Lecture 1

01NLEJMManufacturing processes

(MECHANICAL ENGINEERING- Torino)

PROF.SSA MANUELA DE MADDIS Department of Management and Production Engineering (DIGEP)

+39 011 0907234

manuela.demaddis@polito.it

Assistants : Prof. F. Lombardi, Ing. J.Sauza.

30/09/2015 Manufacturing Processesmanuela.demadis@polito.it

Lectures/Practical lectures

Thursday 10:00-13:00 classroom 17 A/ Laib 3BFriday 10:00-13:00 classroom 6N

Didactic Portal

- any changes on lectures timetable and classroom

-didactic material

-information about the exams

All information about the course are on the website

https://didattica.polito.it/pls/portal30/sviluppo.guide.visualizza?p_cod_ins=01NLEJM&p_a_acc=2015

Exams information

DURATION MIN 1,5 h/MAX 2 h

Compulsory written examination

The written exam will concern all course programmeand will be made up of theoretical questions and practical exercises

Rules and regulations

The students are allowed to use a personal formulary (a single A4 page) where they can note formulas which they are unable to remember.

They cannot use any material (e.g. books or any other type of materials)

The students are permitted to use a simple calculator (i.e. not scientific), but cannot use any other electronic device such as mobile phones or notebooks.

The overbooking students can attend the course but are not allowed to the examtill they will not be regularly registered.

Unless they have a official justification released by Politecnico di Torino30/09/2015 Manufacturing Processes

manuela.demadis@polito.it4

30/09/2015 Manufacturing Processes manuela.demadis@polito.it

During the lesson will be registered the signatures of the present students.

The Student which attend at least 70% of the course lessons may present a report ( not compulsory) on a topic, of them choice, explained during the course to get a vote between 0-3 that they can sum to the written exam result.Exemples:Compulsory written result: 15; report result 1. Not pass examCompulsory written result: 15: report result 3. Pass exam with 18Compulsory written result: 30; report result 3. Pass exam with 30L

The report have to contain only material used during the course ( slide of the professor - exercise carried out during the laib - book suggested from the professor) not information taken from internet or other source. The report should be an, ordered and good structured, word file on a theoretical subject of the course program with the explanation of the relative exercises. The relative exercises have to be soved also in a added .xls file.You can work in a team maximum of 3 students. Each group have to chose a different topics.

At the end of each lesson only one group can reserve the topic explained during the lesson. The team will have to upload the report on the didactical portal in the session “elaborati “ within 2 weeks.

Course programme

?Manufacturing processes

“Manufacturing”

Manufacturing is the use of machines, tools and labor to produce goods for use or sale. The term may refer to a range

of human activity, from handcraft to high tech, but is most commonly applied to industriasl production, in which raw

materials are transformed into finished goods on a large scale

“Process”

A particular course of action intended to achieve a result.Systematic series of mechanized or chemical operations that are performed in order to produce or manufacture something

Manufacturing processes

TRANSFORMATIONSWhat do we intend as transformations?

Def. :The variation in time of one or more properties of the part obtained by suitable elementary processes.

t (time)

Part’s property)

Transformation’s trajectory

Starting state

Final statef

Examples:

• Shape and size transformation (macrogeometry of the part);

• Transformation of the surface finish of a partsurface (macrogeometry of the part);

• Transformation of mechanical characteristics (hardness, max load);

• Transformation of state, of temperature.

WHAT DO WE NEED TO CARRY OUT A TRANSFORMATION?

Factors that contribute to a transformation

• Material

• Energy

• Information

• Resources

MaterialSemimanufactured / Finished

Chips/Scraps/wastes

TrasformazioneTransformation

M1 M2 MATERIAL

MaterialRaw /Semimanufactured

Further Materials

Product obtained after the transformation.•Semimanufactured /Finished

Material into excess presents in the raw and exported during the transformation.

• Chips

Product finished / Semimanufactured which does not respect the specifications.

• Scraps

Start product on which we want to operate the transformation

•Raw/Semimanufactured

•Materials that may be called for the correct execution of the transformation (Ex. Coolants);

•Materials that can be added to the raw part during the transformation.

•Further Materials

State of the Material

SolidCompact

Granular

Liquid

Gaseous

• Transfomations involve a mass variation M of the finished/semimanufactured product (M2) with respect to the mass of the raw/semimanufactured part of the beginning (M1).

• Three possible cases:– M = M2 - M1 < 0

– M = M2 - M1 = 0

– M = M2 - M1 > 0

After transformation the mass of the finished part is smaller than that of the beginning.

