 (Oct. 1963). HAYES, S . V . and TOBIAS, S . Α . : The project method of teaching creative

mechanical engineering, Proc. Inst. Mech. Engrs. 1 7 9 , 1 , 4 , 81 (1964-5). JENNINGS, A. E. P. : Towards better laboratory work, Chart. Mech. Eng. 549

(Nov. 1963). MALHERBE, M . C. DE and OGORKIEWICZ, R. M . : Design studies to aid the

teaching synthesis, Chart. Mech. Eng. 317 (June 1962). MALHERBE, M . C. DE and SOLOMON, P. J. Β . : Mechanical engineering design

tuition at universities, Proc. Inst. Mech. Engrs. 1 7 8 , 1, 28, 779 (1963-4).


PICKUP, F. and PARKER, Μ. Α.: Engineering Drawing, Hutchinson (1959). PULLMAN, W. A . : Teaching design to sandwich course students, Proc. Inst.

Mech. Engrs. 1 7 9 , I, 4, 100 (1964-5). STEED, R . W. : Education and training for corporate membership—a member

survey, Chart. Mech. Eng. 606 (Dec. 1963). STEVENSON, A . R . and RYAN, J. E.: Encouraging creative ability, Creative

Engineering II , A.S.M.E. (July 1944).

C H A P T E R 2

CONCEPTION OF DEVELOPMENT

2.1 . Economic Principles

PHILOSOPHY

The satisfaction of functional requirements and the appearance of the product are intimately connected with the financial return which stems from their realisation. These aims should form the basis of technological progress in industry subject to available resources and technical competence of the staff. For the purpose of convenience two aspects may be considered separately:

1. Special purpose components or appliances produced in quantity.

2. Machines or special systems, which may begin as special purpose plant but evolve later by demand or policy into a quantity product.

The main impact of development on these aspects will be economic as they have to provide profits, representing interest on the in-vested capital. Profits can only be achieved if the economic benefit of functional and aesthetic considerations are clearly understood and reliably assessed.

The profitability of the project, therefore, should determine whether work should proceed or whether it should be suspended until a better solution offers itself, either through a new design concept or through more effective and cheaper ready-made parts. On the other hand, the profitability consideration may become less important because of different and more ambitious process requirements which have arisen meanwhile. Hence a periodic

9

10 FROM PROJECT TO PRODUCTION

ACCOUNTING

Whilst economic principles and company policy provide the objectives, accounting is the tool used to check the financial commitments involved. Accounting can then be regarded as an activity concerned with recording the financial aspects including

revision of suspended projects is important and should not be left to chance. In consequence the project objective itself may undergo a modification or the degree of its priority in the de-velopment programme may be reclassified. Projects may equally well merge or split as and when the long-term economic interests of the company demand. The limitations of a project or the ob-stacles which prevent the objective being achieved should also be defined, and the possible conditions for reinstatement of the project stated and entered in the project reference card index. Thus a project should never be abandoned, but suspended and the paper work and prototype preserved in accordance with an es-tablished procedure.

COMPETITION

Whilst dealing with economics one cannot avoid a reminder that no firm can afford to neglect the influence of existing or future possible competition whether at home or abroad. [For implications see Fig. 3.] To a professional engineer this may smack of heresy as it is extraneous to the technical contribution he is making to the success of the product. But the engineer can afford even less to hide in an ivory tower than a scientist, because the firm's future and thus his own is at stake. The fallacies of national impregnability or repute for quality or technical brilliance are cases in point; because they do not last for ever, nobody can afford to rest on laurels, or feel that he has earned a respite without laying himself open to danger and a rude awakening. The dangers of remaining complacent can be found all around us.

CONCEPTION OF DEVELOPMENT 1 1

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80 -

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FIG. 3. Company performance chart. Business analysis chart for measuring past performance, evaluating present position and projecting

future growth.

and accepted, it is not usually changed. Various devices are operated to overcome this difficulty. The most frequently used method is standard costing. In this system the predetermined cost of material and labour is subject to periodic revision based on trade index fluctuations.

This chapter would be incomplete without touching on the influence exerted by a trained accountant on the enhancement or detriment of a company's progress and growth. It may not be desirable for him to be in a position in which he would be called upon to decide to what extent expenditure on development should

those of the development process. No firm can operate satis-factorily (though many seem to try) without a valid cost account-ing system. It will show where the money went and when and, in retrospect, where it should not have gone. It is on past history that most cost estimating is based, but even with a first-class cost accounting system it can be as long as 6 months before changes in cost become apparent and still longer before they can be introduced effectively into fresh estimates. The position is further aggravated by the fact that once a quotation has been submitted


be incurred. This should be based on the needs of the future from the point of anticipated technical progress and the state of the market. Only history will show how effective these assessments were. The tendency to look narrowly at recent expenditure and compare it with profits during the same period without consider-ing the average length of the development cycle can be particularly misleading. There is danger that an accountant may become the enemy of all long-term interests of the company due to an in-herently unimaginative approach.

An accountant, on the other hand, could greatly assist dévelop-p e n t by earmarking money for the development programme with budgets for individual groups of projects and by supplying.in-formation with which the current expenditure can be checked. Where special prototypes or systems are being developed within the quoted price, it would be justifiable for the accountant to undertake the costing of such a project. Failure to keep within the budget deprecates the engineer out of proportion to the sum overspent. It is very desirable for an engineer to bear all this in mind when considering the implications of expenditure control and accounting generally.

2.2. Development Policy

COMPANY POLICY

After critical evaluation of a firm's resources, the state of home and foreign markets, the chances of the product against the com-petition already existing and that to be expected, and the Govern-ment's fiscal and credit policies, the management should formulate a general policy in respect of all the firm's activities and the various managerial functions. Normally the assessment of funds available in excess of current operating needs is based on part profits, whereas allocation for product and plant development purposes should be made on the basis of desired future per-formance. A useful step is to form a product planning strategy by programming the growth which is the prerequisite of survival as Avell as that which will provide the means for overtaking or

CONCEPTION OF DEVELOPMENT 1 3

staying ahead of competition. Another step is a decision whether or when to make and sell one's own production machinery. When considering Fig. 3 it is important to realise that there is a time lag between profits and sales (see Fig. 4), preceded by the time a project requires to materialise as a product. It is in the broad, cumulative engineering experience and the outlook this brings, coupled with the flexibility of mind of its engineers, that the greatest asset of a firm lies. However, this is often nullified by the lack of organisation or the ignorance of non-engineering

1 T H E B A S I C

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FIG. 4. Company development policy.

management regarding development potential. There are, of course, exceptions where the chairman or president of a company actually enjoys watching his money being spent in such a good cause as improving the long-term prospects of the firm. It would be idle to pretend that the technical competence of the production and marketing staff is not equally as important as that of those engaged on design and development. 'Cross-posting' on a limited scale for short periods could be very helpful and could increase teamwork considerably; many a design engineer would benefit by trying to sell his wares. One can sense, if not describe, the atmosphere of helpfulness and efficiency as opposed to that


MANAGEMENT POLICY

The formulation of development policy will depend, of course, on broad decisions based on reports from executives coupled with their experience, but the following queries can be quoted which will be presented at the weekly executive meetings by the chief engineer, who is ultimately responsible for implementing the policy.

1. Is the allocation of funds adequate to see the policy through ? 2. Should the policy statement be submitted to the board of

directors and possibly approval sought at an annual general meeting?

3. Do articles of association in the U.K. or the corporate charter in the U.S.A. provide for new undertakings?

4. Is the company's organisation structure suitable ? 5. Will there be interference with existing product ion? 6. Is the spare capacity sufficiently adaptable ?

brought about by not-so-helpful attitudes. From this will follow in turn the particular approach to project development. This does not imply that a development policy cannot be a self-imposed one, proposed at a lower level and submitted for ap-proval. The existence, however, of such a policy will reflect the management's quality and progressiveness and could influence the issue of whether there is to be a development programme and how to administer it.

Although devising a system helps to facilitate development, it still leaves the channel for new ideas open, the screening and appraising to be done, the testing and evaluation to be allocated, the commercial possibilities largely unexplored, and the produc-tion unplanned. The importance of the senior executive and directors seeing and meeting customers at home and overseas cannot be overstressed ; the effect of such contact is not solely to create good will but also to provide a very rewarding source of ideas from outside.

CONCEPTION OF DEVELOPMENT 15

RESPONSIBILITY

The furtherance of the development policy in a non-engineering firm is usually entrusted to the chief engineer or head of technical services. Large non-engineering organisations which have sub-sidiaries with their own large engineering facilities usually benefit from a central advisory service and a co-ordinated programme. They may have a technical director for materials, manufacturing processes, and product research, as well as a director or head of engineering services who is responsible to the board for plant specification, installation, maintenance and development. A purely engineering organisation is likely to have a director who is head of engineering research. This is necessary because large firms are obliged to undertake their own research in basic engineering science. Sometimes the findings may be made public as par t of a research thesis or through papers read before learned societies and institutions, or only within the one group of companies. Apart from

7. Are marketing arrangements and personnel sufficiently flexible?

8. What additions and changes are required to achieve a more even distribution of engineering talent?

9. Which policy directives of the company require modifica-t ion?

The development policy should be formulated in simple terms and could be prefaced as follows: T h e development programme reflects the continuous effort to provide the company with the best possible means for the successful prosecution of its business, and to ensure its continuous growth. ' This statement could be printed at the top of each project folder to emphasise the under-lying significance of this activity. Naturally other points of detail will be brought out by the printed questions on the folder to-gether with any procedures which have been adopted for the execution of the programme and data relevant to the project itself.


this there may be need for a director of design and development who would co-ordinate the development work on product and plant throughout the whole group. In either case a senior executive would be advised by other executive directors before making his recommendations to the managing director on project develop-ment, administration procedure, and on the final allocation of priorities for the inception of new projects. He will also make suggestions about changes in priorities and allocation of funds based on periodic reviews of projects in existence. To elicit the necessary details he will be in direct contact with the chief en-gineers of the various subsidiaries from time to time. The decision whether or not to proceed with a project rests ultimately with the board of directors or more usually is delegated to the managing director or general manager, advised by the management com-mittee. Finally, it is always possible for the board to sanction the allocation of additional funds, personnel or equipment or to over-rule opposing opinion.

The development activities themselves can be broadly divided under two main headings, Engineering Products (Section 2.3) and Production Plant (Section 2.4).

2.3. Engineering Products

The following subdivisions of products could be detailed for further consideration based on their different economic functions in manufacture.

N E W PRODUCTS

Designing and developing a new product is a comparatively rare phenomenon which requires cultivation. Usually there is something preceding the new product either in the same field or somewhere else. Not only can it be said that there is nothing new, but that products have invariably features which were used somewhere before and, what is equally important, engineers and scientists are frequently working on parallel lines, quite unaware of each other's work.


Rarer still is a product inspired by a major technological break-through. In a case where there is little or no knowledge or experience to call on extraordinary caution is indicated, because considerable inroads may be made on available manpower and financial resources. On the other hand, a successful conclusion may bring a considerable reward. The objective here would be to ensure adequate return by embarking only on profitable ventures. This condition can be met when all product develop-ment projects are subject to a thorough survey, eventually sup-ported by a market analysis before the product is released for sale in quantity.

A new product may perform a new function, an added function or may embody cost reducing features. The advantages accruing from making provisions for orderly development of new products are numerous but the more obvious a re :

1. Ensuring continuous growth of the company. 2. Providing an insurance against recession or seasonal fluctua-

tions in demand. 3. Through diversification replacing lost turnover. 4. Better use of production capacity by subcontracting and

eventually discontinuing unprofitable lines.

The importance of industrial growth which is not generally appreciated lies in the fact that a company cannot stand still; but it must constantly produce new designs and refinements of the product or manufacturing process. The resulting growth is the only alternative to obsolescence. The onset of obsolescence may be imperceptible and the result may be hidden by otherwise efficient existing manufacturing methods. Even if a firm does manage to maintain its volume of sales, does it maintain its share of the marke t? Can it meet a possible and sudden exposure to foreign competit ion? A firm unable to provide for new products because of dearth of engineering talent or financial resources, or both, will not provide for new plant either and in consequence will eventually only provide for its extinction. Unpredictable and


unexpected circumstances in its markets or sources of supply will then merely seal its fate.

IMPROVEMENT OF PRODUCT

Product improvement should always be under consideration and schemes prepared and sifted, although no actual steps to in-corporate them should be taken until a number of them can be introduced at the same time, constituting an advancement all round. In this field one can reap the benefit of being always consciously a step ahead of competition with a balance of new products and a series of improvements to existing ones. Crash programmes are liable to be wasteful and more expensive. They also betray a weakness in management policy. As a rule, the de-velopments have to be originated before any undesirable market-ing trends develop and then introduced as soon as the production aspects can be organised.

PRODUCT SURVEY

The sales staff in most companies provide information regard-ing market prospects contained in sales reports. Although no extra expenditure is involved, how many design engineers know the market requirements before they start? The process by which conditions surrounding a product can be assessed is called a product survey. The survey (see Fig. 5) should provide the de-velopment engineer with the answers to the following:

1. What would be the important, novel or improving features? 2. Will patent or licence protection cover the development costs

and capital investment needed for the manufacture of the product?

3. The market potentialities, i.e. life, saturation, estimated rates, customer and geographic peculiarities, timing.

4. Price to secure equitable volume of sales. Estimated develop-ment and manufacturing costs and profits.


PRODUCT RESEARCH

World Industry

— Ι — British

Industry

— r ~ B.O.T. Grouping

of Industry

I

PRODUCT SURVEY

CONSIDERATIONS TAKEN INTO ACCOUNT

Processes Involved (Capacity Available and Required - Man-Hours)

Pressing Polishing Plating Machining Castings Plastic mouldings Bought-out parts

Product Fields

X Product Groups

—^— Individual Products within groups

Questionnaires for completion by engineers

I Γ " • ι

— Sales Organisation Required .(For comparison with existing sales organisation)

Existing sales force Sales force modified and slightly expanded Completely new sales organisation

Evaluation of Results

Presentation of Selected Products

to Client

"Tinai shorts list of

products for full market

k investigation and j economic

study

R-Channels Of Distribution J Direct to manufacturer ( Direct to industrial user

Direct to commercial user Through distributors Through retailers Direct to public

- — Development Work Required Laboratory and Drawing office Improvement or modification to existing products New inventions Production under foreign licence Development of foreign products

FIG. 5. Product survey.

5. Technological advancement. Has the threat of new materials and processes even in unrelated fields been assessed? What will be the effect on established product lines?

6. How long will it take for the competition to begin to feel the pinch and market a competitive product?

7. What is the most feasible method of distribution?


M A R K E7" r JVESTIGATICN

Market

U.K. Export

Volume (Units)

Volume ( i )

Trends

P R O D U C T 1 Competitors

U.K.

- Ε -τ ι

J Export

Product Range

Qual i ty

1 Price

Sales (£)

Finan Posit

cial ion

Selling

Requirements

1

Design Requirements

Time and Cost Est imat ion

I Design Development

Time and Cost

Volume Required and Production

Rates

Type of Sales Organisation

Type of Sales Promotion

and Advt.

Type of Service

Tooling Time and Cost

Total Production Costs

Selling Price

Cost of Service I

Distribution and

Selling Methods

Estimated Probable Share|

of Market

Total Turnover j and

Prof i tabi l i ty ι

Acceptance or Rejection of Product

FIG. 6. Marketing research.

MARKETING RESEARCH

(a) Object. The purpose of marketing research is to conduct a comprehensive study and analysis of the product and consumer relationship with respect to a single item or a whole range of products (see Fig. 6). Due to its high cost, to institute such a comprehensive survey would be a board decision.


l . T o discover what the consumer needs, so that his wishes may be more accurately and profitably anticipated by fitting the product more exactly to his known wishes and un-expressed needs.

2. To define the consumer's buying habits so that marketing tactics may be synchronised with them. The product should preferably be described in the same language and terminology as that used by the consumer.

3. To seek the consumer's vulnerable spots, so that he may more readily be converted to the use of specific brands of products.

4. To provide a statistical measure of: the potential market for a particular commodity; the share of the market that the manufacturer may be expected to secure to determine on a factual basis considerations of product development; the trend and prospects of home and export sales.

(b) Application. The information from the market survey is used by the chief development engineer to assist him in the product survey apertaining to the project in hand. However, whichever method is chosen as suitable for marketing research it is unfortunately true that the analysis is rarely carried out at carefully selected intervals. The decision has then to be taken also whether an on-the-spot enquiry by a senior executive is required to supplement the available information and how this should be done. This will depend on the desirability of :

1. The examination of consumer reactions to the product. 2. The establishment of market prospect details in relation to a

possible new product to be developed to meet needs not so far catered for.

3. The ascertainment of modifications necessary to a product already being sold, with specific reference to the possibility of introducing a new model of that product.

(c) Sources and methods. Of necessity, marketing research is a highly developed activity, the study being based concurrently or separately on the following:


1. Past performance. Available records and information from which the experience with, and results of, previous market studies or market information can be extracted. The information would concern the selling achievements in different markets, the spare parts and after-sale maintenance position.

2. Economic trends. Reports and statistics on general economic trends and trade figures at home and abroad can be presented in the form of a diagram (see Fig. 7). The information required can be extracted from government statistics in the respective countries, but these figures have to be supplemented from the figures pub-lished by trade departments and trade associations, e.g. Monthly Digest of Statistics by H.M.S.O., Board of Trade Journal.

3. Sales staff reports. These will be succinct observations, opinions, reports, made by sales representatives, agents, sales and service engineers.

4. A questionnaire to ascertain from the sales staff either the history of sales of existing products or their opinions on future sales of products could cover these points :

Description of outlets for various models of similar products. What are relative sales or their relative degree of popularity ? Which income group, sex, age, is the individual who buys the

product ? Where is it bought? Is the demand steady or seasonal? Are sales growing or shrinking? What is the effect of ad-

vertising? How do the profit margins compare with competing products ?

5. Field research. This is a more sophisticated approach, usually organised and carried out by outside specialists in association with advertising agencies, making use of consumer questionnaires and representative sampling techniques. The questions asked by post from selected customers, or by trained personnel in door to door or random street interviews, are likely to include these:

Is the type of product in use? Which make ?


FIG. 7. Market evaluation and kWh disposals.


Where, when, how often, at what price and what quantities of the product are purchased ?

What is it used for and when ? What other make has been used ? Why and when has the use been discontinued?

2.4. Production Plant

The development effort on production plant is as important as the provision of new products. Where the main activity of a company is not of an engineering character, new plant design, development and provision will form an important part of the essential engineering activities.

GENERAL AND SPECIAL PURPOSE PLANT

The aim is to increase manufacturing efficiency, as part of a drive for greater productivity. To establish the current position, preliminary work study assessment is required. Such a study should at least answer the following:

1. Is there a machine on the market which would better meet the case? If not, cannot a machine be modified?

2. Are there other steps which can be taken to enlarge the scope of proposed improvements to production ?

3. Could one production line be subcontracted or abandoned to help?

4. Will it be possible for the proposed production improve-ments to pay for themselves on the basis of the existing production programme ?

5. If not, how long will they take to implement and how will future trends affect the exploitation of improved manu-facturing facilities ?

6. Will the proposed development form a link in the general increase of production efficiency and provide spare manu-facturing capacity? If so," how is the surplus capacity to be used? Where the improvements create an advantage over


the competition in cost, should they be exploited fully by marketing new product lines or more intensive marketing of existing lines?

7. How important is it to increase manufacturing flexibility and provide for diversification of manufacture to overcome fluctuations in demand ?

TOOLING

Tooling means special additional equipment utilised only for a given product on existing plant such as jigs, fixtures, form tools and gauges. In fact, as will be seen, it is the next step in the direction of automation once machinery has ousted hand working. The aim is t o :

1. obviate marking the component prior to machining; 2. increase accuracy; 3. reduce time in setting u p ; 4. facilitate handling on the machine.

To fulfil these conditions a jig and tool designer will try to marry the component and the machine and in so doing may question the proposed sequence of operations or even the design of the component itself.

ECONOMIC FACTORS

1. Tooling or even minor plant modification may be needed to satisfy quality and precision requirements or to cut production costs. The expenditure involved must be absorbed by the current order or at the most within 12 months.

2. Tooling improvement costs for products in continuous de-mand must also be absorbed into the cost of the products. The price can be spread over several batches but not over a longer period than 12 months. This will not apply to completely new machines or to machines which have been practically rebuilt.

3. Replacement of unsatisfactory tooling or duplication of

26 FROM PROJECT ΓΟ P R O D U C T I O N

existing tooling to cope with greater production (where a higher degree of mechanisation is not justified due to limited sale prospects) should also be written off in 1 year.

4. The price of a prototype or a special purpose machine may be much higher than that of a standard model, so presenting a special problem. In instances where a period of years could be considered satisfactory for such plant to pay for itself, a budget control of project expenditure should be exercised and reviewed together with cost control of products, to achieve a more realistic provision for plant and tooling costs for the future. The choice of a particular number of years is arbitrary and in fact in highly competitive conditions an even longer period may prove ac-ceptable, particularly if the machine or plant is not worked to full capacity.

5. To invest in increased plant efficiency should be a sound proposition in its own right and any depreciation allowance regarded merely as a bonus. It must be borne in mind that the Government 's fiscal policy, in their allowances for depreciation, apply to industry in general and cannot bear any relation to the economics of a particular firm or process. They are also liable to arbitrary change.

2.5. Outline of Development Activity

EVOLUTION STAGES

There are in general machine development evolution stages, applicable in a complementary sense to production plant and its tooling; each stage representing a higher degree of mechanisation. Each step in presenting a design should thus constitute a further advance along the discernible path of evolution and it is a matter of skill and economics which one can be made next. The sur-mounting of each stage could be a useful guide to greater produc-tivity (this applies equally to machines or domestic appliances);

0 Handwork with elementary tools. 1 Hand tool ; hand driven but guided ; component held by

hand.


il Tool hand driven; component held in a jig. I'll Tool or component, one of them being machine driven,

the other being held by hand. IV Hand replaced by holding in jig on machine. V Pedal lever or push button to start and stop operation.

VI On completion of cycle, microswitch or timer stops the machine.

VII Hand loading of jig changed to magazine loading and automatic cycle control.

VIII Hopper loading for continuous automatically self-adjusting operation.

IX Transfer mechanisms connecting individual synchronised machines, each with automatic operation.

X Optimising central process control and self-adjustment to quantity, quality, size and shape.

CYCLE

Arbitrary figures have been quoted below as representative of the total gross time needed for individual development projects N o claim is being made as to their general validity. Nevertheless, the figures can be taken as normal performances by management, applicable to the machine and appliance fields. Electronics have a smaller production engineering (but greater scientific) content, hence the following figures can be reduced to 18 months with a corresponding increase in development cost. If they appear pessimistic they emphasise that nothing much can be achieved without perseverance, application and time. The actual per-formance can still be considered as a measure of the efficiency of design and development activity. It can be judged by the time taken during the particular phase of the development cycle of a prototype and also by the total time needed. It should be realised that some of the phases may be repeated several times before a quantity product prototype step is reached, hence the term 'development cycle'.

The respective phases a re :


1. Feasibility study (2 to 3 years). Market examination or work study and production development research to see whether there is a design that can enter the market, or assist the production process.

2. Engineering proposal (6 months to 1 year). Selection of the final design concept with sufficient detailed design to estimate development costs and hence justify its introduction.

3. Planning (6 months to 1 year). Estimated date of com-pletion. The provision of funds and facilities for development. This may also be the time needed before the required per-sonnel can be made available.

4. Development (1 to 4 years). Preparation of tests; five to twenty models of prototype for one final prototype.

5. Tooling (1 year). Tool design and tool making. 6. Pilot production batch (10 months) twenty-five off. The last

two steps usually overlap.

TIMING

The moment of inception of the project as well as rate of progress will be influenced by these factors:

1. Result of production survey and market survey, including profitability of the existing range of products and the change in percentage of the total size of the market.

2. Number, nature and cost of field complaints. 3. Rationalisation of production methods resulting from work

study and production requirements. 4. Major alterations or maintenance of plant including moves

to new factories and holidays.

DEVELOPMENT EXPENDITURE

The amount spent on research and development is decided by board policy and varies widely according to the type of industry. It is interesting to note, however, that there is a strong correlation between the percentage of the company's turnover spent on re-


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•Mach

• O e c •

Ins D #Els

0-3 0-40-5 l-O 2 3 4 5 10 20

Research expenditure as a percentage of net output 30 40 50

FIG. 8. Research expenditure and growth of industries.

search and development and its growth. This is especially true of a rapid growth industry, such as electronics, where the rate of growth in Britain and the United States is similar. The accompany-ing chart (Fig. 8) is of special interest. 'Net output ' of an industry is sometimes known as the 'value added ' ; it is the net sales value excluding the cost of materials.

The points for the U.S.A. and U.K. in Fig. 8 are made on a real value of comparison, i.e. the rate of exchange has been corrected to a research exchange rate of $6-3 to the pound, which takes into account the fact that research staff salaries in the States are about three times what they are in Britain, but that cost of materials is about the same. This shows that for metal products the expenditure may be around 1%, for electronics around 20%, and for aircraft around 4 0 % of net output. A com-parable figure for simpler electrical appliances would be about


5-6%. It is only in the field of aircraft that Britain is spending the same proportion as U.S.A., but this is principally due to govern-ment expenditure on defence projects in both countries. The survey is based on 350 large companies in each country. The tendency, with competition growing daily, is to increase the amount spent on development in order to remain competitive until presumably the price becomes prohibitively high. This is especially true of industries with a scientific content in which obsolescence occurs, owing to rapid advances in technology.

EXPENDITURE HYPOTHESIS

Assuming that the variation of development expenditure is not so much due to the type of industry as to the length of the de-velopment cycle, a curve can be obtained which would hold good for the development of any commercial engineering product. This is based on the belief that the length of the development cycle is imposed by the laboratory, drawing office and model shop work content of the project. Hence.,, for each product with adequate facilities in equipment and personnel, an optimum length of cycle can be obtained. This will in turn provide a maximum return on the funds earmarked for development. But if, in spite of ex-penditure, there is a deterioration in the resulting company's share of the market then clearly the adequacy of the provisions made are in doubt and all the factors influencing this position must be re-examined. The graph shown in Fig. 9 is to indicate a possible check of the performance of the development activity ρ = Cy\ The really efficient firm should do better than ρ = 10>>-°·

6, i.e. C < 10 and — n> 0-6. The actual curve applicable

will be also incidentally a measure of the potential growth. The graph probably does not cater for feasibility studies and develop-ment under contract of products with stringent requirements. The amount to be spent can be allocated into six roughly equal par ts :

1. The first part, to be spent simply by virtue of the firm being


5 2 -

6 J I I L I ! I I I : ! ^ 0 1 2 3 4 5 6 7 8 9 10 y

Average Tote: Number of Years Required for Project Development

FIG. 9. Law of expenditure.

2.6. Development Programme

RESPONSIBILITY

The engineer-in-chief, or director or head of technical services or operations, director of engineering or technical director, is usually responsible for the co-ordination of engineering product and plant development of an engineering firm or a group of engineering companies. In this capacity his duties are likely to comprise the following:

1. Approves and allocates development projects among the

in business, covers items which do not fit under any particular heading and which may appear to be only of prestige value.

2. Improving existing product. 3. Rationalising the manufacturing process. 4. Diversification within the range of manufactured products. 5. Feasibility studies and exploratory development. 6. Diversification into fields outside the present range of

products.


development programmes of the various engineering divisions under his control.

2. Receives notification of any amendments of board policy. 3. Supervises progress of the development programme by per-

sonal visits; receives progress reports and (after considering their contents) guides the development activity.

4. Keeps abreast of applicable engineering research being undertaken by research associations, regional colleges, poly-technics, colleges of advanced technology, universities, by his personal contact, and from material published in pro-fessional and commercial publications.

5. Takes note of information to which his attention has been drawn by those of his colleagues who are responsible for non-engineering matters, whenever there is anything which involves engineering design or which affects factory plant and services.

PROJECT ORIGINS

To assess the number and value of the contributions made towards the fulfilment of a development programme it may be useful to classify project origins:

1. Administrative. Work study, inspection, quality control, marketing, accounts, and via group engineering director. The detailed proposal will reach the chief engineer through normal channels. He may then re-route it to any other department for further information, or to work study to fill in more details before placing it on the development committee agenda.

2. Suggestion scheme. Every employee should be free to submit any suggestion inside or outside his allotted tasks, with separate rewards for the initiation and implementation after the successful conclusion of the project; the suggestion committee would consist of one representative from each executive division committee, an equal number of elected representatives of employees and an elected chairman. Awards would be made by the suggestion


committee on the findings of the appropriate divisional com-mittees in accordance with the management policy for incentives. Whatever their origin, suggestions should be coded by the per-sonnel department who could be entrusted with running such a suggestion scheme and could supply a secretary. The name and department of the innovator should be suppressed until the suggestion has been accepted for implementation. After coding with respect to their nature, suggestions could then be forwarded via the appropriate executive to work study for analysis. All those with engineering content are referred to the chief engineer for further action. Of those dealing with plant or product de-velopment, some can go before the development committee for allocation of priority straight away, others may require further interdepartmental processing. Other proposals are dealt with by the respective senior divisional executives and their committees.

INCENTIVES

The propagation, communication and harnessing of creative ideas can be greatly encouraged by a comprehensive system of acknowledgements and rewards. The rewards should be in ac-cordance with advance arrangements, realistic and separate from any profit-sharing. In consequence there should be no lack of communication upwards once a constructive attitude has been established. The first category provides rewards for ideas which have originated through the suggestion scheme and some of which will become projects. The amount of the reward could be graded inversely from 0 - 4 % to 2 0 % of the best annual attr ibutable earnings or savings over a period of 3 years. In addition, they can be assessed after 1 year of operation after the conclusion of a project. One such system in operation is graded as follows :

$25 For merit on a disclosure of a patentable invention. Applying to design and development personnel as well, it covers 5 0 % of received disclosures under an assign-ment agreement.


S50 At the time of commercially valuable patent applica-tion.

$5000 When the invention proves to be of substantial com-mercial value.

$5000 As at the end of an arrangement, when the inventor is leaving, if the invention continues to give a commercial advantage.

$200 On the best disclosures out of 50. $25 If not patentable but useful. If the idea is also com-

mercially valuable then salary increase is justified.

Assignment applies to company's products in development only. Next come rewards which should form an integral part of the

successful conclusion of a project. They would, however, be equal in value to those allocated for the inception of the project under the suggestion scheme procedure. They take the shape of cash, promotion or other incentives for rank below that of the project engineer. The project engineer will have the right to assume that his contribution to the common effort is reflected by a salary increase at the annual salary review.

Finally come rewards for ideas which aid the project under development. These are best dealt with administratively within, say, 5 % of the saving in development time on conclusion of the project, based on the recommendation of the project engineer. It would be in the project engineer's interest to foster an atmos-phere of co-operation to ensure that there is no shortage of con-structive criticism which could have an immediate and important impact in removing obstacles which might hinder the speedy con-clusion of a project. This would include all those suggestions which do not strictly qualify as being connected either with the inception or execution of the project.

COST OF PROJECT

1. The cost of improvement of a product or plant is closely connected with its feasibility. The estimated cost of a project or


selling price of a product should bear some relationship to the market price of a similar item. It must, however, be appreciated that a prototype cost can easily be three to five times that of the normal production model.

2. Any saving in manufacturing costs following the introduction of the completed plant must pay off the capital cost of plant development in 3 to 5 years. A longer period can only be accepted where it is known that the plant is versatile and has a very long life. A figure of 'well under ten years' is quoted for the textile industry. The rate of technical advance, however, is in fact underestimated if obsolescence, or partial obsolescence resulting in virtual rebuilding of plant, is forced on manufacturers by com-petition and not as a result of policy.

3. At its inception every project should indicate a substantial benefit when finally in use. Comparatively, the benefit must be at least marginally higher than for other projects already being undertaken within an approved budget. It would be safe to assume that this margin will tend to disappear once the project is embarked upon. The .position must be reviewed periodically and recommended to be held- in abeyance when adverse factors emerge. Thus by implication, for every new project accepted one must be completed or an old one must be shelved or transferred to another division, or more staff taken on.

2.7. Implementation

Useful methods of administrative procedure are discussed under this heading.

DEVELOPMENT COMMITTEE

The development committee should consist of the smallest number of people who represent adequately those concerned with the end product, to form the broadest yet most manageable basis for the implementation of the development programme (see Fig. 10). The development committee has to discharge the follow-ing functions:


Sales Market research

Consumer preference Competitor information

Suggestion scheme

Development

Engineer

Specification volume

Project Design, Design Engineering, Feasibility, Research, Project Engineering, Project Development, and Testing

Prototype Final product

Development

Committee

Facil i t ies Requirements

X Cash availability

Work study Manufacture

Economic tooling Labour

Floor space Plant

Estimate of expenditure

Finance Cost availability Cost and prices

Profit on Investment

FIG. 10. Development activity and functional relationships.

modified to ensure that good income-producing ideas are not overlooked whilst lesser ideas get attention. Whilst the develop-ment committee makes recommendations collectively, its de-liberations are frequently a valuable source of reference for the individual project folder. This is in practice achieved by the chief engineer directing, or the chief development engineer requesting, the secretary to take down a concise statement summing up the position on each topic. It may be that a work study is requested or a feasibility study suggested, because of a particular factor.

2. To progress projects under development. It is customary to

1. To make recommendations collectively on new projects and their priority. All technical development ideas should come through the existing chain of command or through a specific channel formulated for the suggestion scheme. In either case the report is prepared by the chief engineer with reference, when necessary, to the appropriate departmental heads; it is duly con-sidered by the committee and its objectives accepted, enlarged or


Project Proposal

Z3Z Development Committee

Initiation Meeting Represented by

Agree to proceed with any or all of the following

' Development Design Sales Production Finance

f

• t Finance | | Sales | 1 Design |

Project

Engineering

Project

Engineering

Expenditure Appropriation

Testing of Competitors

Models

t Development Committee

Reassessment and Specification Meeting

Decision to Proceed Wi th Design a n d .

Development. Agree Specification Production

Engineering |

H Workshops

FIG. 1 1 . Product development, initial phase. Feasibility study and specification.

review all work being undertaken at monthly meetings and offer constructive criticism (see Fig. 11). It is desirable for the project and design engineers to submit their reports to the chief develop-ment engineer and chief designer respectively a week in advance. This will enable the latter to isolate snags, difficulties and successes and to report accordingly. At the same time, the other participants wiH be able to consider the individual achievements in the light of current requirements and suggest a change in priorities, movement of personnel or equipment.


3. To consider projects which have been shelved, to see whether any occurrence warrants their reinstatement, or to recommend amalgamation with other projects. To recommend those which should be shelved among current projects because they no longer merit immediate action. Such minutes should refer to projects in the development programme under their code numbers and titles and would normally be kept by the chief engineer's sec-retary, signed by the chief engineer and copies distributed to obtain maximum circulation consistent with the company's security. The security being determined by the length of the de-velopment cycle and the value of information to the competition. The agenda with new projects would be circulated in advance and would automatically include existing projects.

PERSONNEL

The chief engineer is usually the person entrusted with im-plementing the development policy and is expected to assist in the execution of the development programme. He does this by :

1. Personal advice. 2. Allocation of manpower and funds. 3. Taking the chair of the development committee to settle the

priorities to be suggested to his superiors for revision. 4. Recommending revisions of the priority already allocated to

projects by his superiors. 5. Arbitrating on points of conflicting interest, if and when they

arise or are likely to arise in the discharge of the project commitments.

The chief development engineer would be the most intimately concerned, in view of his executive responsibility, in managing the development programme. The other members representing the various departmental functions involved are : the production engineer (for engineering manufacturing methods), plant engineer (for plant maintenance, repairs and overhauls), work study engineer (for operations and methods of production), design


engineer (engineering design), chief draughtsman (admini-stration of the drawing office), sales engineer (representing market-ing manager on problems of technical sales).

M E T H O D

Proposed projects are entered in the internal project register (see Fig. 12), irrespective of whether they are truly departmental in origin, i.e. initiated by a departmental report or that of an individual employee. The register is kept by the chief engineer, who is also concerned with preliminary project assessments and the provision of any other relevant opinion and data which he obtains as follows :

1. Brief method analysis by the work study department of existing production techniques affected by the proposal, in-cluding determination of the benefit accruing within a given time.

2. The assessment of created spare manufacturing capacity has to be related to the rate of growth of the overall capacity of the factory. This includes the possibility of diversification to make use of capacity and provide against the probability of machine failure.

3. Time and motion analysis indicating the points where a saving appears to be feasible, those factors that are likely to remain constant, and those likely to change during de-velopment.

4. Improvements in production methods for periodically re-curring items, sales figures and the estimated future sales are relevant and will be obtained from the marketing department.

5. Estimated length and cost of the project in labour and material with particulars on which the anticipated expenditure is based.

This information is returned to the chief engineer for compila-tion. The next meeting of the development committee then agree on the inclusion and suggested priority, if the project is to be added to the development programme.

Where originated : Serial No.

Date:

Classification and type of product: To be a special or standard product ?

Reasons for consideration:

When required Likely sales Target selling price

Expected competition: Machines to be superseded :

Other relevant factors:

Committee's decision and reasons :

Project number allocated

Any detailed comments on technical or sales aspects to be attached to this form as separate sheets.

FIG. 12. Project proposal form.

40 F

RO

M

PR

OJ

EC

T T

O

PR

OD

UC

TIO

N


All outstanding projects constituting the development pro-gramme are listed in priority sequence. This, together with the

1. Concurrence is obtained from the development co-ordinating director.

2. Agreed projects are now taken over by the chief development engineer and absorbed into the development programme, provided with folders and distributed by him among the available project engineers.

3. Project work which is suspended because of a change in circumstances leading to its inception, or which is not being progressed because of some economic factor, should be identified by the chief development engineer, with reasons for discontinuation, and listed in the programme. The reasons for the discontinuation will be given in the periodic reports to the chief engineer and possibly the director, when the project has a high priority, for further considerations.

4. Individual members of the development committee are re-sponsible for drawing attention to factors within their respective spheres affecting priority or economy of the various projects. In this way funds and manpower available for the development programme can be matched against the current order book or sales trend. Thus expansion, curtailment or change of priority can be effected early on.

5. The implementation of the programme should not be held up by lack of manpower, space or machines. If funds are available, outside assistance should be sought.

6. When curtailment of the programme is necessary as a result of change in management policy, then the effort where possible should be redirected by the chief engineer to in-dustrial research associations. The remaining resources should be concentrated on speeding up the most advanced projects, giving preference to projects which can materialise in the shortest space of time.

PROGRESS CONTROL


commencement date, is entered into the chief engineer's project index register. The development programme is kept in loose-leaf form by the chief development engineer and, as shown on the example Fig. 13, it contains the following information:

1. Reference number and year. 2. Name of project. 3. Direct expenses incurred by the end of the preceding year

for work done by other departments or subcontractors. 4. Material. 5. Time spent (man hours) by the end of the preceding year. 6. Project specification with changes and dates in sequence of

issue.

This information forms the background for all the deliberations of the Development Committee which acts as the information assess-ing and disseminating body.


FREEMAN, C : Research and development, a comparison between British and American industry, Economic Review, No. 20 (May 1962).

HABACH, G. and others: Procedure in developing new design. Session I, Proc. A.S.M.E. (1957).

HODGE, J. : The organisation of design and development in a medium sized engineering company with a wide range of products, Proc. Inst. Mech. Engrs. 1 8 0 , Pt. 3M (1965-6).

KARGER, D . W . : The New Product, Industrial Press (1960). MARVIN, P. R.: Planning product strategy, Machine Design (June 1957). PEARSON, D. : Application of modern management and organisational tech-

niques to engineering, Production Engineer 396 (Aug. 1965). RAPER, J. F . : Economic and technical problems associated with the develop-

ment and introduction of textile invention, Journal of Textile Inst, 5 1 6 , 4 6 / 4 8 (1955).

REDMAYNE, P. B. and WEEKS, H . : Market Research, Butterworths (1951). S mer nice predsedy statniho uradu pro vynalezy a normalisaci: Prague c. 164,

U.I. 85/57. WILLIAMS, L . A. and FINLAYSON, R. J.: Engineering market research, theory

and practice, Chart. Mech. Eng. (1963).

Date Issue. Serial No Project No Title

CODE TIME COST

1 Design Study & Layout

SECTION I 1 Detailing & Checking

3e$ign Office 1 Enquiries & Requisitioning for prototype(s)

1 Finalization & Part Numbers

1 Parts Lists

7 Precosting Cost

TOTALS

Number of prototypes to be manufactured—

EÇTION II 2 Prototype components—Development M/c Shop

rototype 4 Prototype components—Other H.B. Shops lanufacture rks Cost) 5 Holman Standard Parts & Components

6 Bought Out Materials & Components (at cost)

6 Patterns, dies, tools, etc. (at cost)

TOTALS

CTION III 3 Assembly & Fitting

sembly & Test 3 Development, Testing & Reporting (including fuel and other costed supplies)

3 Test Rigs & Equipment special to project

TOTALS

TOTAL ESTIMATED COST

ARKS

a) Prototype(s) will/will not be suitable for sale b) Patterns, dies, tools, etc. will/will not be suitable for Production c ) Anticipated completion date d) Estimated expenditure in current financial year •i) Estimated selling price (Ex Sales) 0 Estimated Sales volume per annum (Ex Sales)

FIG. 13. Budgeting form.

C H A P T E R 3

RATIONALISATION OF PROJECT WORK

3.1. Techniques

PHILOSOPHY

Apart from design, which has generally received some limited attention, there is virtually no literature on the organisation of project work. The magnitude of the problem can be gleaned from Fig. 14. One still comes across the opinion that, given a few engineers with a corresponding number of machine tools or laboratory facilities, ingredients are complete and management can expect great things, time being the only other factor. The fetish of providing freedom and opportunity for inspiration still persists in some quarters. That it occasionally produces results is not in itself a very good argument, particularly if the results could be obtained more cheaply and quickly. This state of affairs is being perpetuated, particularly in the U.S.A. where one reads of 'brain storming' which appears to be in practice, as a method of overcoming the lack of results and confusion caused by lack of system. There is yet another school which champions an embellish-ment by replacing the random nature of the former approach with statistical methods of evaluating the uneven field of develop-ment project factors thought of on the spur of the moment and then abandoned. This is not to say that the solution of problems by committees has no place in a well organised system. Conferences can be useful to further project development in the event of specific and urgent problems cropping up, such as a production bottle-neck or other major obstacles. The conferences are then best summoned on an ad hoc basis. These should not be looked upon as a regular feature or even as a substitute for departmental

F.P.T.P.—c 4 3

FIG. 14. Generalised model of an engineering project.

