Product Development process

5.3.2015

Ing. Jan Valtera, Ph.D. – Design Metodology

Introduction

Systematic product design (Systematic approach) is a complex engineering task that can be roughly classified into two phases:

1. Conceptual Design phase (looking for the solution principles and the concepts based on the defined requirements list)

2. Embodiment Design phase (defining of the design layout (or process) to fulfil the concept functions)

The fundamentals for systematic approach are:

• Solution Findings Methods (Collecting information: searching the literature, analysing trade publications, assessing catalogues of competitors, exploring patents; Brainstorming, Cross-functional Task Force, Gallery method, etc.)

• Selection and Evaluation Methods (Cost-Benefit analysis, VDI Guideline, QFD, FMEA)

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Motivation

• Why is it useful for designers to follow the systematic approach?

• methods can be used regardless of designers speciality (comprehensive

for general design team)

• introducing a working steps – iteration loops (links between objectives,

planning and control)

A systematic approach aims to keep the iteration loops as small as possible in order to make design work effective and efficient. This helps to avoid the design team to start again from the beginning if a design failure is found)

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General Working Methodology

• Define goals by formulating the overall goal, the individual sub goals and their

importance. This ensures the motivation to solve the task and supports insight into the problem.

• Clarify conditions by defining the initial and boundary constraints.

• Dispel prejudice to ensure the most wide-ranging search for solutions possible

and to avoid logical errors.

• Search for variants to find a number of possible solutions or combinations of

solutions from which the best can be selected.

• Evaluate based on the goals and conditions.

• Make decisions. This is facilitated by objective evaluations. Without decisions and

experiencing their consequences there can be no progress.

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General Problem Solving Process

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General Problem Solving Process

• Every task involves an initial confrontation of the problem, which involveselucidating what is known or not (yet) known. The intensity of this confrontationdepends on the knowledge, ability and experience of the designers, and on the particular field in which they are engaged. In all cases, however, more detailedinformation about the task itself, about the constraints, about possible solutionprinciples and about known solutions for similar problems is extremely useful since it clarifies the precise nature of the requirements. This information can also reduce confrontation and increase confidence that solutions can be found.

• Next comes the definition phase, where the essential problems are defined on a more abstract plane, in order to set the objectives and main constraints. Such solution-neutral definitions open the way to an unconstrained search for solutions because this abstract definition encourages a search for more unconventional solutions.

• The next step is creation, where solutions are developed by various means andthen varied and combined using methodical guidelines. If the number of variants islarge, there must also be an evaluation which is then used to select the best variantthrough a decision. Because each step of the design process must be evaluated,evaluation serves as a check on progress towards the overall objective.

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Product planning – Life cycle of a product

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Development processes of different types of products

• One-off product development (design of a machine/device, where a serial production is not required)

1. Customer requirements processing

2. Processing and submitting of the offer (already known design concept)

3. Design

4. Manufacturing

5. Assembling

6. Testing (system tuning)

7. Submitting (Design specification, user’s guide, safety information, certificate of conformity)

This process may last for approx. 3 months

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Development processes of different types of products

• Mass-produced product development (design of a complex machine (or set of machines/devices), where its serial production is required)

1. Detailed research of technical (dimension, power, productivity, etc.) and economical parameters2. Solution finding (physical principles, state-of-art systems, etc.)3. Solution evaluation (e.g. Cost-Benefit analysis)4. Functional model design (verification of required functions and weak elements)

• Design• Manufacturing• Testing

5. Design of a prototype (0 – series, design optimization – material, weight, price, etc.)• Design• Manufacturing• Testing (in very complex tasks a second prototype may be required)

6. Serial layout preparation• Production technology (methods and devices used for production of machine components)

7. Production line testing and parameters tuning8. Serial production started

This process may last for approx. 12 months

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Stepwise development from the one-off produced product to a mass-produced product

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Timing and Scheduling

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Systematic Product Design – Conceptual phase

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Example of the design of Multi-thread tensioner with electronic control: Problem requirements:

Problem basic requirements: • Tensioner for 10 parallel threads• The tension range 20 – 300 cN• Electronic control of the thread tension• Thread count range (50 - 100 tex)

Systematic Product Design – Conceptual phase

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Example of the design of Multi-thread tensioner with electronic control: Problem requirements:

1. a) Requirements processing:

Definition of the requirements importance (on scale 5-highest, 1-lowest)

• The tension range 20 – 300 cN 5• Electronic control sensitivity (tension 10 cN) 4• Even force distribution 4• Low cost 3• Parallel yarn guidance 3• Easy thread inserting 3• Small size 2• Thread count range (50 - 100 tex) 1

Systematic Product Design – Conceptual phase

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Example of the design of Multi-thread tensioner with electronic control:List of sub-functions:

Based on the research of available yarn tension systems and on the requirement list, all the basicworking principles and sub-functions have been structured into the classification scheme.