M2 < M1Semimanufactured/ Finished

Chips / Scraps

M Chips = - ∆M

M = M2 - M1 < 0

TransformationTransformation

Further Materials(coolants)

The transformation leaves unchanged the part’s mass.

M2 = M1Semimanufactured/Finished

M = M2 - M1 = 0

Trasformazione

The transformation involves an increase of the mass of the final part, because it is the output of the assembly of more parts.

Trasformazione M2 = M1a + M1b + M1cSemimanufactured / Finished

M = M2 - M1 > 0

M1cPart c

Part b

Part a

Transformation

• Material

• Energy

• Information

• Resources

Energy HeatEnergyTrasformazioneTransformation

ENERGYM1 M2

• Transformations are operated thanks to an exchange of energy;

• The energy exchanged may be of various type:– Mechanical;

– Thermal;

– Chemical– …..

Mechanical Energy

• The exchange of energy occurs by means of forces that perform mechanical work;

• Examples:– Bending– Turning– Shaving

Thermal Energy

• The exchange of energy occurs estabilishing a suitable temperature difference between parts.

• Examples– Melting butter in a pot;– Melting metal;– Solidification of an ice rock.

Chemical Energy

• The exchange of energy occurs by means of chemical reactions.

• Examples:– Elimination of stains through detergent.– Deposition of CVD coatings.

TRANSFORMATIONS

Transformation

• Transformations are realized through elementary processes (processing);

• These elementary processes may be classified by type of energy used.

TRANSFORMATIONS

Elementary processes which use mechanical energy

• Elastic deformation (ex.: to pull an elastic,to compress a spring);

• Plastic deformation (Ex.: to fold a plate, coining a coin);

• Break (Ex.:to break a glass plate);

• Mixing (Ex.: to mix powders)

• Heating/Cooling– (Ex. To heat a component to stretch it or cool it to

contract it - Coupling forced)• Melting

– (Ex. To melt tin to assembly a component –Welding)

• Solidification– (Ex. To solidify steel melted in a form – Foundry

Processes).

Elementary processes that use thermal energy

• Evaporation

- (Ex. Drying of a green mold)

• Condensation

- (Ex. To condense vapours of metals on a surface)

Elementary processes that use thermal energy

• Solution (Ex. Solution of zinc in copper to obtain brass);

• Combustion (Ex. Combustion of hydrocarbons)

• Diffusion (Ex. Atoms of carbon penetrate by diffusion in the steel’s structure changing properties - Cementation).

• Hardening (Ex. Hardening of the cement).

Elementary processes that use chemical energy

• Material

• Energy

• Information

• Resources

INFORMATION

Transformation

Information

InformationFeedback from the process

Feedback from the part

Information Technolocal

Managerial

• Transformations, to be activated, need suitable information of two types:

Information

– Technoloical Information:• List of types of instruments needed to execute the trasformation

(machines, tools, fixtures).• Trajectory of the process.

– Managerial Information:• When to execute the trasformation• Which part is to be transformed (among possible alternatives).• What specific instruments to use (among possible alternatives).

• Material

• Energy

• Information

• Resources

RESOURCES

Transformation

Resources

Tool It allows to transfer the energy from the machine to the raw/semimanufactured part.

Resources Any trasformation needs suitable resources.

Machine It supplies the energy needed for the transformation and carries out the trajectory of process.

Fixtures It allows the raw /semimanufactured part to be integrated in the machine.

TECHNOLOGICAL TRANSFORMATION SYSTEM

Together with the raw/semimanufactured part the resources allow to define the technological transformation system.

This is therefore composed of:• Raw/Semimanufactured part• Machine• Fixtures• Tool

Coconut(Raw material)

Stone(Tool)

Man(Machine)

Hand(Fixture)

Example of of a technological transformation systemTo break a coconut

Example of technological transformation systemDrilling of a part

Drilling Press(Machine)

Part(Raw/Semimanufactured part)

Drill(Tool)

Work tableClamps(Fixture)

Example of technological transformation system Mold Polishing

Robot(Machine)

Stamp(Semimanufactured part)

Abrasive Brush.(Tool)

Work TableClamps.(Fixture)

CLOSED TECHNOLOGICAL TRANSFORMATION SYSTEM

CLOSED SYSTEM:The force loop closes inside the machine’s structure

OPEN TECHNOLOGICAL TRANSFORMATION SYSTEM

OPEN SYSTEM:The force loop is external to the machine’s structure and closes with the ground.