RESEARCr

. INVESTIGA

FEASIΒI LIT

S P E C I F I C A I

P R O J E C T ' D E V E L O P S

^DESIGN "REALISATIC

„ P R O J E C T ' C O N C L U S I C

RATIONALISATION OF PROJECT WORK 45

responsibility. A conference can produce ideas or suggest remed-ies, but these can only be administered from above as a normal management function. Each decision should remain the responsi-bility of the individuals concerned at the various levels of the project work, all along the line.

RECOMMENDED METHOD

The only satisfactory alternative to an absence of defined re-sponsibilities, which involves jockeying for an opportunity to take credit without responsibility for decisions, is for the development engineer to exert positive but indirect guidance of the project work by the co-ordination of the various tasks, based on the division of labour and responsibility analogous to the one exist-ing on the shop floor. It is not suggested that this should be carried to the same degree of functional specialisation as is now prevalent for quantity production. The team concerned with any one project or part thereof would consist of not more than one design engineer, with an unspecified number of draughtsmen made available from time to time by the drawing office, as well as a project engineer who may be assisted by a fitter mechanic and/or laboratory technician provided by the model or develop-ment shop or laboratory. There is, however, one important distinction to be made: whereas the project engineer will be able to request assistance direct from the shop foreman, or ask the development engineer to authorise amendments on the loading chart of the workshop, it will be up to the development engineer to secure for the project engineer appropriate design assistance. In this case, if there is no planned provision for additional draughts-men to work on the project, the request has to come from the chief engineer to the chief draughtsman via the chief designer; this is due to the fact that most of the work in the drawing office is of routine nature including minor design work under agreed priorities.

46 F R O M P R O J E C T T O P R O D U C T I O N

3.2. Project Inception

The realisation of the development programme is the develop-ment engineer's responsibility for which he is answerable to the chief engineer.

CHIEF DEVELOPMENT ENGINEER'S DUTIES

1. Overall decisions in accordance with the management policy directives as detailed by the chief engineer for the most effective execution of the development programme both in respect of projects and personnel. In other words, the development engineer should be able to match the two and, if necessary, change the projects round at opportune moments or stages; but only if through lack of response there is a danger of failure to complete the project. The step should never be taken in such a way as to cause loss of self-confidence by the project engineer or the engineering designer allocated to a task.

2. Positive and indirect guidance by asking questions or making suggestions, without actually committing his subordinates to a definite line within the scope of the project specification, in ad-vance. This means allowing them to arrive at their own con-clusions and merely harnessing their creative effort without the introduction of additional frustrations.

3. Administrative supervision of project engineers, development workshop (model shop) foreman (but not designers) and arbitra-tion between them on matters of engineering principles, develop-ment activities and methods. This will include the responsibility for planning and scheduling of project work and its correlation with monthly project progress reports from the project engineers.

4. Seeking the advice of the chief designer and chief draughts-man's co-operation on outstanding design tasks as they occur.

5. Keeping the chief engineer informed by monthly reports of the progress, or lack of it; pointing out when special outside assistance is desired; passing on such technical information as may be of use elsewhere to stimulate co-operation of the highest


degree with the subsidiaries and associated companies on all aspects of project work, i.e. work which is important for the future of the whole organisation.

FEASIBILITY STUDY

When the project cannot be fully determined, a separate in-vestigation may be called for, which would result in better project assessment. The investigation may consist of a search for pre-cedents in analogous circumstances. The modification of pre-ceding solutions which resemble more closely the given situation are then contemplated. The investigation may eventually consist of a prototype test which adequately demonstrates the feasibility of launching a project by testing its principal or most critical solution under the most adverse conditions likely to be en-countered.

The initial ideas for a bellows restraint unit shown diagramatic-ally in Fig. 15, sprang in the first instance from a study of pre-cedents and their l imitation^ A preliminary search for precedents resulted in the isolation of applicable alternatives 1 and 2, these in turn were superseded by preliminary specifications 3 and 4 respectively. Then it is reported that specification 5 was derived from another more distant precedent. It is said that this enabled the design task to be determined on the basis of the evolved idea 5 (b). During the preparation of preliminary drawings, the prototype design was abandoned in favour of 5 (c). The activity up till and including a full-scale test is considered to represent a feasibility study. The test results confirming the feasibility of the contemplated solution, formed the basis for revising the design further and building a successful production unit shown in Fig. 16.

The feasibility study does not in itself guarantee success, as new and unexpected development problems have the habit of cropping up as soon as the previous ones are overcome. If this happens within the project work, it could indicate inadequate specifica-tion of the project originally; the problems have nevertheless to

Flu. 15. Feasibility study. Duct restraint unit of a nuclear reactor.


be investigated, if only to establish more clearly their nature and consequently the prospects of the project. Whether a feasibility investigation forms an integral part of a project or one which would merely lead to a better project formulation is immaterial as far as the nature of the work is concerned. This preliminary stage may well be concluded by calling in outside assistance through the

FIG. 16. Final product. Frusto-conical restraint unit.

channels kept open by the engineering director. As the effort to achieve desired aims or to yield required information cannot be predicted with certainty, reference has to be made constantly at all levels to the aims and economics of a given problem in order to ensure a successful conclusion whilst maintaining flexibility of approach. Expenses should be budgeted for such contingencies


separately, or later charged as a phase in the development cycle where applicable. Project assessment costs are not otherwise recoverable, but are economically justified as they form an essential basis for any efforts to meet the challenge of the future.

Criteria. Below is a suggested list of benefits to be derived from project development.

1. Reducing cost of production. The reason for the introduc-tion of new processing plant will lie in the reduction of processing costs through its use. This may be achieved by functional im-provements which give increased output due to increased speed or capacity.

2. Reducing operating cost to user. By improvements to the accuracy of performance of machines, parts can be made to narrower tolerances with less scrap and lower labour costs. At the same time marginal improvements can be introduced to reduce maintenance, lengthen life of machine and increase accessibility.

3. By careful breakdown and reconstruction of parts or units to increase their versatility with the help of extensive standardisa-tion, components or groups of components can now be assembled in a variety of ways to constitute an increased range, user require-ments not being overlooked. Examples are modular construction or items which are sold as special purpose proprietary com-ponents (e.g. air valves, integrated and solid circuits, etc.). In-stead of marginal improvement a whole new range may thus be offered with marginal aspects such as lighter weight, better packaging, making for easier handling including transportation.

4. Improving aesthetic appeal. Convenience of the user and aesthetic appeal may predominate in the case of domestic ap-pliances.

5. Developing new technical characteristics. Nowadays an im-portant point will be comparative efficiency and limitations of performance due to the influence of consumer associations; an aspect which has been neglected for too long.


End product types

FIG. 17. Product profitability and variety reduction.

Variety of end products manufactured and sold (for a given sales income)

FIG. 18 . Manufacturing costs and variety reduction.

6. Discovering uses for by-product.

7. Reduction of product variety. Failing all this, a case should be made out as Figs. 17 and 18 show, for the reduction of variety of the products by subcontracting less profitable items and by


discontinuing marketing only those which do not affect the company's reputation for service.

8. introducing a new article. Only a thorough evaluation of existing practice (see Fig. 11) and the new advantages gained, would determine the suitability of the new product.

SOURCES OF INFORMATION

In order not to make a premature disclosure the senior develop-ment engineer should initially restrict himself t o : standards, technical and commercial publications, such as trade, technical and scientific journals, proceedings of professional institutions, with their respective design guides, codes of practice and data sheets. Some items are obtainable from technical libraries, abstracts services, manufacturers' catalogues and the national Press. In Britain there are two special state-aided services: The National Lending Library and 'Aslib', which is a technical enquiry service, which, for example, publishes an index of un-published translations. The obvious difficulty is not so much the number of sources to be explored, as the promptness of the atten-tion which an enquiry will receive at the sourceof information.

The buyer will be able to assist with obtaining trade guides from trade*organisations and sometimes quotations for a com-peting product. The chief engineer will be able to provide in-formation from his contacts with research associations and visits to trade exhibitions at home and abroad. Before launching a new development project it may be desirable to contact one's own government departments or ministries. As the project progresses, contact should be established by the marketing or sales office with chambers of commerce at home and overseas to supplement information on suppliers of alternative products and representa-tion abroad. One's own embassies, legations and consulates can be relied on to provide addresses of foreign trade group organisa-tions. Consumers ' associations and customers could also be of assistance. Customers generally are quite keen to avail them-selves of the opportunities which a new product has to offer and will co-operate enthusiastically in its evaluation.


INDUSTRIAL R E S E A R C H AND D E V E L O P M E N T Functional Relationships

Phases

Fundamental research - a search for new knowledge

Applied research - a search for knowledge relating to a specific problem

Development - application of knowledge to the design of new products and processes

Scientists' Engineers' Managements'

function function ^unction

Planning, organizing

and controlling for

optimum output

through effective

working relationships

Proportional responsibilities by phases

FIG. 19. Functional relationship of R. and D.

RESEARCH AND RESEARCH ASSOCIATIONS

Whenever possible research will be concentrated normally on specific and important problems with direct bearing on the tasks in hand. For problems of more general nature and interest, use can be made of universities on science matters. Colleges of tech-nology should prove useful on technological problems. Figure 19 deals with the relationship of science and engineering. Assistance and specific advice and information from national and industrial research associations could be of particular help, but technical competence is required if the information supplied by the various bodies is to be put to good use. Not only can engineering research associations be consulted, but non-engineering research associa-tions also employ engineering personnel to deal with engineering aspects within their field of main interest. It must be recognised, though, that short-range work is best carried out within each


firm. The major source in Britain of research information is through industrial research associations; about 60% of all manu-facturing industries in Britain are covered by these bodies, most of which are state-aided. The state aid is channelled through the Ministry of Technology, who incidentally can give information about all research associations even if not state-aided. O.E.E.C, technical enquiries are also dealt with by them. It is quicker, however, to go direct to the appropriate association if known. British firms with foreign associates or foreign firms can join most British industrial research associations and have the follow-ing rights:

1. To put technical questions and have them answered as fully as possible within the scope of the research association's activities.

2. To recommend specific subjects for research, and through the council of the particular association, to have a voice in the selection of the research programme.

3. Free or preferential use of any patent resulting from re-search.

4. To ask for specific research for their sole benefit at cost price, provided this can be undertaken without detriment to the general programme.

5. The communication in convenient form, of the results of research conducted by the association; the results not to be published except with the consent and approval of the association.

6. Regular services of an information bureau, by means of which they keep in touch with technical developments at home and abroad.

Most associations give a 'user' service as well as member service, though some (notably in the paint industry) specifically exclude a user service.

France, for example, is similar to Britain in having a central grant aid body, though this is not state-aided but maintained by an imposed levy on industry. Reciprocal arrangements are fairly

R A T I O N A L I S A T I O N OF PROJECT W O R K 55

new in this field, but Britain (through the Ministry of Technology) is associated with France (and the A.R.N.T.) . Most other coun-tries keep their research within their own trade association, though there are some notable exceptions, e.g. lithography and meat in the U.S.A. and shoes in Britain, where foreign members are welcomed. There exist also direct international contacts on research problems between interested associations. Apart from the industrial research associations in Britain, there are two levels of governmental research stations: the civil, of which the National Physical Laboratory—N.P.L. , is a typical example and information from which is published and available to anyone; and the armed forces, where a large amount of the work is secret and the publication is a matter for the establishment con-cerned. Both types, however, licence their patent to British and foreign firms without distinction, the licencing usually being car-ried out by a government-aided body set up specifically for this purpose—the National Research and Development Corporation —who will incidentally accept suitable patents from individuals, companies or university research teams for general exploitation.

3.3. Planning and Scheduling

These functions are undertaken by the development engineer and his staff who could not possibly hope to discharge their duties effectively otherwise. The particulars of the functions are :

J . Planning consists of stating tentatively each key project ac-tivity in the order in which the project engineer considers that they should be performed. To reach agreement a meeting with the chief designer or development engineer and others involved, such as the chief draughtsman, may be necessary.

2. Scheduling consists of putting the plan on a calender time table and, as in Fig. 20, is best carried out for main subassemblies of a prototype and then the departmental group activities within each. It is also best that scheduling of a project is carried out by the project engineer supervised by the development engineer to

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R A T I O N A L I S A T I O N OF P R O J E C T W O R K 57

ensure the overall priorities of the development programme. Where the activities of the development workshop are involved, the overall programme will be influenced by the shop loading sche-dule and the use of spare capacity for assistance with project tasks of a minor nature. The conflicting priorities may have to be resolved by the development engineer in the presence of the shop foreman and the project engineer. The project engineer has to bear in mind that allowance has to be made for items or processes from outside suppliers, and this information is supplied by the buyer.

SCHEDULING FACTORS

The factors which have to be considered when scheduling are :

1. The detailed requirements of the various individual project jobs.

2. Provision should be made for project development functions whether undertaken separately, or jointly, by the various depart-ments, including the availability and competence of the personnel.

3. Ready-made components. The importance of the avail-ability of proprietary components cannot be over-emphasised. They will determine the position and timing of the other key jobs. As buying is a non-engineering activity close liaison must exist between the project engineer and the buyer, the chief development engineer being free to contact suppliers and arrange details direct, sending the buyer only a copy of his letters. It will be desirable, however, that the placing of orders still remains with the buying department and for this purpose they must have an up-to-date copy of suppliers' price lists. Catalogues, on the other hand, are for the particular use of all engineering personnel and should be available in the drawing office library for reference purposes. It may even be of advantage if the buyer, although administratively belonging to the buying department, were to reside within the engineering division. This arrangement may be necessary where buying is generally of a non-engineering character.

4. Tests. It would be prudent if project job tests of the same degree of importance are planned within the same intervals, as a

58 FROM PROJr:CT TO P R O D U C T I O N

number of tests may govern the completion times of each project stage. Products of a highly technical nature can thus often be broken into separate sections for testing purposes. The different behaviour of an electrical bread-board hook-up and a final assembly is well known. This is also standard procedure for complete electronic equipment fitted into cabinets, from which sections can be removed and tested separately. This will not naturally guarantee that the interconnecting wiring is not at fault. The principle of checking by parts or stages must include the completed prototype.

CONDITIONS FOR OPTIMUM SCHEDULING

Scheduling normally aims at obtaining maximum workshop output by full machine loading. When scheduling the work of individual development projects, normal methods do not ensure their rapid completion or the priority of development work over normal manufacturing operations. But a critical analysis of a project schedule, which aims at ensuring the completion of the project in the shortest possible time with due regard to the neces-sary sequence of operations of a given individual project, may achieve this. Such an optimum schedule for project work can be undertaken by one of two similar analytical procedures: critical path method by diagram, or a network analysis by computor. The choice depends chiefly on whether an individual can readily com-prehend the number of interlocking operations or the size of the project involved, or whether the size of the task is such that the assistance of a computor is called for.

The next stage in optimum scheduling consists of making pro-vision graphically or by computor for harmonising individual jobs for the various projects in hand, whilst paying due regard to the bias expressed in the priority rating of each project. The con-flicting interests can thus be resolved in a way which will cause least interference with the schedules of individual projects. As with the older methods, optimum scheduling can be attended to week by week or day by day, varying in detail with the supervisory


level utilising it and with the nature and magnitude of the develop-ment programme governing it. The success of optimum scheduling depends entirely on the extent of its contribution to effective supervision of project work and to the general efficiency of the company's administration. The following paragraphs describe separately the characteristic features of each optimum method of scheduling.

C.P.M. (CRITICAL PATH METHOD)

The name of this method of project scheduling analysis derives from the use which this method makes of critical path. Hence, it is also known more recently as C.P.A., critical path analysis, or C.P.S., critical path scheduling. The method used in this system is basically to prepare graphically a network of planned opera-tions for a project. Each operation is divided into 'Event' (shown as a circle on the diagram) and 'Activity' (shown as an arrow), linking events in which each succeeding one is made possible by its predecessor or predecessors and the interceding activity. The length of the arrow is irrelevant, but its direction provides a necessary reference to the sequence of events. When all events have been interconnected the diagram is complete. The network on the diagram (Fig. 21) will show a number of paths that the work on the project takes. The path with the longest time content is known as the critical path. The path represents key operations, because if anything disrupts the time taken for any activity on this path it upsets the time for the whole project, whereas delays on other paths need not upset the project time unless the delay is longer than the time made available by the critical path events. The difference of time between critical and non-critical paths is called the 'Float ' as shown on the bar diagram of Fig. 21 . Con-struction of a C.P.M. diagram and bar chart does not require an engineer or a draughtsman. To consider the implications of the analysis does require an engineer. In its simplest form a mental analysis may be superseded by scheduling key jobs or a group of jobs directly in a bar chart. Nevertheless, a C.P.M. diagram is a


F

Bar chart March April Activity

I I 12 13 14 15 ! 18 119 20 21 22 25 26 27 28 29 I 2 3 4 5 8 Ref. Description

I I 12 13 14 15 ! 18 119 20 21 22 25 26 27 28 29 I 2 3 4 5 8

0 ~—~ 1

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1 — 3

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5 — 6

2 — 6

D

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2 — 4

3 — 4

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FIG. 21. C . P . M . diagram with bar graph. The critical path is indicated by the crossed arrows. Alternatively, thick lines can be used for the same purpose. The earliest and latest time can be added to each event number where only a small number of events is involved, thus dis-

pensing with the bar graph.

useful exercise even on simple projects as it ensures that events are not forgotten. The interdependence of activities is clearly shown as are the points at which concentration is required to keep the project on time. On the other hand, it shows where there is no need to concentrate resources, thereby possibly cutting out overtime on non-urgent tasks. In a project costing $50,000 to $100,000 and of 3 months ' or less duration with up to say 100 events, it is possible to assess the critical path by eye.


M.O.S.T.

Management operation system utilises the bar diagram of the C.P.M. but, unlike the bar diagram, which may, as an elaboration, indicate float times with a dotted bar as in Fig. 21, the M.O.S.T. bars in Fig. 22 are hollow at first and shaded in as the job pro-gresses. Vertical arrows connect the tail-end of each discontinued bar to the remaining path to show the relationship between them. Events appearing as flags divide the bars into segments represent-ing activities. The bars are drawn against a time scale counted backwards from the completion date to the last commencing date. It is then possible to add additional bar diagrams of other small projects which complete the total development activity. Such a procedure will enable the chief development engineer to survey the sensitive spots in the development programme and focus his attention upon a particular phase of each development project. Moreover, the chart in Fig. 22 may be further sup-plemented with data for manpower and cost allocation. By allowing for test results at the end of each phase, a realistic pro-gramme can be arrived at and maintained.

P.E.R.T. (PROGRAMME EVALUATION AND REVIEW

TECHNIQUE)

Critical paths can be plotted as part of a systematic analysis of an engineering project network under any system of optimum scheduling. The network diagram in Fig. 23 shows ladder ac-tivities as an innovation to C.P.M. diagrams. These progressively staggered activities are grouped to commence with a circular event and end in a square event. But once this situation becomes complex, a computor is invaluable to scan the whole network, particularly when changes in starting and completion dates call for periodic revision. The programming is relatively simple and the cost nominal (i.e. about is. 3d. per event). After the network has been processed on the computor, the resultant information can be printed out in several different ways as well as stored by

62 FROM PROJECT T O P R O D U C T I O N

Week

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M a n - d a y s

Labour

Mater ial

Overheads

Subcontr .

T o t a l cost

- R

A c t i v i t y code:

A - Detai l drgs.

Β - Procurement of mater ia l and b o u g h t - o u t parts

C - Shee t meta l shop

e tc .

L inks: •

Cr i t ica l Non cr i t ica l

FIG. 22. M.O.S.T. Management Operation System.

FKÌ. 2 3 . IM . R I . engineering network. ( i ) Description. The plan shows the interrelationship of all the activities

which hare to be undertaken in order to manufacture a special

purpose machine.

( i i ) Horizontal divisions. The network has been divided into horizontal

divisions to show the area of responsibility for each activity. Thus

each department can quickly determine its responsibilities and

dependencies on the project.

( i i i) Critical path. The critical path for this project is shown in thick lines

on the network.

( iv ) Ladder activity. Progressive or ladder activity is denoted by events

marked as squares.

(v ) Network errors. Certain errors in network logic can he detected and

printed out by the computar so that corrective action can be taken.


the computer and easily updated for each periodic revision to facilitate progress control. The computor will thus be fed, for example, with scheduled dates, holiday periods and provide in the form of printouts shown in Fig. 23, nos. :

(1) management report with summary of selected key events for development programme supervision, printout Fig. 23.1 ;

(2) list of critical activities constituting in effect a critical path for project supervision, printout Fig. 23.2;

(3) bar chart with float (slack time) for workshop loajding purposes, printout Fig. 23.3;

(4) list of all activities with respect to their relative importance to the completion of the project in time, printout Fig. 23.4;

DATE 1HAR66 ICT 1900 SERIES PERT ANALYSIS OF TSEP EN5INÌERINS PROJECT ST66 Z-.iO I J C ' i ii PAJC 1

Τ IME ANALYSIS EVENT REPORT SEQUENCED BY EARLIEST START

EVCNT TYPE DESCRIPTION 3 β PROJECT SO AHEAD

36 Y SUB CONTRACT UNITS AVAILABLE 50 / COVERS AVAILABLE 45 / 'OKMfcNCE FINAL ASSEMBLY 52 / MACHINE C 0 H P U

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FIG. 23.1. Time analysis I. Management summary report giving overall control information.

R.A.M.P.S. (RESOURCE ALLOCATION AND MULTI-PROJECT

SCHEDULING)

When resources are to be computed, the computor has to be fed with resource restrictions such as allowed overtime, allowed over-run in time, cost restrictions. When several projects are to be considered, their priority has to be decided on beforehand. As a result of this the computor may provide:

(1) (i) aggregation by earliest start date ; (ii) aggregation by latest start da te ;

(2) resource allocation as shown on printout Fig. 23.5;


FIG. 2 3 . 2 . Time analysis II. List of Critical Activities on the project. These must be started and finished on schedule if the completion dates

are to be kept.

3.4. Project Specification

The main instrument of guidance and control issued by the development engineer to the project engineer consists initially of a folder, with general data on the cover and a record sheet with dates at the rear for important information about the progress of the project. Inside the folder are two pockets, one for information, the other for notes connected with the execution of the project work. They will contain loose sheets which can be readily filed later into a loose-leaf folder.

GENERAL DATA

1. General policy statement. This can be reinforced with any general instruction thought to be important and applicable to the firm's activity.

(3) time limit resource allocation; (4) cost of individual activities ; (5) total and summary cost of various processes; (6) cumulative costs of different materials ; (7) cost of sections of a project; (8) statement of actual and estimated expenditure ; (9) statement of the value of accomplished work and actual

expenditure; printout (Fig. 23.6) shows both latter state-ments in the form of a graph.


2. The name of the project. 3. Development programme item number with year or years

of inclusion into the programme. 4. Authority and reason for the inception of the project. 5. Where originated and by whom. 6. Particular directives which define the aim of the project. 7. Priority classification. 8. Project engineer's name.

TIME ANALYSIS I : Τ 1VI Τ Y BAR CHART Si.

OtSCRtfTION

COMP STORAGE SUB ASSEMS

COMP SCAN SUB ASSEMS

ASSEMBLE S'OP'GE UNIT

FREPARE COVER ORGS

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COMP FEED SUB ASSEMS BO

ASSEMBLE SCANNER UNIT

COMP FEED SUB ASSEMS

ISSUE COVEP ORAUIHGS

CRQER PROTOTYPE COVERS

MAKE COVERS

A S S E O IE FEED UNIT

DELIVER COVERS

STAGE 1 FINAL ASSEMBLY

STAGE XI FINAL ASSEMBLY

STAGE 111 FINAL ASSEMBLY

FU'.C-.'CNAL TEST

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FIG. 23.3. Time analysis III. Bar chart printed out to suit given project management requirements.

Items 2 to 8 may be provided in the form of a copy of the new project proposal form from the internal project register (Fig. 12).

INFORMATION POCKET

1. Ideas towards solution of the project, such as a suggestion sheet.

2. Planning sheet with anticipated key operations and schedule.


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FIG. 23.4. Time analysis IV. All activities listed in order of the available float.

PROJECT EXECUTION POCKET

1. Project diary sheets with time expended in monthly totals by himself, drawing office and model shop and/or laboratory.

2. Job sketches and calculations. 3. Copies of intermediate and monthly progress reports. From

these it should be possible to trace reasons for modifications and the conclusion of each project stage.

4. List of drawing office design tasks, drawing numbers, draw-ing time and design folder reference dates.

5. Model shop tasks. 6. Copies of correspondence which do not belong to a particular

design folder but rather to the development of the project itself.

3. Technical details including standards to be met. 4. Work study and sales reports, product survey. 5. Feasibility study, including market research analysis i f this

is already available. 6. Details and prices of bought out items. 7. Additional information.


FIG. 2 3 . 5 . Resources analysis. Histogram printed out in tabular form showing the forward load in the assembly department, an integral factor in establishing the availability of resources at the right time from which

meaningful work schedules can be drawn up. Key: * = normal availability

Τ = threshold availability — = utilisation

3.5. Project Realisation

The person who is primarily concerned with the realisation of the project on a day to day basis is the project engineer. His position with regard to the model shop is equivalent to that of a design engineer to the drawing office. Neither have administrative responsibilities and the division is primarily functional so that the realisation of the project will be a joint affair. Whether during this

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12SEP46 I CT 1900 Si. RI I S * Ί AI Y S ! S 0Γ FKOJfCT FOR Τβί Ρ ' 'l'i IM' I Ρ I Ν i " . l Ό . :« * · C»TT. l^S-.P**

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[ expenditure? £3,200

E i tmia teo Ο»·.·· ' in. Tnif.j T w o and a H'alf W . .

;Ovcr -cfxpcndn*urc at 12th September; 1966 £800

; Va lu t p t f l c f t ;af 1'2rn;Sfcp\(rn)l30r-1966 Ϊ 2 . 4 0 0 '

16JAN

FIG. 2 3 . 6 . Cost analysis. The graph is one of the forms of presentation of financial progress to enable management to see at a glance current status

and future trends of project costs. Key: X = planned cost

A = actual expenditure E = revised estimated expenditure V = value of work completed


phase the chief designer will fill the role of a 'consultant ' or that of the senior partner to the chief development engineer will depend on the personalities involved and the type of project.

PROJECT ENGINEERING

The project engineer will be concerned with all the practical aspects of project realisation. He will be expected to make sketches, but not actually to draw on a board. He would refer all problems which require drawings to the designers in the drawing office. It will be up to the latter to decide whether to make a sketch themselves or whether something more elaborate is called for. Because it is the project engineer's main function to co-ordinate the various jobs which constitute a project, he sponsors the activities of all the contributing departments such as the buying and model shop. He keeps the designers in the drawing office, connected with the project, informed of progress. He fol-lows up all the work being done simultaneously for the various parts of different development phases, to form a well-integrated picture of the whole project.

1, Defining the job. To proceed with the work in an orderly manner all the facts have to be marshalled which fully define and classify the aim of the project. The first step will be to isolate problems presented by key jobs in the light of the project aims. The following questions may help: Is the end product to perform a new function? Is it clearly defined? Are all the ways in which the function has so far been performed listed? What are the other or additional reasons for the new product? Will it be cheaper? By how much? Is it to have a better performance? In what way—i.e. technical improvements, speed, operational economy, greater output or capacity, easier or less maintenance, smaller or lighter, easier transportation, longer life, greater con-venience by user? Is it to have a greater aesthetic appeal? What is known about the competition at home and abroad ? Is it necessary to redesign to get round a restrictive patent?

2. Establishing data. Have the following technical points been


made: outputs (normal, overload), degree of accuracy, efficiency, power factor, safety factor, and any other point to cover com-pletely function and performance? What are the working condi-tions; such as ambient temperature, humidity, atmospheric dust, chemical fumes, vibration? What is the influence of human fac-tors, such as those concerning operators, i.e. degree of skill, age of user? Have the safety regulations, including relevant Factory Acts and Board of Trade recommendations, been considered ? Is the patent position and the competitor 's coverage at home and abroad known ?

3. Analysing requirements. Attention has at this point to be concentrated on the key jobs and their scheduling. To do this successfully it is necessary to analyse all the known facts about the project and to establish the governing ideas in order of diminishing importance to the success of the key jobs under con-sideration, weighing carefully expressions of personal opinion against facts revealed in the supplied information. Have all the suitable personnel been approached to express their views and have the relevant views been added to the folder ? Have any of the topics connected with the project been discussed in the technical press ? Has one's own topic card index or notebook been searched ? Has the library of the professional institution been visited and have the journals of learned societies been searched ? Is it known that all foreign language journals now carry synopses of the principal articles in the world's principal tongues?

4. Classification of solutions. With the principal features of each problem connected with a particular job established, it is possible to select solutions which will offer maximum opportunity for solving contingent aspects and which will least endanger the final successful outcome within the scheduled time of the job or possibly the whole project. At the same time one should assess the probability of being wrong, the consequence of being wrong, the cost of finding out and the time available.

5. Decisions. At this point, initial decisions for the execution of the jobs by allocation of tasks can be made, in particular for those jobs which can be undertaken without delay. When pre-


REQUIREMENT

'Automatic Inserter

ι 1

1 Batch Counter Count Switch Mechanical Unit

BASIS FOR DESIGN

FIG. 2 4 . Slip inserter. Project history tree.

paring sketches of simple parts or modifications of existing parts to be utilised in the project, has provision been made for accessi-bility, ease of removal of adjoining par ts? Has availability of bought out components been adequately considered, orders placed and samples obtained in all the instances where their application can be fully determined? Finally, design specifica-tions can be prepared by the project engineer for the design engineers concerning those aspects of the work which require the


FIG. 2 5 . Slip inserter. Completed project.

use of existing assembly and detail drawings or the making of new ones, to be checked by the development engineer and approved by the chief engineer. Care must be exercised not to make design decisions which would impose restrictions on the design potential of the designer.


PROJECT HISTORY

When considering the reopening of a project, the launching of a similar scheme, or simply a modification of an objective, it is desirable that past endeavours can be easily traced to avoid repetition and to take full advantage of the experience gained so far. The history of a project for a slip inserter (Fig. 25) can be represented by its ' tree', showing principal changes in the essential characteristics of the project. Such a diagram as in Fig. 24 is drawn at each stage by the project engineer and completed before closing the file. The diagram should not only show the prototype, but also the principal common features with reasons for their adoption or abandonment. It could also reflect steps taken due to changes in project and design specifications.


BATTERSBY, Α.: Network Analysis for Planning and Scheduling, Macmillan (1964).

BERMAN, H.: The critical path method for project planning and control, • The Constructor (Sept. 1961).

D.S.I.R., Ministry of Technology: Technical Services to Industry, H.M.S.O. (1962). Engineering Design, H.M.S.O. (1963). Ergonomics for Industry, H.M.S.O. (1962-6). Research at Your Service, H.M.S.O. (1962).

IANNONE, A. L . : A network chart for smaller projects, Chart. Mech. Eng. (June 1967).

LAMBOURNE, S. : Resource allocation and multi-project systems. Critical path analysis, Proc. Instn. Mech. Engrs. (1963).

LOCKYER, K. G . : An Introduction to Critical Path Analysis, Pitman (1966). LOCKYER, K. G . : Critical Path Analysis, Problems and Solutions, Pitman

(1966). MODER, J. J. and PHILLIP, C. R.: Project Management with CPM and PERTt

Rheinhold Pubi. Corp. (1964). POPE, J. A. : Technological research, Proc. Instn. Mech. Engrs. 1 7 3 , 20, 547

(1959). TRIMBLE, E . G . : An introduction to network analysis. Critical path analysis,

Proc. Instn. Mech. Engrs. (1963).

C H A P T E R 4

ENGINEERING DESIGN

ENGINEERING design could be defined as the end product of a purposeful, comprehensive, creative but critical forethought of a technical image, developed with the aid of information for the construction at minimum cost, representing an optimum solution to meet the project requirements. Such a definition requires the qualification that the design must be not so much spontaneous, as planned for a result through the exhaustive search of facts pertinent to the task given.

4.1. Hypothesis of Good Design

By implication good design means a functionally and aesthetic-ally successful solution of design problems. An engineering pro-duct is thus better, the more reliably it performs its function, the easier it can be built, operated and maintained, the longer wearing are its parts.

DESIGN AND THE ENGINEER

The practice of design includes evolving a central idea to solve the problem which would represent in some respect a signifi-cant advance in the product 's evolution. Novelty and ingenuity are only incidental features of a creative insight employed in the search of good design. Design attributes sought are a fool-proof assembly with a minimum number of parts, which lend themselves to economic production. In the engineer a frame of mind is required that makes him desirous to find snags, formulate

7 4

E N G I N E E R I N G D E S I G N 75

the problems and solve them. Curiosity, perseverance and opti-mism are also needed. Professionally, the engineer is likely, in Britain, to belong to one of the senior engineering institutions I.Mech.E., I.E.E., I.Chem.E., or the institution of Engineering Designers. In the U .S .A . ' t he appropriate Institution is the A.S.M.E., S.A.E. or I.E.E.E., in Germany V.D.I. He is likely to read their journals and proceedings and a number of other tech-nical journals, which if not circulated within a company are available from the libraries of the appropriate institutions. To satisfy these conditions the development, design and project engineers require engineering knowledge and experience to ap-preciate the factors involved and to co-operate in consultation with specialists such as mathematicians, industrial art designers, technologists, or standard, inspection and patent engineers. The engineer is rarely a research scientist making new scientific discoveries, but more often a technologist making a tentative proposal and then using his knowledge of applied science and scientific methods and his engineering experience in design and production technology to resolve a technical problem. The theo-retical grounding needed is in fact taught at technical colleges and universities, though one sometimes wonders whether the student is actually told how far a particular discipline falls short of the goals towards which professional tasks may later direct him. To be more specific, the practising engineer often feels that much useful knowledge is left out of the syllabus because it cannot take the form of an examination question which would yield a numerical answer. In fact he may become acutely aware that information describing existing industrial practice, which he did not experience and which will otherwise take him years to get to know, is equally important to his progress.

The person in charge of all design paper work is the chief designer. Whereas he assists the project engineer to produce a prototype from his designs or has parts designed at a request from the chief development engineer, redesigns, modi-fications and the product actually being produced to drawings, are all his own responsibilities. The question of who is likely to


play the dominant part, the chief development engineer or the chief designer, will depend on work content, i.e. whether the project is manufacturing an engineering product for sale or rationalising its manufacturing process. Unlike the chief development engineer, the chief designer has to be free from administrative duties and detailed work. His main concern, apart from supervision of the design work being carried out in the office, is to ensure that the person who is allocated a task derived from a previous design concept is of adequate calibre. The designer should display sufficient sensitivity towards his predecessors' work and to the product, otherwise he could lose the very qualities which the original designer initiated. It is very important that the same designer or his immediate superior retains the overall responsi-bility throughout, to ensure that modifications to a product would facilitate greater rationalisation of machines and materials in its production. Moreover, this should still be the case when an industrial designer or other outside consultant is employed.

DESIGN TECHNIQUE

Designing is the manifestation of a mental capacity for sensory perception, imagination and intuitive insight as the creative part of a thought process. The basis of all successful design is a skill in experiencing and anticipating movement and restraint. The thought process could be represented more clearly by a physio-logical model of an ascending and expanding series of spiral links or steps, with both the analytical and creative components inter-locking to provide a continuation. The links could be labelled thus:

1. Questioning. This is a necessary part of familiarisation with the specification, objectives and problems. Even to query the specification itself is legitimate, as it makes for a better under-standing of what is really wanted.

2. Observation. Contemplation of the phenomena which charac-terise the problem usually means personal observation in the workshop, factory floor or site. This will provide a very useful

ENGINEERING DESIGN 77

background to the task. The handling of the existing equipment by the designer may help to drive some points home! The perception of the problem is not, of course, confined to sight, but to insight also.

3. Knowledge. This includes memory of diverse practical and sensory experiences and the power to recreate them.

4. Association. This step concerns all similar and dissimilar occurrences in the past. Likeness of the problem to one for which a standard answer exists, or to something which resembles a known technique or existing practice or an available design solution. Thus it may be possible to use an object or process for something other than its usual purpose, or to alter the circum-stances of its use.

5. Reflection. A period of germination by reviewing collected thoughts, possibly by the negative approach of establishing what are not the solutions sought. The only difference between reflec-tion and the analysis employed later by the designer is that this is not a fully conscious and critical mental process.

6. Imagination. The power to weave ideas into new conceptions while the designer is engaged in deliberate thinking. It is appropri-ate at this point to imagine what would be an acceptable solution by implication.

7. Inspiration. The result of an accidental stimulus which leads to the discovery, or rather realisation, of the only satisfactory solution which has presented itself so far.

8. Hypothesis. The incorporation of the implications of the solution put forward into requirements and limitations for the analysis of the subsequent associated problem or sub-problem.

9. Models, tests, experiments, calculations. All are tentative tests of the validity of the formed Hypothesis.

10. Design decision. Apart from forming the last link in the first loop, the decision will have determined to a considerable extent those which are to follow and for that reason recognition must be made of the decision taken.


4.2. Design Ability

Apart from a constructive attitude of mind, design ability depends on a synthesis of knowledge and the correct employment of engineering and drawing experience and creative capacity.

DESIGN PHENOMENOLOGY

Success or, more accurately, a measure of success will only be assured by establishing and keeping to the design task and the clearly defined design objectives. Whilst the designer should have a craving for originality and ingenuity he must be prepared to be only rarely rewarded by a break-through. In the majority of cases, the designer is obliged to fall back on his engineering and design experience. When considering a task he should select a path along which the criteria will naturally point to the solution of problems by analogy through a similarity or contrast to known phenomena. He should then find out by exhaustive search of references whether there is any likelihood of his being wrong in adopting a particular solution. He may be using existing machine components or a commonly used device, but he should still consider whether the circumstances differ in any way from their previous uses as described in a journal, textbook, or known to the designer from some other source. He should also bear in mind the consequences of his being wrong. This could mean allowing for a failure by arranging for a test at the earliest possible opportunity and before the design has advanced too far by be-coming too dependent on the correctness of the adopted solution. Whether a test or series of tests is instituted will depend on the importance and cost of finding out. Tests may also indicate by comparison where and how the performance of the design could be improved, or point a direction in which a solution is likely to be found. The designer may still, in the interest of efficiency or safety, decide on critical speed tests, heat runs (including a scaled-down evaluation model test), range of strength destruction test (in support of analytical design and stress calculations), or guesswork


where these are not practicable. All that can be offered to make this work easier, though hardly less tedious, is to suggest a technique to prevent a cardinal point being overlooked in the process of designing. The procedure recommended may in itself appear cumbersome at first glance, but should prove helpful in the long run. Tedium in design and development work is something which must be endured and not resented as beneath the dignity of one with higher technical education. Actually the resentment could be constructively channelled to create a climate of personal participation in producing a simpler and more advanced design. The same does not apply to frustration, which goes hand in hand with even good design, because unforeseen external factors inter-vene to prevent further advance. In this case the designer must restrict himself to a brief post-mortem to determine what went wrong and when; whether it was the specification at the outset, and why. He might have recalled Rudyard Kipling's serving men earlier: Ί keep six honest serving men, (they taught me all I know), Their names are What and Why and When, And How and Where and Who. ' He could also make suggestions to his superiors to improve the specifications or procedure. He could then add the cause to the list of factors which limited the effectiveness of the specification and its initial assessment for future use.

DESIGN BACKGROUND

Experience is gained as a result of detail drawing, drawing modification, tool design, graduating eventually to special purpose machine design work. It is a process which may take possibly 8 years, particularly if one includes workshop training. It is con-ceded that 5 years' apprenticeship is too long, but 3 years is approaching the minimum, although it could be argued that this could include 6 months in the drawing office for academically suitable personnel. There seems to be a little merit in completing the education of engineering graduates at the expense of training 2 to 3 years earlier than the non-graduate engineer. In this con-nection, incidentally, it should not be overlooked that even


electrical products may involve 7 0 % to 9 0 % mechanical en-gineering in design and manufacture. It can be readily understood that full-time workshop experience will not be popular with the graduate student. In spite of this, it would be preferable, in view of the present university curriculum, for such men not to spend their vacations in the drawing office and less frequently in the stress office. Prior to this, 2 or even 3 years spent getting workshop experience and attending suitably organised part-time classes at a local technical college would relieve the pressure of the theoretical subject matter later and reduce overcrowding at universities. It could also lead to an integrated continuous educational system, which appears to be a necessity with a rapidly developing tech-nology, in order that talent may be provided where it is needed. The universities do not appear to have provided us with the number of practicing engineers which was hoped for and the technical colleges in the past have only helped to fill the drawing offices throughout the country with those who were unsuccessful in their engineering education at some stage in their careers. Could not similar courses be followed by different streams of varying length, forming an integrated crosslinked system, with the longer ones still catering for the mature student on a part time basis, so as not to increase the demand on public funds, thus serving engineering design and manufacture better?

KNOWLEDGE

In spite of the advances in engineering science, lack of know-ledge about some of the most fundamental phenomena limits full exploitation. Is enough known about friction apart from a set of rules supplemented by a 'factor of ignorance' called the 'coefficient of friction' ? Is enough known about the mechanics of wear to predict it for any pair of mating surfaces? Can it be accepted that engineering science will of necessity be to some extent lagging behind the best known practice established by trial and error? Even exhaustive scientific tests have so far revealed only the validity of certain relationships and seldom the under-


lying causes. Having said this, knowledge of engineering science is important nevertheless, as it helps to avoid traversing the ground already explored sufficiently for engineering purposes. Also, science does provide a very useful, although sometimes inadequate, set of analytical methods and calculations. It is thus a useful guide to the limitations of our knowledge, leaving the rest of the field open to 'rule of thumb' , a justifiable cause of suspicion to the engineer-scientist and a source of disappointment to the design engineer.