Systematic Product Design – Conceptual phase

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Example of the design of Multi-thread tensioner with electronic control

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feTT

The First principle is based on a disc tensioner, where disc are pressed together by an acting external normal force.The tension force T is given by the following equation

The additional multi-thread variation can be designed by patterning the disc units over the length. Insertion of yarns into working positioncan be achieved by releasing the acting force and opening the inner space between discs.

The second option uses principles based on the gate tensioner, where yarn is wrapped at certain angle α around the non-rotating gate of the tensioner. The resulted tension is calculated using the Euler´s formula

Systematic Product Design – Conceptual phase

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Example of the design of Multi-thread tensioner with electronic control

In order to accommodate more yarns in parallel, the length of gates can be easily extended.An additional opening mechanism is necessary to enable yarns being inserted into the working position.Similar principle of friction transmission is used in the third option, where the yarn is wrapped aroundthe driven cylinder in more twists. These are necessary to stop the yarn sliding over the cylinder.Hence, the tension is provided by a controlled braking of the cylinder. The multi-thread variationcan be achieved by sufficient extension of the cylinder to accommodate more yarns in parallel.

In order to insert yarns into the proper position, it is however necessary to wrap them aroundthe cylinder, one by one.

By a combination of component functions, several working solutions have been defined. The multi-thread disc tensioner with electromagnet as the most appropriate design has been then evaluated in the QFD by means of the importance of required parameters

Systematic Product Design – Embodiment phase

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Example of the design of Multi-thread tensioner with electronic control: QFD

By a combination of component functions, several working solutions have been defined and evaluated in the QFD (quality function deployment).

Systematic Product Design – Embodiment phase

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Example of the design of Multi-thread tensioner with electronic control: Final concept design

1-inner rod with cut grooves2-ceramic discs3-distance elements4-housing5-sliding rod6-pushing element7-electromagnet8-front and rear set of yarn guides9-line rails for the yarn guides

Systematic Product Design – Functional model testing

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Example of the design of Multi-thread tensioner with electronic control:Functional model testing

Basic rules of embodiment design

• Clarity—that is, clarity of function or lack of ambiguity of a design—facilitates reliable prediction of the performance of the final product and in many cases saves time and costly analyses.

• Simplicity generally guarantees economic feasibility. A smaller number of componentsand simple shapes are produced more quickly and easily.

• Safety imposes a consistent approach to the problems of strength, reliability, accident prevention and protection of the environment.

In short, by observing these three basic rules, designers can increase their chances of success because they focus attention on, and help to combine, functional efficiency, economy and safety. Without this combination no satisfactory solution is likely to emerge.

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Summary

• Systematic Product Design (systematic approach) – conceptual and embodiment phases

• Steps of the General Problem Solving Process (from task to solution)

• Differences in Product Development Process of one-off and mass produced product

• Basic rules of embodiment design

• Quality Function Deployment

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References

• Pahl, G.; Beitz, W.; Feldhusen, J.; Grote, K.H: Engineering Design – A systematic approach, Springer, ISBN 978-1-84628319-2, Springer-Verlag London Limited, (2007).

• Valtera, J.; Zabka, P.; at al.: Výzkum nových struktur textilních a jednoúčelových strojů, Technical University of Liberec, ISRN TUL – KTS/TZ/PZ - - 12/01/CZ – CZ +SGS, Liberec, (2011).

• Elsner, J.; Zabka, P.; Valtera, J.: Mereni charakteristik brzdicky ovladane elektromagnetem, Technical University of Liberec, ISRN TUL – KTS/VZ/PZ - - 12/02/CZ – CZ +SGS, Liberec, (2012).

• ELSNER, J., VALTERA, J., ŽABKA, P.: CONCEPTUAL DESIGN OF MULTI-THREAD TENSIONER WITH ELECTRONIC CONTROL, Structure and Structural Mechanics of Textiles, 19th International Conference, TU Liberec, Czech Republic, ISBN 978-80-7372-913-4.

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Design for Quality - Quality Function Deployment (QFD) – Study Example

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