Example of closed technological transformation system.MACHINING CENTRE FOR BURRS REMOVAL.

Raw part Fixture

Machine

Example of open technological transformation system.ANTHROPOMORPHIC ROBOT FOR TRIMMING

Raw part Fixture

Machine

Example of open loop techological transformation system.

Welding Robot

Laser cutting Robot

WJ cutting Robot

tagliolaser3d_2.mov

Manufacturing processes

Sequence of processes ( trasformations) thatmodify the shape, size, surface conditions

of single parts

4830/09/2015 manuela.demadis@polito.it 48

Theory of transformations. Introduction on manufacturing processes ( Prof. De Maddis)

Mechanical fundamentals ( Prof. F. Lombardi)

Mechanical behavior , testing and manufacturing properties of materials (F. Lombardi)

Deformation Processes ( Prof. Lombardi/ De Maddis)

Solidification processes ( Prof. ssa De Maddis)

Material removal Processes ( Prof. De Maddis)

Computer Numerical Control ( Ing. Sauza)

Books:Manufacturin Engineering and Technology

Kalpakjian_SchmidPearson

Fundamentals od Modern ManufacturingMikell P. Groover

John Wiley & sons, inc.

Mechanical MetallurgyGeorge E. Dieter

Mc Graw - Hill Book Company

…….

Deformation processes

Q-Form

Deformation processes1. Bulk deformation

RollingForgingExtrusionWire and bar drawing

2. Sheet metalworkingBendingDeep drawingCuttingMiscellaneous processes

Solidification Processes

Casting

Cast metalMold Blank

30/09/2015 manuela.demadis@polito.it 5630/09/2015 Manufacturing Processesmanuela.demadis@polito.it

Turning DrillingMillingMaterial removal processes

BroachingGrinding

AwjcEcm

CNC simulator

Some Fusion Welding Processes• Arc welding (AW) – melting of the metals is accomplished by electric

arc • Resistance welding (RW) - melting is accomplished by heat from

resistance to an electrical current between faying surfaces held together under pressure

• Oxyfuel gas welding (OFW) - melting is accomplished by an oxyfuel gas such as acetylene

Some Solid State Welding Processes

• Diffusion welding (DFW) –coalescence is by solid state fusion between two surfaces held together under pressure at elevated temperature

• Friction welding (FRW) - coalescence by heat of friction between two surfaces

• Ultrasonic welding (USW) - coalescence by ultrasonic oscillating motion in a direction parallel to contacting surfaces of two parts held together under pressure

PROCESS SELECTION

Each process have certain attributes: the materials itcan handle, the shapes it can make, their size,precision, and an optimum batch size (the number ofunits that it can make economically).

Case study Manufacturing Process

Scales in Manufacturing

Illustration of the range ofcommon sizes of parts and thecapabilities of manufacturingprocesses in producing theseparts.

PRECISION OF THE TRANSFORMATIONS

t ( time)

Part’s properties)

Transformation’s trajectory

Starting State

Final State

Ideal transformation : the starting and final states are defined in deterministic manner.

REAL TRANSFORMATIONS

All real transformations are affected by phenomena that aren’t controllable (disturbances) and that modify the final result.

Starting State

Final State 1

t (time)

(Part’s properties)

Final State 2

Finale State 3f3

f2 Variability of the results

REAL TRANSFORMATIONSEven if, with suitable techniques, the features of the input materials of a transformation may be controlled (acceptance control), nevertheless, generally, the starting state of the transformation isn’t precisely known.This makes more uncertain the final result.

t(time)

Part’s properties)

Starting State 1

Starting State 2

Variability of the result

Variability of the starting state

Energy

Material

Energy

Information

Semimanufactured/Finished

chips/scraps

Feedback from the process

Feedback from the part

Transformation

Resources

Information

MaterialRaw/Semimanufactured

Further Materials

TechnologicalManagerial

MachinesToolsFixtures

Troules

Disturbances

Every transformation is subjected to disturbances of different origin

• The variability of the final state depends on many different causes (Disturbances) that contribute to determine the variability of the output and cannot be eliminated.

• The process may be also subjected to variations that are caused by specific reasons which may be identified and eliminated:– Wear/breakage of tools– Wear/breakage machine’s mechanical components.– Introduction of inexpert operators.– …..

REAL TRANSFORMATIONSExample: operator replacement

The variability of the output increases due to the presence of an inexpert operator. In this case there is an assignable cause and the variability of the output may be and must be reduced (replacing the operator, through suitable education courses, through more clear instructions, etc…)

Introduction of an inexpert operator

Example: Tool Wear

Due to tool wear the average value of the dimensions produced increases continuously. In this case there is an assignable cause which may be and must be removed (for example replacing or reconditioning the tool, adjusting its trajectory to take into account progressive wear).