It is not for the designer to seek explanation, he is too busy providing the goods, but it is hoped that a case has been made out for some legitimate doubt as to his training. There is now a school of thought which believes that the teaching of the method used for designing could be organised to develop imagination and judgement. This should then follow on after elementary engineer-ing drawing courses at school or local college as an integral part of all higher general engineering education, namely during one or two years of part-time attendance at advanced level at local technical colleges, followed by participation in complete design schemes at university.

Whilst design ability cannot be instilled or design taught easily and in detail because of the already crowded syllabus, the technique can and should be imparted in tutorials and the student examined on the actual preparatory work done after he has been able to select one of several design problems given. These problems could follow the usual analytical calculations of machine elements which, with the inclusion of kinematic syn-thesis and design methods, form a truly comprehensive theory of machines.

CREATIVE CAPACITY

The actual conception of relevant ideas can be traced to a momentarily heightened state of consciousness. This state is not entirely rational, containing emotional elements triggered off initially by intuitive or conscious opposition or criticism to a set


of circumstances such as an existing cumbersome arrangement. In most cases a solution will be the result of a considerable personal involvement by the expenditure of time and effort. Innate ability is less important than the cultivation and exercise of the creative urge. Creativity is followed by a period of dimin-ished sensitivity which is only incidental, but highly desirable in that it should be used as a period of consolidation. It thus provides an opportunity for the designer to use his critical faculties in turn. It is not unusual for a creative thinker to begin with a certain indifference to the task; progress to a rather sudden interest; leading to complete absorption as he proceeds with his work on it, becoming annoyed when stopped by a problem; resulting in weariness if he works too long on it; or exasperation when it finally defeats him; even delight when a solution presents itself, and intense activity as he develops new ideas.

Outwardly, even if restraint is exercised, the creative urge may demonstrate itself by discussion, even argument between the designer and his colleagues, giving way to periods when the de-signer allows an idea to crystallize and is then seen contemplating quietly the resulting di awing in front of him, assessing its merits. However, to make creative thought more effective, it is desirable to limit prolonged deliberate thinking to a thorough under-standing of the problem from all the points connected with the design task in hand. Then, when further progress is not possible or is not satisfactory, time may be allowed for reflection till next day whilst work is carried on in some other sphere. Taking a walk soon after breakfast, utilising a long commuting trip to the office, a warm bath or laying awake in bed in the morning, can provide the relaxed atmosphere needed to give the mind the chance to come up with a solution so impatiently and fruitlessly searched for previously.

INTUITION

Also a by-product of creative imagination but unlike inspira-tion, intuition is less definite. It plays a prominent part in assessing


results where exact information is not otherwise available, i.e. when data are unreliable or absent. This is particularly true in a new field of activity or in a sphere of technology not fully explored. Although deprecatingly referred to as ' the rule of thumb' , be-cause it is influenced by personal preference or bias with little analytical data to support it, it is a long favoured stand-by to fill the gaps in theoretical knowledge. It could be argued that in-tuition is an acute perception of underlying principles or an appreciation of a relationship between shape and movement, demonstrating itself when the appearance of some part is causing uneasiness or worry. Thus it may be a partially developed faculty for the subconscious awareness of natural laws. In this way in-tuition would help create an engineering design in concert with natural laws, as opposed to a limited and never quite adequate, logical, rational, and disciplined academic procedure. Fortunately inventiveness (another important characteristic attribute of the designer) does not depend on the creation of a successful method of analysis for its success. The powers of analysis, whether exact or intuitional, merely reduce the incidence of failure to a more tolerable degree. Thus the adoption of a solution in spite of lack of tangible proof in its favour is not to be mistaken for tangible proof to the contrary. What then is the use of intuition in such demanding circumstances as aircraft design? A keen anticipation of the direction in which worthwhile results are to be obtained in the shortest possible time.

4.3. Design Tasks

A necessary corollary to purposeful design activity is a clear understanding of the aim and objectives to be pursued.

A I M

It cannot be sufficiently emphasised that a good specification is half the battle. It follows that if the factors pertaining to the task are sufficiently clearly defined, the logical solutions tend to


present themselves as a natural consequence. Afterthoughts can only be useful if they are presented in a form that will be of assistance in the direction of the pursued objectives; otherwise they could lead to a change in the specification and cancellation of an existing scheme with an accompanying waste of time. The main impact of the specification will consist of drawing up or supplementing the technical objectives to be achieved in agree-ment with the aims of the design task. They fall into three cate-gories: principal objectives, inflexible in their aim and definition; minimum objectives, which by defining the minimum target, leave some freedom of action; and finally desirable objectives, whose satisfaction is left mostly to the designer's discretion. As the design task passes through the organisational chain, the ob-jectives should in theory become more clearly defined and should leave the designer in less doubt about what is wanted. Some of the minimum objectives could even become defined as secondary objectives, whilst some desirable objectives could equally well become achievable minimum objectives. It may be almost im-possible to resolve some of the opposing requirements in the specification and a note of where this has to be done by the designer should be included in his brief. To those points which properly form a project specification, the following have to be added subsequently, as more information becomes available, in order to form the appropriate technical image.

TECHNICAL OBJECTIVES

A design engineer or, for that matter, the industrial designer may be employed to supplement the development effort in some of the following directions :

1. Design a new machine or product from scratch. This is a very rare occurrence indeed. They may be more frequently employed in one or more of the remaining tasks.

2. Modify design to adapt the product to new or additional uses.


3. Utilise new materials for the construction of the product, making it cheaper and more convenient for production, assembly or for the user.

4. Make the design, size, or weight more advantageous. 5. Change or add functional or decorative refinements. 6. Introduce functional or structural simplification. 7. Provide for standardisation or restriction of the number of

production models, or variation in characteristic or quality. 8. Add service features such as accessibility or reduction in

wear or in maintenance. 9. Meet the need to secure balanced and stable loading at all

stations or stages of each production line. 10. Secure the benefit of utilisation of by-products. 11. Supply the need for rationalisation and harmony of pro-

duction plant and distribution channels. 12. Adapt for special climatic conditions, or make the product

more acceptable for new markets. 13. Introduce a new colour scheme or surface texture. 14. Ease packaging and meet^ handling requirements, i.e. by

making the quantity or units more convenient. 15. Ensure fuller utilisation by elaborating the directions for use.

DISTRIBUTION FACTORS

A list of possible factors which, although of secondary value, should influence design tasks by determining them more closely rather than limit unduly the designer's scope of work:

1. The necessity to meet as many needs of the customer as possible.

2. Changes in style, fashion or taste (cars, vacuum cleaners, food mixers, sewing machines, radio and TV sets).

3. Objections of distributors in connection with the provision of spares or maintenance schedules.

4. The influence of competition where the firm is not sufficiently ahead, safe in the knowledge that others have to catch up


first before the versatility or saleability of the product could be affected.

5. The demands for a complete line or range of products. 6. The degree of standardisation attained in the industries to

which the goods are supplied.

4.4. Documentation

This concerns particulars of a specific design task within the project. It lists the circumstances, such as environment, external forces, and the requirements of the Project Specifications (Section 3.4) which will fit the design into the fully defined pattern of the project development.

DESIGN SPECIFICATION FOLDER

The details of specification and all other information which accompanies a design until the work is completed is contained in a folder. Once the design has been finished, the contents can of course be filed more permanently. The folder used could be the same or similar to the project folder, but its contents refer to the particular design problem under consideration. One pocket could have all the information defining the problem and the other could contain notes, calculations, and sketches connected with its execution.

(a) Cover l . T a s k ref. number. Each design and its modification (as

distinct from drawing modifications) should form a separate folder or envelope, bearing a ref. number identifying it with the project, as well as its mark or model number; the object of this number is to avoid going over and over the same ground without in fact making a worthwhile contribution to further the project.

2. Design task title, name of designer. 3. Name of project, name of project engineer.


4. Design aim. A definition which is a clarification of the design task in accordance with the project objective. The character of the definition of the task or aim will depend on whether an attempt is being made to design an entirely new product, a new machine or a new mechanism.

In these cases the definition may be purposely vague, un-restricted by prior conceptions and personal bias. This will not, of course, prevent assistance with advice when the opportunity arises. If the redesign of an existing product, already in produc-tion is being undertaken, or if the design concerns one so far only produced by competitors, then all known factors limiting the scope of the design should be given, since they are available.

(b) Pocket: 1. Objective. The enumeration of primary and secondary ob-

jectives should be set out in a tentative sequence of import-ance. They should define the function or functions the design is to perform with respect to its performance and manu-facture. Another objective should state whether and possibly which existing parts are to be considered for use in the design. If a new function is to be performed a reference should be made to all the ways in which the work has been done in the past. Additional information could be provided inside the folder. It must be understood, however, that this does not absolve the designer from the responsibility of supplementing the information from all sources at his disposal.

2. Technological factors. Inside the folder should be various points dealing with technological requirements which need attention when the functional aspect of the machine or mechanism is to form part of a production process or in-stallation. The circumstances of its proposed employment with respect to the nature of the work and the operator. Time and motion requirements, work flow considerations, the useful life of the machine, its maintenance, servicing, in-cluding ease of removal of certain parts, safety and output


targets should all be stated, as should the required ease and flexibility to accommodate changes of position in the pro-duction line, together with dismantling, stowage and assembly requirements.

3. Cost. The maximum permissible cost of the designed item. Quantity required. Is it to be cheaper than an existing i tem?

4. Performance. Is it to be more effective by giving better per-formance? Which technical improvements are required and in what order?

5. Policy restrictions. Manufacturing restrictions stemming from the management policy for balanced loading of pro-duction plant, the availability of bought out parts and other internal and external facilities, e.g. casting, heat t reatment . Patent position, competitors' coverage, customer preferences. Surface finish and protection.

6. Special requirements. Quietness, appearance, weight, pack-aging.

7. Time. An important factor to facilitate scheduling design and prototype work, tooling and manufacture as planned.

8. Other considerations. These are mostly the by-product of the design specification and do not fit under any of the previous headings, e.g. standards, inspection, market or sales reports.

D A T A

Neglect to supplement data by personal investigation may render the whole process of producing a satisfactory design scheme inoperative. The need to analyse requirements from all angles of project engineering, manufacturing and sales cannot be overstressed.

1. In particular it is important to weigh carefully expressions of personal opinion against facts revealed by work study or market research.

2. There may be many cases when the customer does not in fact know clearly what his needs are and the designer must ultimately bear responsibility for the findings he has adopted.


3. No one can afford to reject summarily views which may throw light on points likely to make the product more acceptable. It does not mean that all the opinions can be or even should be reconciled, but rather that they merit careful consideration. Be-cause of this they should be recorded for reference purposes and filed.

4. Inside sources of opinion. It is not intended to suggest that a designer should spend his time canvassing all and sundry but rather that he does not fail to consider obtaining an opinion on some activity connected with his task. Thus he will have to sound out those who will possibly be connected with it at a later stage. Into this category come engineers at all levels, draughtsmen, sales staff, suggestion scheme proposals which may have a bearing on the task, production personnel and inspectors, production committee members, industrial design staff, work study, and technical research reports.

5. Outside sources. Technical sales, erection and service en-gineers, consultants and other sources indicated on p. 52.

CLASSIFICATION

The most useful guide in this respect is the Universal Decimal Classification (U.D.C.) . The classification depends on the an-alysis of idea content so that related groups of concepts are brought together. It is a universal classification including every field of knowledge as an integral pattern of correlated subjects. At the conceptual level it is supported by notational devices which permit the linking of simple main numbers or by auxiliaries denoting place, time, and similar recurring categories—forming combined or complex numbers. The decimal classification is con-structed on the principle of proceeding from the general to the more particular, each level being subdivided to the required degree. It divides the accumulated knowledge into nine main groups. Of these, Group 6 deals with Applied Science, the group 62 with Engineering and Sub-subgroup 621 with Mechanical and Electrical Engineering. See Table 1. The system was originally


derived from Dewey's Decimal Classification and is available as a standard B.S. 1000A: 1961 in Britain.*

In addition to Table 1 the following individual items merit a mention:

.001.1 Project. General plan or conception—project and design files.

.001.2 Conditions. Requirements, calculations—project and design files.

.001.3/.6 For project files only.

.002 Realisation—project files.

.003 Commercial and financial aspects—project and design files.

.004 Use. Operation—project and design files.

This classification is not entirely satisfactory and whilst any classification method is better than none at all, it is hoped that the British Standards Institution will be able to make a contribu-tion in the form of a suggested revision of U.D.C, to the Centra) Classification Committee of the Federation International de Documentation, viz.

.001.11 Project specification.

.001.12 Design specification.

.001.21 Performance calculation.

.001.22 Strength calculation.

It could be useful to know the following for the reference book shelf:

621—1 (075) Theory of machines. 621.7:744 Engineering drawing including B.S. 308 and in-

ternal D.O. standards. 621.753. Fits and limits for B.S. 1916 I & II and any

deviations from the primary and secondary selec-tion of fits. Also B.S. 969, B.S. 919.

* Dewey Decimal Classification, Edition 17, 1965, is the standard used in the U.S.A. Whilst the two standards remain recognisably the same, divergence is growing as there is only an informal contact between the American and the international body.

TABLE 1. U.D.C.—EXAMPLE OF SUBDIVISION OF MAIN TABLES

General 60 considerations

Inventions

61 Medicine

62 Engineering

sciences

General 620 questions

Materials testing, etc.

Agriculture Forestry

63 Stockbreeding Animal produce Hunting Fishing

64 Domestic economy

Commercial sciences

65 Communication Management Publicity

chemical 66 technology.

Metallurgy

Various 67 industries based

on processable materials

Various industries for

68 manufacturing complex objects

69 Building industry

621

Mechanical and Electrical engineering

622 Mining

623 Military engineering

Civil 624 engineering

(general)

625 Road and rail engineering

Hydraulic 626 Engineering

works.

Watercourses 627 Harbour and

Marine works

628 Public health engineering

629 Transport engineering

621.0 General questions

Steam 621.1 engineering

Boilers

Water power 621.22 Hydraulic

machines

Electrical 621.3 engineering

Internal combustion

621.4 engines and other special motors

621.5

621.6

Pneumatic machines Refrigeration technique

Fluid storage, distribution Fans. Pumps Pipes

621.7

Workshop practice Plastic forming, etc., processes

621.8

Machine parts Materials handling. Attachment

621.9 Machine tools and operations"

.01 Mechanical engineering principles

.03 Physical technology. Technical physics

.08 Prime movers. Spring and weight motors

.11 Steam engines (land engines) in general

.12 Ships' steam engines

.13 Steam locomotives

.14 Road locomotives. Steam tractors

.15 Semi-portable steam engines

.16 Stationary steam engines

.17 Working of steam plants. Condensation

.18 Boilers, tubes, etc.

.221 Waterwheels

.224 Hydraulic turbines

.225 Hydraulic pressure machinery, pumps, accumulators

.226 Hydraulic presses

.227 Hydraulic rams

.228 Other applications of hydraulic energy

.31 General electrical engineering

.32 Electric lamps

.33 Electric traction

.34 Electric drives other than traction

.35 Electrochemical industry

.36 Thermo-electricity and electric heat generation

.37 Technique of electric and electromagnetic waves, etc.

.38 Electronics. Discharge tubes

.39 Telecommunication. Radio. Television, etc.

.41 Hot air engines

.43 Internal combustion engines. Oil and gas engines

.44 Engines using vapour mixtures

.47 Solar and radiant energy machines

.51 Compression of air and gases. Compressors

.52 Rarefaction of air and gases. Air and vacuum pumps

.53 Conduction, distribution of compressed and rarefied air

.54 Application of compressed and rarefied air. Air pressure motors. Wind motors. Pneumatic tools

.56 Refrigeration technique. Refrigerants. Refrigerators

.57 Refrigerating machines

.58 Ice manufacture

.59 Apparatus for production of intense cold and for lique-faction and solidification of gases

.61 Blowers. Bellows. Simple ventilators

.63 Centrifugal ventilators. Fans. Exhausters

.64 Means of transporting fluids. Containers. Pipes

.65 Pumps with reciprocating pistons. Membrane pumps

.66 Pumps with rotary pistons

.67 Centrifugal pumps. Screw pumps. Turbine pumps

.68 Special pumps. Measuring pumps. Separator pumps

.69 Pulsometers. Injectors. Ejectors

.72 Pattern and press die making

.73 Forges. Heavy and light forgework. Smithery

.74 Foundries and foundry work. Moulding. Casting

.75 Tools and machinery manufacture

.76 Powder metallurgy, etc.

.77 Rolling, sheet metal working, drawing, etc.

.78 Heat treatment of metals

.79 Welding, finishing, packaging, etc.

.81 Elementary machine units, assemblies, etc.

.82 Shafting. Axles. Bearings. Journals. Couplings. Cranks. Eccentrics

.83 Toothed parts. Gearings. Cams. Racks. Ratchets. Friction wheels and discs

.85 Flexible transmissions. Driving belts. Chains. Ropes.

.86 Materials handling, other than cranes and lifts

.87 Cranes, lifts, etc.

.88 Mechanical attachment

.89 Lubrication. Lubricants

.91 Planing. Slotting. Milling and hobbing. Filing

.92 Polishing, grinding and crushing. Grinders. Crushers. Sieves. Sorters. Mixers

.93 Saws. Cutting machines

.94 Lathes and lathework. Turning

.95 Drilling machines and operations

.96 Punching, blanking, striking, splitting, cleaving, etc.

.97 Hammers and hammering. Presses

.99 Screw cutting. Manufacture of screws

Generalities 0 Bibliography

Libraries, etc.

Philosophy 1 Ethics

Psychology

2 Religion Theology

3 Social sciences Law

4 Philology Linguistics

5 Pure sciences

6

Applied sciences (Medicine. Technology)

Arts 7 Entertainment

Sport

8 Literature Belles lettres

Geography 9 History

Biography


858.57 Research, development and design, for standard internal procedure, periodicals, etc.

The classification should, however, be carried out by a respon-sible member of the library or the drawing office possibly as soon as any printed matter has been received. Relevant information is then listed on index cards by the first reader of technical literature coming into the company.

DISTRIBUTION

This is best done by the reference library but, in its absence, the most suitable person is the chief engineer's secretary, who could issue a library additions list. The person responsible would keep all printed matter for a short period on view, fill in reference index cards under authors and U . D . C . , then manage the distribu-tion of the printed matter departmentally, among the appointed readers and the subsequent circularisation to persons whose at-tention has been drawn to a particular topic. After this the litera-ture is shelved. Annual subject indexes of articles in journals, proceedings, etc., should then be kept on the reference shelf, whereas the journals themselves can be put away in stacks to be preserved for, say, 5 years. In the absence of a reference library, the drawing office is the most suitable department to perform this function.


ASIMOW, M.: Introduction to Design, Prentice-Hall Inc., Englewood Cliffs, N.J. ( 1 9 6 2 ) .

BALL, K . : The teaching of engineering design, Engineering Designer (Nov. 1961) .

BRICHTA, Α.: Engineering design analysis, Engineering Mat. and Design (May 1962) .

B . S . 1 0 0 0 A : 1961—Universal Decimal Classification, Introduction, section C, Principles, p. 6 .

CLAUSEN, H.: Engineering Research Development and Design, Inst, of Eng. Designers ( 1 9 6 5 ) .

CONWAY, H. G.: Design and designers, Chart. Mech. Eng. 2 8 6 (June 1963) .

92 FROM P R O J E C T TO P R O D U C T I O N

EASTON, W . H . : Creative thinking and how to develop it, Creative Engineering II, A.S.M.E. (1945).

HYKIN, D. H . W . : Teaching a systematic design procedure, Chart. Mech. Eng. 444 (Sept. 1964).

JONES, I. C : A method of systematic design, 1962 Conference on Design Methods, Pergamon Press (1963).

KETTERING, C. F . : How can we develop inventors?, Creative Engineering I, A.S.M.E. (1944).

LEYER, Α . : Design as a College Subject, Engineering Design Bottleneck Conference, Munich, 1964. The Inst, of Eng. Designers (1965).

NOBLETT, F . : The choice of a career—design engineering, Chart. Mech. Eng. 354 (June 1964).

O'DOHERTY, E. F . : Psychological aspects of the creative act, 1962 Conference on Design Methods, Pergamon Press (1963).

SIKORSKI, I. and PALUEV, Κ . K . : Inventiveness and intuition, Creative

Engineering I, A.S.M.E. (1944).

C H A P T E R 5

INDUSTRIAL DESIGN

5.1. The Industrial Designer

There is still a good deal of mistrust in Britain for the term 'industrial design'. Engineers seldom combine engineering ability with artistic sensitivity, and this is why there is a need for the industrial designer. The belief that all an industrial designer does is tidy up or 'streamline' the engineer's work is erroneous. The dividing line between the engineering designer and the industrial designer depends on their respective experience and knowledge, as well as the type of product involved. Ideally, the appearance of the final product should be an integral part of the conception, which should be-kept in mind throughout development, as it will be an important consideration in a buyers' market. Even if en-gineers were properly trained in aesthetics, and it is rare that they have any such training, the role of the industrial designer would remain important, as he brings a different and wider-ranging approach to that of the engineer. His experience from other, and often quite unrelated, fields can be a major advantage. He can query broadly the engineering design before making proposals to the design engineer to utilise materials and techniques which might not otherwise have been considered. In the case of an en-gineering product it is rare indeed that the industrial designer is unable to contribute in an important way to the project. Subtle improvements in shape, choice of colour or nameplates can con-tribute to a more acceptable product. An inspired handling of the functional requirements distinguishes industrial design from mere 'styling'. In Britain 'styling' carries an implication of applied art and is not generally used, but in the United States it is inclined to

93


be synonomous with industrial design, especially where appear-ance dictates the final form, as in the design of motor-cars.

TRAINING

Before considering how an industrial designer carries out his work, his training must be outlined. Primarily the industrial designer is an artist and he must, therefore, have some aesthetic sense and art training; it is this aspect which separates him from the engineer. However, the artist who becomes an industrial designer will have more than artistic sensibility. A good deal of this extra experience will depend on his training, which varies enormously from school to school, both in Britain and in the United States. Ideally, no industrial designer should be able to call himself such unless he has had at least a year's practical experience on machine tools, some drafting experience and a wide knowledge of manufacturing processes and techniques, together with some specialised knowledge. After some years working within industry, he will learn enough about engineering design to employ manu-facturing terminology and think in terms of production.

Until relatively recently, only architects have had the benefit of a combined education in art and engineering. It is for this reason that many of the industrial designers of the 1920s and 1930s came from this field and of course some still do. The specialised training today for industrial design depends largely on the historical back-ground of the teaching establishment. Among art schools which have industrial design departments, those specialising in painting as their traditional subject might well produce first-class de-signers for textiles or printed matter, but sculpture is more related in its application to the engineering industry because of its three-dimensional mode of expression. Those schools which were craft based and produced great artisan craftsmen in Europe are better placed. For example, the Central School of the London County Council has produced more recently some of the best industrial designers in Britain. Now, however, the Royal College of Art, with its new equipment and a separate faculty, is introducing in addition problems of engineering technology with applications of

INDUSTRIAL DESIGN 95

the results of modern science, such as the subject of human en-gineering, more succinctly known as ergonomics. It would be useless to pretend that training at a normal art school is adequate to deal with engineering products, because some knowledge of machine tools and of manufacturing techniques is essential.

Ideally, engineers should be their own designers in all aspects, as they were originally during the Industrial Revolution, but in the intervening period they have lost the art. Courses for engineers in the appreciation of industrial design are now organised in Britain by the Council of Industrial Design and are also included as a subject in the post-graduate courses of some universities, notably the Manchester Institute of Science & Technology. It would be desirable if the proximity of technical colleges and art schools was utilised in the training of engineers.

5.2. Environment

The requirement for good design, in all senses of that term, should stem from the top as a matter of management policy. Without encouragement towards modern design the policy often fails to have its impact and leads to frustration at all levels. With conviction about the importance of good design nothing would be purchased in the Company unless someone somewhere had asked himself : 'Is this the best looking product there is that the Com-pany can afford?' This applies whether it is an ash-tray for the board room table, a label for a product, the notepaper, or the product itself. In an environment such as this, a 'house style' or company image can be built up in which everything speaks, as it were, with one voice. World-wide examples of this policy are the companies Olivetti and I.B.M. In a small company, assistance for such a service can be given by a consultant or a small group of consultants, sometimes working closely with the firm's advertising agents. In a large company or group, the policy would stem from the director responsible for design. Even when the director controls his own industrial design department within the company, the use of consultants is not precluded, either for special products, or for


such matters as typography, trademarks, exhibition stands, or the interior design of offices and showrooms. The provision of new factories and offices may also be the responsibility of the director of design who would commission and brief the architects. In the United States one company has allowed its industrial designers to design their latest office block with the architects acting as con-sultants to them. Unfortunately, in Britain, architecture is rarely looked upon as an extension of the company's image. An en-vironment where engineers, architects, and industrial designers work in close harmony has yet to be achieved in Britain to the extent that it has elsewhere.

FACILITIES

When bringing an industrial designer into the company, it must be understood that he is to have freedom to go on business into any part of the factory, in the same way as drawing office and engineering staff. It is desirable that he should enjoy the full confidence of the works manager. In this way he will be fully in-formed before he starts work, regarding the type of machinery, equipment, and skills available. For example, he should know what are the capacities of available brake presses, standard bend-ing and punching tools, etc., in the same way as the engineers know this information. On the other hand, works managers have been frequently surprised at the knowledge and experience in-dustrial designers have been able to bring from other industries which often provides short cuts. It needs stressing that the in-dustrial designer's job is to make the product easier to manu-facture and not, as is commonly expressed, more difficult.

Where industrial designers have apparently failed in their task, this can usually be ascribed either to lack of support from the top, or failure to get into the project team at an early enough stage. It would be unjust in such cases to claim that the industrial designer has designed something that could not be made in the factory. It takes a long time to overcome prejudices set up through such failures.


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attention directly on a selected functional feature. It achieves this by promoting affinity between the various components making up the object, using the simplest methods available. It can also be brought about by promoting the reduction of manufacturing cost at an early design stage. Practical reasons such as installation or access or economy in the use of piping or wiring, such as copper busbar, may prompt the arrangement of distribution units on either side of an in-coming feeder (see Fig. 28.1). If circumstances dictate a supply input on the left with outgoing lines to the right, the alternative layout Fig. 28.2 is preferable.

2. Proportions. The proportional relationship is governed by the operational requirements and aesthetic influences which result in a particular spacing of sub-assemblies, or sub-division of panels. An example of the aesthetic influence is the 'Golden Rule ' derived from the proport ions of buildings built in ancient Greece. The shape of parts , on the other hand, is largely determined by functional considerations.

3. Repetition. This is clearly the result of standardisation in size


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In the case of control and indicator boards composed of units there is a tendency to group these units to form a balanced pattern. This may be justified if the most important board is in the centre and thus more visible and easier to reach (see Fig. 26.1). Otherwise it is best to consider a layout based on operational utility such as the correct sequence of operation, instrument logging (see Fig. 26.2) or on some practical reason such as minimum length of pipework or wiring (see Fig. 28).

In Fig. 27.1 two similar knobs are used for different purposes. The arrangement in Fig. 27.2 is preferable because each knob serves its purpose better.

(b) Unity. This is an overall impression produced as a result of the inter-relationship of major parts, in the manner in which they may be disposed with respect to each other. The overall im-pression can be created by:

1. Simplicity, which consists of modifying the geometry of the object to give an intensified aesthetic appeal by focusing the

can only accentuate it or mask it. Of these two the former is truer and thus preferable.

2. Symmetry. As it is associated with turning, milling and boring, this is the most common feature to be encountered in engineering products. Used mainly for reasons of production economy, it has the advantage of assisting in balancing machine parts in some instances. Symmetrical components do lend themselves to asymmetrical positioning within main elements of a uniform standard construction.


design register of the Council of Industrial Design. After discuss-ing the problem, the type of manufacturing facilities and the scope, the manufacturer will be provided with a short list. The final choice, if any, will be left to the manufacturer who pays a small fee to the council for its advice. The council will also show the applying manufacturer examples of the work that the designer has already carried out and the manufacturer can then interview the suggested designers without obligation. This is helpful, as the designer will have to work closely with many people in the firm and personality will therefore affect the choice.

5.3. Aesthetic Influences

Whilst the engineering designer tends to concern himself with the relationship of the product to its function and its manu-facture, the industrial designer concerns himself with the re-lationship between the product and the user. There are a number of basic considerations which the industrial designer, perhaps sub-consciously, would apply to any problem. The way to discuss aesthetic influence is to regard all identifiable features as the product of shape, texture and colour. It may be just as well to appreciate that, whilst shape is clearly a three-dimensional factor, the texture has only an element of depth, whereas colours can only give a certain impression. The problems, in which these three main features combine can be resolved into two parts, the overall appearance and the details.

AESTHETIC CRITERIA

The overall appearance will be affected by the following factors:

(a) Balance. The impression of balance will require considera-tion of the centre of gravity of parts or assemblies, whether real or implied. It is characterised by:

1. Stability. Clearly the functional position of the centre of gravity cannot be changed appreciably. Hence, appearance


PROFESSIONAL ORGANISATION

Industrial designers either work individually, in groups, or as part of a manufacturing concern in a special department. In countries other than the United States there are not yet large design organisations where up to 200 designers may pool their resources to give a comprehensive service from market research, via the complete product design with working drawings, to packaging and sal,es literature. There are a few smaller groups with their own model shops, but even individual consultant in-dustrial designers rarely work on their own, and they have assistants who can make models of a simple kind to show the appearance of a product and to provide some drawing office facilities. The larger groups of companies, especially those de-voted primarily to domestic appliances, will have their own in-ternal team of industrial designers, although this may not always be the most satisfactory procedure.

Whether an individual consultant is used, or a group of con-sultants, the method of work is similar. The outside consultant who may be an individual, a small group of two or three, or a larger group of around twenty, has a number of advantages, es-pecially for a small firm who cannot afford the overhead of a separate industrial design department. The consultant is likely to be retained at an annual fee by a wide variety of industries, but his contract would preclude him from working for competitors in the same field. He would probably be paid a separate fee for each major project, which gives him an incentive to produce his best. Royalties are a nuisance due to the frequent modifications of engineering products and the concomitant accounting. Sometimes, with smaller companies, the industrial designer himself may suggest this in order to encourage his client to be more forward-looking than he might otherwise be. Fees are laid down in general terms and information about them is available from the Society of Industrial Artists and Designers in Britain and by professional groups in other countries who form an international association. Selection of industrial designers in Britain is facilitated by the


of parts or sub-assemblies and is an acceptable feature, en-hancing the impression of unity.

(c) Interest. Giving prominence to parts or assemblies by a variation of pattern or other artistic element because of aesthetic or user considerations, will produce interest. It will be caused by:

{.Emphasis. Accentuation of a functional difference in the controls of a machine can be obtained by a change in spacing, by lifting or lowering the surface. Where colour is used, a complementary matching effect is sought.

2. Contrast. This is a characteristic which is most easily achieved by combinations of colours, or by illumination. It is used with effect for instruments, control knobs, trimming, or simply as a narrow strip to break up monotony.

3. Rhythm. This appears as the regular or proportional occur-rence of a feature, as an aesthetic element in the overal appearance.

COLOUR

The industrial designer is guided by a theory of colour which is devised from the natural placing of colours in the visual spectrum, ranging from blue, through green, yellow and orange to red. These may be shown arranged around a circle and subdivided into a number of segments. There have been many variations of circle diagrams (viz. the Munsell colour chart) ; the more recent ones are divided in equal steps of wavelength (20 m/x). They are constructed to show the interrelationship of individual colours, which can be obtained by mixing two of three primary colours (blue, yellow and red light together give white). The Munsell diagram can then be of assistance in explaining colour harmony and discord and the conception of complementary pairs of colours. Thus when adjoining colours follow in their natural (spectral) sequence (by wavelength), between any two primary

102 FROM P R O J E C T T O . P R O D U C T I O N

colours, they give harmony. When the sequence is ignored, discord occurs. Where the colour in the colour chart is far enough re-moved so as to adjoin the second primary colour in the opposite segment, it provides for emphasis and the two are called comple-mentary pairs. Contrast is produced by black and white or yellow, or any primary colour in combination with either. To use colours appropriately industrial designers are trained in the theory of colour, although they usually treat this subject intuitively. However, colours chosen can be then specified scientifically to alleviate problems of matching and repeating when colours must be used in widely divergent materials, such as stove enamelled paints or plastics. The C L E . system (Commission International d'Éclairage) gives values in terms of predominant wavelength, purity and luminence (x, y, ζ chromaticity co-ordinates), using a colour comparator, or in terms of wavelength and relative spectral energy distribution with a filter (25 filters) spectrograph. Whatever aid is employed, if any, a standard method of specifica-tion is preferable to relying solely on manufacturer's sample cards.

Colour has been placed alone in this list of aesthetic influences because it is a separate and important factor in the appearance of a product and because commitments may have been made in advance to conform to house style, tradition or fashion. White is traditional for hospitals, but ethnically a sign of mourning amongst the Chinese and regarded as unlucky by others. The same product can be supplied in several colour schemes to gain the widest possible market. Theories of colour harmony and contrast are sometimes fashionably disregarded, but in engineering products overall consideration may have to be given to convention or standard (red for stop buttons) as well as the environmental effect of colours. Yellow has the best visibility and suggests warning; orange attracts most attention and suggests warmth ; red has high visibility and suggests heat or danger; blue has low visibility and suggests coldness; and green is soothing in its effect. The total number of colours used by any one firm should be restricted owing to expense and in this respect B.S. 2660 gives a restricted but adequate and well-grouped range of colours.

I N D U S T R I A L D E S I G N 103

E V O L U T I O N O F A P P E A R A N C E

In the final assessment, the customer must like what he sees, he should be drawn to the product as much by its appearance as by its function, it should excite curiosity, distinguishing the product from its competitors' without distracting from its function or its ultimate environment. An example of the evolution of a product is shown in Plates 1 to 4.

PLATE 1. Magic lantern late nineteenth century.

Changes in design through a few years of the history of the slide projector are typical of a product where the pace is quickened by world-wide competition. There was very little change basically from the magic lantern (Plate 1) to the slide projector of the 1940s (Plate 2) other than in materials and finish: the lamp housing, lens assembly and base have been considered as separate entities and corners rounded off without much thought of the appearance of the whole. The demand for higher wattage lamps required the addition of a fan which added another ' lump' on to the assembly of parts mounted on the platform (Plate 3). To con-form to pressure die-casting in metal some thought was given to

F R O M P R O J E C T TO PRODUCTION

PLATE 2. Aldis Star slide projector.

PLATE 3. Aldis '303' slide projector.

104


PLATE 4. Aldis 'XT434' slide projector.

integrating the parts, but the handle and nameplates look like afterthoughts. Only a few years later the demand for feeding slides direct from magazines forces a new model (Plate 4), but this time the industrial designer has been allowed to integrate all the parts in a single casing and at the same time some fashion influences have been introduced, notably the patterned inset front panel and the 'modern ' nameplate. The factors involved are difficult to describe, hard to learn, subject to sudden change, and always contain an element of risk. No manufacturer can afford to ignore them, however. The attitude of 'We've always made them this way, and this is the first compla in t . . .' is fraught with perils. For each manufacturer who can claim to have re-sisted successfully demands for change without serious loss of sales for a number of years, there are many more who can show that forward-thinking industrial design pays off.


in spite of their importance, the aesthetic criteria should not be an end in themselves and should contain the following elements:

1. Traditional theme. This is the aspect or feature of a firm's product which can be repeated on each successive model to serve as a useful identification characteristic of the particular make. When presented in an aesthetically acceptable form, traditional theme goes some way towards inspiring confidence in the product . It also enables the customer to identify himself with something which may have an intrinsic appeal. A car radiator is an example. Traditional themes should not restrict completely the approach to a design task and the degree of emphasis to be used will call for inspired handling (e.g. the famous Rolls-Royce 'classical' radiator design still determines the frontal appearance of the motor car even though it is functionally no longer part of the cooling system). Traditional influences can be carried beyond their useful life. Owing to resistance to change, some of these influences may be insisted on too long and market research can be used to separate the valuable elements (a modern example of this technique at work is the change in cigarette packs after 40 years).

2. Styling. This involves evaluating the importance of influences in the trends of appearance by anticipating future desirable features. Although a restricting influence, styling helps to predict the trend of things to bring about a 'modern ' appearance in a product. The mere fact that the industrial designer is working over a wide field will ensure that he keeps up to date with fashion. He must read and travel widely, however, in order to observe and recognise general trends affecting products. Internationally the most important exhibition is the Trienalle in Milan. Various journals such as Domus (Italy), Industrial Design (U.S.A.), and Design (U.K.) should be standard reading matter for all designers. Shape and colour are the most common changes, e.g. refrigerators changed from bulbous to square, motor car lettering spread to other products, colour shades switched from strong to pastel, or to no colour at all (black, white and grey). Scientific advances are felt in totally unrelated fields (e.g. space travel affects vacuum


cleaners (with 'the Constellation') adds tail fins to cars or useless streamlining to fixed objects). These are usually transient charac-teristics as opposed to genuine trends which have to be separated. The industrial designer may, however, be called upon to intro-duce some of these gimmicks as market research may show that the public will not buy without them. Trends in shoes, for ex-ample, show a disregard for medical opinion to such an extent that some designs could be positively harmful. Nevertheless, fashion does not absolve the manufacturer from making the best possible compromise.

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3. Hpuse symbol. In the case of one company or independent division this symbol is the traditional feature, or one of its selected aspects, applicable to the whole group of companies and all its internally and externally projected activities, constituting only one. of the possible items of the company image, house style. The style is seldom defined but is usually the result of employing an in-dustrial designer (or an advertising agent in the case of a com-ponent manufacturer or material supplier), who is capable of exerting an influence on all the company's activities. Thus there will be a distinct but meaningful family resemblance between all the various products of a company, company notepaper, leaflets, advertising matter and packaging to ensure maximum impact on customers. The company nameplate and symbol should be mounted on the front of the product. In the case of an even number of units (shown in Fig. 29) where it is impractical to centralise, top right may for instance, be the correct location. For very long panels one at either end may be justified.


5.4. Related Activity

E R G O N O M I C C O N S I D E R A T I O N S

The difficulty of employing an ergonomie specialist lies in the fact that he may be trained in applied psychology but unable to read a drawing and thus cannot be brought in at an early stage. However, even an industrial designer trained to interpret draw-ings may find it necessary to investigate the problems involved in simulated working conditions and employing typical operators/ users with full-scale mock-ups, diagrams and charts and with particulars of a comprehensive motion study before presenting his findings. These findings will not be restricted to the operator but will include the requirements of maintenance and erection crews— an area not normally studied by engineers. If there is already a similar machine in use, a work study may be available already for reference purposes. Where not, it may be desirable that such a study is undertaken during the design stage and both the in-dustrial and engineering designers should avail themselves of the opportunity of discussing their design with the work study depart-ment. An example of the work involved is shown in Fig. 30 and on Plates 5, 6 and 7. Figure 30.1 is the usual symmetrical solution. Figure 30.2 is the functional equivalent and Fig. 30.3 includes the ergonomie consideration of grouping each indicator with the associated controls in the sequence of operation.

D E T A I L S

After the general shape has been evolved and the dispositions made for the major parts, the industrial designer pays attention to detail. In some instances this may be all that he can contribute, because of restrictions imposed on his freedom of action. Never-theless, however good the overall design may be, it can be spoilt by thoughtless detailing, even in such simple matters as the placing of a trademark. This will be equally true of supporting members of electronic components. Widely divergent engineering


PLATE 5. Old type overhead crane cabin. The driver must lean out to see the picking up or laying down of load.


PLATE 6. Modernised cabin. On the recommendation of ergonomics specialists, the view, degree of control and operator comfort has been

improved.

products are steadily becoming more alike in appearance due to common methods of manufacture (e.g. refiigerators, cookers and domestic boilers on the one hand, or electric radiators and loudspeakers on the other). This places a special responsibility on the designer to make his product identifiably different from other types of product, as well as being different from products of com-petitors. In order to cope with this aspect, detailing is of vital importance ; the shape, lettering and placing of a trademark, the type of handle, the treatment of joints, hinges, etc., can make all the difference between a successful or unsuccessful product. In this instance it is far more often the sum of the parts which makes for a distinct design.

{.Layout of panels. The size and shape of knobs, levers, switches, etc., are matters of considerable importance; where

I N D U S T R I A L D E S I G N 1 1 1

PLATE 7. Modern version currently being supplied. Visibility and appearance further improved. Remote-control switches replace ugly

cast-iron isolator and fuse boxes.


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there is a logical sequence of operation, controls should be so grouped and aligned that they follow each other. The use of clearly divided areas for groups of control elements, indicating instruments and lights is important and a change of texture or colour can be used. The practice of laying out controls in sym-metrical straight lines is to be abhorred (e.g. consider the difficulty of finding the right switch on a motor car dashboard, if all are the same size, shape and height as each other). Indicators should not only be clearly related to the controls they concern, but should be arranged so that the indications change in an expected way (i.e. if a control is rotated clockwise, the meter reading and the func-tional vector associated with it should rise; if a control lever is moved, the controlled element should follow by moving in the same manner). Inconsistencies in tradition may have to be over-

I N D U S T R I A L D E S I G N 1 13

come (e.g. hydraulic engineers turn off the flow by rotating the valve clockwise, electronic engineers anti-clockwise).

The push-buttons, lamps and variable control, as in Fig. 31.1, require close inspection, the labels are hard to remember and lead to mistakes. In Fig. 31.2 the first lamp indicates that power is on to unit No . 3. The first button is then pressed and three lamps light up successively after time delays. The second button is then operated to switch on H.T. which is then adjusted by rheostat with reference to the instrument above. Next is the button to

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switch off H.T. before the filaments, which are switched off by the last button. The third version is merely more consistent, see Fig. 31.3.

2. Typography. This covers specifications and disposition of numbering and lettering of controls, meters, scales, etc. This is specialised work which the engineer cannot normally be expected to know. Engineers are usually only familiar with standard B.S. 308 engraved or stencilled letters, but these can well be un-sightly, lend incorrect emphasis and are sterotyped. The industrial designer is familiar with the many methods of reproduction (e.g. hot press, silk screen printed, anodised, engraved, cast, applied letters, transfers, etc.) and is usually trained in typography, or


would have an associate with this skill as well as an ergonomie approach.

3. Bought-out components. The final choice of these items which are visible (such as hinges, clips, locks, screw-heads, fastenings, etc.) is important, as these details can spoil an otherwise excellent design. The industrial designer will know his sources of supply and, in some cases, may persuade the supplier to allow him to design additions to his range. It is imperative that certain aspects of a part should nevertheless remain standard to facilitate later replacement through wear or accident when the part has gone out of stock at a later date.

5.5. Method of Work

There is no doubt that the industrial designer belongs within the design team. It is desirable that he should attend the original development committee meetings, so that he is aware of trends of thought in the company management—he needs to know the company's marketing policy for the product at home and over-seas just as much as the project leader and development engineer. Market research reports should bè made freely available to him and he in his turn should provide his own consumer research facilities. The consultant may have to call in specialist services on his own account, but this is his own concern. For example, he may need the services of specialists in model making, or of the ergonomist who can advise on human factors in the use of com-plex machinery; in the consumer industries of the United States, colour consultants are used, but this is an aspect which the ex-perienced industrial designer will frequently be able to carry out himself.

Depending on the complexity of the product and its past history (i.e. whether it is like anything the company has done before), the industrial designer, after due consultation with members of the design team, will start work on the ultimate shape of the product. Before making models or sketches, he will study and amplify the terms of his brief. Some consumer research may be


necessary. Scandinavian countries have a prejudice against over-ornamentation, whereas some Middle East countries prefer it— these generalisations are important and, furthermore, are chang-ing. He will also consider at this stage similar products, or products which are complementary but made by other companies both at home and overseas. It is the responsibility of the marketing manager to provide the industrial designer with catalogues of competing products and comments on the features which help to sell, or militate against sales, in the countries in which he aims to market his own product. The outline in the brief cannot be adequate at this stage and invariably shows the need for amplifica-t ion; a necessity which will continue throughout the project.

His method of working will vary widely according to the product. If this is entirely new so that no one knows what the final shape will be, it may be best to let the design engineer com-plete his proposal for a prototype first, or to allow the industrial designer to compose a possible outer shell initially. In either case these men have to keep track of each other's work as the design progresses. Alternatively, if it is a simple product or a redesign of an existing product, the industrial designer may produce his 'final appearance' model first and leave the design engineer to work from there in close consultation. This is obviously necessary when the industrial designer is virtually providing the interior details as well as the outside envelope of a box such as a re-frigerator, cooker, or television cabinet.

T H E BRIEF

The industrial designer cannot start work without his brief and, assuming that he is a consultant, his fee will be agreed on this brief. In the written brief it is impossible to do more than imply management intentions; the environment, the designer will get himself from working within the company. To design any product in isolation is dangerous and unprofitable; hence during the briefing, the industrial designer must find out how the product is to fit into the manufacturing and marketing programmes, the

1 16 FROM P R O J E C T T O P R O D U C T I O N

preferred machines to be used, limitations in size of tools, etc. This is especially important with machined parts for casing, metal stampings and pressings, die-cast parts, plastic mouldings, etc. Curious as it may seem, this vital step is often overlooked by the manufacturer carrying out the briefing. Some designers are too timid to demand this knowledge for fear of losing the brief. It is best that no work should be done by the industrial designer until he has the confidence of all the project and design en-gineers working on the job . It is equally important that no work should be done by the design engineer involving layout of com-ponents, position and type of controls, etc., until the industrial designer has at least a general idea of how the project is likely to evolve. The industrial designer, with his realisation of user facility, may often suggest a different layout of certain parts as suggested by past experience. This is known to happen frequently in the layout of components in electronic chassis where there is considerable freedom, but where the industrial designer has been presented with a fait accompli.

A typical brief would contain the following items:

1. Specification. The main features of the product. The function and purpose. The advantages to be sought over existing and competitive products. Influences in appearance likely to predominate.

2. Preliminary limitations. Size, weight, position of sub-assemblies, controls, etc. Climatic conditions for use. Markets, with approximate percentages of distribution to each market. Any variations required for each market to-gether with preferences and reasons for them: extracts from market surveys where these have been carried out. Existing components and tools; whether these must be used or can be altered. Preferred materials. No te : when limitations are given the reasons must be clearly stated.

3. Quantities and costs. Full production programme should be given to the industrial designer. Tool costs envisaged and time limit allowed (see Chapter 2).

I N D U S T R I A L D E S I G N I I 7

4. Industrial designer's task's. This should be divided into finite stages with fees payable at the end of each stage (some pro-jects are very long term and it is not justifiable to keep the designer waiting to the end for his fees). Full-size model or scale model. Whether more than one design is to be given. What final form it is to be presented in by the industrial designer, i.e. whether perspective drawings are required, with particular reference to precise detail. Whether an in-dustrial designer is to produce actual samples of materials, colours, or bought out items. Whether he is required to design or advise on packaging, sales literature, etc.

5. House style. If the designer in question is already responsible for this the instruction may not be required, but if a different consultant advertising agent is used, he will need a full brief on typography, colours, finishes of house symbols and trade nameplates, etc. Larger companies will have their own briefing book on house style but, failing this, the designer must be supplied with details of associated products (con-temporary and historical) with actual samples if possible.

6. Time-table. Schedule of dates for industrial designer's work. (As this will depend on progress by engineers, an estimate will have to be given.)

T H E MEDIUM

The industrial designer will probably start work with sketches and plasticine, clay or plaster, to enable him to think three-dimensionally (see Plate 8). This is one of the strong contrasts in his approach to a problem compared to, say, that of the engineer-ing designer, who has no difficulty in 'seeing' functional arrange-ments in three dimensions by looking at a drawing. If the design task concerns a close-fitting cover of a machine, for instance, most of the work will consist in subtly defining the shape, and in choosing curvatures that are easy to manufacture but which give the whole that indefineable character of making the design look cohesive (see Plates 8 and 9). Sometimes special efforts can be

1 18 FROM PROJECT T O P R O D U C T I O N

PLATE 8. Model of a shaver.

directed towards making the object look smaller or larger and, in this respect, some very cunning deceptions can be carried out by the designer. On the other hand, if the cover for the product that the designer is producing is in the form of a loose-fitting box, then greater attention will have to be given to fitting the parts together, making access to the interior easier and hiding ex-crescences such as screw heads, covers, etc. This aspect may in turn influence the product within in such details as the supporting members for components. He will assiduously avoid the engineer's usual approach of symmetry (all knobs in a straight line and all the same size). Controls will be sized according to the use to which they are put ; size and shape should reflect the amount of force needed to make the adjustment; colour contrasts should be worked out to make scales easier to read; typographical details to ensure legibility regardless of material and process (cast figures, for example, need a different treatment to engraved figures).


PLATE 9. Electric shaver, Duke of Edinburgh's Award 1963.

T H E MOCK-UP

The mock-up model will now have taken shape. It may be built round the laboratory i a sh -up ' with real components or a drawing, but will in more instances be in woods, clay, plastic, metal, plaster (as in Plates 62, 63 and 64) or cardboard or a combination of all these (see also Plate 6). It may be full size or scaled down. It is, however, essential that the mock-up should look as near the real thing as possible. Great care is often exercised by designers to ensure that this is so, for example, a full scale mock-up of a car, made of clay with aluminium film for metal, looks so like the real thing that it is often used for the photographs (in colour) which appear in the sales leaflets. On the other hand, some industrial designers prefer not to provide models but rely on perspective


drawings in colour; this depends on the product and the person making the decision for acceptance within the company. How-ever, on the whole, models are to be preferred as they can be ob-served from all angles and are readily understandable by all persons connected with the project. A good perspective view is useful for advance literature and, although it can be obtained from specialist artists if needed, the result to the eye can some-times be misleading and some of the subtlety of the design may be lost. The industrial designer should present the model to the development committee in person. Furthermore, it is desirable that by the time the design is presented there are no alternatives or variations other than those specified in the brief (i.e. colour changes for different markets, or finishes for different climates). The model should be produced in such a way that there should be no need to 'explain' it. However, once it has been studied by the committee, the industrial designer can answer questions. Samples of the materials used, finishes and drawings of details difficult to show (for example, the fitting of an inspection door) can be presented at this time. The marketing manager will now be in a position to complete the product survey or market research. From now on great care should be taken of the model which should be retained in, or adjacent to, the drawing office, even after the product itself becomes obsolete.

STAGES OF WORK

The stages of work from the time of acceptance of the model depend on the brief. If the designer has been working with the company for some time he should be able to entrust the detailing and drawing to the chief draughtsman, as it is wasteful of the industrial designer's talents to provide working drawings, though some groups of designers are organised to give this service. Where the industrial design department is integrated into the drawing office it is not unusual for working drawings to be produced there, at any rate for exterior components, sheet metal, plastic mouldings, etc. The industrial designer's advice should, however,

I N D U S T R I A L D F S I G N 121

be called for at all stages of the development, especially if modifi-cations are required, or changes in materials are dictated by shortage of supply or some other factor. The industrial designer's work is not likely to be taken as it stands before the board for decision until a working prototype is available. At that stage it is desirable for the project leaders and, where appearance is im-portant, for the industrial designer to be present, in fact, any changes in the prototype should always be checked back with the industrial designer. Many a product has been spoiled on a second run by a change in supplier resulting in a changed finish or colour.

Plate 8 shows sketches of the original rough line drawings for the electric razor which won the Duke of Edinburgh's Award for elegance in 1963 (Plate 9). The model in front is made from wood with an aluminium foil ring to represent the switch. The product utilises several polymers as recommended by the industrial de-signer, notably melamine for the housing, nylon centre-piece, neoprene sockets, cellulose acetate for the grey translucent case— there is also an expanded polystyrene pack for transit (not shown). This product was an entirely new venture for the manufacturers who had previously specialised in needle manufacture.


A.E.T. (Manchester) Ltd.: Steps in Designing. Industrial Design Office, Manchester 17.

A.E.I . (Manchester) Ltd.: Appearance in Design, Bulletin No. 11, Industrial Design Office, Manchester 17 (1956).

ALEXANDER, C : Notes on Synthesis of Form, O.U.P. (1964). BOARD OF TRADE: Report of Departmental Committee on Industrial Designs,

H.M.S.O., Comnd. 1808 (1962). CONWAY, H. G.: Industrial design and its relation to machine design, Proc.

Inst. Mech. Engrs. 177 , 164, 2 (1951). CONWAY, H. G.: Design and designers, Chart. Mech. Eng. 286 (June 1963). D.S.I.R., MINISTRY OF TECHNOLOGY: Ergonomics for Industry, H.M.S.O.

(1962-6). DÖREN, H. VAN: Industrial Design, McGraw-Hill Book Co. (1954). FARR, M.: Design Management, Hodder & Stoughton (1966). FLOYD, H. F . and ROBERTS, D. F . : Anatomical and physiological principles in

chair and table design, Ergonomics 2 , 1 (1958).


FLOYD, H. F. and WELFORD, A. T.: Human Factors in Equipment Design* H. K . Lewis, London (1954).

KAY, R. M . S.: Industrial design in engineering, Engineering Mat. and Design (Feb. 1959).

KAY, R. M . S.: The Metropolitan-Vickers Gazette (Sept. 1959). MURREL, K . F. H. : Data on human performance for engineering designers,

Engineering (1957). PILDITCH, J. and SCOTT, D. : The Business of Product Design, Business Pub-

lications (1965). SHARP, P. Ε . M . : The industrial designer, Journal of Inst, of Elect. Engineers

(Dec. 1963). WELFORD, A. T.: Ergonomics of Automation, H.M.S.O. (1960). WESTON, H. C. : The Relation between Illumination and Visual Performance,

I.H.R.B. Report No. 87, H.M.S.O. (1953). WILLSMORE, A. W . : Product Development and Design, Pitman (1950).

C H A P T E R 6

OPTIMUM DESIGN

THIS chapter deals«with design practice as opposed to the philos-ophy, of engineering and industrial design. That is, with some of the more important design decisions to be made in the course of the evolution of a design; the tools that can be employed for this purpose, and the results thus obtained.

6.1. Concept of Optimum Design

UTILISATION

When the type of problem requires it, several sketches and sometimes even layouts representing alternative solutions may be produced, together with performance and principal stress- calcu-lations, before a selection is made. These alternatives, plus refer-ences to other related information, have to be preserved in an easily accessible manner for further use. For all this the folder mentioned in Chapter 4 will be very useful. Whenever possible, the methods to be employed with advantage to the actual design-ing would be broadly those of inductive thought, channelled into a framework formed of useful reminders of design steps and optimising techniques.

TECHNIQUES

Some of the methods used and shown in this chapter are in the nature of sophisticated devices, rather than pure design steps. As distinct from Chapter 4, most of the rational and analytical steps are now discussed in detail. Further, the techniques may

1 2 3


play a prominent part either in the design work required for a higher degree (M.Phil., or Ph .D. or Master Degree in U.S.A.), or in feasibility studies as submitted under contract by outside con-sultants. On their own, these not inelegant tools will still appeal to the engineer, though a practising designer will usually find some over-riding factor which restricts the scope of this purely ac-ademic approach. Too frequently, economic conditions ra-ther than theoretical technical criteria will simply impose a solution. However, the finalisation of a design does entail a close scrutiny of detailed features, for some of which optimisation can be given full scope. It would be merely incidental whether a study is made of purely functional factors, or of appearance, or, as will more frequently be the case, a combination of both, when applying some rather arbitrary criteria.

MARSHALLING OF DATA

This may involve the classification and tabulation of all avail-able data according to their functional importance or order of influence, in accordance with the design and project specifica-t ions; by dividing the task into main problems and sub-problems, then considering separately the known factors in the light of available data and selected criteria for each problem. The selec-tion and acquisition of data is likely to become relevant within the general aim and detailed objectives of the design task. The data could for this purpose be detailed as follows:

1. Selection of information which has a bearing on the problem or is likely to be required in view of the design specification. See Fig. 32, which constitutes a design task.

2. Research into missing factors. Search of published informa-tion in technical journals and scientific papers and reports. This is where research associations can often help by advising on refer-ences and supplying data.

3. Establishing the scientific, functional, aesthetic and produc-tion factors underlying the problem. It is useful to divide the data into those already available and those still to be established.

O P T I M U M D E S I G N 125

Having established all the factors, it is wise to consider investigat-ing the range and magnitude of their influence. Figure 33 is used to demonstrate this point. The item shown in the diagram was first referred to in Figs. 15 and 16.

4. Test. Some factors cannot be calculated because they depend on circumstances outside those which figure in the established methods of machine element analysis. Hence test results are necessary to complete the gaps in information or provide verifi-cation, particularly where the factors prevailing, or their limits,

FIG. 32. Design task: provision of a rotating net platform.

cannot be predicted with any degree of accuracy. Tests are also needed for novel conceptions incorporated in the design scheme. They are usually within the scope of the project engineer although they may in fact involve some design. The deciding factor would appear to be whether sketches or drawings are called for to produce the necessary models. For example:

(i) A spring balance held by the designer and attached to a machine part will give a quick indication of the order of magnitude of the forces involved.

W = 3t

Aim:-To provide α platform rotating about the vertical axis which can be easily removed without leaving holes in the afterdeck

Objectives:-The platform is placed in position by derrick. The vertical axis to contain all but vertical forces.

Δ runner d = 2 5 0 0 is to be employed. Minimum of space to be needed for dismantling of platform (with bearing ring and struts) Quantity:- 100 off


FIG. 33. Effects of torsion and shear on frusto-conical bellow restraint unit.

(ii) When vibrations are caused or likely to be caused by a number of reciprocating and rotating parts where higher speeds are to be achieved, then it is necessary to keep in-creasing the speed whilst eliminating or reducing the

OPTIMUM DESIGN 127

causes of vibration as they become apparent. These may be caused by the shape of the cams and the mass acceler-ated and can be balanced out by trial and error if not by calculation. Thus in the case of a cam, the acceleration curve is suspect; when this cannot be altered effectively, then inertia effects of the follower can be reduced by using a lighter alloy for its material. When the cam is at the end of an overhanging shaft, it is necessary to reduce its weight, or to provide an additional shaft support, or both.

(iii) If a large air ram is employed, its speed may have to be reduced by trial and error, choosing copper tubing of a smaller than usual diameter. This restricts the flow of air and hence the speed of the piston inside the ram.

SUGGESTED CRITERIA

The next step may consist of the formulation of criteria to be used in the examination σΡ data, on the basis of the guiding principles of engineering economics. The criteria can be formu-lated from some of the following aspects :

1. Simplicity of solution with the resultant economy. 2. Feasibility, that is positiveness of action and reliability in the

mechanical sense. 3. Degree by which each approach contributes to the com-

pleteness of the solution. 4. Utility and cost of the contemplated solution and of other

possible solutions.

6.2. Optimisation

SCOPE

The analytical method called optimisation has been evolved to systematize the evaluation and selection of alternatives as part of the design process. The techniques are a challenge and stimulus to


TABLE 2. ROTARY KNIFE OF SLIP INSERTER

Factor Component Snag Result

a Insertion of knives accuracy needed considerable difficult time and skill

b Blunted knives jamming, driving motor stalls refusal

to cut c Grinding of knives removal difficult maintenance d Holder bearings shock loads inadequate

greater creativity and an inducement to produce a worthwhile advancement on previous practice at each design step. Optimisa-tion can be applied to the principal design concept and to its in-dividual problems and sub-problems. The method commends it-self also for use in any reassessment of a design scheme to increase the effectiveness of the completed solution with respect to the design task and objectives. It could be also a useful insurance to reduce the possibility of economic failure in the venture.

Initially the paperwork will be in the designer's scrapbook, but the notes are eventually selected and transferred from there into the design folder, layouts and drawings. They form then, cu-mulatively, a source of information to be scrutinised and evaluated by a series of operations on paper and in model form. It is not suggested that a creative thought-process is not or cannot be employed instead to a considerable extent; this will be particu-larly true with the minor points, although in all such cases the method used is not optimisation, but simply a combination of intuition and inductive thought.

G R A D I N G OF FACTORS

1. Enumeration of technical factors applicable, obtained as a result of tests or of design analysis, Table 2.

For example: slip inserter. As a result of tests, the following snags were revealed before arriving at an acceptable solu-tion (Figs. 24 and 25).


Criteria: Will it work and if so, how well? 2. Separation of factors into constants and variables and

division into problems of the first and subsequent orders. For example : slip inserter. To cut clips and allow them to fall

onto a pile is an unsatisfactory procedure, because each sheet which falls onto the pile is blown away by the dis-placed air. This is therefore a constant factor which must find its way into the specification, as an additional new objective, before work can successfully proceed further.

3. Limiting scope. Design is facilitated by establishing the extent of the previously tabulated factors, and deciding the sense in which they may apply, and the order of their importance. This includes forces as well as the rule by which they change direction, magnitude and speed. It also includes the availability of space, shape of the proposed and adjoining components, choice of fit, material, environment, safety and cost. Technical colleges and universities can be consulted, particularly in connection with research undertaken which is applicable to the problem in hand.

For example: compression spring. The space required by a compressed spring for a given stiffness C/δ and shear 'mod-ulus varies with d*/D

3

W Cd* from — =

δ WD*

where d = dia. of wire, D = mean coil diameter, W = force, C = shear modulus, Ν = no. of coils, δ = de-flection. When, however, the required load or force, for the same spring stress is considered it varies with d

3/D

iromW = q

^ SD

where q = shear stress.


VARIATIONS

This aspect involves the isolation of the remaining factors and the arrangements of significant or principal features of a set of various solutions to a problem or sub-problem, and their schem-atic presentations as in Figs. 34, 35 and 36, by scale drawings, models or diagrams. If none of the proposals are feasible, a search for further alternatives must be instituted.

\ Slope Λ —

"* F •

h L2 L\

Spring length

FIG. 34. Compression spring design. Load-length curves for several compression spring designs which have different wire diameters but satisfy the same specifications for initial lengths (LO, load (P^ and deflection ( F ) with free lengths (H) final, lengths (L2), loads (P2) and

compressed solid height (h).

COMBINATION

This stage follows from the possibility that the factors or com-plete designs presented by variations of the solution to each sub-problem can be reconstituted and again combined into several solutions of the problem with perhaps other associated sub-problems. Figure 37 represents two variations of rotation be-tween screw and nut giving four combinations when assembled in a housing to make a screw jack. Similarly it is possible by modular


• ^ ; ι . c j r s i c e i r r e r e r

d0pt

Wire diameter, ö

FIG. 35. Compression spring design. Effect of wire diameter on final stress, all other factors remaining constant. Each curve represents a specific outside coil diameter, the curves progressively shifting to the

left as the diameter decreases.

Coil outside diameter

D o ^ o /

/ Allowable stress

dmin d x d o pt Wire diameter, d

FIG. 36. Compression spring design. Allowable stress curves for shorter and longer life superimposed on actual working stress curves for comparison and analysis of springs with two different outside coil

diameters ( D ) and varying wire diameters (d).


C O M P A R I S O N

This is a critical examination of alternatives using identical criteria. At least two or three conditions must be satisfied. If only

Variations

Nut ( r o t a r v i

S p i n d l e ^ ( r o t a r y ) ^

Combinations give four solutions

?\ A p t

FIG. 37. Screw jack design. Variations and combinations.

one solution is available then it can be compared with an ideal solution, although it must be borne in mind that perfection can be merely aimed at and rarely achieved. On the other hand, a better assessment would be reached if a broader basis of criticism is possible. Figure 39 represents a comparison by graph of critical variables in spring design.

Thus, theoretically, comparison is best achieved by considering in parallel the factors for the group of problems of the same

design to vary vertical and horizontal spindles with four types of pillar assemblies of piano-milling machines in Fig. 38.


Portal type p iano-mi l l ing machines

FIG. 38. Family of Gildermeister plano-millers.

order and then considering in series their sub-problems in the following sequence :

1. Characteristics, quality, advantages. 2. Technical feasibility (which includes search for intractable

sub-problems). 3. Cost. 4. Desirability (which reflects the personal contribution of the

designer, his 'flair' for what is needed).


FIG. 39. Compression spring design. Comparison of possible values of final load (P2) and stiffness (K).

The degree of satisfaction of each technical criterion versus each alternative factor can be tabulated as a percentage, where 100 means that the requirement is being met entirely. Alternatively the following point system of point values from 4 to 0 could be used instead:

4 pts. = perfect, 3 pts. = good, 2 pts. = satisfactory, 1 pt. = just acceptable, 0 pt. = unsatisfactory


SUBSTITUTION

If the results so far obtained through comparison appear in-complete, the designer becomes dissatisfied with them, or un-willing to accept them. An attempt is then made to :

(a) consider some important aspect further such as : (i) manufacturing or operation feasibility;

(ii) safety or economy or increased productivity; (iii) introduction or the use of a still more technical ad-

vanced conception incorporating perhaps a novel feature, or new materials;

(b) to enhance some characteristics whilst eliminating a weak point, or reducing the influence of the factors involved in a solution by:

(i) 'addition or equalisation', such as including extras to improve safety or convenience to the user;

(ii) 'cancellation' ; omitting anything that is unnecessary or seldom used; reducing the number of par ts ;

(iii) 'replacement' of one part by another, so that the same objective can be carried out by different means, making things bigger or smaller, stronger, faster or slower, lighter.

Thus when it is found that there is no satisfactory solution, substitution will assist in achieving what could be classified as a perfect solution and will lead to the crystallisation of the principal conceptions for the realisation of a design.

For example :

l . A valve design problem, where the main requirement is isolation of a two-pressure system in case of failure. The complete satisfaction of the problem, which after com-parison is deemed unattainable, is replaced by a slightly lower degree of isolation represented by a coaxial duct which was accepted because it had the advantage of bung feasible.

2. Windscreen. In another case the introduction is a local temper-ing of the toughened glass windscreen in front of the driver


PLATE 10. Leitz Pradovit slide projector.

which increases visibility when it shatters and therefore almost equals the safety of a methacrylate screen ( 'Pe^pex ' ) . See Table 3.

3. Tyre. In an initial comparison, only tyre building factors were assessed, such as the materials and shapes of the tread and the type of reinforcement. Now, by replacing the inner lining material of the tyre with an impermeable one, tubeless tyres are produced, which are claimed to be safe from blowout. By adding an anti-hysteresis layer in the walls, higher speeds are possible. Lastly, better road-holding is ob-tained if the tread has high hysteresis rubber.

4. Projector. As an alternative to the die-cast projector (Plate 4) there are also manufacturers using sheet metal covers for it (Plate 10) which may be cheaper to mass produce but suffer from being more easily knocked over in use. Plate 11 shows


PLATE 11. Kodak Carousel slide projector.

fresh thinking about the problem of a magazine carrying a much larger number of slides. Rectangular magazines can be awkward when pushed into a tunnel: jams are difficult to clear and the magazine has to be moved to reverse a slide put in upside down. Magazine has been replaced by a circular type holding eighty slides. Incorporating contemporary taste in architecture results in side panels being broken into functional modules, thus involving smaller lower-cost sheet metal tools. Note also how the handle has been incorporated into the design so that it is tucked away when not in use. Following the introduction of the round magazine another manufacturer (Plate 12) came along with a 'universal' model that will take in addition the original rectangular magazines, the round ones and an ingenious feed, which dispenses with a magazine altogether. In the attempt to incorporate all


PLATE 12. Sawyers Rototray slide projector.

these functions (plus remote control) the integrated appear-ance has been lost but the story obviously is not complete.

5. Electric Typewriter IBM72. Replacement of moving carriage (Plate 26) by moving type head (Plate 13). By reducing weight of moving parts, vibrations are lessened and the extra space, utilised by the carriage movement, is not needed. This de-velopment can, in fact, be traced to an old typewriter design which used a rotating and lifting metal cylinder rather than the present hollow plastic ball.

6. Λ 30-inch router. This machine has been in production for some time and had collected a number of excrescences (see Plate 14). A decision was made to call in industrial designers


PLATE 13 . Electric typewriter I B M 7 2 , with a sphere-shaped typing element which moves and tilts at high speed.

who worked with the company's engineers to redesign the product. Controls were regrouped for easy access, safety and convenience. Cast doors, requiring considerable machin-ing, were replaced by sheet metal. It is claimed that manu-facturing costs were reduced by 1 5 % and that the enhanced appearance resulted in doubling sales (see Plate 15).


PLATE 14. Heavy-duty routing machine older type.

6.3. Evaluation

It will be appreciated that there are a number of solutions to a problem, depending on the formulation of the problem and on the knowledge and experience of the designer. As far as the satisfac-tion of the technical objectives and production requirements is


PLATE 15. Heavy-duty routing machine redesigned.


concerned, hypotheses have been formulated in such a way that

the Engineering Value of an engineering product can be rationally

assessed.

TECHNICAL ASSESSMENT

A particular solution for small differences in the relative im-

portance of criteria is technical value,

π

Σ ρ ν

Pi + Ρ 2 + Ρ* + ... + Ρη (Ο Χ =

npmax ηρ„

Ρι + Ρ- + Ρζ + · · · + Ρη

η ρ (2)

w h e r e p l 9p 2 , P 3 = point values for the respective criteria for a given solution;

ν = 1, 2, 3 . . . η number of each criterion; ρ™™ = the maximum number of points a criterion can

secure under the point system in use; η = the number of criteria; ρ = the arithmetic mean.

For example, Table 3 is an example of technical assessment by percentage, but in brackets are given the corresponding points. The subject under consideration is the choice of car windscreen materials and their characteristics.

Substituting into eq. (1) from Table 3 for technical value,

0 + 1-5 + 1-25 + 4 + 4 10-75

5 x 4 20 = 0-54

similarly x B = — = 0-7, .v c = — = 0-65, x0 = H _ Z ^ = 0 - 6 3 , 20 20 20

TABLE 3 . CAR WINDSCREEN MATERIAL

V Material characteristics g A Β c D Plateglass 'Triplex' Toughened k Perspex'

1 Safety (Perspex = 100) 1 0 0 ( 0 ) 8 0 ( 3 ) 9 0 ( 3 - 5 ) 100 (4 )

2 Machinability OPerspex' = 100) 1 5 0 ( 1 - 5 ) 5 0 ( 1 5 ) 5 ( 0 - 2 5 ) 100 (4 )

3 Weight 0Perspex' - 100) 2 4 5 ( 1 - 2 5 ) 5 0 ( 1 - 5 ) 4 5 ( 1 - 2 5 ) 100 (4 )

4 Scratch resistance (Plateglass) = 100 9 100 ( 4 ) 100 (4 ) 1 0 0 (4 ) 5 ( 0 - 2 5 )

5 Thermal expansion (Plateglass = 100) 5 100 (4 ) 100 ( 4 ) 100 ( 4 ) 10 ( 0 - 5 ) OP

TIM

UM

D

ES

IGN

1

43


* b is the optimum technical value based on the assumption that all material characteristics are of equal importance.

it is desirable for some of the characteristics, such as safety for instance, to exert a proportionately greater influence on the choice of material. A biased or weighted technical value will distinguish between the relative importance of each criterion to an optimum solution.

Pi gi + Pi gz + . · .

Biased technical value x' = & + & + Pmax

= (3)

where g is the importance or influence factor. To allow for the relative importance of the criteria, an enlarged point system can be employed which will grade the criteria themselves with respect to each other (see Table 3). The biased technical value is particu-larly useful where the previous method showed only small differ-ences in technical value.

For example, * Ά =

0 χ 1 0 + 1 · 5 χ 1 + 1 · 2 5 χ 2 + 4 χ 9 + 4 χ 5 _ 60

25 χ 4 TÖÖ = 0-6,

. . . . , 90-5 Λ 0_ - , 9 3 7 5 Λ Ω. similarly, χ Β = = 0*875, . ν c = = 0*94,

100 100 56-75 Λ ς7

X D ~~ = 0*57 100

x'c is the optimum biased technical value. Both technical assessments have the drawback that they do not

include visibility after impact, an important factor in the criterion of safety. Nor do they include the price of the alternative materials, an aspect which would be dealt with under production costs.


PRODUCTION COSTS

H = M + L + G

where H = production cost, M = material, L = labour, G = direct expenses.

The above quantities can be expressed as percentage cost

H' = M' + L + G' = 100%

100

' 8 0

6 0

4 0

20

0

o ο

CVJ

ο

. m

- - - . I V I

I

5x10* 5x10* 5x106

Q u a n t i t i e s produced

(a)

100-rV-%

e o i

m Ν

60

4 0 i

20

0

H ' L -

Γ

5 x 1 02 5 x 1 0

4 5x10

6

Q u a n t i t i e s produced

(b)

FIG. 4 0 (a) Absolute and (b), percentage cost distribution for (c), turned component in aluminium alloy with respect to quantities pro-

duced.

(a) Production methods when applied on the same component

Figure 40a shows the absolute cost, Fig. 40b shows the per-centage cost and Fig. 40c the component. The production methods are represented by: I : lathe; I I : copying lathe; I I I : capstan; IV: automatic. The relationship in Fig. 40 is based on cost of material M which is not affected by the quantities involved as long as they are not the result of a radical change in production technique. The down time is significantly influenced by the method of production and thus labour L. The percentage of


direct expenses G' increased noticeably but the absolute direct expenses G, fall. The percentage G' will increase as seen from Fig. 40b, as a result of the influence of increase in the capital in-vestment. Of special significance is the behaviour of percentage of material costs Λ/', as shown in Fig. 40b, which increase with the increasing rationalisation of production methods and are re-garded as generally true. This suggests that cost of material will be of growing significance in any estimate of production costs in the future.

G' = 2 5 %

L' = 8 %

M/ = 6 7 %

G ' = 4 5 %

l_' = 3 0 %

M ' = 2 5 %

FIG. 4 1 . Percentage cost distribution for (a) wagon and (b) precision wrist-watch.

(b) Evolution of design to rationalise production

Figure 41 shows the percentage distribution of cost for: goods wagon a, or precision wrist-watch b, and Fig. 42 for three evolu-tion stages of a small automatic switch. From the example of the automatic switch it can be seen that, in spite of extensive modifica-tion, the percentage distribution remains the same. The percentage by weight is indicated by bars with short dashes and is not ap-plicable.

(c) Percentage of material costs of different products

The percentage for some of the groups of products are shown in Fig. 43. The estimate of production costs is an essential step to obtain the productivity value.

Μ ' = ~ Ι Ο Ο %

Cranes

Vacuum cleaners

M o t o r cars Diesel engines for cars

P e t r o l engines for c a r s T r a n s f o r m e r s l O t o l O O O k V A

Rai lway t r u c k s

Large a p p a r a t u s

Free a r m sewing machines with m o t o r . .

Passenger c a r r i a g e s

W a t e r t u r b i n e s

I n d u c t i o n m o t o r s , 5 0 t o 100 kW

Desk te lephone

L o w v o l t a g e s w i t c h g e a r

A m p l i f i e r s

Car r i e r f requency ampl i f i e rs

E l e c t r i c a l i n s t a l l a t i o n equ ipment

Mains v o l t a g e e q u i p m e n t

Carr ie r f requency o s c i l l a t o r

S t a t i o n a r y diesel engines

S t e a m t u r b i n e s , over 2 0 M W

L o w v o l t a g e m e a s u r i n g t r a n s f o r m e r . . .

H igh v o l t a g e s w i t c h gear

Radio g o n i o m e t e r s

F requency i n d i c a t o r s

H igh v o l t a g e measur ing t rans former . . . .

Low f requency o s c i l l a t o r

Induct ion m o t o r s , I to 5 kW

S t e a m t u r b i n e s , up t o 2 0 M W

E l e c t r i c a l c o n t r o l s

W a l l c locks

T a c h o m e t e r genera tors

Heavy m a c h i n e t o o l s

Big D .C m o t o r s

M o t o r i s e d s e l e c t o r s w i t c h

Domest ic sewing machines wi thout motor.

S m a l l a p p a r a t u s

A l t e r n a t o r 5 0 0 t o 5 0 0 0 kVA

Wave b a n d f i l t e r s

E l e c t r i c a l f i l t e r s

Measuring precision i n s t r u m e n t s

L o w v o l t a g e ampl i f i e r

L i f t i n g r o t a r y s w i t c h

Electr ical measuring instrument generally.

Telex t y p e w r i t e r

T e l e g r a p h and te lephone relays

P a n e l i n s t r u m e n t s

E l e c t r o n i c measuring i n s t r u m e n t s

Microwave c i r c u i t r y

Med ium m a c h i n e t o o l s

E l e c t r i c a l c lock w o r k s and c a s i n g s . . . . R e c o r d e r s e l e c t r i c a l E l e c t r i c a l prec is ion i n d i c a t o r s

Drawing i n s t r u m e n t s

Mater ial as a percentage of production cost M'

0 10 20 30 4 0 50 60 70 80 90 100

Τ

Π

FIG. 43. Percentage of material costs by product.

OPTIMUM DESIGN 147

Productivity value, ν = —'

Hi, are ideal production costs. They represent a fixed quantity for the purpose of comparison but only as postulated from time to time on the basis of available production facilities. It has been suggested that new designs are just acceptable when ideal costs are 0-8 of the actual costs.

FIG. 4 2 . Percentage cost distribution for three prototypes I, II, III of a small automatic switch. The interrupted line bars represent the weight

of material.

ENGINEERING ECONOMICS

The final and cumulative assessment of both the technical and the productivity value is the engineering value.

Engineering value, S = -χ

The value, S, for two successive solutions in Fig. 44 indicates their relative merits with respect to an ideal solution, 5,.

6.4. Crystallisation of Design

DECISION MAKING

The work involved in the rational execution of a design task can very well be divided into two stages : first, arriving at a principal


0 0-2 0-4 0-6 0-8 10

Technica l value, χ

FIG. 44. Engineering value of three successive designs.

Preference could be given to the solving of the first-order prob-lems initially, leading on to each subsequent problem, until the designer is confident that the remaining points are of a minor nature. In this way the principal modes of solving the task can be anticipated and considered at the earliest possible moment against the various alternatives available at each stage. Even so, assump-tions are often made where all the factors are not known, or in circumstances which are not fully understood, and consequently some of them will prove erroneous. In any case, it is seldom pos-

design concept, using the design objectives as criteria; and then, dealing with the resulting problems in the order of importance to the concept. Using the principal concept as an additional criterion, each problem of any order will then depend on some immutable machine element and critical factors for its solution. The allevia-tion of each cardinal factor must then be considered in the order which is most likely to result in a successful solution to the problem.

The aim should be to pursue the work in the direction which satisfies the main functional requirements first, filling in the func-tional details next, by using a continuous system of criteria.

i-o -*·

.0 -8 > »

α ί

"5 0-6 >

Ζ 0-4 3 Ο at

0-2

OPTIMUM DESIGN 149

sible or even considered reasonable to process each problem fully, or for that matter sub-problems, because of the time involved; particularly as it may be already delineated by preceding work.

SEARCH FOR SOLUTIONS

This aspect consists of sketching out, or even laying out to scale, all or at least some of the possible main solutions, whether it concerns only a simple item or a large or complicated one. This

Slip,

Feed rolls and cutter

FIG. 45. Schematic version of an early prototype of slip inserter. The inserter was driven via a solenoid-operated pawl, ratchet and cam counting device. Both main conceptions would not work reliably.

involves far more hard thinking, hard work and discussion than inspiration.

49 9 % perspiration and 1% inspiration' (T. A. Edison: 'What

makes a genius').

T H E PRINCIPAL DESIGN CONCEPT

The main guide-lines for adopting the necessary means to satisfy the aim and the possible objectives of the task within the given or derived limiting factors are the project specification and the related design specification. To achieve the aim and possible objectives, it is essential to define the function in order to arrive at


FIG. 4 6 . Principal design concept : cantilever-type slip inserter.

of principal concepts. However, it should be possible to claim at least one of these as having a family resemblance with the final design. Figure 45 represents an earlier unsuccessful prototype of the slip inserter (Figs. 24 and 25), whereas Fig. 46 shows a schematic diagram of the successful design. Figure 47 shows similarly three alternative design concepts of a duct restraint system.

PROBLEMS

When dealing with principal problems and sub-problems, it is desirable to preserve independence of mind in posing each

Next printed sheet

Motor, cams, etc.

the principal design concept, which can then be used as a basis for posing the problems of the first and subsequent orders. This principal concept, however, may have to be supplemented at different stages during the evolution of a design by the results of tests acting as additional criteria. Other information that becomes available later, particularly where the specification was incom-plete because of the nature of the problem, may also indicate the need for reassessment. This will apply to both the specification and the design task with its aim and objectives. Hence it will affect the proposed solution or solutions of the various problems. The profound influence exerted by tests could result in a number

O P T I M U M D E S I G N 1 51

FIG. 47. Principal design concepts of duct restraint units.

problem initially, in order that the net can be cast over the widest possible area. Once this is done, it is not advisable to disassociate the proposal from preceding work, or to neglect existing facts. See Figs. 15 and 16 for steps which followed an adoption of the system in Fig. 47b.

The possibility of using here examples within the author 's own experience has unfortunately to be excluded due to the commercial value of the designs in relation to the work currently undertaken


by the firms concerned. The understandable reluctance of these firms to permit publication has necessitated using examples al-ready published. The example used to demonstrate the inter-dependence of individual steps in the evolution of a design is for a fishing net platform. Figure 48 postulates the design task, defines the principal problem and suggests the principal design concepts. Figures 49 to 52 trace the evolution of a complete design using the optimisation technique discussed in Section 6.2.

Principal problem (resulting from the objectives):-What is the main purpose? - " T o take up a weight ' W' which is rotating about the

vertical axis and transfering it to a surface not parallel to the plane of rotation."

Principal design concept:-How is the objective to be achieved?-"By the provision of concentrical runner (a),

supported by struts of varying height."

FIG. 4 8 . Principal problem of fishing net platform and design concepts.

SCHEME TREE

A diagram could be made up to trace the crystallisation of a design scheme in recapitulation and to show the relationship of individual decisions taken in the appropriate order of im-portance.

6.5. Design Scheme

In order to present each solution to a design task in a compre-hensive manner for possible future use, the following points

OPTIMUM DESIGN 1 53

Principal solution I order

(— a.l-Sliding friction

Design concept η

Element 'α

Runner-

Factors (D^Jn"d

o;;,in̂

Purpose Application Forces Weight Efficiency

Installation Cost Production Special factors

L - a ^ - R o l l e r friction

IP

I I order HL order

r - a 2 . l Roller or ball bearing

SX ΊΧ r a 2.2.1

2500

Τ

U a 2 . 2 . 2 -a 2.2 Independent—»

roller

FIG. 49. Design concepts of net platform and principal solutions of element *a\ runner.

would have been considered before their incorporation in a design scheme.

KINEMATIC SCHEME

The provision of measures for the integration of elements into kinematic-chains and mechanisms of the principal concepts by intuition and kinematic synthesis, consisting initially of sketches, form an indispensable part of the designer's scrap book. The representative tear-off sheets should be kept in the design folder. The eventual scheme determined by the kinematic element will consist of the following:

1. Direction, range and type of movement. 2. Degree of freedom and restraint. 3. Forces and reactions.


RBL

Design concept

Element V

Height adjustment

! in • m 1 i

+ 1

Dominant factors

Forces

Space taken up

Production

Installation

4 - m m

I +1

Variants - V b

I Form g

Fastening ^N

2 Force

3 Weld

4 Rotating nut at centre turn buckle

5 Threaded strut at centre

6 Tubes welded

7 Tubes threaded

8 Circlip

9 Clamp

FIG. 50. Design concept of net platform and solutions of element *b\ height adjustment of strut.

4. Shape and proportions. 5. Accuracy, reliability.

The selection of the most suitable scheme is made by detailed evaluation and assessment mentally, although brief notes may accompany alternatives. The method used is essentially the same, whether used for the principal concepts or for problems and sub-problems. A typical example is the design of the slip inserter cam (Fig. 54), to change rotary into reciprocating motion required of the gripper rod in Fig. 56.