Tool Wear

• The presence of Disturbances implies that the output of the transformation will never be the same, but it will vary inside an interval of possible values.

• Disturbances due to assignable causes must be identified and eliminated (control charts).

• Once eliminated the Disturbances due by assignable causes, the problem is to ensure that possible outputs of a transformation are contained inside a tolerance interval defined during the design phase (specifications).

How to consider Disturbances?

t (time)

Part’s property)

Variability of starting state

Tolerance interval

Starting state 1

Starting state 2

Variability of output and tolerances (capability)

t (time)

Part’s property)

Variability of starting state

Starting state 1

Starting state 2

Variability of the output and tolerances (capability)

Variability of the output

NO !!!!

REDUCTION OF OUTPUT’S VARIABILITY

When the variability of the output is higher than thespecified tolerance we may:

– Improve the process

– Change the process

Example of process improvementDRILLINGSpecification:Obtain a blind hole with axis laying at d=10 mm from a reference surface.The specified tolerance for this dimension is + 0.1 mm.We need to determine the process which allows to realize this hole, with the specified tolerance.

d = 10 + 0.1

Unit: mm

t (time)

d(mm)Position of hole axis)

Tolerance interval

INTERVAL OF SPECIFIED TOLERANCE

10 - 0.1

10 + 0.1

1st CASE Drilling with standard drill

Variability of hole’s position : + 0.18 mm

Helicoidal drill

t (time)

d(mm)Position of hole’s axis)

10 - 0.1

10 + 0.1

10 - 0.18

10 + 0.18

NO !!!!

Variability of result

Tolerance interval

Drilling with standard drill

2nd CASEDrilling after a center drilling

Position variability of the axis: + 0.1 mm

2. Standard drill1. Center drill

t (time)

d(mm)Position of hole’s axis)

10 - 0.1

10 + 0.1

LIMIT SITUATION

Variability of result

Tolerance Interval

Drilling with center drill

3 rd CASEDrilling with a guide bushing after center drilling

Variability of hole’s position: + 0.05 mm

1. Center drill 2. Standard chisel drill with guide bushing

t (time)

d(mm)Posiotion of hole’s axis)

10 - 0.1

10 + 0.1

10 - 0.05

10 + 0.05 Variability of result

Tolerance interval

Drilling with a guide bushing after center drilling

CHOICE OF PRODUCTION PROCESS

Production Process

Technical practicability Economical practicability

TECHNICAL PRACTICABILITY OF THE PROCESS

The process that makes the part must guarantee:

• Technical Specifications of the part indicated in thetechnical design (tolerances, roughness, etc.);

• Required amount (production capability) ;

• The respect of environmental laws;

• The respect of safety lows.

• Besides technical practicability of the production process weneed to verify also its economical practicability.

• This means that the costs associated to the process must besustainable with respect to the income derived by the use of itsproduction capability.

ECONOMICAL PRACTICABILITY OF THE PROCESS

The production activity must guarantee to the firm a profit in monetary terms.

. In first approximation, neglecting financial proceeds (ordinary and extraordinary), the profit derives by the difference between theproduction’s value and production’s cost.

PROFIT = PRODUCTION’S VALUE – PRODUCTION’S COST

PRODUCTION’S VALUE

Manufacturing add value to the materials as they become discrete products and are marked .

Monetary value:

• Use value reflecting the function of the product

• Prestige value reflecting the attractiveness of the product that make its ownership desiderable

" Value engineering" conducts a value anlysis jointly to designers, manufacturing engineers, and quality-control, purchasing, markeing personnel and managers to obtain the maximum performance per unit cost

PRODUCTION’S COST

• Material cost ( type material, processing history, size, shape, surface characteristics)

•Tooling cost (tools, dies,molds,patterns, fixtures required to manufacturing a product)

•Fixed costs ( electric poer, fuel, taxes, rent etc…)

•Capital costs (Machinery, tooling, equipment, investiment in building, land)

•Direct-labot Costs (labor rate * amount of time that the worker spends producing the particular part)

•Indirect-labor Costs (supervision, maintenance, quality control, repai, research, sales activities etc…)

CHOICE OF PRODUCTION PROCESS

Production Process

Technical practicability Economical practicability

chap 1and chap 40

Manufacturing Engineering and Technology Kalpakjian

Lecture 1

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