OPTIMUM DESIGN 155

Design concept

Strut base

Î Ball

Dominant factors

Space taken up

Ί

Design scheme 2

FIG. 5 1 . Design concepts of net platform and solutions of element 'c', strut anchorage.

STRUCTURE

1. Frame construction. Some elements of the kinematic scheme will call for pivoting or guiding. This will entail the introduction of frame elements and will raise problems of avoiding variation in wall thickness whilst maintaining required stiffness and will result in one or more such units being used. When these units are com-bined to form an integrated whole, its centre of gravity influences stability. The scheme also reveals problems of balance and indi-cates where alleviation of vibrations may be necessary. For this purpose, the various functional frame portions will be enclosed to form the outer shell.

Tubular welded structures are more and more frequently em-ployed because of their favourable weight-to-strength ratio. But a tubular, or encased, structure poses almost insoluble difficulties


Proposal based on scheme 2

Comparison-machining Cost Weight Section

1 Turning 40 90 65

2 Turn spherical seat and weld 60 90 75

3 Forging 70 90 80

4 Pressing (sheet M.S.) 100 100 100

5 Cast steel 70 95 82

7

= -- - l

oo

ν 7 /

- Ι ~ 21

Base plate M . S . - I 0 0 0 o f f - i - ( 28 )

FIG. 52. Roller support proposal for a net platform problem.

in stress calculations and should be produced or handed over only after full scale, preliminary trials under operating conditions. These would have to confirm the validity and accuracy of cal-culations or scale model tests to determine the anticipated behaviour of the structure.

2. Unit construction. The conception of a central frame possibly consisting of several components but acting as a skeleton holding all the moving and guiding elements has been considered. It is possible to design instead an integrated structure, which is self-supporting. In such a structure main components carry the secondary and ancillary elements. This is achieved by designing stronger primary elements, capable of discharging the additional duties imposed on them. Their stiffness increases progressively towards the frame and its foundation. This approach helps in vibration isolation and damping, contributes to economy by


Assy, on site

DESIGN SCHEME TREE

Design Task and Aim

Objectives

Sub-assy, in workshop

Function

I Criteria

Concept

Problem a

ι — " - ι 3-1 a - 2

• L i a -2 - ι a -2 -2

Problem b Problem c

b-1 c-1

b-l b-2 b-3 b-4 b-5 b-6 b-7 b-8

I α - 2 · 2 Ι α - 2 · 2 2

I L

Scheme α - 2 · 2 Ι / b - 2 - 6 / c - 2 - 3

c - 2 _ J

DESIGN PHASES

Design specification

Incomplete spec. Ada it ion a I objectives

Evaluation of limiting and constant factors

Principal design

Principal problems

C - 2 - I C -2 -2 C -2 -3 C -2 -4

Scheme .

a - 2 - 2 2 / b - 2 - 6 / C - 2 - 3

Problems of 1st order

Rejected design scheme

Selected design scheme

FIG. 53. Design scheme tree of a fishing net platform.

obviating redundant members, reduces cost of maintenance, re-placement and redesign and leads to the conception of modular units.

3. Monoconstruction. This consists of utilising integral parts of the outer shell as a stressed construction member whose strength or resistance moment and stiffness gradually increases as the external and internal forces combine. This approach leads to a reduction in cost and weight. It has been used in the leading edges of aircraft wings, which are machined out of a solid for reasons of strength and shape. Other fabricated structures include the floor sections of cars, which are now increasingly employed instead of separate chassis. In cars, where integrally stressed body parts lead


FIG. 54. Sub-problem analysis for a kinematic scheme of a pushrod cup cam. Slip inserter.

OPTIMUM DESIGN 159

to costly body repairs (because portions cannot be repaired without scrapping a substantial part of the structure) this method is really less justifiable. In these circumstances the main functional purpose of these parts is to exclude weather and to carry load rather than to provide fixing points for the suspension or to carry the motor. Although it can be argued that the main task of the car body floor is load carrying, it is likely to remain a stress member for all mass-produced, cheaper cars where a lower purchase price is an important factor.

TABLE 4. STRUCTURAL CRITERIA OF DESIGN

Strength

All stressed parts, where the elastic deflections do not interfere with the operation of the equipment or lead to resonance effects

Nearly all studs, bolts, spigots

High-pressure pipe work and pressure vessels

Moderate-speed * shafting systems not used for timing purposes or subject to torsional vibration

Component designed for

Stiffness

Structural frames for all types of machines

Flanged joints for low pressure

Machine tool bedplates .shafts and slides

Shaft systems used for timing drives

High-speed shafts for low torques

Bearing support structures

Strength and stiffness

Springs of all types

Highly loaded machine parts where vibration characteristics are important

Flanged joints for high pressure

Frames or vehicles, where weight saving is important

High-speed shafts for high torques

Flat plates subjected to fluid pressure

STRESS DISTRIBUTION

As by now the shape of parts is being forecast and the direction and magnitude of forces are known, it will therefore be desirable


to consider the stress distribution likely to result from the em-ployment of these parts. As a comprehensive stress analysis is not always feasible or even practicable at this stage, intuition is heavily relied upon. This may be supplemented later by stress analysis (invariably in aircraft) and full-scale destructive and non-destructive tests. The shape eventually selected should ideally give uniform distribution of the safe working stress, avoiding stress concentrations of any kind as far as possible.

WEIGHT

Having dealt with forces, reactions and stresses, the next con-sideration is weight. Lightness combined with strength is of con-siderable importance when considering handling and transport. From tools and trolleys to railway carriages and especially air-craft, weight is the principal criterion next to strength. Reduction in weight can be achieved by designing all components to be uniformly stressed to a permissible maximum working strength throughout. In addition it may be possible to employ a higher stress-to-weight ratio by using aluminium " alloy or plastic, in order to effect a saving.

To a lesser degree and in an opposite sense, weight is required to absorb vibrations, which may be due to the inertia and out-of-balance effects of rotating and reciprocating masses, or to counter-act the momentum due to the functional employment of impact in the manufacturing process. For instance, higher operating speed applications call invariably for a stronger and usually a heavier frame construction. Machine tools, which have to meet the effect of a multiple cutting-action or of intermittent chip-forming in facing operations during machining, also require heavier frames and stronger parts.

M A T E R I A L

With such a variety of engineering materials available on the market, it is important to select one in accordance with its physical


characteristics to meet the functional circumstances, saving in weight and machining cost. Care should be taken in the choice of dissimilar metals in direct contact as these may cause severe corrosion through electrolysis.

l.Castingandpressuremoulding.DiQ-castzincalloys havestrengin which approaches that of structural mild steel. They are some-what lighter, but are stress-relaxing, less wear-resistant, and brittle. They suffer from being inadequately designed for strength or not safeguarded from wear by a mating steel part . Aluminium alloys have a further weight advantage, but unless they contain copper their strength is only approximately half that of mild steel. The same applies to magnesium alloys except that the weight advantage is greater still (specific gravity 1 · 8). Unfortu-nately, they are inflammable and require special care during machining.

Plastic components are cheaper still to produce in quantity, but they are less scratch- and heat-resistant. As their specific gravity is only between 0 · 9 and 1 -9, they constitute an appreciable saving in weight, and are also corrosion-resistant. Some plastics have tensile and compressive strength equal, but their strength L only one-fifth that of steel (e.g. nylon). This ratio increases up to one-half in the case of compression moulded glass fibre and polyester resin and phenolics, for example, approach the strength of steel in compression. Others not structurally useful show con-siderable variation in strength depending on the manner in which they are stressed, the lower value being only 3000 lbf/in

2.

Dimensional tolerances to I.S.A. Bulletin 25 are not feasible because of shrinkage, but a system with two grades for plastics and another one with three grades for rubber is in use in Germany.

All materials have in common the desirability for continuous and unchanging wall section, adequate internal radii, a draw angle on either side of the mould parting face and absence of redundant sharp edges. Grain flow in steel stamping, forging and cold heading, or orientation in plastics, are a contributory factor to the ultmate strength of the part .

2. Rolling, drawing and extrusion. When sheet-metal is used as


an addition to an existing structure for functional reasons or be-cause of cost, to reduce heat losses, or exclude dust or weather, then only simple bends can be introduced unless the quantity (such as in domestic appliances and cars) would warrant ex-pensive deep-drawing moulds and press tools at a later stage. If a machine is to be fabricated from steel plate, sharper corners and flat surfaces will be the rule. If heat-treated, riveted, aluminium-alloy sections replace steel, these can be selected to maintain the strength of a structure undiminished, but resulting in a saving generally of up to 50% in weight. This will sometimes allow for additional load-bearing capacity to be used instead in the design.

ENERGY BALANCE

Sketches have to be produced with some detail of the direction and magnitude of forces and reactions. The detail will include temperature effects and an estimate of heat to be supplied or heat insulation desired. It will also include hydraulic and electric power requirements. The design proposal should be further supported by calculations and sufficiently detailed information which would enable one or more alternative design schemes to be put forward.

PROPOSAL

As the principal concepts emerge, it becomes possible to present them as a partially or totally integrated whole, on paper or in the mind of the designer, ready to be dealt with as a formal proposal or in one or more design schemes. Eventually these schemes will consist of a number of layouts which represent a functional graphical solution of the design task. The schemes will show:

1. The functional reasons or guiding principles for the proposed outer shell, with suggestions on shape, to which the industrial designer can begin making his contribution. He may, of


course, have been called in already by the chief development engineer before the preparation of a project specification.

2. Operation cycle. The functional phases of employing grip-pers in a slip inserter followed by further detailed breakdown with interaction between grippers and their shaft is shown in Fig. 55.

dun

& >\

-=©

(c)

ictionai solution

FIG. 55. Cycle of operations: grippers pointing inboard, open to receive strip. Grippers close on strip, whilst guillotine cuts slip from strip. Grippers swing outboard. Grippers open to release slip. Grippers swing

inboard completing cycle.

3. Method of control. The detailed solution, satisfying the re-quirements in Fig. 55, is indicated isometrically in Fig. 56.

4. Instrumentation. 5. Suggestions of colour and texture where this is relevant.

It is not unusual during product manufacture to have several design teams engaged on one prototype project, each specialising on a different portion of the product. Where machines are con-cerned, once the overall layout is available it is more likely to be

G α = ι

3 ·

A S 4

<C£> - = D 5

Q > 3 D <36 t

Ο ° = 9

(α) (b)

Pnncipal position Breakdown Fun


FIG. 56 . Sketch of the method of control of grippers. Slip inserter.

the task of a single team organised to produce a design and drawings together in the shortest possible time. The division is preferably functional to facilitate the replacement, modification, or redesign of relevant sub-assemblies or parts as necessary.

6.6. Final Shape and Appearance

The aesthetic influences on the underlying criteria of shape, surface texture, colour and ergonomics were outlined in Chapter 5.


The industrial designer-artist is a competent arbiter in this sphere. It is now intended to suggest the common ground which the industrial designer shares with the engineering designer, in the resulting appearance of the final product. As the main impact of the appearance lies in the originality of the conception, due regard should be paid to the following points: The product cannot be aes-thetically acceptable unless it performs its functional purpose. The satisfaction of functional requirements, however, does not neces-sarily represent an aesthetically acceptable solution. The key would appear to be in meeting unobtrusively the functional re-quirements and bringing them to their natural conclusions without extravagant styling. Hence, functional considerations will take precedence over purely aesthetic ones, unless there are over-riding reasons to the contrary. For examples see Plates 16 to 24.

VERACITY

The shape of moving and structural elements and their pro-portional relationship to frame structure, leading to equal distribu-tion of stresses, should actually enhance functional considerations. This should also be accomplished by using discernible and aptly chosen material thus lending veracity to the whole. Accessibility for maintenance such as adjustment, repair or cleaning, as well as ease in handling must not be impeded, in effect: 'What is right will usually look right' to a trained engineer or experienced designer, whether with respect to functional considerations or the materials which are being employed. See Plates 16, 17 and 18.

STABILITY

Careful choice of material and purposeful distribution of weight will add to weight economy and stability. An impression of balance can be further reinforced by identical or proportional treatment of all separate or moving parts. See Plates 19, 20.


PLATE 16. Shipyard crane.

OPTIMUM DESIGN 167

PLATE 17. Theodolite .

COMPACTNESS

By the judicious grouping of enclosing walls and connecting surfaces, a compact but functionally satisfactory design can be achieved. No useful purpose can be served by attempting to disrupt the optimum functional grouping of the machine merely in order to satisfy a superimposed shape or pattern. See Plates 21 and 22.

SLEEKNESS

Cast or moulded surfaces can be produced with smooth flowing external outlines composed of curves and/or large radii. All

F R O M P R O J E C T T O P R O D U C T I O N

PLATE 18. Radial drill with pillar detail.

168


PLATE 19. Turret lathe.

covers and sometimes even boxes can and should be of similar appearance and usually made of the same material as the frame, incidentally reducing noise and adding strength, making the whole a visual entity. The visual impression will be radically in-fluenced by the choice of materials, as the choice will impose re-strictions on their final shape. Covers and lids will be flat but could with advantage still be bedded in, to give the impression of an unbroken surface. See Plates 23 and 24.

AFFINITY OF SHAPE

Together with all the points mentioned so far, the need for continuity and affinity should be remembered in the design of each detachable or movable part, so that unity in the build-up of a machine can be easily preserved. This will result in mutually matching shapes of sub-assemblies, owing to repetition of identical or similar features. See Plates 25 and 26.

F R O M P R O J E C T T O P R O D U C T I O N

PLATE 20. 40-inch cassegrain coude reflector telescope.

170

PLATE 21. Guillotine.

PLATE 22. Telephone apparatus.

F . P . T . P . — G

PLATE 23. Ringmaster communication unit.

PLATE 24. Twin screw kneader.

O P T I M U M D E S I G N

PLATE 25. Plano-miller.

173

PLATE 26.1.B.M. Executive typewriter.

PLATE 27. 'Mondiale gallic' lathe.

O P T I M U M D E S I G N

PLATE 28. Internal communication unit.

PLATE 29. Instrument console of a power station.

175


SURFACE

The need for a plain, smooth and unbroken surface can easily be upheld when geometrical continuity has been preserved. Naturally, flat surfaces may equally well be selected and success-fully maintained, but care should be taken that smaller radii are chosen in such a case. Where curves or inclined planes are used, the impression of box-like construction has to be maintained. See Plate 27.

PARTING LINES

The separation of machine elements and adjoining sub-assemblies can be utilised for decorative purposes, or used as a means of strengthening them, or both. The gap or rim can also be utilised to suggest or endorse the functional purpose of parts of a machine. Purely decorative trimming and corner strips which un-like bumper bars or safety strips have no functional purpose, should be avoided. See Plate 28.

COLOUR

Whilst being a decorative element colour can also be ergo-nomically useful. Contrast can be justified where very delicate instruments requiring careful handling are concerned. It should be noted, however, that poor application, as with an inferior finish, brings out manufacturing shortcomings. See Plate 29.


BAUERFEIND, R . : Zur Ökonomik des Konstruieren, Maschinenbau Technik 4» 12, 6 1 7 ( 1 9 5 5 ) .

BAYER, R . : Kinematic Synthesis of Mechanisms, Chapman & Hall ( 1 9 6 3 ) . BOOKER, P. J. and PRINCE, J. : Special purpose machine designer, Engineering

Designer (Mar. 1961) . BOOKER, P. J. : Principles and precedents in engineering design, Engineering

Designer (Sept. 1963 ) .


D.S.I.R.—Ministry of Technology: Good Design Pays, H.M.S.O. (Nov. 1963) .

KESSELRING, F.: Bewertimg von Konstruktionen, V.D.I.-Verlag, Düsseldorf ( 1 9 5 1 ) .

MARPLES, D. L.: The Decisions of Engineering Design, Inst, of Engineering Designers (July 1960) .

V.D.I . -V.D.M.A.: Formgebung technischer Erzeugnisse. Richtlinien 2 2 2 4 , V.D.I.-Verlag, Düsseldorf ( 1 9 6 0 ) .

V.D.I.-Fachgruppe Konstruktion: Technischwirtschaftliches Konstruieren, Richtlinien 2 2 2 5 , Blatt 182 , V.D.I.-Verlag, Düsseldorf ( 1 9 6 4 ) .

VOTTA, F. Α . , Jr.: Compression spring design, Machine Design 175 (Apr. 1954) .

C H A P T E R 7

INVENTIONS, PATENTS AND DESIGN REGISTRATION

T H I S chapter deals with the three forms of protecting an original idea: patent, copyright and design registration. Sometimes the dividing line is difficult to distinguish, but it is hoped to elucidate the factors which should influence the decisions to be made. More attention has been given to design registration than to patents, as this is least generally understood and is often allowed to go by default. The number of design registrations (except in the field of textiles) is remarkably small in Britain considering the scope that it can offer. All types of registration grant a monopoly to the inventor and care is therefore taken by the authorities that this does not result in malpractice. This is probably the main reason why the process of registration is thorough and lengthy.

7.1. Patent

There is no sharp line of demarcation between what constitutes an invention and what engineering design and development pro-duce, except that an invention covers a particular aspect of design work only. The governing factor is whether a specific part, end-product or process is patentable. Whether it is a justifiable object of a patent application is quite another thing.

HISTORY

In the early days of inventions, monopolies were granted as a means of raising money for the state; these were abolished by

173

I N V E N T I O N S , P A T E N T S A N D D E S I G N R E G I S T R A T I O N 179

James I in 1614. It is interesting to note, however, that the proviso in the Statute of Monopolies opened the door to the present universal system of registration, which read: to be made of ' the sole working or making of any manner of new manufactures within this realm, to the true and first inventor and inventors of such manufactures, which others at the time of making such letters patents and grants shall not use, so as also they be not contrary to the law nor mischevious to the state, by raising prices of commodities at home, or hurt of trade, or be gen-erally inconvenient'. The term 'patent ' is interesting (O.E.D. Latin patentant = lying open), as this relates to a royal document addressed to all and sundry. It is on this Statute of 1623 that other countries have based their Acts and Rules. In Britain legislation is given under the Patents Act (1949), the Patent Rules (1949) and the Patents (Amendments) Rules (1955 and 1961): the Rules give the procedure and are obtainable from the Patent Office. The first attempt at getting international recognition of patents goes back to the International Convention for the Protection of In-dustrial Property in 1885. Of the seventy-five relevant countries only the Argentine is now outside the Convention : Russia came in as recently as July 1965 (Her Majesty's Stationery Office publish in Britain a guide entitled Soviet Patent and Trade Mark Law (Code 70-80)). In spite of international agreements, separate cover has to be taken out for each country and the procedure can be very extended, although the members of the Common Market are attempting to work out a common patent and discussions were taking place in Budapest in 1966 on the subject of a European patent. Ultimately, as this extends, it should effectively ensure originality internationally on new patent applications and avoid much of the pilfering from one country to another that now goes on. Most manufacturers use a firm of patent agents to investigate the patent position, but this is by no means essential. Drawing up a patent specification is best done through a legally trained or professionally qualified patent agent. Some large manufacturers have their own patent department.


PATENTABLE INVENTIONS

An invention is patentable if it is any manner of manufacture which inter alia is new and not obvious, complies with the law, is not against public interest, contrary to scientific principles or against morality. Any method of testing which is applicable to the control or improvement of manufacture is also patentable. Novelty requires that the invention shall not have been used or published. However, if a defect in an existing machine or process has been known for some time and there has been a demand for the removal of this defect which demand has remained unsatis-fied, there is a strong assumption that the solution is not obvious. Working along known paths to a conclusion may result in a new product, but is unlikely to be invention. Only work beyond the known path will produce this. Furthermore, if a new material is introduced in an existing product (or part of it) to meet properties already known to be required, this is not invention.

A PATENT OR A SECRET?

The commercial success of an invention depends on the recog-nition of the advantage it bestows on the manufacturer who makes use of it. There is a telling relationship between the patents granted and the sales of new products seen in Fig. 57.

If the patentable feature is a selling point and can be easily appreciated by looking at an example of it, or by making use of it, then patent protection is highly desirable. If the new feature is unlikely to be appreciated or if the machine on which it is used is not for sale, then there is no point in advertising the invention to all and sundry, as one of the prerequisites of a patent is that it shall be fully described. A better protection than a patent could be an impression created in the mind of a competitor that the solution adopted is a wasteful or unnecessary refinement, when exactly the opposite has been demonstrated to the satisfaction of the owner of the invention! This would be useful in a case where the whole product or machine is of a highly specialised nature

INVENTIONS, PATENTS AND DESIGN REGISTRATION 181

1945 4 6 4 7 4 8 49 1950 51 52 53 54 55 56

FIG. 57. The significance of lack of new product development. (See Fig. 3.)

catering for a limited and specialised market. However, once it has been decided to patent an invention, certain actions have to be taken as quickly as possible. Furthermore, it must be remembered that the progress of a development programme can be dislocated if a design engineer has to be deployed to deal with what may become a long-drawn-out affair, bearing in mind that no details of the product using the patent can be released safely until the provisional patent has been deposited. A way round this problem is to classify the matter as 'confidential' if some of the information has to be disclosed in correspondence with suppliers and com-ponent part manufacturers.

TECHNOLOGICAL FACTORS

Sometimes a simple invention, although inexpensive in itself, may involve the manufacturer in a very large capital expenditure on new replacement plant and savings must pay off the capital cost in well under 10 years. Hence, there should be a clear economic advantage over existing practice with a substantial re-duction in production costs. The importance of minor improve-ments should not be discounted in this connection and piecemeal


introduction can be avoided by utilising overhauls or grouping several successful ones together. On the other hand, as the patent may well be applicable to a broader field than that which is of immediate interest to the manufacturer, consideration has to be given to its value as a commercial proposition in its own right, i.e. its capacity to raise revenue through sale or licensing at home and overseas. The decision to take out a patent usually rests with the engineering or technical director, who should consult the commercial director, but, in any event, it is not the decision of the development engineer.

Functionally the central and novel idea may fit in with existing practice by using as far as possible existing plant and by giving a cheaper and better product. Generally, however, the probability that machine developments can substantially improve the quality of the product is small. On the other hand, the invention may equally well make a clean sweep of existing practice and produc-tion, as in the case of a product using a new material or a new process. In the latter case the obstacles are far more formidable and require of the inventor a considerable single-mindedness in pursuing his idea. Other difficulties to be met and overcome in the realisation of an invention arise from adherence to present prac-tice, investment in capital equipment, resistance among personnel, reorganisation of the structure of industry, allowance for tradi-tional methods in the use of materials, assessment of the standards involved, the cost of perfecting an invention and last but not least, the timing of the whole project.

7.2, Ownership

When an inventor is his own employer and has made the in-vention alone, there is no problem over ownership. However, it is more usual for the inventor to be an employee. Unless there is an agreement to the contrary, an employee who invents something not related to the present or projected work of his employer, owns the patent, even if the invention was made in the employer's time with the employer's materials. On the other hand, whatever


the status of the inventor, the patent belongs to the employer if it relates to the inventor's normal duties. Procedures are laid down in Britain for settling disputes between employers and inventor employees through the office of the Comptroller of Patents on the application of either party. Upon settlement, a portion of the benefit can be shared between them, depending on the inventor's level of responsibility. Normally the patent is taken out in the name of the company as patentors and the employee-inventor as the patentee. This, incidentally, confers no rights on the employee even if he leaves the company. However, there are circumstances where ideas emanate from the shop floor and the employer may find that the invention belongs to the employee. In the United States, however, the employer has what are known as 'shop rights', i.e. he can use the patent without redress to the employee, but the employee can still take the patent elsewhere and sell licences to other manufacturers.

PROCEDURE FOR APPLICATION

Application for a patent can be made by the original inventor or his assignee. Where the inventor is an employee the assignee is usually the company. Should the inventor die, his heir can take out the patent. In the U.K. the inventor or assignee can delegate the application to a chartered patent agent, or in some cases a solicitor, to an attorney and counsellor in the U.S.A. Joint in-ventions can be registered in more than one name provided all the parties have contributed and not merely worked on the invention. The naming of the right inventor on the patent application is of vital importance, as this can invalidate the patent if not correctly stated. It is thus undesirable to name a senior executive auto-matically as the inventor unless this is in fact true. Co-ownership may arise if the patent is granted to joint applicants, or is assigned. Unless it is agreed to the contrary, joint grantees are each en-titled to an equal undivided share in the patent, but each joint proprietor can further it without reference to the other unless the question of exclusive licence arises. As for the actual specification


of the invention, it has been implied that the purpose of a patent is so that the invention is fully described and may on expiry be made by anyone skilled in the art. There are, however, other factors which the Patent Office will consider before granting the monopoly. Generally the applicant can take out a 'provisionar which gives him a full 12 months ' grace to complete the invention and decide whether it is worth a full specification. If he lets this lapse, only a further 3 months ' extension can be applied for in Britain after which he cannot patent the invention. Alternatively, he can file the complete application without holding a provisional patent, but in this case a patent agent's assistance should be sought. It is more usual to take out a 'provisional', as this gives a breathing space and most of the drawings can be omitted from the application. However, as many alternatives or uses of the invention as possible should be given at this stage even if some of them are highly improbable. For the purpose of securing prior validity in a claim, a date must be attached to it. This is especially important when foreign cover is required, as the date is normally that on which the provisional specification is filed. If an applica-tion is based on a foreign application it may back date to the original provisional application under the International Conven-tion. Foreign applications must be considered and decided on well before the end of the period of 12-months' grace, from the date of the first application. As soon as the application is filed, disclosure can be made. There is one word of warning required here: if a competitor at this stage infringes the provisional patent the in-ventor can only claim damages and royalties from the date of publication of the full application. No action can be taken until the patent is sealed. Generally all paper work connected with a design can be useful as evidence in patent or registered design claims if preserved in a folder and if the roughs have been date-stamped.

After the full application has been made and the necessary searches and recommended amendments taken care of, the Patent Office publishes details; if no objections are made within 3 months application is then made by the inventor for the patent

INVENTIONS, PATENTS AND DESIGN REGISTRATION 1 8 5

to be 'sealed'. This gives 4 years cover from the filing of the full specifications. It can be renewed thereafter annually for a further 12 years or in special cases beyond this, though it usually be-comes a matter for the High Court at that stage. Fees and periods of renewal vary from country to country, so that special care is necessary to ensure that the patent is not allowed to lapse.

ADDITIONS TO PATENTS

An inventor may often discover an improvement to one of his own patents in the course of development and he should take steps to register this as an improvement or modification to the original patent at the earliest opportunity. Such changes can be made during the period of the patent, but they only last as long as the original application is maintained. The alternative is to take out a separate patent of addition. The procedure is then similar to taking out a normal full application. As cover dates from the addition and not from the original patent to which it relates, this can be an effective way of extending the span of the patent. It is also possible to improve on someone else's patent ; to do so, however, confers no rights to the original patent on which it is based nor does it replace it. Use of the improved patent must be negotiated with the original owner who may well be prepared to come to an agreement in order to have access to the improvement, if he wishes to block the use until his own patent runs out he can do so. Similarly the original patentee has no rights to the im-provement without the consent of the person registering the improvement.

SAMPLE SPECIFICATION*

The narrowness of the dividing line between invention and design can be illustrated by reference to the history of the steam engine. The position in 1712 was as follows. The steam engine, as

* A sample specification has been added for didactic purposes only, it does not constitute a formal requirement of the British Patent Law.


j Title of patent j

Fast steam engine

Subject of potent

Whot is the a i m ? - " T o reduce time of steam engine cycle"

I Patent objective |

What is the main purpose?-"Faster condensation of steam after work has been " done in the cylinder"

Principal concept -heat transfer

Claim I order

I. Water as medium

I.I Contact with water inside cylinder

2. Other medium

1.2 Separated from water by cylinder wall

Water

. _ Steam f boiler

I.I.I Separate| marking out of cylinder

1.1.2 Injection I of water into

steam

1.2.1 Surface steam

condensator

1.2.2 Water injection

Icondensator

FIG. 5 8 . Newcomen's steam engine. Sample specification.

a prime mover, consisted of a single-acting vertical cylinder with a movable piston rod. Steam at atmospheric pressure expanded into the cylinder, lifting the piston. The return of the piston was caused by the condensation of steam in the cylinder after the steam entrance va lve 'd ' was closed (see Fig. 58).

Newcomen's discovery was of a method to increase the rate of condensation. He fitted a second valve V through which cold water could be injected. The 'specification' would have read : 'The subject of the patent specification is a steam engine consisting of a cylinder " b " provided with a valve " e " through which water can be injected into the cylinder to increase the rate of condensation. ' This determines the nature of the patent claims, giving the method of their employment. The main objective was to achieve a faster condensation and the means was indicated. One could have en-quired into other possible methods and means of achieving the required cooling effect, in an effort to cover a wider field by making subsidiary claims. The water could act indirectly through a cooling jacket or, as was the case, in direct contact with the


steam under the piston. From this it follows that the claim could have been worded ' that condensation is achieved by the action of cooling water after work has been done by the steam in the cylinder'. Thus the invention of a condenser 70 years later could have been covered rather than anticipated by this patent. On the other hand, the even farther-reaching claim 'that the steam gave up heat to the cooling water on condensing' would merely describe a known physical phenomenon which could not form a valid patent claim. Even the wording that condensation is achieved by cooling water would represent only the main subject of the preceding invention of Savoury merely describing a cause which produced the known required effect. But the patent specification must also give fully the technical means and the method of assembly used to realise the described invention.

AVOIDING INFRINGEMENT

Designers may purposely avoid examining competitors 'products earlier on, so as not to be influenced unduly. On completion of a design scheme such a step cannot be delayed longer. On the other hand, a project may call for a complete investigation of existing patents in order to progress in a field already well covered by the patents of competitors who will naturally have sought ways to protect their interests. This study to find new or alternative methods can often embody a creative approach. If no acceptable alternative can be discovered, then a licensing arrangement may be sought. A licence is also desirable whether or not the patent has been fully exploited by the owners, as a way to save develop-ment costs. There is, of course, a distinct difference between evasion and deliberate infringement! A patent agent's help in this context becomes imperative. Typical alternatives to a cam prob-lem are shown in Fig. 59.

7.3. Design, Copyright and Registration

This subject has often proved confusing to manufacturers and certainly the existing complacency (indicated by the very slow


INVENTION OF ORIGINAL W H E E L BY "A" ε / (a)

A INVENTION O F ECCENTRIC

W H E E L O R C A M BY

\ C O M P E T I T O R "B"

/ (b)

INVENTION O F H E A R T

SHAPED CAM BY

\ C O M P E T I T O R "C"

(c)

FIG. 59 . Alternatives to avoid infringement.

rise in registrations) is unwarranted. Unfortunately, a the time of going to press, the position is complicated by the fact that a powerful opinion in the U.S.A. is against a change, whilst in Britain a Government Committee has produced a Report, the recommendations of which may still be modified by Parliament before they find their way into a Bill. It is therefore wise to look at the position as it is today with an eye to the future.

COPYRIGHT

The British Copyright Act of 1956 (most countries have similar legislation) relates principally to literary or artistic works, but an


industrial design cornes within this category under certain con-ditions which are sometimes difficult to determine because of variation between cases. It is, however, as well to know that a drawing, sketch or original design for a product is automatically copyright and cannot be copied without infringement. It is the interpretation of Original' which leads to legal problems. Under the Copyright Act no registration is involved, therefore copyright has the great advantage of conferring immediate protection and injunctions for restraint can be very quickly obtained in the case of infringement. (In the case of design registration or patents the legal wheels grind slowly.) Although it is nominally the initial design that is protected by copyright, manufacture can be made of up to fifty articles. The original intention of this apparently somewhat arbitrary quantity was to differentiate between craft objects and mass-produced items. Copyright is automatically can-celled over the fifty, but under this quantity has the added merit of lasting for 50 years, whilst registration lasts for only 15 years (provided the renewals have been made).

DESIGN REGISTRATION

Design registration has had rather a chequered history and has been the subject of some rather interesting law cases ; however, the present position is clearly laid out in the 1949 Act and the wording is remarkably free from legal jargon. Under this Act (which is quite short) it is feasible to register a design with the assistance of the Patent Office and without the intercession of a patent agent (who also looks after these matters). There is also a good book on this subject (see Bibliography). Although design registration (called design patent in the U.S.A.) is carried out by the Patent Office, it must not be confused with taking out a patent. As will be seen, there are merits in registering a design where a patent would not be permitted, or give cover, although there are cases where patents allow features of design to be pro-tected where design registration will not (methods of fixing, for example). The principal difficulty of the working of the 1949 Act


is that it has to cover such a wide field: clothing, for example, is very complex—the fashion industry could not exist unless an element of copying were allowed and the law must, therefore, be flexible enough to permit the trade to carry on ! Similarly it has to ensure that in engineering products a slight twist becomes an in-fringement. Interesting examples of successful litigation resulting in protection were shown in Design magazine, September 1956 (namely a lavatory cistern in plastic and an electric iron), but the variety of designs registered during the first 7 months of 1961 show that the field of engineering products is fairly fully covered. For example, under 'Machinery' the following individual articles were included: printing press, water tube boiler, concrete mixer, compressor, pump, winch, machine tool, fan rotor, reduction gear, data processing machine unit, gas turbine nozzle, cash register, typewriter, sewing machine, etc. Under the Miscellaneous section comes: nail clippers, ironing board, anti-radiation lead shielding brick, pocket calculator, portable garage, aircraft seat, hypodermic needle, laboratory balance, etc. Of course this category will also include some extraneous items like wedding cakes, grave memorials, and lace! It is, however, essential to con-sider the question of design registration if novelty or an original shape is a major selling point of the new product. As with patents, world coverage should be seriously considered and a loose-leaf textbook on this subject is published (details are given in the Bibliography).

BRITISH REGISTERED DESIGNS ACT, 1949

In view of the relative lack of familiarity with this subject, the Act will be considered section by section. Note that only relevant portions are quoted here, but full details can be obtained from the Patent Office or H.M. Stationer}' Office.

Designs Register able Under Act:

1. Subject to the following provisions of this section, a design may, upon application made by the person claiming to be the

I N V E N T I O N S , P A T E N T S A N D D E S I G N R E G I S T R A T I O N 191

proprietor, be registered under this Act in respect of any article or set of articles specified in the application.

2. Subject to the provisions of this Act, a design shall not be registered thereunder unless it is new or original and in par-ticular shall not be so registered in respect of any article if it is the same as a design which before the date of the application for registration has been registered or published in the United Kingdom in respect of the same or any other article or differs from such a design only in immaterial details or in features which are variants commonly used in the trade.

3. In this Act the expression 'design' means features of shape, configuration, pattern or ornament applied to an article by any industrial process or means, being features which in the finished article appeal to and are judged solely by the eye, but does not include a method or principle of construction or features of shape or configuration which are dictated solely by the function which the article to be made in that shape or configuration has to perform.

The first three paragraphs are fairly straightforward, but 'design' in this context needs clarifying. This is done to some extent in (3), but it might be difficult to differentiate between shape and con-figuration, or pattern and ornament ; although these fine distinc-tions can be ignored when considering engineering products. At first sight it would seem that the design must have some artistic merit, but cases have proved otherwise and so long as the design is something that can be perceived, i.e. seen, and is different from anything yet existing, it can be registered. The decision rests, of course, on the outcome of a search which takes time. A particular problem that arises in the search relates to the discarding of 'accepted forms' for products which are well known and in order to register something within an accepted form it must have some feature which is quite different. (For example, a chair has to be a certain shape to perform its function, but there are many shapes which do not conform to the accepted which can be registered.) As the Act stands at present, part of a design cannot be registered


unless it is sold separately, this gives rise to problems (e.g. is the lid of a saucepan sold separately?). One answer may be to patent the method of fixing one part to another. The Act also specifically excludes a design dictated solely by function ; items excluded under this category have covered such widely separated things as ladies' underwear and fuses for electrical machinery where the conforma-tion of the fuse was dictated by the holder.

Certainly all methods of fixing and assembly are ruled out from design registration.

Proprietorship of designs:

1. Subject to the provisions of this section, the author of a design shall be treated for the purposes of this Act as the proprietor of the design: provided that where the design is executed by the author for another person for good considera-tion, that other person shall be treated for the purposes of this Act as the proprietor.

2. Where a design, or the right to apply a design to any article, becomes vested, whether by assignment, transmission or operation of law, in any person other than the original proprietor, either alone or jointly with the original pro-prietor, that other person, or as the case may be, the original proprietor and that other person, shall be treated for the purposes of this Act as the proprietor of the design or as the proprietor of the design in relation to that article.

This section, dealing with the ownership of the design, is self-explanatory as it merely guides the consultant designer as to the sale of his designs to the manufacturer which then becomes the manufacturer's property.

Section 3 lays out the procedure for registration and indeed is simple enough : the cost for the first 5 years is £4, second 5 years £8, third 5 years £16. At the moment it is necessary to register the design in other European countries to obtain protection there (the Commonwealth is covered by the British registration). The Hague


agreement of 1960 has not yet been accepted in Britain, but when this comes about a fee of about £9 will cover registration in about ten countries (the principal adherents to the Hague Act at present are France, Germany, Holland, Belgium and Switzerland). Cur-rently the initial charges for overseas registrations vary (providing there are no complications), but they are in the order of £20-30 including the costs of the agents at home and overseas (e.g. U.S.A. £21-30 depending on period, Germany £22, Japan £30). The full procedure for registration will be found in para. 3 of the 1949 Act and period of cover in para. 8.

LIMITATION OF EXISTING LAW IN GREAT BRITAIN

A report of the Departmental Committee on Industrial Design. This important report, usually known as the Johnson Report, was published in August 1962. It sets out the limitations of the existing copyright law and the Design Registration Act. It makes sug-gestions for extending the value of both Acts and, in order to avoid the confusion that now exists, suggests calling them 'Design Copyright' and 'Design Monopoly ' . It suggests that designs for copyright should be deposited (rather than registered) to give almost immediate cover and that no searches will be in-volved; the onus for originality will rest with the depositor. Design Monopoly ' would replace the existing registration but

would involve a search and would provide a much better protec-tion than the existing Act. This proposal also extends the scope to cover integral parts and to abolish artificial divisions between groups of products, so that a design registered in one group cannot be pirated by another (this applies particularly to decora-tion). A reading of this report, together with the existing Act, provides the engineer with all the basic knowledge he needs to make a decision. Help is needed from a qualified patent agent if it seems at all likely that infringement will take place by manu-facturing the new product, or that the design is liable to be pirated by others. The expense of an agent is fully justified in the initial stages of registration, by the later value of his services for


the inevitable legal wrangling! It is, however, pointed out that a

straightforward registration is simple and a matter for the

designer himself. If this report leads ultimately to a new Act then

this will pave the way for Britain also signing The Hague Agree-

ment, which will be of great value in a Common Market situation.


A.E.S.D.: Inventions and How to Patent Them, D.A.T.A., Richmond, Surrey ( 1 9 4 6 ) .

BAUERFEIND, R . : Zur Ökonomik des Konstruieren, Maschinenbau Technik 4, 1 2 , 6 1 7 ( 1 9 5 5 ) .

BOGSCH, A. and SYTHOFF, A. W . : Design Laws and Treaties of the World, Leyden, Holland and Bureau of National Affairs Inc., Washington, D . C .

DELORME, J.: Patent or secret, Rubber & Plastic Weekly, 9 142 , (Mar. 3 , 1962) .

LOCHNER, R . : The New Patents Act, Nat. Union of Manufacturers. PATENT OFFICE: Applying for a Patent, H . M . S . O . (June 1965) . ROLT, L. T. C . : Thomas Newcomen—Father of the Steam Engine, Chart. Mech. Eng. 2 5 0 (May 1963) . ROTHBART, Η. Α . : New developments in design and application of cams,

Eng. Design Conf., Session II, Proc. A.S.M.E. ( 1 9 5 7 ) . RUSSEL-CLARKE, A. D. : Copyright in Industrial Designs, Sweet & Maxwell

( 1 9 6 0 ) . SHELLEY, K. E.: Terrei ά Shelley on Patents, Sweet & Maxwell ( 1 9 6 1 ) . TAIT, W . H.: HOW to make inventions less of a gamble, Chart. Mech. Eng.,

3 8 1 (Sept. 1967 ) . WHITE, Τ . Α . Β . : Patents for Inventions, Stevens ( 1 9 6 2 ) . WOODLING, G. V.: Developing new products from prior patents, Machine

Design, 3 2 2 (Apr. 1954) .

C H A P T E R 8

DESIGN REALISATION

T H E work of the engineering designer does not quite end with the design scheme, layout or submission of a proposal ; nor does it end with his responsibility for the general arrangement or the comple-tion of detail and assembly drawings. From the moment the drawings or sketches have been completed, the responsibility for the project rests directly with the project engineer or, possibly, the chief development engineer. The chief designer and the other engineering designers (detail and design draughtsmen) be-come their consultants instead. However, having acquainted themselves with the problem, they should be allowed to retain the initiative to sponsor and later to assist with modifications neces-sitated by production and operational considerations. Because of the time involved, their assistance should be facilitated, where appropriate, by changes in the project and design specification for the purpose of record control and the continued goodwill of the drawing office.

The final product and the manufacturing drawings are again the responsibility of the chief designer. The type of work in-volved can be best seen from Fig. 60.

8.1. The Drawing Office

The organisation of the Drawing Office, which is a separate entity where the drawings are produced, merits some further thought, because it can be the cause of considerable waste. This waste may be due to inadequate procedures for performing routine tasks and superficial design task specifications, conducive

195


Design Department

Responsible for

Patent Application

General I A p p r o v a l ] — D e s i g n

Layout

Modif ication if

necessary

Provisional Cost Estimates

Preparation of detail drawings and parts lists

Development Committee Provisional

Design Meeting Represented by

Decision on internal and B.O.components

FIG. 6 0 . Design realisation.

Design Production

Supply

to poor appreciation of the problems and indifferent execution of the tasks. It may also be due in part to the absence of a recognis-able method of work. A systematic training procedure for new-comers is the exception rather than the rule.

ENVIRONMENT

The work, even in its simplest form, is exacting because errors must be avoided. The office must therefore be modern and well decorated. Ample daylight and sound-absorbing floors, walls and ceiling are of great help and have the benefit that a greater power of concentration is brought to bear on the work in hand because of the improved conditions. Nor must mechanical aids be over-looked. Designers should be given good equipment, even the best,

D E S I G N R E A L I S A T I O N 197

just because of the stimulation it provides. The latest, easily ad-justable drafting stand with a balanced drafting arm, individual light, adjustable stool, a reference shelf and reference table with its own chair should be standard equipment for all design per-sonnel. This is desirable even if the personnel may have to be encouraged to make more use of the drawing boaids at times. Other mechanical aids should not be overlooked whether they consist of electric erasors or reliable electrical calculating machines on trolleys, placed at strategic points. Although the personnel will have their own slide rules and logarithmic tables, absence of these aids in the office is inexcusable. It will be realised that government contracts on the 'cost plus ' basis may not be very conducive to a high degree of efficiency. Where the contract consists of feasibility studies which cannot have a more realistic basis of payment, or where it would be difficult to establish such a basis, not only the qualifications of personnel but also the equipment should be periodically scrutinised. In any event, ap-proximate estimates of design and drawing time should always be made so that planning and scheduling can take place. Allowance should be made for the fact that such estimates are nearly always a gross understatement. This is primarily due to unavoidable changes in the original or subsequent specification and modifica-tions to satisfy ultimate production requirements, which only be-come fully apparent during the planning and jig and tool design stage. Where several designs are of equal merit, it is sometimes not realised until the work is scheduled for production which alternative method of production should be employed to avoid bottlenecks during manufacture.

DISPLAYS

Drawing offices will require quite a large amount of display space for components, designs, models and special tools. This space should be carefully planned or (as too often happens) models degenerate into a scrap heap in the corner. Small com-ponents such as trademark plates, knobs, escutcheons, etc.,


FILING SYSTEM

The drawing office will contain the following, strategically and

accessibly placed :

1. Internal standards, national standards and books by filed U.D.C, on shelves.

2. Project and design files, filed in number sequence, on shelves or in cabinets with drawers.

3. Catalogue subject matter filed in card index under subject headings, whilst catalogues are then filed alphabetically under manufacturers' name—all in the drawing office.

4. Card index for drawings under drawing number with size, title, date and entry initials, in the print room.

could well be mounted on boards in the centre of the drawing office. Use of a central pillar with the boards hinged at one side enables both sides of the board to be used, and does not take up wall space which is usually required for filing cabinets and cup-boards. Obsolescent models or special tools and pressings from standard tools (such as louvres and brackets) can be kept in cupboards in the corridor outside, but in any event models should be looked after and if necessary repaired before being put away. It is desirable that one person should be delegated this task by the chief draughtsman—if he takes a pride in his work a drawing office can be one of the most pleasant rooms to take visitors to.

Thus failures and successful prototypes should be displayed with photographs of the ultimate production model. It is im-portant that faults of design are brought out and commented on. As these are bound to appear, it is not out of place to be 'wise after the event', it would be only fair if these failures were shown as denoting stages in the evolution of a more advanced design. The atmosphere created in this way will also be conducive to a better and happier relationship within the department and with other departments.

DESIGN REALISATION 199

5. Filing cabinets for drawings are positioned in the print room so that they are easily accessible to D.O. personnel but also under surveillance of the printing clerk, in some instances a strict booking-out system may have to be enforced. Some cabinet drawers may require dividing to take different sizes of drawings and are appropriately marked in front with the standard sheet size and the groups of drawing numbers they cater for.

6. Card index for drawing subject matter in the D.O. unless a drawing number classification system is in operation. Also this would deal with individual components.

There is usually some form of booking-in and -out but some standard books of reference and catalogues may be freely avail-able, providing that each person keeps these references on a specially provided shelf, when taking them out, where they can be easily identified and claimed by other members of the staff. In a drawing office the most suitable person for keeping the filing system in operation is perhaps the one who prints and files drawings.

TRAINING

It would be idle to pretend that training in projections, symbols, abbreviations, dimensioning, limits and fits, surface finish and geometrical tolerances is all that is necessary. In fact, some train-ing nowadays is acquired already at secondary or grammar school level. If training is not obtained here, it is as much a part of the syllabus of the Ordinary National Certificate in Engineer-ing as are loci and drawing up simple engineering problems. Thus the apprentice will have a good grounding before he is admitted to the drawing office, or alternatively, one may include a relatively short period during his training as office boy and general factotum, before he passes his examination at the local technical college. The grammar or high school boy will also need to catch up on workshop practice. Perhaps a part-time attendance at the


final engineering drawing and workshop practice class at the local college, coupled with full-time industrial workshop practice, is the minimum which should be required of every entrant to a college of advanced technology. The course could conceivably be only of 3 years' duration if it included a Higher National Certificate as an entrance qualification for those wishing to study engineering science or technology. This procedure, whilst desirable in Britain, would require modification to suit the U.S.A. or continental practice, where a university curriculum takes a minimum of 4 years. In the latter case 1 year prior endorsement course in in-dustry and local technical college may be adequate. Having said all this, it is pertinent to say that the drawing office is no place to impart engineering fundamentals; these should be imparted periodically in an emergency class-room adjoining the workshops, in working time and by senior workshop personnel. The function of the drawing office is to inform all novices about drawing office organisation and procedure so that they do not feel lost or are not too much of a burden to senior colleagues. It should be possible to cover the ground for the new entrants in a few hours interspersed with their regular duties in the first few weeks.

Access to the factory workshops on business should be allowed for all drawing office personnel in works time. General access during breaks could be particularly rewarding for new personnel to enable them to settle more quickly. Visits to stores can also be very helpful, especially if stock lists are available. It may be easier and quicker to find the actual part needed as reference than a drawing of a particular component. It is helpful if the stores are logically laid out by category first (rubber and leather seals, linings, wheels, unmachined castings) and then within each category by the drawing (part) number.

Even so, it has to be accepted that it will take some years in the drawing office before it becomes clear whether the entrant has developed the ability to design. He is likely to be successful if he has developed an aptitude for technical drawing. Three-dimen-sional appreciation is something for which he will need consider-able practice in what will amount to ordinary drawing office


modification and routine work, until he absorbs the much-needed feel for the simplest solution and the care to avoid errors. He may feel restrained or curbed in his desire for original and interesting work and frustrated in not making his mark quickly as an en-gineering designer; sympathy and understanding during this phase can be shown by management in numerous ways. His superiors should ensure that no more than a fair share of chores is being allocated and that qualified personnel get breaks in work by being sent to postgraduate courses. Interesting work should be rotated even among junior members of the* office, if possible, under a planned grading system. This could be part of a deliberate training policy. Even so it is unlikely that it will take less than 4 years in the drawing office, and possibly longer, for a novice to make the grade as an engineering machine designer. The main reason for this is the length of time it takes to make complete sets of drawings; even a hand-operated machine will take one person 8 weeks from scratch. Incidentally, in this case it would be impracticable to employ more people for other than auxiliary work.

T H E CHIEF DRAUGHTSMAN

Ideally, the chief draughtsman will be a mature person with extensive drawing office experience and an even temperament. Before issuing a task to the draughtsman he will satisfy himself as to the correctness and completeness of the information in the specification. On allocating the task he will point out some of the pitfalls in the specification and then check progress from time to time. The completion and issue of production drawings will also be his responsibility. The allocation should be done with a view to bringing out any latent talent in the personnel under his charge, by distributing the work with care and exercising enough cir-cumspection to prevent friction being caused. This can be achieved by denying free access to the index of pending and allocated modification and design work, except in the case of the chief designer. 'Hogging' of jobs can be effectively discouraged and


efficiency increased by entering the date of issue and time taken onto the combined drawing index and record card. When lack of space for drawing storage necessitates it, microfilm can be used to advantage and larger firms can have the negatives recorded on punched cards. A punched card system is also useful for the drawing subjects and parts cross reference because it speeds up the search for data before commencing with a task and promotes standardisation.

By taking care of the office discipline the chief draughtsman will ensure that the atmosphere is relaxed, with a minimum of noise, to facilitate the exchange of information between any two individuals. He should discourage a greater number of people joining a discussion, except for purposes of instruction.

The chief draughtsman will be responsible for the initiation of new entrants into the organisation and methods of work in the drawing office. He will also be constantly revising the grouping of personnel as necessitated by the work in hand. In so doing he will allocate gioups of draughtsmen to specific projects and then select their individual tasks for them. He will thus be mindful that advance familiarity with project aims could be useful. When the amount or type of work has reached a stage which calls for a team, a varying number of draughtsmen is likely to be put tem-porarily under the supervision of a senior man who will then be responsible for producing the required drawings. This supervisor will delegate the detailing whilst producing the more important drawings himself. Some larger firms and certainly smaller ones could not be expected to maintain with advantage a permanent organisational structure based on the grading of personnel into junior, intermediate, design and senior design draughtsmen and design engineers. It is preferable, in the interests of team work, that apart from such distinction as is justified by experience and education, stratification is left to pay reviews; indeed it may be highly desirable that, with the exception of the chief designer, the design function is performed in proportion to seniority, exper-ience and salary. Beginning as an occasional task at the inter-mediate draughtsman level, design should form the major part of


the work of all capable engineering designers and design engineers. The complexity of the task and the amount of assistance and supervision has to be adjusted as the task progresses in accordance with the designer's experience and ability. This supervision can be exercised indirectly in the form of advice and could be delegated to senior people from time to time where training is concerned. Such a policy can have a salutary effect by leading to a more rapid utilisation of personnel who received a higher theoretical education. It is the chief draughtsman's duty to bear all this in mind and make suitable recommendations periodically to the chief designer.

T H E CHIEF DESIGN ENGINEER

Called chief designer in an engineering firm, he is a man of vision, who is expected to travel at home and abroad, see cus-tomers and suppliers, visit exhibitions, and attend lectures and symposia to keep himself abreast of new advances. In this activity he will alternate or share his activities with the chief engineer and the chief development engineer, but will not be burdened with reports, correspondence and committees. The chief designer is only an ex officio member of the drawing office. Organisationally he is its nominal head, who delegates everyday administration by defining the duties of the chief draughtsman, although he may choose, after consulting the latter, the personnel to be given those design tasks which he has selected for his special attention. In the same way he relegates from time to time some of the work in his care to be continued in the care of a senior member of the office instead, deputised for this purpose. Alternatively, he may decide that the work is to be completed under the general supervision of the chief draughtsman at a stage when only details remain to be settled, in which case the work will follow the normal office drafting routine. This will leave the chief designer and perhaps some members of the staff, free to deal with other important and complicated design jobs. The responsibility for all design work remains with the chief designer and he


exercises it by giving advice and by selecting or even deciding on the most promising design solution.

8.2. Drafting

Nowhere is the importance of conforming to a standard pro-cedure so essential as in the drawing office. At the same time nothing can be so wasteful unless it is adjusted to the needs of the circumstances prevailing. The procedure, as well as the work content in the office, will depend on whether the job concerns jig and tools or a special type of product or machine. Hence if the draughtsman is in doubt about the job specification, he is not likely to get very far just by drawing it up without the encour-agement by the chief designer. Eventually the chief designer has to rely on the initiative and good sense of the draughtsman. The work of both may be wasted if the person at a higher supervisory level cannot read the drawing. In such cases it may be necessary to make a model, but this is not really justified unless it is connected with appearance or ergonomics. The situation where a simple model can prove a point is not all that frequent.

Normally each part in the production workshop is represented by its own drawing. Simple routine tool design will be an ex-ception, particularly when the use of stocked standard parts is involved and reference to them and to known jigs or fixtures can be made. Thus no drawing should be made at all for tool room or model shop which takes longer to draw than the part takes in the making. In this instance an authorisation to the toolroom with relevant information will be adequate as the toolroom has highly skilled personnel at its disposal who can be relied on to use their own initiative within reason. Where an authorisation with references is inadequate a free hand sketch under a drawing number should meet the case.

For the rest, the drawing, if properly supervised, provides an opportunity when most of the problems and errors can be ironed out before they reach the workshop. For prototype and toolroom work close liaison should be maintained between the designer


and the fitters. This can be encouraged by the draughtsman being readily available to assist on request with the ' interpretation' of the drawing. In justified cases the draughtsman can then discuss the problem or error with the senior designer responsible. A correction can then be initialled by them on the existing drawing if it does not affect the function materially and does not interfere with the interchangeability—no further action need be taken. Where there is a drawing error which affects parts being made in the workshops, the query should be sponsored on a modification form and the remedy authorised. Where scrap has resulted the sponsor should be on the works side in order that the cost can be allocated.

The personal involvement does not end with the designer but includes his superiors as well as all those draughtsmen who assist him in the drawing office. Where the chief draughtsman is overloaded it may be necessary to have several drawing offices. The division is likely to be into special purpose machine, product, engine or chassis sections, each with their respective design en-gineers but with one chief designer between them. The jig and tool design may be put under the production engineer with the main drawing offices providing personnel and facilities. The appointment of section leaders would not be justified where design engineers can provide the design leadership without de-tracting from the administrative responsibility of the chief draughtsman. An exception would be made in the case of a person in charge of the clerical section for specifying standard parts or equipment, requisitioning of stocked parts and ordering bought out parts.

STANDARDS

With the present advanced state of engineering technology in many fields, it is imperative that existing standards are fully ex-ploited for the selection and specification of materials and com-ponents. The limits and fits of kinematic pairs can also be decided by reference to the appropriate standard to ensure inter-


changeability of parts and their functional reliability. Parts and their overall dimensions, assemblies and sub-assemblies of prod-ucts or machines, their methods of installation up to the making of provision for the workpiece itself, are all likely to be covered by standards. Chances are that if national standards do not exist foreign standards will and should be considered whenever new ground is being covered. The Standards Institutions of the re-spective countries act as agents for each other and this may be very useful. The national standard (which may incidentally be an agreed international version) or foreign standards are normally supplemented by internal ones, leading to a still greater degree of efficiency in production and performance of the product. Two examples are shown: the first deals with general tolerances (it concerns all dimensions which do not show the permitted devia-tion to be read into the given nominal figure); the second example concerns the manufacture of jigs, tools and gauges.

Each draughtsman should have a copy of the national standards for drawing practice (B.S. 308) and a set of company standards detailing procedure. The standards will include methods of pro-cedure: how to complete a part list; how to record modifications on a drawing; how to take out a drawing number and cross-reference the title. They will introduce such symbols and tech-niques as will be considered useful.

T H E DRAWING

The purpose of a drawing is to communicate in the most economical manner all essential information for the manu-facture of a product. The criterion of efficiency and economy in a drawing should be the ease of producing the drawn item and in particular of the production phases or the work of departments through which it will accompany the product, as well as the speed with which it can be completed. It is pertinent to realise that there can be several types of drawings in use. It is sometimes overlooked that this has the advantage of reducing considerably the drafting time. When the part has been completed and in-

TABLE 5. GENERAL TOLERANCES

In inches (1 unit = 0*001 in.)

over 0-04 Piameter

(in) up to 0-12 0-22 0-40 0-70 1-2 2 0 3-15 4-75 7-10 9-85 12-4 15-75 19-70 31-5 49-2 78-8

Holes to H12 + 4 + 5 + 6 + 7 + 8 + 10 + 12 + 14 + 16 + 18 + 2 0 + 2 2 + 2 5 + 32 + 4 0 + 52

« a Shafts to hi2 —0 ο «β

à° —4 —5 —6 —7 —8 —10 —12 —14 —16 —18 —20 —22 —25 —32 —40 —52

H Length to j l3 ± 3 ± 3 - 5 ± 4 - 5 ± 5 ± 6 ± 8 ± 9 ±11 ±12-5 ± 1 4 ±15 ±17-5 ± 2 0 ± 2 2 ±27 ± 3 4

ined

rt

s

Holes to HI3 + 6 —0

+ 7 + 9 + 10 + 12 + 16 + 18 + 2 2 + 2 5 + 28 + 30 + 35 + 4 0 +48 + 6 0 + 80

Mac

h

pai

Shafts hi3

Length j l4

+ 0 —6 ± 5

—7

± 6

—9

± 7

—10

± 8

—12

± 1 0

—16

±12-5

—18

±15

—22

±17-5

—25

± 2 0

—28

±22-5

—30

±25

—35

± 2 8

-^0

± 3 7

- 4 8

±37

—60

±45

—80

± 5 7

tion

Holes H14 + 10 —0

+ 12 + 14 + 16 + 2 0 + 2 5 + 30 + 35 + 4 0 + 4 5 + 50 + 56 + 6 0 + 74 + 90 + 114

îldec

tr

uc

Shafts h 14 + 0 ^ c

g —10 —12 —14 —16 —20 —25 —30 —35 —40 —45 —50 —56 —60 —74 —90 —114

Length j 15 ± 8 ± 9 ±11 ± 1 4 ± 1 7 ± 2 0 ± 2 3 ± 2 6 ± 3 0 ± 3 5 ± 4 0 ± 4 5 ± 5 0 ± 6 2 ±75 ± 9 5

Cas

ting

s

precision j l5 and J15

± 8 ± 9 ±11 ± 1 4 ± 1 7 ± 2 0 ± 2 3 ± 2 6 ± 3 0 ±35 ± 4 0 ± 4 5 ± 5 0 ± 6 2 ± 7 5 ±95

Cas

ting

s

general J16 and j l6

± 1 3 ±15 ± 1 7 ± 2 0 ± 2 5 ± 3 0 ± 3 6 ± 4 2 ± 4 9 ± 5 6 ± 6 3 ± 7 0 ± 8 0 ± 9 2 ±112 ±142

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TABLE 6. TOOL LIMITS AND FINISH

General limits (to ST.9). Dimension in decimal figures, holes to H12, shafts to h 12, length to j l3 . fractional figures of 6 in. and below ± A in.

over 6 in. ± in. over 12 in. ± A in. ± v

Special limits: Centres of holes —in line Ί equal limits up and —on P.C.D., equally spaced > down from normal

(i.e. perp. co-ordinates between holes) J

{ Holes and shafts On design schemes and proposals letter and figure for each tolerance to show desired fit.

Shafts on detail f max. size and minus tolerance. Holes drawings-^ min. size and plus tolerance.

B.S. 969 and B.S. 919 Gauges I max. and min. sizes in full.

Undimensioned chamfers and/or radii: shall be understood to remain as left by tool (one can satisfactorily replace the other).

General finish. In order to maintain actual datum faces of stored tools in proper condition, it is undesirable that faces should be ground other than those shown on drawing. When unavoidable, one such additionally ground surface for setting purposes should be sufficient.

Sharp edges. Even where shown on drawing must be deburred. Guide-in chamfer on male parts to be 30° to surface. All datum faces which are usually ground should have a chamfer of -3\$ in. to Λ in. at 45°.

Identification marking. Main item of each tool drg. no. = component no./tool letter,

inspection stamp, last two figures of year with the month no. as date of issue.

All loose or detachable items at least component, no./tool letter, (including slip bushes)

DE

SIG

N

RE

AL

ISA

TIO

N

207


spected according to its drawing, the latter is filed with the in-spection department 's used drawing file. Only the latest issues need be kept, except where modifications are involved. The draw-ings can be numbered according to a preconceived code and those intended for prototype work can have a prefix or suffix 'X ' added if it concerns a test or experiment and 'Ρ ' for provisional or prototype components. This will make it possible for the number to be retained for production drawings provided that there is no danger in it being mistaken for normal production components (i.e. so that the manufacture of T ' parts is confined to the model shop and they cannot reach the stores).

When it comes to making drawings, draughtsmen should be guided towards austerity and clarity of expression as well as brevity (i.e. should put down only the necessary information, using fully standard abbreviations and symbols and bearing in mind also the eventual utilisation of the drawing). It is also recom-mended that they should avoid the repetition of details that are unnecessary—holes, identical sub-assemblies, bought-out com-ponents, recurring features, shapes which are punched from existing tools, such as louvres, electronic valve holders, affixed name plates, etc. These things only need indicating in rough outline with centre marks—actual outlines can be avoided. School or college training naturally mitigates against this policy and whilst a draughtsman should not be discouraged from taking a pride in his work, neatness is not the same thing as over-detailing. On the other hand, drawings of sheet metal parts which require forming must include a perspective sketch to prevent their being made inside out. Furthermore, if a fully dimensional free-hand sketch with the appropriate drawing number will do for a simple item, then unless this goes into quantity production, its proper drawing-up is only justified for training purposes.

For prototypes, tools and gauges, the following steps can be taken:

I. Omnibus drawing. A drawing could be a composite one with tabulated dimensions, usually setting out the formulae from which these are derived. This will save time, particularly as


routine additions to such a drawing can be made by clerks rather than draughtsmen. Although standard items, produced in quantity, are made to individual drawings, this does not preclude the use of a composite drawing for reference and inspection purposes. In such a case, a sketch of the standard article would be printed onto a sensitised transparency with figures inked into blank spaces provided. For toolroom pur-poses where more skilled personnel are employed, it is even possible to dispense with drawings other than the composite drawing by underlining the figures referred to on the print with a coloured pencil.

2. Fabrication drawings. On the other hand, some composite drawings show several permanently assembled items on one sheet and for these the term fabrication drawing is used. In the case of a fabricated part such as a welded machine frame member, each welded item will be fully dimensioned because it forms a separate part initially, even though it belongs to a permanent assembly. Each item can also be denoted by a small letter of the alphabet and 'keyed' in a corner of the drawing and possibly again on a part list, where the quanti-ties involved warrant a separate materials list.

3. Composite drawing. Again for special purpose machines, it is simply a matter of convenience to have the number of separ-ate drawings restricted to the least number of standard sized ones. In this case the title of each part will give the part number, title, scale (if different), material and size. A table listing common parts should be added to the drawing which is showing the assembly.

LAYOUTS AND GENERAL ARRANGEMENT

Produced by engineering designers, usually to scale, but not necessarily representative of the proposed product in their di-mensions; the schemes or layouts will perhaps consist of several subsequent or superimposed issues, variable in content or detail. The last may perhaps be almost identical with an assembly


drawing and will show the general arrangement. The guiding principles of construction and all the major design features will by then have been specified and are ready to be incorporated into the drawings of a machine or an engineering product. Accordingly, it may be good practice that when design schemes have resulted in a layout, this is initialled as 'checked' by the project engineer to signify acknowledgement of its main provisions and the acceptance of the responsibility for its subsequent integration with the project work in hand. It is then 'approved' by the chief designer. When supplementary design schemes or layouts have been added

and the general arrangement stage has been completed, the drawing is checked by the chief development engineer and ap-proved by the chief engineer.

The cultivation of 'feel' on drawings at this stage is a necessity, because lack of analytical data and methods, operational cycle, procedure or applicability of test results, still make it an impor-tant, time-saving, constructional factor. Calculations can then be restricted to tangible issues. In addition, when fabrication by welding is proposed, it is possible to proceed to design stage with a minimum number of parts initially, leaving reinforcement to empirical methods when the structure is tested.

POWER SUPPLY

Although some estimate has already been made of the type and magnitude of energy required, calculations have to be made to determine the power input in detail from the following:

1. Application of force. The means of performing the required tasks have been clarified earlier and must now be supplemented ; e.g. to give satisfactory work-holding to oppose the action of a tool and other forces acting upon it.

2. Work cycle. The cycle length and its variation has to be determined fully in the light of existing and future possible use of the proposed machine to ensure its widest adaptability. The case for control and programming of a complete processing cycle can now be considered and should take account of heating, cooling,


heat insulation and other external factors, such as vibration in-sulation or isolation.

3. Work handling. It may be desirable to introduce a magazine or a hopper to provide for a useful bank of work, or else a pick-up or transfer mechanism working to or from an adjoining machine. The power requirements involved should be considered.

4. Power source. This will be determined by the prime mover. Its nature and its utilisation for primary and, occasionally, secondary work through a suitable linkage has to be specified. It will be influenced by the mechanical advantage and velocity ratio of the link mechanism and hence mechanical efficiency maybe affected. Power, when not used continuously, can be provided separately for the secondary effects for reasons of economy or even externally when reliability of performance or automatic operation demand it. When a slightly larger electric motor has been chosen after an estimate of the inertia of parts to assess the starting torque and normal running, an accurate check will still have to be made on completion of the machine. There will be a number of factors at work to make the calculation in-effective; the chief one being misalignment. Selection points a re : type, output, position in use, direction of motion, speed and length of movement.

5. Circuit diagrams. Wiring circuit, hydraulic and pneumatic circuit diagrams have standardised symbols and form an essential part of a general arrangement. The cables, tubing and individual items of equipment can then be specified by part numbers, leaving the assembly drawings less 'cluttered', as the necessary channels and passages can then be indicated in part only.

PROPRIETARY ACCESSORIES

1. Power and facilities. Electric motors, heating elements, switches. Hydraulic power packs, cams, valves. Pneumatic or vacuum equipment (filters, reducing valves, lubricators and a whole family of valves with varied operations, including cylinders with or without cushioning).


R O U T I N E W O R K

The normal routine work in the drawing office could be divided into:

1. Modifications of administrative nature. These include cor-rections of drawing errors. This should take precedence for the obvious reasons that, if not attended to, it will seriously jeopardize the manufacture of parts succeeding the prototype. Also, the

2. Power transmission (couplings, bearings, pulleys, clutches, brakes and constant or variable speed drives).

3. Lubrication and oil seals. 4. Instrumentation, gauging solids, liquid, temperature, pres-

sure, humidity. Counting, weighing, recording, controlling.

instruments and their panels all have to be placed within the line of vision and the controls within the reach of the operator. This includes indicators, signal lamps, switches and their fuses, levers and press buttons.

DETAIL AND ASSEMBLY DRAWINGS

The purpose of these is to facilitate production. These drawings are usually the result of the combined effort of engineering de-signers, draughtsmen and sometimes a tracer, organised by the chief draughtsman. The chief designer will on the other hand, exercise technical supervision. Checking for areas of possible simplification he will consider whether anything can be eliminated or combined to serve more than one purpose. He may consider whether for example, access is required so frequently that a door with lift-off hinges is necessary rather than a simple cover with a quick-release fasteners; whether even this is needed; whether full use has been made of standard and proprietary par ts ; whether a common earth return is permissible; whether the house symbol or trademark can be moulded onto the cover; or whether alternative colour schemes can be reduced in number.


longer such correction is delayed the less clearly will the cir-cumstances surrounding it be remembered. The request for alteration would be raised in the workshops or by the inspection department and should as a rule go back to the draughtsman con-cerned via the persons who checked and who approved the drawing. In this manner it may be possible to devise a way in which the error could be minimised. The procedure will also act as a deterrent to shoddy draughtsmanship, although care is needed not to discourage draughtsmen too early in their careers. Good practice requires a modification reference sheet which should be made out if the recall of an issued drawing is involved.

2. Errors in the workshop. To preserve the goodwill of the production side, manufacturing errors should be attended to in a constructive way, irrespective of whether the request is based on an inspection reject slip or is the result of an informal approach or memo. However, a modification reference sheet must be made out whenever a permanent change in a drawing is desired.

3. Salvage. If a temporary sanction is needed for a part to pass inspection, this is best done by making a change in dimensions to be initialled by the senior engineering designer, which indicates that the functional requirements are not affected; it should also be initialled by the chief draughtsman to indicate that its inter-changeability is not affected either. (It should be noted that special regulations and procedures exist for aircraft components.) For prototype work only the interchangeability of sub-assemblies is inviolable; otherwise parts can be utilised which do not conform to drawing, always providing that they carry special labels and that a correct part is eventually used before proving trials are completed. Where it is simpler to build a new product, the old one can be relegated to form part of the development display or scrapped.

4. Modifications due to changes in design. Simple changes in dimensions seldom suffice and it may be desirable to take a print of the original, microfilm it for record purposes, or else redraw and file the old drawing into the cancelled drawing drawer. Naturally a modification reference sheet must be made out as


before. The design and drawing up of new parts have been dis-cussed earlier.

CHECKING

1. Detail drawings. These are produced usually by more junior engineering designers from a general arrangement. The work is supervised and checked by a senior person, usually the one who has produced the arrangement. The suitability of the drawing for production purposes and the completeness of manufacturing in-structions is approved by the production engineer or model shop foreman.

2. Sub-assembly drawings. The existence of these is sometimes dictated by assembly procedure, and sometimes by the sheer size of the assembly drawing which would otherwise be required. It is desirable that they be drawn by yet another draughtsman using available detail drawings. This constitutes a very useful check on interchangeability and dimensions and is an excellent method of training. On these drawings, however, mating faces for assembly into larger units should be dimensioned by the nominal figure and fit. Overall installation figures should also be given. They are checked by the senior designer and approved for formal appear-ance by the chief draughtsman.

3. Assembly drawings. Sub-assembly drawings would prefer-ably be used for making up an assembly drawing. If sub-assembly drawings are not available then detail drawings would be used as before. Assembly drawings are checked for interchangeability of parts and for completeness by the chief draughtsman and ap-proved by the chief designer for operation.

It should be clear from the preceding notes that the checking and approving procedure should always be observed. Therefore, work should not go out without the requisite initials, nor should the procedure be abused by accepting indiscriminately the initials of one and the same person. Where appropriate, Installation or Service Engineers are the persons to 'check' an Installation lay-out or an exploded view assembly.

D E S I G N R E A L I S A T I O N 21 5

8.3. Safety and Factory Inspection

The following points should be considered when designing and drawing special purpose machines or appliances.

(a) Guards and cowlings. Moving parts can be dangerous and have to be guarded. Whereas guards are special covers re-stricting or preventing access to moving dangerous parts, cowlings in aircraft are faired into the general outline of the machine to reduce drag as well as to facilitate access for inspection, maintenance and setting up purposes.

(i) Prime movers must be securely fenced. (ii) Transmission must also be fenced unless it is in such a

position or construction that it is as safe as if it were fenced (i.e. overhead position of shaft).

(iii) Every dangerous part of a machine should be fenced.

(b) Adjustments. Operation of unfenced or exposed parts should be by special permit and only allowed for absolutely essential work by appointed personnel (lubrication, in-spection).

(c) Cleaning of machinery. This work is not for young persons or women if the prime mover or transmission is involved; other parts should only be cleaned by such personnel if there is no risk of injury.

(d) Dangerous machines. A part is dangerous if it may cause injury to anybody acting in a way a human being may be reasonably expected to act in circumstances which may reasonably be expected to occur. Young persons must not work a dangerous machine unless fully instructed of the dangers, trained to take precautions, or under supervision. (Revolution presses, guillotines, semi-automatic wood-working m/c, dough mixing, sausage m/c.)

(e) Plant maintenance. For boilers, steam or air receivers, cranes, pulley blocks, lifts (cage guides), hoists, lifting tackles, there are statutory requirements for examination and a record has to be kept of inspection and test dates.



BALDWIN, E. N. and NIEBEL, B . W. : Designing for Production, Richard D. Irwin ( 1 9 6 3 ) .

BOOKER, P. J . : Engineering drawing practice, Chart. Mech. Eng. All (Sept. 1963) .

B.S.T.: Engineering Drawing Practice, B.S. 3 0 8 ( 1 9 5 5 ) . Workshop Practice, Handbook No. 2 ( 1 9 5 3 ) . Commentary on B.S. Wrought Steels, Eng. Series B.S. 9 7 0 ( 1 9 4 7 ) . Guide to the Selection of Fits, B.S. 1916 , Pt. 2 ( 1 9 5 3 ) . Primary Selection of Fits, B.S. 1 9 1 6 C . Data Sheet No. 1 ( 1 9 5 4 ) . Grey Iron Castings, B.S. 1 4 5 2 ( 1 9 6 1 ) .

BUCK, C . H. : Problems of Product Design and Development, Pergamon Press ( 1 9 6 2 ) .

MATHER, W. L.: The Design Problem of the Machinery Manufacturer, A.E.I. (Manchester) Ltd., Publicity Dept. ( 1 9 5 9 ) .

SANDERS, T . R. B . : Mechanical engineering standards, Chart. Mech. Eng. 127 (Mar. 1963) .

(f) Electrical safety. Standard institutions, electrical institu-

tions, governmental departments responsible for public

transport of various kinds, issue regulations governing the

selection of equipment, its commissioning and maintenance.

C H A P T E R 9

MATERIAL AND STRESS ANALYSIS

9 .1. Analytical Methods

STRESSING

Although some stress calculations are likely to be undertaken during the preliminary stages to establish the feasibility of a particular objective, a stress analysis cannot be undertaken until a proposal has been put forward, and even then it is usually con-fined to a selected new aspect of the design concept. However, when the design has been realised, resulting in the preparation of a complete set of drawings, a more critical and comprehensive stress investigation. is carried out. A particularly thorough in-vestigation is called for in aircraft and other means of transport as well as in such products as turbines, where safety is a dominant factor. In these cases the work is undertaken by specialised per-sonnel in the stress office, which forms organisationally a separate section of the drawing offices, and where stressing is undertaken for all components by analysis and destruction tests. When stressing is a less frequent occurrence, the work will be carried out within a separate group research department. This kind of analytical work is very much of the type which would appeal to an engineering science graduate. Indeed, it is doubtful whether, even with a modicum of creative talent, with preliminary in-dustrial training and attendance at a local college, a student would be capable after a 3-year concentrated dose of engineering science to do anything other than stress work without additional industrial training.

It is suggested that all articles should be at least partially

2 1 7


'stressed'. To facilitate reliability, this dictum should apply equally to mass-produced articles such as plastic coffee and tea spoons and not merely to aircraft and some means of transport . That this has not been so in the past can be noticed around us. For example, the comparative cheapness of plastics appears to militate against the application of the most common principles of engineering science and technology to such mundane articles as spoons. Thus, for instance, the universities and technical colleges in Britain are at present (without protest) letting the students and staff cope with the irritating phenomenon of a plastic spoon being broken when stirring coffee! Here is a practical design problem to be tackled. This is also a case where a firm should, if necessary, seek to employ consultants to help them to cope with the problem. To a 'stressman', a designer's approximate estimate of stress is not adequate. He employs at least one of the known analytical and experimental techniques to check the weakest par t or parts of each component. Nevertheless, some structures can be stressed accurately by simple mathematics :

1. Non-redundant members in pin-jointed framework.. ' 2. Shallow and simple beams or circular and rectangular plates,

subject to bending by a point or distributed load. 3. Circular shafts and beams of certain sections subjected to

pure torsion. 4. Cylindrical and spherical pressure vessels. 5. Rotating discs with gradual changes in section. 6. Shaft systems subject to torsional oscillations.

The stressman submits his report to the chief designer pointing out the weaknesses and suggesting remedies. Where these are acceptable to the designer they are put in hand immediately, where not, the chief designer must decide the alternative. For aircraft and similar work a special procedure is usually ob-served as part of the contract. In any case, the calculations and findings should go into the design folder, a copy of which is re-tained in the stress office.

MATERIAL AND STRESS ANALYSIS 219

SAFETY FACTORS

Neither the shape of the component nor the forces imposed on it present a completely determined problem for maximum stress evaluation. Hence the most important tool for any analysis is the safety factor. Known in some quarters as 'the factor of ignorance', it actually covers a multitude of inaccuracies inherent in the system of physical properties used and assumptions and ap-proximations made to simplify stress problems and make them solvable by normal means. So demanding is stress analysis for the optimisation of a design and for increased reliability, that addi-tional techniques have come into existence. To this category belong relaxation methods, but even with these some elementary and dominant factors which influence the performance of en-gineering components remain intractable and are overlooked. These problems concern residual stress of cold worked, or even accidentally overstressed, components and the effects of heat treatment. Whilst the former will show in a photoelastic analysis, the grid method has to be used foi the latter. The accidental overstressing and cyclic stressing, usually alternating in character, are more intractable and are dealt with as 'fatigue phenomena' . It is thus common practice at present to select a safety factor from an appropriate standard or handbook either as a fraction of the proof stress or ultimate strength, or as the maximum allow-able stress.

The continued use of the rather wide margins which these factors provide may be justified because working conditions are never completely predictable in practice and accurate assessment is seldom economically justifiable.

9.2. Experimental Methods

APPLICABILITY

Compared with some of the more ambitious analytical tech-niques, experimental methods have the advantages of being quicker and easier to apply. In this category belong full-size


analysis scale models and analogy methods such as the membrane analogy. Although they do involve some expenditure on ap-paratus, they represent a considerable saving in man-hours where applicable. These techniques are likely to influence profoundly the reallocation of manpower and to reduce the demand for scientific engineering personnel. This will not affect stress analysis alone, of course, but other branches of engineering activities as well. The proving and introduction of experimental methods, on the other hand, is likely to remain the preoccupation of engineering scientists.

It must be appreciated that there is no change in the basic assumptions of the theory of elasticity and that these still limit the accuracy and applicability of stress analysis:

1. Perfect elasticity. It is now well known that not only metals at elevated temperatures, but rubber even under normal tempera-ture does not maintain its shape under constant stress (viz creep), nor is the same stress required to maintain its deformation (viz stress relaxation). Apart from the known phenomenon of buckling, there is the added problem of instability when absence of initial deformation leads to rapid failure of a component under cyclic stress. The assumption of perfect elasticity must be taken to be nearly true, for any complex analysis, and the results correlated later if necessary.

2. Homogeneity. The assumption that the material is evenly distributed throughout its volume is not now believed to describe the situation correctly. This change in thinking may have been brought about by the extensive use of high polymers (plastics and rubber) as engineering materials. These consist of almost endless molecular chains which lend the material its extensibility. Ac-cepting the random distribution of chain links and crosslinks, the degree of crosslinking in vulcanised rubber can be assessed by an average value. This is analogous to alloying element particles within a pearlite matrix in steel. The criterion becomes critical with a coarser particle structure such as encountered in cast iron with its dentrites of austenite. It is also of considerable influence when considering the impurities which can be encountered. (See

M A T E R I A L A N D STRESS A N A L Y S I S 221

Plates 46 to 61 and paragraph on metallography.) While these facts have an influence on the thinking of metallurgists or polymer chemists, they are as yet not very useful to the steel or rubber spring designer, who still defines his material in terms of tensile, compressive or shear stress and strain, based on values resulting from standard tests.

3. Isotropy. It is sometimes assumed that properties are in-dependent of the direction of external loads. This is a fallacy, known to be wrong in stampings and in chilling contours of castings, but also known to be disproved in the case of plastic sheets where orientation has a marked influence.

4. The principle of St.-Venant. It is not always realised that the proximity of external loads to the point under consideration has no significant influence only if the distance is large. As photo-elasticity reveals in Plate 30, there is a considerable difference when the regions considered are close to the point of load ap-plication. There is also a marked influence on the relationship of the loaded to the unloaded surface area (seen in Plate 30) c.i.f. paragraph on photoelasticity). This is particularly true of a rubber specimen in compression where it leads to the introduction of a form or shape factor in rubber spring design.

5. Hooke's law. Only for some of the conventional materials does this law apply within the elastic limit. The elastic limit and the limit of proportionality do not coincide for aluminium alloys and ultimate tensile strength is even further removed ; thus 1 % proof stress has to be employed to replace ultimate tensile strength. Moreover, in the case of rubber, neither during com-pression nor tension is the relationship between stress and strain directly proportional. Plastic fibre reinforced mouldings and rubber in shear are the exception.

6. Elastic constants. It has been convenient up to now to assume that Young's modulus is the same for compression and tension. In plastics the modulus is dependent on temperature. For cast iron and rubber, for instance, it would be necessary to establish Young's modulus for a given deformation. It has been possible though to find a common formula for tension and compression of


(a) (b) (c) P L A T E 3 0 . Stress distribution in the vicinity of surface forces in bodies of small volume and large loaded surface. The local influence in (a) does not extend to the central portion of the member where stress

= PI A . Such is not the case in (c).

rubber which holds good up to 50% or 4 0 % deformation, by using shear modulus.

G A U G I N G METHODS

The methods used are as follows :

(a) Gauges

1. Mechanical extensometers are well established, but because of their comparatively large gauge length, their usefulness is limited to machine frames and larger components.

2. Optical comparators read off a mirror movement directly or through an optical lever system. Also collimators or auto-collimators, could be used in some instances.

3. The method which has been found very useful in measuring residual stresses is the replica grid method. The measurement consists of comparison of two grid line systems in a line com-


parator measuring microscope, taken before and after stress relieving.

4. When the measurement required is in one direction only, such as when measuring deflection of a part , it is possible to investigate the change in a gap consisting of the measured part and a reference part . For this a pneumatic comparator or acoustic wire comparator could be used. Because of the need for calibra-tion to a nominal value, this method is more likely to be used as a means of inspection rather than as a tool for investigation.

5. Electrical strain gauges work on the change in resistance of a sensitive wire cemented to the part to be measured. These gauges have the advantage of smallness ( 3

Α

2 in. to 6 in.), easy attachment, insignificant weight and reasonable sensitivity. If they are of the semiconductor type they can be very sensitive. Dynamic strains can be measured and a remote indicator can be employed. The points to watch are : that the gauge can short to earth through the cement; the cement is subject to creep due to temperature changes so that calibration may be required with each reading and a temperature chart to cater for temperature effects on the gauge itself, unless temperature compensation is provided for.

(b) Photoelastic analysis

Based on the properties of polarized light, double refraction and interface phenomena, the analysis can be undertaken with the help of :

1. Photoelastic bench with an ordinary and monochromatic light source, a polariser, analyser and quarter plates.

2. Models are made from biréfringent material which does not absorb moisture and has a low fringe value. Unfortunately, as the model is two-dimensional only, layers may have to be sandwiched with a high biréfringent value material before an analysis is pos-sible, or a frozen stress technique employed. On the other hand, the magnitude and direction of principal stress and maximum shear at any point of the section can be ascertained.


(c) Stress coats

These can be employed tor curved surfaces and are of the following types :

1. Brittle lacquer, in which only lines of maximum principal stress are revealed without an indication of the magnitude of stresses, except perhaps a varying degree of crack density to in-dicate stress concentration.

2. Photoelastic coat. The technique used in analysis is identical to that used on the photoelastic bench. In this case, instead of a bench and model, a hand viewer, a small field or large field meter can be employed. Providing the surface is accessible to light, a coat can be applied to any surface, giving an overall picture of the stresses. The coat can be applied to any structural material which is to be subjected to elastic or plastic deformation. It is possible to measure stresses at any point including stress concentration. The strain patterns can be photographed and for cyclic loading filmed with stroboscopie light and a camera or just a high-speed camera. Temperatures well below freezing point and up to 176°C can be accommodated. Higher temperatures up to 277°C can only be tolerated for short periods and correction factors have to be employed.

(d) Rubber models

Qualitative and quantitative information can be obtained by casting components in a mix of silicone compound and catalyst into a wooden or plaster mould (see Plates 31 and 32).

9.3. Fatigue failures

Wear and 'creep' will make their presence felt and should lead to the timely replacement of the affected part . Fatigue failures, on the other hand, are much more serious because they result in an apparent sudden breakdown. If the failure occurs in a critical part it may cause the destruction of the whole machine.


P L A T E 31. Three silicon rubber models with dynameter rings used in the development of a main bearing support of a Diesel engine.

P L A T E 32. Time-exposure of the left-hand rubber model in Plate 31. Relative magnitudes of total deflection at different points are shown

after the model has been marked with black spots.


PHENOMENA

Fatigue is said to be caused by alternating tensile and com-pressive stress, reciprocating linear shear, or fluctuating torsional load, as well as by momentous localised excessive stress loading due to machine breakdown. It may spring from one or from a combination of these causes. This failure is perhaps better known as such by various methods of testing (i.e. repeated impact, bending reversal and possibly by full-scale test failures) than by

Compression

Goodman's law

Soderberg's law (modified Goodman's)

Modified Soderberg's law

Mean or equivalent stat ic stress

F I G . 6 1 . Soderberg-Goodman diagram.

the accuracy of prediction of such failure in practice. With the more widespread use of photoelasticity, the more obvious sources of stress-raising can be better understood and hence minimised.

A Soderberg-Goodman diagram can help to relate static and dynamic strength in order to avoid fatigue failure.

For a plain specimen, the Goodman 's law represents a good approximation, as most results fall above the straight line from the endurance limit to U.T.S. It may be safer still, and thus preferable, to use the modified Soderberg-Goodman law which utilises the yield point. Whilst U.T.S. is mentioned in every

M A T E R I A L A N D S T R E S S A N A L Y S I S 2 2 7

standard, the yield point has to be frequently assumed as 0-8 U.T.S. Figure 61 shows the laws about which there is general agreement within the tensile mean stress region. There is less agreement when the mean stress or equivalent stress is com-pressive.

For a notched specimen (with undercut) it is necessary to estimate the notch sensitivity, or for components in general, the stress concentration factor. Similarly, allowance must be made for the effect of the manufacturing process (for increased strength, cold rolled, shot-peened or ground; and for lowered strength in machined, hot rolled, forged or hardened components). In this way it is possible to establish a lower or higher safety factor for a given set of circumstances, which could be represented by a parallel line below the one in Fig. 61.

Nevertheless, service conditions can never be fully ascertained and steps must be taken continually to remedy the causes and their effects on fatigue; to avoid repetition or reduce their in-fluence after failure has already occurred. Thus more care should be taken when using a machine for a purpose for which it was not built. What is also sometimes overlooked is that failures in service may be caused by cracks which are started by a period of over-loading due to a previous seizure or breakage of some part. In the design stage, such an occasion would indicate the need for introducing shear pins next to likely sources of trouble, when a local failure is preferable to a subsequent major failure.

C H A R A C T E R I S T I C S

Ductile ferrous metals show two distinct areas on the ruptured surface (see Plate 33) :

{.Fatigue crack. Smooth, discoloured, conchoidal rippled markings are the fatigue crack proper, indicating the gradual creeping of the crack from one or more centres.

Plate 34 is an example of the difference between crack initiation and crack propagation. Initiation of the crack is influenced by the conditions in a small volume of metal near the point of origin.


P L A T E 33. Typical fatigue crack in ductile mild steel.

Propagation is caused by stress distribution in the remainder of the cross-section in the plane of maximum stress. Plate 35 shows the shaft of a landing gear fractured during take off. Whilst nearly the whole surface of the fracture appeared as an overload failure (see Plate 35c), there was an abraded area near the fracture origin where surface markings were obliterated. At the edge of this area there was evidence of a small fatigue crack Ό ' on Plate 34. Subject to reverse bending the shaft had a small fatigue crack also in the fillet (Plate 35A) opposite to the original fracture.


P L A T E 3 4 . Landing gear pivot shaft fractured due to a small fatigue crack marked by arrow *o\

P L A T E 35 . Fatigue crack in side of shaft opposite to where fracture originated. A = undercut fillet, Β = fatigue crack, C = area fractured

in laboratory to reveal crack.


When broken open the depth of the secondary crack was found to be about 0*015 in. (see Plate 35B). By comparison with the size of the two abraded areas it was estimated that the original fatigue crack in the final fracture was not more than 0-030 in. or 2 % of the shaft diameter.

The distinction between the initial crack and the crack propaga-tion zone is of considerable practical importance, because it is the initiating fatigue crack that determines the fatigue life of the component more reliably and accurately. This may have to be based on an estimate after complete failure in the first case, but could from then on be anticipated more closely for the purpose of preventive periodic maintenance whilst redesign or modification of the part is being considered. Such a scheme should be in operation, supplemented with crack tests of troublesome parts, as part of the normal preventive maintenance inspection procedure.

2. Failure. This is the remaining area of the fractured surface of the section. It has a crystalline, occasionally fibrous appearance, showing the area of the final overload failure (Plate 35c).

CAUSES AND LOCATION

(a) Primary causes

A failure can be brought about by:

1. An error in assessing service conditions or the use of an old machine for a new purpose. Ignorance of the effects of introducing a new material to be worked on an existing machine. If such a step has to be taken, as is frequently the case, then it should be done in the laboratory first with the deployment of strain gauges and measurement of the current consumed to guard against overloading.

2. Assembly. Local overstressing in the absence of an adequate opportunity for the mating parts to bed in. Bolt failure could be caused by the bolt head or nut face not being square with the thread (see Plate 36). Fitting of mild steel washers under high tensile bolts may be the answer.

3. Erection. Failure can be avoided by gradual running in. The


need for an alignment check on erection can bé met where a flat bed machine is involved, but is more difficult where shafts and gears are concerned. Flexible couplings can remedy this.

4. Breakdown, overhaul and crack tests. Failure of some parts in a machine may easily and directly induce a local overload or even indirectly cause a temporary misalignment and seizure in another part of the machine. Shear pins and crack detection of suspected parts during repair and overhauls are called for. The method of crack testing consists of immersing a magnetised steel article in a bath of kerosene with a suspension of fine iron dust particles, where the cracks act as magnetic poles and collect the iron dust; or a dye penetrant such as anthracene in benzine and ultraviolet light may be used.

(b) Geometrical discontinuity

This is the most common factor to which a failure can be traced. Moreover, the failure can be anticipated and the factor can be positively identified as the focusing feature.

1. Change in diameter. Even a small change in shaft diameter, with an undercut or inadequately radiused (sharp) fillet, could be the location of a fatigue failure. (See bolt-head failure, Plate 36). Driving shafts of band saws which are subject to bending re-versal and varying torsional stress are an example (see Plate 37). From this it follows that the ratio t/r and a/r should be checked against the diagram Fig. 62 giving a stress concentration factor av. Thus a shaft with D = 105 mm, d = 95 mm, r < 0-2 mm gives av for bending too large for the diagram in Fig. 62; when fitted with a fillet, r = 10 mm although a/r is still outside; av

can be guessed as less than 1 -0. The edge of the inner race of a bearing abutting against the shoulder of a shaft when it is press-fitted is also an identifiable location of a crack, unless the shoulder is made redundant as a stress-raiser by a similar reduction in diameter on the other side.

2. Stress raisers. As the initial crack would start from a point of high stress concentration, features utilised for transmission of

232 FROM PROJECT TO P R O D U C T I O N

PLATE 36. Failure in a T-headed bolt.

force such as a keyway or splines have to be considered more carefully than others. Plate 38 shows two longitudinal cracks propagated radially, which originated in the keyway of a shaft which failed. The cracks are radially divergent because both side walls of the keyway are being pushed apart under load. If only one corner between the base and the wall of the slot is sharp, then the crack will propagate truly radially, perpendicular to the lines of maximum torsional shear stress. Plate 39 shows the simultaneous initiation of a transverse fatigue crack in an identical shaft as

MATERIAL A N D STRESS A N A L Y S I S 233

P L A T E 37. Typical cracks in rotating shafts.

Plate 38, but this time failure was due to bending and maximum shear. If the key is loose in the keyway it strikes one side of the slot and a fatigue crack appears, resulting in a failure by peeling (see Plate 40). The reason for this type of failure could be localised


F I G . 6 2 . Stress concentration nomograph.

The principal stress in the crank is more critical because of the presence of the oil hole than is the maximum shear induced by torsion. Bad design can be responsible for incorrect assessment of the loading imposed by the proximity of two stress-raising features in the same plane (see Plate 42).

(c) Surface discontinuity

In this category belong tool marks :

1. A roughly machined surface mark can easily act as a second-ary stress raiser (see Plate 43).

2. Grinding is no exception, as it sometimes requires undercuts. Alternatively, it leaves 'chatter ' marks when grinding is carried out into the fillet radius (see Plate 44).

over-stressing; the longitudinal crack has no opportunity to develop a transverse branch.

It has been suggested that the recurrence of a failure in the keyway can be reduced by radiusing both sides with the bot tom of the keyway with a radius of one-third of the depth of the slot. Similarly it is felt that a slot produced by a side- and end-cutter is to be preferred to the one produced by end-milling. Plate 41 shows two cracks initiated at the sharp edge of an oil hole and the oiling groove along the lines of principal stress due to torsion, which will produce a stress reversal from tension to compression.

M A T E R I A L A N D STRESS A N A L Y S I S

PLATE 38. Fatigue failure in the section of a keyed shaft.

PLATE 39. Fatigue cracks revealed by dye penetrant method in shaft, Plate 4 1 .

235


P L A T E 4 0 . Appearance of fatigue failure by peeling in a keyway.

P L A T E 4 1 . Failure of crankshaft initiated at the sharp edge of the oil hole.


PLATE 42. Fatigue cracks in forward steering arm of a car.

PLATE 43. Crack due to badly cut thread on stud.

237


P L A T E 44. Torsional fatigue fracture in a crankshaft initiated by bending, the fillet radius having grinding scratches.

P L A T E 45. Typical corrosion fatigue cracks.


3. Welding. Discontinuity of a fillet weld. 4. Corrosion. The endurance limit is lowered by corrosion,

even under conditions of mild corrosion when the loss of metal is negligible. Numerous fatigue cracks will start from the sharp pits, giving the edge a jagged appearance (see Plate 45).

(d) Influence of material

{.Insufficient factor of safety in design. The ratio of fatigue limit to ultimate tensile strength is 0-45 to 0-55, but can be as low as 0-4 for high tensile steel to compensate for strain hardening.

2. Residual stress. Cold heading reduces the fatigue limit at some points and increases it at others (cold rolling of car axles). Heat treatment by carburising, nitriding or induction heating by low, medium or high frequency and welding or welding repair, have a detrimental effect.

3. Electrodeposition. It is not advisable to build up stressed, worn parts by chromium plating. Flame deposition is preferable.

4. Inclusions. This is a form of material discontinuity and will be dealt with under the heading of Microscopical Metallography, being a phenomenon of sufficient importance to be dealt with in its own right (see Plates 47, 48, 51, 56, 60 and 61).

9.4. Microscopical Metallography

The purpose of a microscopical investigation of a suspected component or indeed any component, is to achieve a closer identi-fication of the nature of the structure or to make a search for flaws in the crystalline structure. Indeed, any investigation of a component failure would be incomplete without a check for flaws of the surface and fracture itself. The fibres or grains should be at right angles to the maximum shear or principal stress. Where the material is suspected as being the cause of failure, or where such a failure is difficult to establish, a metallurgist should be consulted. In the U.K. he is likely to be fully qualified by membership of the Institution of Metallurgists and he may be a graduate of a School


of Mining and Metallurgy, whereas if he studied abroad he will invariably be a graduate. The mechanical engineering syllabus does contain some theoretical metallurgy leading to the construc-tion of equilibrium diagrams for steel and carbon, but not always to the identification of faults in the microstructure of the material (i.e. practical microscopical metallography, a discipline of considerable technological importance to the design and development engineer and plant engineer).

M E T H O D

Samples are J in. to 1 in. square or in diameter and in. to f in. thick. They are separated from the parent component with a band saw or abrasive wheel in the case of hardened steel. Violent mechanical action or heating must be avoided. They are then mounted in resin and the surface is levelled by filing or wet grinding and finally polished. The recommended polishing medium is aluminium or magnesium oxide suspended in water, or diamond paste and the preparation requires practice. Softer metals can be polished electrolytically. An alcoholic solution of an etching agent may be employed but the etchant will depend on the material being investigated. Electrolytic etching can also be em-ployed with yet another etchant. The microscope used is a metallurgical microscope.

MICROGRAPHS

Only some of the defects occurring in steel are shown, identify-ing various inclusions.

PLATE 4 6 . Mild steel carbon 0*08% showing intercrystalline cracks in ferrite. These were produced by the action of hot sodium nitrate solution, while steel was subject to bending stress. Etched with 5 % nitric acid in alcohol.

PLATE 4 7 . Transverse section across the bottom of a pipe showing slag inclusion. Unetched. xlOO. Associated with presence of 'piping' in wrought iron.


PLATE 4 6 . PLATE 4 7 .



241

FROM PROJECT T O P R O D U C T I O N

PLATE 5 2 .

PLATE 5 3 ,

242


PLATE 54. PLATE 55.

PLATE 56.

243

FROM P R O J E C T TO P R O D U C T I O N

PLATE 57. PLATE 58.

PLATE 59. PLATE 60.

244


P L A T E 6 1 .

PLATE 48. Inclusion of manganese sulphide in a forging of 0-35% carbon steel, oil hardened and tempered. The general structure consists of a ferrite network en-closing grains of coarse sorbite; the separation of ferrite round inclusions (as here shown) is commonly observed. Etched with 1 % nitric acid in alcohol. X250.

PLATE 49. Sulphide films (iron and manganese sulphides) in ferrite in a steel casting containing 0 -4% carbon.


Etched with 1 % nitric acid in alcohol, χ 100 . Present when there is insufficient manganese to form man-ganese sulphide, makes material brittle when worked.

PLATE 50. Alumina in steel. Longitudinal section. Unetched. xlOO. Fine particles, not elongated by hot-working but having the appearance of black specks; difficult to polish without scoring the surface. Occurs in 'killed' steel.

PLATE 51. Manganese sulphide in steel. Longitudinal section. Unetched. χ 100. Dove grey. Not affected by ordinary etching in alcoholic nitric acid, but blackened by etching 5 minutes in boiling alcaline sodium nitrate.

- The direction of sulphide reveals the direction of forging or rolling, least harmful of all non-metallic inclusions.

PLATE 52. Roke in steel bar, carbon 0 - 4 % (ferrite and pearlite), showing decarbonised area (absence of pearlite) round roke. Etched with 5 % nitric acid in alcohol. x 5 0 .

PLATE 53. Roke in steel bar, carbon 0 -4%, etched with Stead's reagent, showing the distribution of phosphorous and the irregularity of flow of metal round the roke. The dark etching bands are those on which copper was deposited and indicate the regions jn which the phosphorous is lowest, χ 25. Rokes are due to blow-hole cavities lying just below the surface of the ingot. During rolling or forging the cavities are broken into, their surface oxidised and elongated often into a partially closed fissure. Micro-examination of trans-verse sections is required to detect seams and rokes with certainty. They are not easy to detect in hot-rolled bar by pickling, as the pickled bar almost always shows a reedy appearance due to fine strings of inclusions at or near the surface. The presence of such inclusions may also introduce some uncertainty into the indications of a magnetic test on machined or


cold drawn bar stock, especially if of free-cutting steel. In either case, micro-examination does not reveal the depth of severity of the defect.

PLATE 54. Distribution of inclusions in the ferrite forming the boundaries of pearlite grains in burnt steel. Etched with 1 % nitric acid in alcohol, χ 100. When steel is excessively overheated the more fusible constituents of steel melt and are squeezed into crystal boundaries and joints.

PLATE 55. Burnt steel 0 - 7 % carbon, showing large grain size, intercrystalline cracks and decarburisation. Etched with 5 % nitric acid in alcohol, χ 100. This happens when gas is liberated at these high temperatures, forming blisters and opening the surface layer for the expulsion of fluid material leading to oxidation of intercrystalline cavities.

PLATE 56. Ghost, consisting of ferrite rich in phosphorous and containing inclusions of manganese sulphide in a heat-treated 0 - 4 5 % carbon steel forging (ferrite net-work enclosing grains of sorbite). Longitudinal sec-tion. Etched with 2 % nitric acid in alcohol, χ 100. These streaks are due to local segregation of impurities during the solidification of the ingot. They become elongated during rolling or forging. If pronounced they may weaken the product in the transverse direc-tion.

PLATE 57. Transverse section from nickel-chromium steel forg-ing, showing dentritic structure. Etched with Stead's reagent. The regions on which copper was not de-posited are richest in phosphorus and appear dark under oblique illumination, χ 5.

PLATE 58. Longitudinal section from the same forging. Etched with Stead's reagent. Oblique illumination. The dark streaks, ghost lines as in Plate 57, would appear bright under vertical illumination in comparison with copper-coated purer regions, χ 5.


PLATE 59. Crack in microsegregated region of an oil-hardened

and tempered nickel chromium molybdenum steel of BHN300. DPN showed differences of over 50 in hardness between closely adjacent regions. Etched with nitric acid in alcohol, χ 100. This indicates ex-cessive interdentritic segregation in the original ingot.

PLATES 60 and 61. Cracks associated with non-metallic inclu-

sions in the martensite of a hardened nickel-chrom-ium steel. The cracks may have been formed during the cooling after forging or during the hardening process. They were not associated with microsegre-gation of the type in Plate 59. Plate 35 is a composite (three exposures) photograph taken by blue light from a mercury lamp with a monochromat N. A. 1.60. Etched with nitric acid in alcohol. Plate 60 χ 500, Plate 61 χ 2500.


BENNETT, J. Α.: Distinction between initiation and propagation of cracks, International Conference on Fatigue of Metals, Inst. Mech. Engrs. 548 (1956).

BRUNEL COLLEGE: The Selection of Materials, Dept. of Metallurgy (May 1966).

CAZAUD, R. : Fatigue failure and service experience and shape of part. Inter-national Conference on Fatigue of Metals, /. Mech. E. 581 (1956).

COTTELL, G . Α.: Lessons to be learned from failure in service, International Conference on Fatigue of Metals, Inst. Mech. Engrs. 563 (1956).

FAUPEL, F . H.: Engineering Design, pp. 644-785, John Wiley & Son (1964). FIELDEN, G . B. R. : A Critical Approach to Design in Mechanical Engineering,

Bulleid Memorial Lecture, Nottingham University (1959). FORREST, P. G . : Recent research on fatigue in metals, Chart. Mech. Eng. 148

(Mar. 1961). GREAVES, R. H. and WRIGHTON, H.: Practical Microscopical Metallography,

Chapman & Hall (1950). HARTMAN, J. B. and BENNER, R. E.: Stress analysis in design, Machine

Design, 187 (Apr. 1954). POPE, J. Α.: Metal Fatigue, pp. 55-80, 239-248, Chapman & Hall (1958). ROLLASON, E. C : Metallurgy for Engineers, Edward Arnold (1949). SPOTTS, M. F.: Mechanical Design Analysis, pp. 28-31, Prentice-Hall Inc.

(1964).


S P O T T S , M . F . : Design for expected life, Product Engineering, 2 7 - 8 0 (June 7, 1965) .

V . D . I . - F A C H G R U P P E K U N S T S T O F F T E C H N I K : Gestaltung von Pressteilen aus hartbaren Kunststoffe, Richtlinien 2 0 0 1 , V.D.I.-Verlag G.m.b.H., Düsseldorf (1957) .

V . D . I . - F A C H G R U P P E K U N S T S T O F F T E C H N I K : Gestaltung und Anwendung von Gummiteilen, Richtlinien 1 5 - 2 0 0 5 , V.D.I.-Verlag G.m.b.H., Düsseldorf (1955) .

V . D . I . - F A C H G R U P P E K U N S T S T O F F T E C H N I K : Gestaltung von Spritzgussteilen aus thermoplastischen Kunstoffen, Richtlinien 2 0 0 6 , V.D.I.-Verlag G.m.b.H., Düsseldorf ( 1 9 5 7 ) .

C H A P T E R 10

MODELS AND PROTOTYPE

T H E provision of models and product prototypes is a development activity which would normally centre round the development workshop and is divided into two distinct categories. Models and model making is best regarded as an extension of the drawing office activity, whereas the building of a prototype is more a continuation of project realisation, or project engineering. The prototype section may, in the case of a smaller firm, form an en-closure in the tool room or maintenance workshop with the ad-vantage of better utilisation of skilled personnel, just as a model-ling bench could be set up in a separate part of the drawing office. In such a case a small firm would perhaps employ a design and development engineer on the one hand and an industrial designer on the other, both reporting to the chief design engineer. For the purpose of process analysis it will be more useful to consider a set-up in which a large engineering division merits the establish-ment of a development workshop, where some of the facilities are shared between project engineering and industrial design.

10.1. Model Making

MODELS AND DESIGNS

The provision of models in different media, ranging from card-board components pivotted with drawing-pins or bent-over clips and held together with elastic bands to simulate a mechanism, to a plywood and papier mâché, plasticine or plaster models which require a particular set of hand tools and machinery with which the industrial designer will be familiar. His advice therefore on

2 5 0

MODELS AND PROTOTYPE 251

the making-up of even the simplest model is likely to prove very valuable. Accordingly he will hold the functional responsibility to facilitate the provision of models for the engineering designers, as well as to deal with those models and drawings which are within his own sphere of activity.

M O D E L WORK

Administratively, the industrial designer will be a member of the drawing office, directly responsible to the chief designer. He will, together with his assistants, form the industrial design section. The range of facilities provided will largely depend on the industrial designer's own requirements. Where necessary the in-dustrial designer should be able to use freely the machines in the adjoining wood-working and sheet-metal section of the develop-ment shop. Alternatively, when assistance by the workshop personnel is required, the industrial designer should be able (after having his request 'checked' by the chief designer and 'approved' by the chief development engineer) to hand the particular work over to the charge-hand of the wood-working and metal section for execution.

Below is a description of operations for making a plaster model of a freezer door handle. Also listed are tools and equipment used in model work.

1. Bench work. To begin with, plaster was cast into a block of suitable size. (It has to be noted that the waste has to be poured into a pail and allowed to settle at the bottom before the water can be poured into the drain, unless the available sink has been fitted with a plaster trap.) The side welts were layed out with a soft pencil. Next they were trimmed down with a skew or straight chisel. Plate 62 shows how the corners were trued and smoothed by scraping vertically with a template of required radius. Then horizontal lines were cut with a woodcarver's parting tool and vertical ones were added to the same depth (see Plate 63). Then the little pillows were rounded over with a gouge and finished by hand sanding.


P L A T E 62. Finishing the outside of a plaster model of the freezer handle.

P L A T E 63. Vertical lines are being added to the plaster model with a wood-cutters' parting tool.

M O D E L S A N D P R O T O T Y P E 253

P L A T E 6 4 . Gouging out a cavity in plaster with a Fosner bit is quicker than coring.

2. Bench tools. Slate plate bench; modelling stand with hand tools such as marking-out equipment ; wood carving tools ; plastic tools; flat rasp; sculptor's rasp.

3. Machine tools. The pillar drill with a Fosner bit (as in Plate 64) can be used at 750 r.p.m. to rout either wood or plaster. Other drill tools are: spar machine; wood boring, expanding and auger bits; countersink and trepanning tool. An end mill can also be employed. The following other suitable machines can be mentioned: oscillating vertical spindle sander; finishing vertical sander; horizontal disc sander or a combination disc and belt sander; jig, band and tilting arbor circular saws; jointer instead of hand plane; wood and medium metalworking lathes (for boring).


10.2. Prototype Work

The normal procedure for the administration of production should be employed as far as possible in building the prototype. Some of the various functions can be combined with advantage, several steps being taken simultaneously. The nature of the activity is shown in Fig. 63. With the submission of the design in

Issue provisional drawings and parts

list for design consideration

Costs Design Supply ι

Tool and component quotation and

delivery promises

Production methods, estimated time.

Standards, jig and Tool requirements

Agree Design, Cost, Volume, Production and Launching dates

F I G . 63. Prototype completion and acceptance.

the form of workshop drawings and/or sketches to the chief de-velopment engineer, the chief designer has discharged his immediate responsibilities. The drawings are then passed on to the project engineer already engaged on the project involving the following:

PROCESSING

The making out of a critical path analysis and obtaining authorisation for:


1. Requisitions to the buying department for all items not in stock. After consulting the latest issue of the list of stocked items (stock list) the requisition is passed on by the project engineer to the chief development engineer to approve, unless the price exceeds a predetermined figure, in which case it is passed on to the chief engineer for authorisation.

2. Works order in the form of a job card which is passed on to the development workshop. This is checked with respect to shop loading and the available production facilities and capacities, in-cluding the allocation of fitters for assembly work by the shop foreman, who receives copies of any requisitions made out with the order and approved by the chief development engineer. Where appropriate, any aspect of the matter can be raised at a weekly meeting.

3. Routing works orders passed to production departments via the production control in those instances where development shop facilities are inadequate. A request to the drawing office for additional full drawings may be necessitated by the physical separation of the production departments from project design and development.

4. Planning and estimating which will be requested from the production engineering department in outline, or where data is available, in detail, based on existing drawings and sketches with an allowance for allocated facilities and labour.

5. Subcontracting requisitions where company facilities are in-adequate or where delay due to other commitments would en-danger the fulfilment of the development programme.

PROGRESS CHECK

The works order having been accepted by the development workshop foreman, preferably in the form of a reference job card, will have dates for the commencement and anticipated completion. The latter date will be provided in conjunction with the shop loading chart, acknowledged by the project engineer and used by him in his project scheduling system. The most practical aspect of this will be :


1. Periodic follow up of all critical jobs to avoid bottlenecks. 2. Follow up at a predetermined date those jobs which, al-

though not critical, could become so if overlooked over a period of time.

3. Reallocation. As a -result of a check undertaken on the pro-gress of a job, the scheduling may have to be revised, the work rerouted and a new works order made out or a requisi-tion passed on for subcontracting with a correction in the C P . MT Subsequently a change may have to be made in the P.E.R.T. chart as well where in use.

COMPLETION

The chief development engineer is informed after the prototype is inspected on completion by the project engineer. The foreman passes on to him the job card with appropriate data and remarks for comment and filing into the project folder as follows :

1. The actual time spent. The total excess cost of any com-ponent up to twice the original estimate is acceptable without reference to the development engineer. Where this figure is ex-ceeded the job card would have to be passed on to the production engineering department to correct their planning and estimating where called for. Transfer from general or total funds allocated under the development programme is checked to see that up to three times the estimate was approved by the chief development engineer. Beyond this figure and up to five times the estimate, the request would have to be made by the development engineer with the support of the production engineer to the chief engineer. Where the total cost of the project was likely to exceed even this figure, authorisation from the managing director would have to be sought before the project was continued.

2. List of drawing errors for the chief draughtsman to take action where corrected drawings have not meanwhile been issued. The list will constitute a paragraph in the inspector's report. The development workshop inspector will be in close touch with en-gineer designs to initiate inspection procedures and later to report on them in the light of his experience.


3. Suggestions for design modifications to facilitate future pro-duction, for the attention of the chief designer, via the production engineer and the development engineer. In the appendix is the foreman's report which goes back to the chief designer with paragraphs for immediate action by the chief draughtsman as under para 2.

PROTOTYPE TRIALS

A brief report to the chief engineer by the project engineer on the performance of the prototype, together with sugges-tions, is checked by the chief development engineer to the project specification and approved by the anticipated user, i.e. shop floor superintendent and foreman, sales department or re-search laboratories, as appropriate. The report is then presented by the development engineer with the project folder to the chief engineer, who institutes further action or accepts the project as completed.

10.3. Development Workshop

ORGANISATION

The foreman of the development workshop is responsible to the chief development engineer for day to day operations. Where possible the foreman will receive a job card for each item, made out by the project engineer and based on data received from the planning and estimating engineers. Alternatively, where these are not forthcoming, the project engineer has to make his own assess-ment of the work wanted. Where the production engineering de-partment has provided an estimate it will be compared with the time actually booked before the work goes into quantity produc-tion, to enable more accurate estimates to be made. Adjustment will then be made between the difference in the appropriate work-ing rates of operators on production work and those in the de-velopment workshop. The workshop is divided into the following sections:


ENGINEERING SECTION

At its head will be an inspector who will, whilst functionally responsible to the chief inspector, at the same time be the acting deputy to the workshop foreman. As a section it will have its complement of light to medium machine tools, with skilled opera-tors and fitters at their benches. It may be noted in view of the fluctuating work content that there will be a preponderance of machines to operators, because fitters where necessary fill the gap by helping out as they feel capable and as directed. The cleaning and maintenance of each machine and its tools, clamps, etc., will be the responsibility of one person. To assist in tracing and replacing broken equipment, booking sheets will be operated. N o person should maintain more than two machines, each fitter looking after at least one of the jointly used machines.

PROJECT ENCLOSURE

The enclosure is a lock-up and the key is with the foreman who provides all the facilities. Duplicate keys are held by the project engineers, each of whom will have a corner for his project as-sembly and project component storage shelves, desk and filing cabinet. A fitter's bench should also be provided in the enclosure, to facilitate work undertaken by the personnel detached from time to time from the engineering section, under the supervision of the project engineer, to assist in the project work. Naturally, where several project engineers have to share certain facilities, it may be necessary to appoint one to be responsible over each facility in preference to their costly duplication.

10.4. Project Conclusion

ELIMINATION OF DEFECTS

When a prototype has been completed and factory tested, a second one is sometimes produced, or the existing one rebuilt, to enable functional modifications or improvements to be incor-


porated. The latter procedure is suited to plant development and special purpose machinery. A complete set of production draw-ings is required if a product batch is to be manufactured. The development committee's recommendation on the allocation of further funds and the chief engineer's approval is required if the project is being referred back or the project specification is to be modified. The project cannot be regarded as closed until it has been shown to be complete and acceptable to the works produc-tion committee (and to the sales director in the case of a new product).

PRODUCTION PLANNING

Unlike a special purpose machine, a product requires further nursing before it is ready to be launched. This is usually a phase in which the chief engineer is more directly involved by having to arbitrate frequently between the works manager advised by the production engineer and opposed by the industrial and engineer-ing designers but supported sometimes by the chief designer. The motivation is the reduction of production costs. Good ex-amples of such an endeavour are Figs. 64, 65 and 66. A systematic method for revision is called value analysis (or value engineering) or preferably as defined earlier, raising the engineering value. Cf. Section 6.3, Evaluation.

PLANT INSTALLATION

Timing or integration of the development project has to be organised in such a way as to cause the least dislocation to production. It is organised by the chief engineer with the con-currence of the whole of the production side concerned. Apart from individually developed special purpose machinery, the chief engineer will be responsible for replanning workshop floors, including provision of buildings with factory services and specifica-tion of new machine tools to conform with planned work flow, before a new product line can be started. Thus, apart from develop-ment project and design tasks, there are production engineering


Lock nut ν Pressed steel body

Re-designed lock body resulting in:-

Reduction in material cost

Reduction in number of components

Reduction in assembly time

Improved appearance

F I G . 64. Lock design simplification.

Original design A f i e r modif icat ion

Sect ion X X

A n assembly comprising a 3 steel pressings b A forging boss c 4 rivets

and requiring

A riveting operation 6 spot welds A machining operation boss

Cost 5 / -

Weigh t . . 88 lbs

Sect ion Z Z

T h e pulley formed as a one piece plastic moulding

Cost____2/ -

Weight . .22 lbs

F I G . 65. Pulley and fan cost reduction.

MODELS A N D P R O T O T Y P E 261

riqinai design of oil pump

Oil outlet

Oil drains away from pump, design modification I required to correct fault

Oil level maintained

( A J i m Suction pipe raised to form oil trap

Steel stud press ft m. casting

Machine cut steel gears

- — O i l suction pipe Section ΔΑ

Design modification to improve function

Gear material changed to sintered iron

Machining eliminated on both gears

Improved production method and cost saving 2/-

Driven gear and stud formed integrally in sintered iron

Machined stud eliminated

Improved production method and cost saving - / 4

d

F I G . 6 6 . Function and cost improvement. Oil pump.

studies and production line reorganisations constituting projects in their own right. Approval is required from someone other than the chief engineer for such involved projects, although some will involve purely production problems.


D A V I E S , H.: Value analysis as a working tool, Chart. Mech. Eng. 6 0 (Feb. 1966) .

G A R R A T T , A. J.: Value analysis, engineering and control, Jour. B.B.S.I. 13, No. 12 , 2 7 5 (June 1966) .

K N O B L A U G H , R . R . : Model Making for Industrial Design, McGraw-Hill ( 1 9 5 8 ) .

S C H L E S I N G E R , G.: The Factory, pp. 2 6 1 - 7 5 , Pitman ( 1 9 4 9 ) .

C H A P T E R 11

LAUNCHING A PRODUCT

THIS chapter deals with the technical activity of an engineering company which is sufficiently large for production engineering to come under the chief engineer and production control (being clerical), to come under its superintendent responsible to the works or production manager. The manufacturing activities are listed by their functions, Fig. 67, A to F.

11.1. Production Engineering

The launching of the production of an article is best organised on the basis of its own C.P.M. diagram and bar graph drawn up in conjunction with marketing, drawing office and production control departments. Where this involves commissioning new buildings or a complete new factory, P.E.R.T. may have to be employed when it will serve in addition as a guide to the chief engineer of the mother plant, who is supervising the work.

ACTIVITY

To the production engineering function of operation planning and scheduling already mentioned in the preceding chapter must be added the allocation of machines, tools and gauges. The posi-tion of the production engineer is analogous to that of the develop-ment engineer discussed earlier on. He will be acting as the executive in charge of the details of the launching operation and the chief engineer will be in the chair of the production committee (see Fig. 68 for the organisational structure).

262

LAUNCHING A PRODUCT 263

From data supplied by Design and Development (engineering)

And by Sales Division

Identity Size Shape No. off per Assy. Material

Production Γnqineerinq ."p^lr.p

I A ) Process Planning — Operation sequence Machine Tools Special Tools and Gjuges Time allowed

© Work Study-Labour requirements Floor space and Lay-out of Machine Tools

Production Control c

afeguard

ι Β ) Pequisition — Buying Stock items

(5) Programming and Progressing — Production orders Production Control (Routing, Scheduling, Progress Plc-frng)

Other manufaclurinq functions

(fT) Cosi Control-Direct cost (Labour, Materials, Direct Fxper.se) Overheads

© ) Quality Control-Inspection Components Final Inspection Product

F I G . 6 7 . Manufacturing functions.

2. The provision of jigs, tools and fixtures. This will be pre-ceded by a tentative plan of operations including information about quantities proposed and manufacturing facilities provided. Figure 69 provides an indication of the relationship between direct cost, type of tooling and scale of production.

3. Seeing through the final planning, estimating, establishment of the production schedule, Gant t charts, C.P.M., and inspection control methods and procedures in connection with the pilot batch is the next stage.

This concluding phase of a project's life cycle can be sub-divided, from the point of the production engineer's responsibility, into the following stages:

1. A pre-production batch of commercial samples for display and market analysis has to be approved by the managing director, accepted by the chief engineer and acknowledged by the sales department. The production engineer organises the production function, possibly by combining the efforts of development workshop and toolroom.

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Issue of Final Drawings and

Release for Tooling*

Sales

Prepare Publicity and Literature

Marketing arrangements Distribution and Sales Promotion Programmes

Design

Service Drawings

Maintenance Instructions

External approvals of

prototypes

Production Inspection

M/C Tool Equipment Inspection programme

Assembly Jigs and Fixtures

Forward Production

Programming

Equipment

Inspection Method

Inspection Personnel

Supply

Tool orders

Component orders

Stores

Trial run Approve

Production Committee Production

Release Meeting

Sample approval

Modification procedure for design changes after this point

Bulk production Production Control

Launching date

Take-over by Works Management

Design Production Supply Inspect ion Sales

FIG. 68. Launching of product. Release for production and marketing.

4. Arranging for pilot batch order to be placed with the works production control. The pilot batch is run off to test tooling and to facilitate product familiarisation by all production departments. Details will have been discussed by the production committee and approved by management on the request of the production side, after having received an initial but substantial order from sales department.

L A U N C H I N G A P R O D U C T 265

Direct cost

Design tooled for small batch size

Design tooled for medium batch

Design tooled for continuous production

Quantity of products

FIG. 6 9 . Tooling and production costs.

PRODUCTION ORGANISATION

The kind of organisation employed will depend on the variety and number of products:

1. Where the batches of assembled products are small, say, 1 to 20, and where the products vary considerably, the production can be grouped according to type, precision and size of work and allocated to self-contained workshops with their own fitting, machining and assembly facilities. The foreman handles material requisitioning and job scheduling. The inspector, as his acting dep-uty, does operator loading, first-piece and 100 % inspection between operations; he also undertakes functional and final inspection of assembled parts daily. Bar charts compiled by the foreman on the basis of works orders, operations and man-hours involved are

5. The processing of data on snags, delays and achieved de-liveries, and the compilation of the confirmed production method with realistic terms of delivery for future orders as ac-cepted by the production committee.

6. To arrange the handing over of overall responsibility from the chief engineer to the general manager, after any remaining misgivings on the production side have been allayed.


produced weekly. Operational research would be of assistance in determining the size of the workshop and the facilities needed.

2. When the variety is restricted to, say, several sizes or models of one machine, -operational research will be able to assist in devising a suitable sequence of operations for doing most of the jobbing (batch) production, on a production line. The first step is likely to be a histogram. Categories or parts may then be grouped into lines to achieve a flow line arrangement to determine the minimum number of operators required to run satisfactorily the required type and number of machine tools. Before introducing a new product, replanning of the production layout of a factory may show that flow line manufacture for short-run batches of similar components and operations is entirely feasible. Gant t machine-loading charts can be made to indicate spare capacity. A game analysis can be used to test the proposed set-up. A bar graph can then be made out for the more important products in order to assess the lag between commencement and completion of scheduled orders. A central inspection department operating 100% inspection of machined parts and functional tests of assembled products and final inspection would be in operation. In addition, first-piece inspection and one or more patrolling inspectors making sample checks on key operations may also be employed.

3. Mass production. The maximum output of a separate produc-tion line will depend on the station with the lowest output. The essential point in the layout of a new flow line is to site it so that where the capacity of a station exceeds considerably the present requirements, additional parallel lines can be built on to it to use up the extra available capacity if required. The siting would then permit the joining of one or more production lines at the station with surplus capacity from where they may again diverge and continue in parallel. Statistical quality control with functional and final inspection of assembled parts may be all that is needed. A separate flow line can be set up as soon as 15% of the envisaged output of the process plant has- been utilised.


11.2. Work Study

As the title suggests, this technique is best exercised on an existing production line with an established production cycle, to indicate where there is room for improvement. Such study could thus form the basis of future development projects.

ACTIVITY SAMPLING

This is another work study technique utilising statistical an-alysis to obtain standard times for work. It is also a useful tool to determine the position and nature of the main hold-ups. The strictly random interval is only necessary when analysing work containing periodic features. Where conveyor work is involved, a rated activity sampling has to be used, by which the tempo is assessed immediately after a snap observation of what the operator is doing. This technique therefore reveals only what is being done and how effectively.

M E T H O D STUDY

This is a technique which will involve a periodic reconsideration of the manufacturing process in the light of technological ad-vances in the intervening period. This is where the creative in-tuitional ability of the production engineer comes into its own.

P . M . T . S .

The predetermined motion time system depends on providing means of analysing tasks into the basic motions of which they are composed and assigning a predetermined time to each motion; the sum of these providing a basic time for each job . This approach appears to be limited to actions which do not have a high content of intricate finger motion, but maintain a reasonably short and regular motion pattern within job cycles.

T A B L E 7. I M P L I C A T I O N S O F T H E Q U E U E I N G P R O B L E M S —

Results of the theory Implications for the storekeeper

1. Service time constant rather than random, halves waiting time.

Study store layout and arrangement so that long 'seeking' jobs are avoided.

2. Even if jobs must arrive at ran-dom arrange that appropriate number of jobs do arrive in work period.

(a) Do not worry about slight queues, but do provide help quickly when build-up starts.

(b) Establish a routine for dealing with regular demands, e.g. hand tools at scheduled time.

3. More than one agency serving will approximately divide pro-cess times by the number of agencies available if arrivals and service is random.

Avoid small one-man stores, try to have big enough stores to keep two windows going. (This does not im-ply large centralised stores.)

4. Reduce the length of service time.

Arrange stores and clerical pro-cedure for expeditious work. This is an argument for small stores.

5. Have major part of a random arriving job done before the whole job is needed.

5. Caution. Avoid spoiling the present by preparing too much for the future.

6. Replace random events by planned events.

6. Caution. Avoid queues going under ground.

Send requisitions to store ahead of workmen, so as to eliminate work-men waiting while storeman looks for materials.




6. Caution. Avoid queues going under ground.

Do not send requisitions to store more than a day before they are needed—provided you know the material is available.




6. Caution. Avoid queues going under ground. Do not object to people waiting at

stores—or they may learn to loaf out of sight.

7. Break large queues before they form.

Put extra trained men in the store to help when need arises.

M E T H O D S O F R E D U C I N G D E L A Y S

implications for maintenance Implications for managers

Try to split maintenance jobs into bits of about the same duration. Do not rush a job if it is going to lead to a longer one next time. Study ways to avoid long jobs.

Avoid being caught on (he hop with rush jobs. Big jobs should be pre-planned to reduce the incidence of crises.

(a) Do not let maintenance get be-hind, schedule and plan ahead for absences, holidays and peak periods.

(b) Schedule maintenance load as far as possible leaving space for expected unscheduled work.

(a) Establish a routine for seeing people before they have big problems building up.

(b) Keep an appointment book. (c) Do not fill every unforgiving

minute', plan to have spare time.

Avoid undue specialisation, train to have more than one man or a ma-chine able to do each job.

Build up subordinates, so that they can, and do, make the same de-cisions you would have made. Check that this happens.

Use method study (man and ma-chine charts and work elimination) to ease work. Keep records of job times to ease work next time and set targets.

Evaluate your performance. Can tidier drawers or files, or visual aids, help to guide decisions, or reduce the need for memory work. Make sure records are useful and easily available.

Get shop work done before the need for breakdown material is made. Use routine inspection to plan work before work is needed.

Do not waste subordinates' time (if you do, they will avoid consulting with you). Try to inform yourself about their problems before they come to see you.

Do not let unused spares pile up. They only confuse. Make use of preparatory dismantling time for shop work.

Avoid detail thinking far ahead. Too much thinking ahead, or on more than a few things at a time, prevents concentration and spoils present decisions.

Use preventive maintenance. In the example studied it would be worth doing twice the necessary work to eliminate random work.

Plan ahead to avoid rush meetings. Warn participants so that they can prepare for it. Rely on system not judgment—usually.

Check used parts. Keep records and estimate job times to keep men from underload as well as overload.

Do not let secretary stone-wall callers. Keep open door for the exceptions. Do not kid yourself that everything is planned.

Avoid regular overtime, use over-time when unusual backlog arises.

Do not overload yourself, avoid regular overtime. Keep fit to work late on costly rush jobs.


OPERATIONAL RESEARCH

The aims of investigation under this heading could consist of: 1. Inventory of idle resources in men, material, machines and

money in production, purchasing and stocks, training and re-placement of labour, and investment policy.

2. Allocation of resources among the activities that have to be carried out. It could include studies of comparative advantages of various alternative company policies, but is more likely to be used to investigate machine loading and work flow.

3. 'Queueing' is an analytical method used to confirm the correctness of decisions made or to check proposed solutions to problems of congestion and delays. It will, therefore, concern itself with the availability of factory service facilities, clerical services and the demand for them, by physically simulating a mathematical situation which resembles the problem (see Table 7). The analytical results can be plotted and graphs drawn as shown in Figs. 70 and 71.

4. Using the theory of games is another way of finding the time in the queue by setting up a numerical model of the situation and observing it to determine what would happen in a real situation.

11.3. Manufacture

BUYING SPECIFICATIONS

At this stage the designer presumably in co-operation with the buyer, would have decided on specifications for materials, bought out components or sub-assemblies, and on the work to be sub-contracted such as heat treatment, plating or finishing. The specifications and sources of supply should be kept under con-stant review. In order to hold down cost the specifications must be unrestrictive, up to date and, where appropriate, should list re-liable sources. On the other hand, it is essential that the buyer should keep the engineering and sales departments informed of fluctuations in prices when these are significant. The buyer, at-


tempting to tie down the suppliers to a firm figure, is frequently faced with reservation clauses (in small print on the back of the acceptance of order), which the vendor introduces to cater for such events as wage awards so that he will be able to pass the cost on. These provisions include changes in import duty of com-ponents and freight. The provisions are seldom applied, except to long-term and large contracts when they could constitute a reason

120

110

100

J= 9 0

- 8 0 ω σ> σ 7 0 ω

σ 6 0 ω . | 5 0

S 4 0 <υ υ 2 3 0 û_

2 0

10

0 1 2 3 4 5 6 7 β~

Average size of batch, hr

F I G . 7 0 . The effect of increasing size of batch on the average process time at two outputs of product. (Distribution of orders and batch times

assumed.)

for non-performance. If materials or components require special handling inside or outside the factory, the designers should note this on the specification in the parts list. It may also be necessary, where appropriate, to specify the acceptance conditions for in-spection. It may even be necessary, for example, to specify certain details regarding packing, while some components may have to be sent out for finishing on jigs so that provision will have to be made for an adequate number of jigs to be included and the method of transport and their return specified and costed.


150

140 ω E

130 α

120

α> (S) I 10 ω c le

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σ E 9 0

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ο. 7 0 ί: 3 Ε 6 0

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to α> ο 2 0 ο α. !0

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^ ^ - ί = 0 · 5

/ζ '/3 Va '/5 '/β '/? ' / β

Set up time divided by machine running time

F I G . 7 1 . Variation of process time with reciprocal of batch size at different outputs. The dotted curve shows how increased output re-

quires larger batches for least process time.

QUALITY CONTROL

This could vary enormously, depending on the inspection re-quirements for an engineering product as laid down by the com-pany's inspection policy, or by the customer (notably by government departments) who may stipulate special conditions. In any event there will be a chief inspector who should rightly report to the general manager or chief engineer, particularly in a non-engineer-ing firm, with copies to the other managers concerned.

The cost of inspection is normally a direct charge on produc-tion and it is best kept this way in a mixed engineering production


unit, as it may fluctuate over quite a large percentage (say, from under 1% to 10%) of direct and indirect labour costs. To pre-serve initiative, prevent discontent and reduce expenditure, some form of piecework can be operated in some cases. Where an improvement in technique is brought about an increment in salary in lieu of promotion can be offered with advantage. The costs of inspection may have to include the expenses of visiting or resident inspectors from the customer, who often carries out his own inspection over and above that carried out by the manu-facturer. Inspection can be considered in relation to the stages of manufacture :

1. Sampling inspection of incoming materials and components where obtained under a specified standard or inspection release from the supplier's inspectors. Generally the degree of inward inspection will depend largely on the supplier; when a supplier is known to fulfil the requirements of the buying specification to satisfaction, only random inspection may be required, although for some components there may be a requirement for 100% in-spection. This should be known from experience and allowed for in the costing. Any rejection slips made out will be passed back to the buyer who will then be responsible for notifying production and engineering departments if production delays may result. The design engineer may be called in at this stage to see whether a lower standard can be accepted, or to offer suggestions for alternatives.

2. Working inspection, 100% inspection or statistical quality control for manufactured products, is usually unavoidable. Random sampling may be adequate in those cases where satis-factory uniformity is provided by production machines. Sometimes checks between operations are required.

3. Functional inspection of the assembly or sub-assembly may be influenced by the degree of supervision on the shop floor and by the encouragement given to mutual supervision in production, which may reduce the cost of inspection but may slow down output. Assemblies and sub-assemblies may be checked on the spot or may have to be taken away to be inspected on special


plant or jigs which cannot be placed in the shops. In electronics this is frequently necessary as elaborate tests may have to be carried out under special conditions in a laboratory.

4. Final inspection will consist of ascertaining whether any damage done during assembly has been put right. This is of great importance as it ensures that the customer gets what he sets out to purchase, as the reputation of a company frequently depends on the reliability of its products. It is for this reason that the chief inspector has an over-riding responsibility delegated to him by the management. He will have copies of rejection slips for periodic approval after they have been initialled (checked) by the foreman concerned.

PACKAGING

Although packaging is the prime responsibility of the industrial designer who ensures that it protects the product, secondary considerations such as its value for advertising, house symbol, product sale appeal, sea or air freight cost may be a job for specialists. The design department should have been informed about the physical requirements for packing, i.e. is it to be despatched by rail, air, or road, is it suitable for export to the various countries concerned (some countries refuse the import of certain packaging materials)? The merchandise superintendent should be called in to design meetings as soon as the external con-figuration of the product is known. He will be able to advise on maximum size and weight of packages for the different means of transport. Where heavy machinery is concerned he will also advise on the necessity for special support frames and removable strengthening members to protect the product in transit. If the quantity justifies it, special cartons may have to be made and it is imperative that these arrive before the products are manufactured as there is nothing more frustrating than to have finished goods lying round the factory getting dirty or damaged while waiting to be packed. This may demand liaison with the packaging suppliers at an early date, particularly where for various reasons the goods may be stowed only partly assembled.


INSTALLATION INSTRUCTIONS

The first set of instructions issued will almost certainly be temporary as there may not be enough experience to give a guide, in which case the methods of reproduction for advance leaflets will apply, except that if installation is likely to be a messy job then protection of the instruction sheets is essential. Varnishing as part of the printing process is suitable for quantity production, but a sealed plastic bag in polythene or PVC is a cheaper method for a double-sided sheet, whilst heated foil coating for lubrication charts is useful. It is desirable to fasten noticeably labelled in-structions to the product to prevent them being discarded with the packaging material. Special care should be taken with electrical apparatus which has to be provided with adequate warnings, in-cluding a tie-on tag on the junction box or lead. This is not only important when indicating supply voltages, frequency and con-sumption but also colour coding which is now agreed interna-tionally but can lead to serious damage of equipment.

11.4. Marketing

PUBLICITY ASPECTS

At all stages of the development of the new product the market-ing department will consider the publicity material required which would assist them in selling the products. Liaison between the engineers and marketing department is essential, except on points of detail relating to sales or production. The marketing manager will, of course, have been kept informed on progress from the reports, but the chief design and development engineers will be able to give special assistance to marketing, particularly in the preparation of sales literature, press releases and technical articles. All these should be well under way before production commences.

For the sale of an engineering product four separate items ought to be considered :

1. Preliminary advance leaflet for distribution to home sales departments, overseas agents and associated companies.


2. Sales brochure. 3. Installation instructions. 4. Maintenance handbook.

T E C H N I C A L A R T I C L E S

There is, in addition, another aspect of publicity which is fre-quently overlooked—the technical article—which can in fact be of immediate value in bringing in advanced enquiries about a new product. This aspect is well worth cultivating amongst engineering firms and their engineers as it adds prestige to both of them. Any fee paid by the technical journal should remain the property of the employee who wrote the article (on the assump-tion that he does so in his own time.) In fact, some companies explicitly encourage this aspect of publicity by automatically doubling any fee obtained by their employees, providing the company's name is mentioned, though the article may not be directly connected with the company's products, e.g. a process or a piece of research. Several weeks of intermittent work are often required for the preparation of a technical article, but the project history and report already provide the theme. The pre-sentation will vary and must be adjusted to suit the editorial policy of the magazine concerned if it is to be accepted. Liaison with technical, journals is properly the job of the publicity officer, but very often the chief engineer or technical director has also been in touch with some of the editors during his career. Special-ised trade journals in particular have a high repute and wide distribution throughout the world and editors can be taken into confidence on new projects so that they can state at an early date whether they are interested in featuring a new project or some special aspect of it. The article may, for example, appeal to a specialist magazine dealing solely with matters of technology, but at the other end of the scale may be a research report ready for publication in an institution journal. It is as well to organise technical articles long before the project draws to a close. Much of the material required such as photos, drawings, graphs, will in


any event have to be prepared for use in technical literature. Whether the initiative stems from within the (irm or outside it, the article will have to be submitted through the chief engineer as a matter of form for approval. Most firms will have a special routine for this to safeguard their interests vis-à-vis patents; the timing too of the article may be important and publications should be in accord with the recommendations of the marketing manager who may wish to tie up special advertising with the article. Engineers should not therefore commit themselves to writing an article connected with their firm without proper approval.

ADVANCE LEAFLET

This may well be a duplicated document showing a provisional sketch of the product, or even merely an outline drawing. Most offices these days are equipped with several types of duplicators, but remarkably little imagination is used in setting out work and not nearly enough is generally known of the flexibility of these machines. A full-page electronic stencil costs under £1 and can accept a combination of typewritten material, lettering (by hand or machine), photographs and drawings : it is particularly useful for reproducing perspective sketches, such as the industrial de-signer might have prepared (see Chapter 5). Colour can also be used, but it is not easy to ensure accurate register on the standard office machine and would be difficult to use on shaded areas, though it is admirable for providing emphasis or interest value. On the other hand, though photographic reproduction is im-possible, the spirit duplicator is effective for colour as several colours can be used with perfect register. It therefore lends itself especially to graphs on which more than one line must be shown as it is much easier to differentiate colours than various types of dashed line. The spirit duplicator is, however, a limited process being restricted to about 200 copies from one original.

The small lithograph machines which are now becoming com-mon in industry are also very suitable for advance information;


drawings and typing can be done direct on to the metai plate, or a plate can be prepared photographically using a combination of photography, drawing and typing. The lithograph machine gives better photographic reproduction than the electronic stencil and the number of copies is virtually unlimited: furthermore, extra copies can be run off at a later date without difficulty. Colour can also be used in this process and a reasonably good colour register can be obtained even from modest office machines by photographic separation. Whatever the method of reproduction, an outline drawing- is essential. This must be dimensioned, pre-ferably in both inches and millimeters. The weight should be stated, or an approximate one if at that stage it is not known accurately. It must be remembered that on these details many overseas agents will have to build up their freight costs; therefore, technical literature of all types should state this, as well as details of performance such as maximum speed or output ; it is amazing how often they are omitted.

If reproduction involves a photographic stage, it is a waste of time to dimension and letter the drawing in ink by hand and the engineer or draughtsman should write legibly in pencil: the figures and lettering can then be typed on gummed paper and stuck on. If drawings are required for technical literature, then these should be charged to the marketing function and not the project. An electric typewriter is particularly valuable for interim technical literature and if not available within the firm, there are many agencies who can carry out this work. Some are now fitted with 'Varitype' machines which can take interchangeable types (including italics), thus making for variety and, furthermore, be-cause they type a whole line at a time, they can be arranged to 'justify' (i.e. all lines are the same length as in printing). Photo-graphic typesetting is now becoming available and this may ultimately be as economic as these specialised typing services.

SALES BROCHURE

Unless the company has its own printing department on a large scale (rarely an economic proposition) this work will be done by


an outside printer and will be handled by the publicity manager. In a large company the publicity department may do their own layouts and typography, but more usually this will be contracted out. The brochure will conform to agreed standards of size and presentation, which is in fact part of the house style (see Chapter 5). The industrial designer working on the product should associate himself closely with the sales brochure, unless the com-pany already has an established overall house style under a central director of design. It is possible that the latter may carry out the design himself, call in someone who can do it, or else arrange it with the company's advertising agents. Most sales brochures are printed on art (glossy) paper in order to make the photographic reproductions as good as possible. It is therefore essential that the illustrations themselves should be of the highest possible quality; the standard of commercial photography used by industry today is often abysmally low and this may be due to the fact that a good photographer is relatively expensive. It is frequently overlooked that a poor photograph has to be heavily retouched before blocks are made and, furthermore, that the costs of retouching frequently exceed the cost of a good photo-graph, which would certainly be valuable for other purposes. Because it is necessary to have the sales brochure ready at the same time (or even before) the product, it is often necessary to arrange the model or prototype to make it look like the finished product. The photographer should be carefully briefed on this as he may be able to change the effect of finishes by careful use of lighting (paint, for example, can be made to look like chromium plate by use of highlighting) ; furthermore, the industrial designer who has special skills in making materials take on other guises, can be of help. A great deal of time can be taken up by photo-graphy and, although it may well be justified, it should not be carried out in the laboratory or factory if it can be avoided. If carried out there it is difficult to avoid including a background of factory roof or untidy benches, the lighting facilities will be inadequate and a good deal of distraction will result (the loss of time in this respect can easily exceed the transport costs). Further-


more, if a photograph is taken under these conditions it is almost certain that the background will have to be removed by retouch-ing and this spoils an otherwise good picture. Record photo-graphs at various stages are valuable, but if a photographer is brought in each time, this will prove expensive; an amateur with good equipment is adequate for this purpose and well worth fostering by the provision of materials and facilities which he can use in his own time.

MAINTENANCE HANDBOOK

Here again the method of production will depend on quanti ty; for machines, where only a few handbooks are required, produc-tion may be by the office methods mentioned under advanced leaflet or by copying from the original typescript on an electro-static copier. The loose-leaf book is, however, preferred for products which require regular servicing due to the fact that modifications to the equipment, and changes in maintenance resulting from use, have to be accommodated. They may also have to be produced in a variety of languages. Certain basic recommendations can be given :

1. A hard and durable cover is preferred. If likely to be handled by personnel with greasy hands, the PVC sheet on rigid board is best as it can be wiped clean.

2. Pages should be numbered clearly (in the same position on each page) and paragraphs referenced.

3. Pull-out drawings, maintenance charts and circuit diagrams are very useful, especially if the area falling within the page width is left blank (i.e. no part of the text obscured when the chart is in use). It is often worth the additional cost of producing these on linen-backed paper and having them covered with foil.

4. N o handbook is complete without a comprehensive fault finding chart to help the customer's maintenance engineers.

5. A new index sheet together with a replacement sheet should always be provided showing the date of issue and any


amendments made. The provision of a separate office index of amendments showing when made, by whom, and where may also be useful. When amendment sheets are sent out it is highly desirable to be positive rather than negative by stating what should remain in the book rather than what should be taken out. This ensures that a missing amendment can be traced.

SERVICING

Most products require some sort of service, either of a regular or emergency nature. In the long term a company's reputation may rest on the speed of action, the availability of spare parts and their reaction to letters of complaint regarding the performance of the product, as well as upon the calibre of the servicing engineers in all parts of the world.

If regular servicing is called for, this is properly part of the design specification; in other words it is considered from the start, even if the details are not known (the preparation of main-tenance charts and handbooks is considered in Chapter 10), but detailing of the material is the responsibility of the chief engineer or the service manager (who may in certain instances be part of the marketing department). There is a great necessity for feed-back of information (especially on a new product) from service to engineering functions so that persistent faults can be rectified in production, picked up by inspection, or, in extreme cases, modi-fications carried out on items in stock. Speed is essential, as service in the field is obviously much more expensive than in the factory.

Experience is usually the factor which determines the level of spare parts to be manufactured and engineering designers usually give guidance on percentages when planning production with the production engineer. Allowances will also have been made for this in the buying specifications of bought out components.


LAUNCHING

The preparation of technical matter for the preliminary leaflet, installation instructions and maintenance handbook will inevit-ably fall on the engineering department and it is as well if the chief draughtsman studies the processes of reproduction available. Manufacturers of the various office machines will be found most helpful.

With the press show and later exhibitions at home and abroad planned, the product is ready to be put on the market. By then difficulties will have been overcome and arguments concerning the design, development and marketing resolved. It will not have been plain sailing, but it is hoped that this book has contributed in some way to a successful launching of a product.


E I L O N , S. et al.: Operational research, Prod. Engineer, 4 6 , 2 (Feb. 1967). N I C H O L S O N , D. L. and H A D N U T T , W. J. J. : Production planning and control,

Chart. Mech. Eng., 522 (Nov. 1962). P A Y N E , J. E . : Work study and related techniques, Chart. Mech. Eng. (Oct.

1963). P U T M A N , A. O. : Machine job lots on production line, Metalworking Production

(Mar. 15, Apr. 19 1961). R O B B I N S , E . L . G . : Company structure and organisation, Prod. Engineer,

236 (Apr. 1966). S H O N E , K. J.: The queuing theory, Time and Motion Study (Sept., Oct., Dec.

1960). T I C H A U E R , E . R . , M I T C H E L L , R . B. and W I N T E R S , N. H.: A comparison

between the elements "Move" and 'Transport" in MTM and work factor, Microtechnic 16 , No. 6 (1963).

T I C H A U E R , E . R . : Human capacity, a limiting factor in design, Proc. Inst. Mech. Engrs. 1 7 8 , Pt. I, No. 37 (1963-4).

W I L S O N , Α.: The Marketing of Industrial Products, Hutchinson (1965).

INDEX

Accessibility 71 Accounting 10 Accounts department 32 Accuracy increase 25 Administrative procedure 16, 35 Administrative project origin 32 Administrative supervision 46 Advance leaflet 275, 277 Aesthetic appeal 50 Aesthetic balance 98 Aesthetic considerations 165

affinity 169 colour 176 compactness, 167 parting lines 176 sleekness 167 stability 165 surface 176 veracity 165

Aesthetic criteria 98 house symbol 107 styling 106 traditional theme 106

Aesthetic element 101 Aesthetic influences 100 Aesthetic interest 101 Aesthetic features 98 Aesthetic unity 99 Aggregation by start date 63 Allocation

of funds 16, 30 of machines, tools, gauges 262

Analysis of design and development 2

Annual attributable earnings 33 Appearance

contrast 101 emphasis 101 evolution of 103

product 9, 93 proportion 100 repetition 100 rhythm 101 simplicity 99 stability 98 symmetry 99

Appointed readers 91 Appointment making and termina-

tion 7 Appreciation of design effort 2 Apprentice 3 Arbitration 46 Art schools 94 Article launching 262 Artistic sensitivity 93 Ascertainment of modifications 21 Assembly

drawing 72, 195 requirements 88

Assignment of patents 33, 34 Associated companies 47 Association, design by 77

Bar chart, diagram, graph 59, 63, 262, 265

Board of Directors 16, 20, 28, 32 Bottle-neck 43, 197 Bought out components (proprie-

tary accessories) 71,114,211 279

Brain storming 43 Breakdown of parts or units 50 Bridge of Fayol 5 Budget control of projects 26

for contingencies 49 for group of projects 12

Buyer 53, 57, 270

284 I N D E X

Buying department 57 Buying specification 270

Capital investment 18 Casting and pressure moulding 161 Central Advisory Service 15 Chain of command structure 4, 9,

36 Chambers of Commerce 52 Chief Design Engineer 203, 250 Chief Designer 5, 37, 39, 45, 46, 69,

75, 76,195, 201,202,204,210, 212, 214, 218, 251, 257, 259, 275

Chief Development Engineer 5, 18, 21, 36, 37, 38, 41, 42, 45, 46, 52, 55, 57, 61, 69, 72, 75, 76, 163 182, 195, 203, 210, 240, 250, 255, 256, 257, 262, 275

Chief Draughtsman 5, 39, 46, 120, 198, 201, 203, 205, 214, 256, 257 282

Chief Engineer 5, 15,16, 31, 32, 33, 36, 38, 39, 41, 42, 46, 52, 203, 255,. 256, 257, 259, 261, 262, 265, 272, 276, 277, 281

Chief Inspector 258, 272 Circuit diagrams 211 Circulation of minutes 38 Classification of information 89 Collective recommendations 36 Colleges of technology 53 Colour chart of Munsell 101 Colour complementary pairs 101,

102 Colour contrast 102 Colour discord 101, 102 Colour harmony 101, 102 Colour matching 102 Colour theory of 101, 102 Command structure 4, 7 Commercial director 182 Commissioning of buildings, fac-

tories 262 Company growth 17 Company image 95 Company management 114

Comparative efficiency 50 Competition 10, 13, 15, 19, 35, 38 Competitive product 19 Completion date (M.O.S.T.) 61 Component design 25 Conceptions

new 77 of ideas 81

Conference 45 Consolidation period 82 Consulates 52 Consumer associations 50, 52 Consumer buying habits 31 Consumer needs 21 Consumer reactions 21 Consumer research 114 Consumer vulnerability 21 Cooling 210 Copyright 188 Correlation between spending on

research and development and growth 28, 29

Cost permissible 88 of projects 11, 34

Cost accountant 4 Cost reduction 17, 50 Council of National Academic

Awards 4 Council of Industrial Design 95,

97 Crash programmes 18 Creative capacity 78, 81 Creative effort 46 Creative ideas 33 Creativity 82, 128 Critical path analysis (C.P.A.) 58,

59 activity 58 event 58

Critical path limitation 60 Critical path method (C.P.M.) 58,

59, 262, 263 Critical path scheduling (C.P.S.) 59 Critical .solution 47 Criticism of circumstances 81 Cross-posting 13 Cross single relationship 5

I N D E X 285

Crystallization 82 Customer 52

preferences 88 Customer's needs 85, 88 Current order book 41 Current requirements 37

Decimal classification Dewey's 90 universal 89

Decision making 147 Decisions 7 Degree of mechanisation 26 Demand fluctuations 17, 25 Departmental group activities 55 Departmental heads 36 Departmental responsibility 43, 45 Depreciation allowance 26 Design 43, 124, 280

ability 78 aim, 87, 148, 149 assessment 79 assistance 45 background 74, 79 competence xv concept 148, 149, 150 criteria 148, 150 data 88 decision 72, 77, 147 definition 174 department 272 draughtsman 3 efficiency 78 experience 78 factors 124 faults 198 folder 128 guiding principles 162 layout 195, 210 methods 81 modifications 84, 213 new machine 84 new product 84 objectives- 76, 78, 87, 128, 148 organisation 97 other considerations 88 performance 78

phenomenology 78 planning 88 potential 72 priorities 45 problems 86, 124, 148, 150

solution 74, 76 proposals 162, 165 records 195 register 97 registration 189

accepted forms 191 act 190 exclusions 191, 192 limitation 193 proprietorship 192

revision 47 safety requirements 78

Design scheme 125, 162, 195, 210 colour 163 energy balance 162 functional principles 162 instrumentation 163 kinematics 154 method of control 163 structure 155 texture 163 virtual work 162

Design simplification 85 solution 78, 148, 149 special requirements 88 specification 71, 76, 79, 83, 124,

150, 195, 197, 281 folder 86

steps 123, 151 supervision 76

Design task 46, 66, 77, 78, 84, 86, 124, 128,150, 195, 196, 259

team 114, 163 techniques 76 tree 152 work 45, 124

scope 85 Design Engineer 2, 13, 37, 67, 71,

75, 81, 84, 116, 240, 250, 257, 259

Designer -69, 72, 76, 78, 81, 82, 84, 124, 196, 205, 270

consultant 192

286 I N D E X

Designing definition 76 for safety 215

Designs 250 Desirable objectives 84 Detail drawing 72, 79, 195 Development 280

activity 46, 250 committee 32, 33, 35, 36, 39, 41,

42 agenda 38 attendance 114, 120 minutes circulation 38 recommendations 36

co-ordinating director 41 costs 18 criteria 50 cycle 12, 27

phases 27, 50 expenditure 28 policy methods 14, 15, 46 potential 13 problems 47 process analysis 4 programme 14,15, 32, 35, 38, 39,

41 execution 46 priorities 10, 33, 36, 37, 38,

57 realisation 46 responsibility 31

project 31, 41,45,259 factors 43 new 52 phase 51

task 58,259 time 28 under contract 30 work priority 58

Development Engineer see Chief Development Engineer

Development workshop 45, 46, 57, 250, 251, 255, 257, 263

charge-hand 251 engineering section 258 foreman 255,256,27, 258 inspector 256, 258 loading 255

organisation 257 project enclosure 258

Director of Design and Develop-ment 16, 95, 279

Director of Engineering Services 15, 31

Direct expenses 42 Direct group relationship 5 Direct single relationship 5 Dismantling requirements 88 Distribution 19

channels 85 factors 85 technical literature 91

Diversification 17, 39 Division

of labour 45 of responsibility 45

Divisional executive 33 Domestic appliance companies 97 Drafting errors 213 Drafting time 206 Draughtsman 45, 195, 204, 205,

278 Drawings 128, 195, 206, 254

assembly " 212 card index 198, 199 checking 214 details 212 experience 78 filing method 199 general arrangements 209, 210 layouts 209 library 57 modification 79, 212, 213 numbering 208 steps

for gauges 208 for prototypes 208 for tools 208

types composite 209 fabrication 209 omnibus 208

Drawing Office 45, 79, 91, 120, 195, 197, 251, 262

catalogue index 198 clerical section 205

INDEX 287

Drawing Office (cont.) display 197

of components 197 of designs 197 of models 197 of special tools 197

environment 196 facilities 97 filing system 198, 199 personnel 5

grading 202 training 196, 199

routine work 212 section leaders 205 staff 96

Economic factors 25, 41 Economic impact of development 9 Economic trends 22 Efficiency of design and develop-

ment activity 27 Elasticity theory assumptions 220 Embassies 52 End product 35 Engineer 74, 75, 124, 277, 278 Engineer-scientist 81 Engineering

ability 93 departments 270 design 32, 80

definition 74 division buying 57 economics 147 experience 78 firms 274 manufacture 80 philosophy 123 principles 46 product 93 proposal 28 science 80 staff 96 talent 2, 17 technology 94 value 142,259

Engineering Designer 46, 98, 108, 165, 195, 201, 202, 209, 251, 281

Engineering Director 49, 182 Environment 95, 96 Equipment 37 Erection crew requirements 108 Ergonomics 95,204

considerations of 108 Ergonomist 114 Escutcheons 197 Established product lines 19 Establishing data 69 Estimated project cost see Project

cost Estimating 263 Evaluation

of existing practice 52 of new produc 52

Evolution stages 26 of product 74

Execution of project 34 Executive Directors 16 Exhibitions 280 Existing projects 38 Expenditure hypothesis 38 Experience

practical 77 sensory 77

Exploitation limits 80 of manufacturing facilities 24

Factory plant 32 Factory services 32, 259 Failure to complete project 46 Fatigue

causes and location 230 geometrical discontinuity 231 material 239 primary causes 230 surface discontinuity 234

characteristics 227 phenomena 226

Feasibility 28, 30, 34 investigation 49 study 36, 47, 124

Fee for piece of research 276 for process 276

288 I N D E X

Fee {coni.)

for technical article 276 Field complaints 28 Field research 22 Fitter-Mechanic 45 Force, application of 210 Frustration 79 Functional aspect of a design 87 Functional considerations 100 Functional division of project work

1,4 Functional improvements 50 Functional reliability 206 Functional requirements 9, 87, 148 Funds 38,41

Gantt charts 263, 266 General arrangement 195 General Manager 16, 265, 272 General policy 12 General and special purpose plant

24 Good design 74, 95 Good photographer 279 Goodwill 14 Government departments 52 Graduate engineer 3 Graicunas 5 Gross project time 27 Group Engineering Director 32 Guidance 46

Handling 25 Head of Engineering Research 15 Head of Research 15 Heating 210

insulation 211 Hopper loading 27 House style 95, 107, 279 House symbol 107, 274 Hypothesis 77

test 77

Ideas from outside 14 Imagination 77

Implementation of Development Programme 47

Implication of solution 77 Improvement of product 18 Incentives 33 Inception of Project 2, 28, 34, 35 Income-producing ideas 36 Indirect guidance 45 Inductive thought 123 Industrial design 93, 94, 250, 251

consultant 95, 97 department 95, 120 details 108 facilities 96 mock-up, 119 packaging 274 section 251 work stages 120

Industrial designer 84, 93, 96, 98, 102, 108, 113, 114, 115, 116, 120, 121, 162, 165, 250, 251, 259, 279

brief 115, 120 house style 117 limitations 116 quantities and cost 116 specifications 116 task 117 time-table 117

medium 117 method of working 115

Information bureaus 54 Information feed-back 281 Information pocket 65 Initial stages of project work 2 Innate ability 82 Inspection 32, 208, 256

cost 272, 273 final 274 functional 274 inward 273 of product 273 requirements 272 sampling 273

Inspiration 77, 265 Installation engineer 214 Installation instructions 275, 276 Intensive marketing 25

I N D E X 289

Interchangeability 206 Intuition 82, 83 Invention 178, 181

disclosure 181 employee's 182 ownership, 182 shop rights 183 technological factors 181

Isolation of problems 69

Jig and tool design 205 drafting 204

Jig and tool Designer 25 Job definition 69 Job scheduling 265

Key jobs 57, 70 Kinematic synthesis 81 Kipling's serving men 79 Knobs 197 Knowledge 77, 80

Laboratory 45 technician 45

Ladder activities (P.E.R.T.) 61 Language of designer 3 Large engineering company 262 Last commencing date 61 Layout

of drawings 128 panels 110

Legations 52 Length of development cycle 30, 38 Liaison

appointments 5 between designer and fitter 204 with journals 276

Library 91 additions list 91

Limitations of knowledge 81 'Line' relationship 5, 9 Link in chain of command 5,10, 31 Loading chart 45 Loading schedule 57

Loading, stable and balanced 85 Loss of self-confidence 46

Machine adjustments 215 cleaning 215 element calculations 81 guards and cowlings 215 loading 268 maintenance 215 safety 215

Magazine loading 27 Maintenance

handbook 276, 280 requirements 87, 108 workshop 250

Major project 97 Management

function 45 policy 12 ,18 ,41 ,46 ,95

directive 7, 35 restrictions 88 statement 64

Management Committee 16 Operation System Technique 61

Managing Director 16, 256 Manpower 38, 41 Manufacturing activities 262 Manufacturing capacity 39 Manufacturing costs 18, 35 Manufacturing flexibility 25 Manufacturing programme 115 Manufacturing techniques 39 Market information

potentialities 18,21 prospects 18, 21 requirements 18 research 97, 120

analysis 66 reports 114

size 28 survey 21, 28

Marketing 32, 52, 262, 275, 282 component 25 liaison with engineers 275 policy 114 programme 115

290 INDEX

Marketing (cont.) publicity aspect 275, 276 publicity material 275 questionnaire 22 research application 21 research, object of 20 research sources and methods 21 tactics 21 trends 18 see also Sales department

Marketing Manager 49, 115, 120, 275, 277

Marshalling of facts 69 Mass production 266 Material costs 39, 146 Material selection 160 Mechanical engineering 80 Merchandise superintendent 274 Microscopical metallography investi-

gation method 240 purpose of 239

Microscopical micrographs 240 Minimum objectives 84 Model of prototype 250, 279

shop provision 250 shop see Development workshop

foreman 45, 57, 214 work 251

bench 251 machine tools 253 tools 253

Model making shop 114, 250 Models and designs 250 Modifications 75

of parts 71 Motion Analysis 51

National Physical Laboratory 55 National Research and Develop-

ment Corporation 55 Net output 29 Network analysis 58

activity' 59 'event' 59

New machine tools 259 New product line 259

New project 35, 36 Numerical model 270

Observation 76 Obsolescence 35 Occurrences

dissimilar 77 similar 77

Operating costs 50 Operation planning and scheduling

262 Operational research 266

games theory 270 idle resources 270 queueing 270 resource allocation 270

Opinion vs. facts 88 Opposition

conscious 81 intuitive 81

Optimisation by combination 130 by comparison 132 by grading factors 128 by substitution 135 by variation 130 scope 127, 128

Optimising process control 27 Optimising techniques 123 Optimum design

analysis 123 criteria 127 data classification 124

examination 127 tabulation 129

factors 123, 148 enumeration 129 grading 128 isolation 130 scope 120

production costs 145 solution features 130 technical assessment 142 techniques 123 tests 125 utilisation 123 Optimum scheduling 58

I N D E X 291

Order acceptance clauses of 271 import duty 271 placing 57 reservations 271

Organisational charts 4 Output targets 88 Outside assistance 41, 49

Packaging 97, 274 physical requirements 274

Patent * additions 185 application 183 co-ownership 183 cover date 184 exploitation 54, 55 infringement 187 or a secret 180 position relating to new design 70 safeguarding 277 sample specification 185

Patentable inventions 180 Performance

of development activity 30 limitations 50

Periodic reviews 16 P.E.R.T. 61, 262

bar chart 63 circular event 61 critical activities 63 importance of activities 63 square event 61 summary report 63

Personal opinion 70 Personnel

movement 37 participation 79

Photographer 279, 280 Photographic records 280 Pilot production batch 28, 263, 264 Planning 28, 55, 263

and estimating engineers 257 Plant

commissioning 216 electrical safety 216 factory inspection 215

installation 259 maintenance 215

Plant Engineer 38, 240 Plates 197 Policy

directives 7, 35 restrictions 88 statement 64

Power source 211 Power supply 210 Precedents, search for 47 Preliminary drawings 47 Premature disclosure 52 Pre-production batch 263 Press releases 275 Press show 282 Previous market studies 22 Price 18 Principal objective 84 Problem

conclusion of 49 congestion of 270 of delay 270 perception of 77

Product and plant development 31, 33

cost 88 design 97 drafting 204 drawing 277, 278 evolution 103 function 149 launching 281 modifications 75 outline dimensions 278 outline drawing 277 performance 88, 278 planning strategy 12 protection 274 redesigns 78 sketch 277 survey 18, 21, 66, 120 variety reduction 51 weight 278

Product and consumer relationship 20

Production administration 254

292 INDÜX

Production (cour.) committee 259, 262, 264, 265 control 262, 264 costs 50, 145 efficiency 24 engineering activity 262 engineering studies 261 grouping 265 improvement 24 launching 262 line 85, 88, 261 manager 262 methods 39, 145 model 35, 198 organisation 265 planning 259 schedule 263 small batches 265 survey 28 techniques 39 technology 75

Production Engineer 38, 205, 214, 256, 259, 263, 281

Productivity 24 value 147

Professional and commercial pub-lications 32

organisations of industrial de-signers 97

Profit sharing 33 Profitability, profits 9, 18 Progress control 41, 63 Progress report 32, 46, 66 Project 45, 46

agreed 41 aim 65, 69 amalgamation 38 assessment 47, 50 completion times 58, 256 conclusion 33, 34 cost 39 current 38 defect elimination 258 design 255 development 1, 16, 255 diary sheets 66 engineering 250 evaluation xv

execution pocket 66 feasibility study 36, 47, 66 folder 36, 41, 64, 70 formulation 49 history 76, 276

tree 73 inception criteria 50 investigation 47 launching 47 length 39 name 42, 65 objective limitations 10 objective modification 73 origin 32 planning 5 priority 58, 65 progress 36, 46, 64 prospects 49 realisation 67, 69, 250 reference number and year 42 register 10, 39, 42 reinstatement 38 reopening 75 report 274 responsibility 195, 250 scheduling 55, 255 shelved 38 size 58 specification 42, 46, 86, 124, 195 tasks 70 team 96 tests 57, 61

discontinuation 41 organisation 43 supervision 59 suspension 41

timing 28, 65 title 38

Project Engineer 34, 37, 41, 45, 46, 55,57, 66, 69,71,75, 195,210, 254, 255, 256, 257, 258

Proprietary accessories see Bought out components

Prototype 75, 121, 279 building of 254 cost 26, 35 design 47 drawing errors 256

I N D E X 293

Prototype (cont.) job card 255 models 198 modifications 256 photographs 198 progress check 255 requisitions 255 subassemblies 55 test 47 trial 257 work 88

completion 256 order 255 planning 255 processing 254 progress check 255 routing 255 subcontracting 255

Provision of jigs, tools, fixtures 263 Publicity department 279 Publicity manager 279

Quality control 32, 272 Queries for management policy 14 Questioning objectives 76

Rationalisation of production 28, 146

Ready-made components 57 Recommended methods of work 45 Reconstitution of parts or units 50 Redesign 75 Reference index card 91

library 91 shelf 91

Reflection 77 Report objectives 36 Requirements analysis 70 Research 53

associations 41, 53, 55, 124 at cost 54 exchange rate 29 grant 54 programme 54 results 54

scientist 75 staff 29 subjects selection 54

Resource Allocation and Multi-project Scheduling, RAMPS 63

cost 64 time limit 64

Resources investment of 268 labour replacement in 270 machines 270 , material 270 men 270 money 270

Responsibility for development policy 15

absence of 45 Review technique 73 Rewards 33, 34 Rolling, drawing and extrusion 161 Rule of thumb 83

Safety 87 Sales

brochure 276, 278, 279 department 263, 264, 270 literature 97, 275 office 52 staff reports 22, 66 trend 21,41 volume 18

Sales Director 259 Sales Engineer 39 Scheduling 46, 55, 70

design 88 factors 57 manufacture 88 prototype work 88 tooling 88

Science and engineering relationship 53

Scientific method 75 Secretary of development committee

36, 38 Security 38 Selling price 35

294 I N D E X

Sensitivity diminished 82 Service engineer 214, 281 Service manager 281 Servicing 87, 281 Setting up time 25 Sequence of operations 25 Short-range research 53 Sketches of parts 71 Solution

classification 70 contemplated 47 preceding 47 of problems 78

Sources of information 52, 54 Spare capacity 24, 57 Special purpose machine design 79 Special purpose machinery 257 Specification

bought out components 270 inadequate 47 inspection 271 material 270 packing 271 special handling 271 sub-assemblies 270

Staff relationships 5 Stages of development 26 Standard costing 11 Standardisation 50 Standards 205 State aid 54

of consciousness 81 Statute of Monopolies 179 Stimulus 77 Stowage requirements 88 Stress

calculations 123, 217 distribution 159 experimental measurement 219 gauging methods 222 photo-elastic analysis 223 rubber models 224 safety factors 219 stress coats 224

Structure, type of 155 frame 155 mono 157 unit 156

Styling 93 Subcontracting 17 Subordinates 46 Subsidiaries 47 Successful design XV Suggestion award 32

coding 33 committee 32 making 46 scheme 7, 11, 32, 33

channel 36 secretary 33

Supervision of development pro-gramme 32

Supplementary chain 7 Supplementary direct communicat-

ing information link 5, 7 Supplementary link 7 System to facilities development 14

Technical activity 262 Technical articles 275, 276

approval 277 timing 277

Technical assessment 142 Technical characteristics 50 * Technical competence 13, 53 Technical criteria 124 Technical development 36 Technical Director 15, 31, 182, 276 Technical information 46 Technical literature 91, 277, 278

drawings 278 Technical literature 91, 275 Technical objectives 84 Technical questions, scope of 54 Technical value 142

biased 144 Technological advancement 19 Technological break-through 17 Technological factors 87, 181 Technological requirements 87 Technologist 75 Tests 78

full-scale 47 results 47 to destruction 78

Theory of machines 81 Time factor 43 Time lag 13 Time motion analysis 39 Time requirements 87 Time scheduled 70 Timing of inception 28 Tool capacity 96 Tool design 79 Tool room 250, 263 Tooling 32 ,33 ,35 ,37

expenditure 25 improvement 25 provision time 28 replacement 25 requirements 25

Trade associations 55 exhibitions 52

Trademarks 197 Training of engineers 4 Transfer mechanism 27 Typography 113

Useful life 87 User

convenience 50 requirements 50 service 54

Utilisation of by-products 85

INDEX 295

Value added 29 Variation reduction of product 51 Vibration

insulation 211 isolation 211

Wage awards 269 Weight distribution 160 Work

cycle 210 flow 87, 259, 268 handling 211 man-hours 265 operation 265 study 28, 32, 36, 66, 108

activity sampling 267 engineer 38 method study 267 P.M.T.S. 267

Works manager 259, 262 Works orders 265 Workshop

drawing 254 errors 213 experience 80 foreman 265 loading see Gantt charts training 79

of layouts 123 of sketches 123

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