Upload
hussein-tarhini
View
214
Download
0
Tags:
Embed Size (px)
DESCRIPTION
fsagf
Citation preview
01NLEJMManufacturing processes
(MECHANICAL ENGINEERING- Torino)
PROF.SSA MANUELA DE MADDIS Department of Management and Production Engineering (DIGEP)
+39 011 0907234
Assistants : Prof. F. Lombardi, Ing. J.Sauza.
30/09/2015 Manufacturing [email protected]
1
Lectures/Practical lectures
Thursday 10:00-13:00 classroom 17 A/ Laib 3BFriday 10:00-13:00 classroom 6N
30/09/2015 Manufacturing [email protected]
2
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
30/09/2015 Manufacturing [email protected]
3
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
30/09/2015 Manufacturing Processes [email protected]
5
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.
30/09/2015 Manufacturing Processes [email protected]
6
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.
“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
30/09/2015 Manufacturing [email protected]
8
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
i
30/09/2015 Manufacturing [email protected]
9
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.
30/09/2015 Manufacturing [email protected]
10
WHAT DO WE NEED TO CARRY OUT A TRANSFORMATION?
Factors that contribute to a transformation
• Material
• Energy
• Information
• Resources
30/09/2015 Manufacturing [email protected]
11
MaterialSemimanufactured / Finished
Chips/Scraps/wastes
TrasformazioneTransformation
M1 M2 MATERIAL
MaterialRaw /Semimanufactured
Further Materials
30/09/2015 Manufacturing [email protected]
12
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
M1 M2
30/09/2015 Manufacturing [email protected]
13
State of the Material
SolidCompact
Granular
Liquid
Gaseous
M1 M2
30/09/2015 Manufacturing [email protected]
14
• 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
M1 M2
30/09/2015 Manufacturing [email protected]
15
After transformation the mass of the finished part is smaller than that of the beginning.
M2 < M1Semimanufactured/ Finished
Chips / Scraps
M Chips = - ∆M
M1Raw
M = M2 - M1 < 0
TransformationTransformation
Further Materials(coolants)
M1 M2
30/09/2015 Manufacturing [email protected]
16
The transformation leaves unchanged the part’s mass.
M2 = M1Semimanufactured/Finished
M = M2 - M1 = 0
M1Raw
Trasformazione
M1 M2
30/09/2015 Manufacturing [email protected]
17
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
M1a
M1b
M1cPart c
Part b
Part a
Transformation
M1 M2
30/09/2015 Manufacturing [email protected]
18
Factors that contribute to a transformation
• Material
• Energy
• Information
• Resources
30/09/2015 Manufacturing [email protected]
19
Energy HeatEnergyTrasformazioneTransformation
ENERGYM1 M2
30/09/2015 Manufacturing [email protected]
20
• Transformations are operated thanks to an exchange of energy;
• The energy exchanged may be of various type:– Mechanical;
– Thermal;
– Chemical– …..
E1 E2
30/09/2015 Manufacturing [email protected]
21
Mechanical Energy
• The exchange of energy occurs by means of forces that perform mechanical work;
• Examples:– Bending– Turning– Shaving
E1 E2
30/09/2015 Manufacturing [email protected]
22
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.
E1 E2
30/09/2015 Manufacturing [email protected]
23
Chemical Energy
• The exchange of energy occurs by means of chemical reactions.
• Examples:– Elimination of stains through detergent.– Deposition of CVD coatings.
E1 E2
30/09/2015 Manufacturing [email protected]
24
• Transformations are realized through elementary processes (processing);
• These elementary processes may be classified by type of energy used.
TRANSFORMATIONS
30/09/2015 Manufacturing [email protected]
26
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)
30/09/2015 Manufacturing [email protected]
27
• 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
30/09/2015 Manufacturing [email protected]
28
• Evaporation
- (Ex. Drying of a green mold)
• Condensation
- (Ex. To condense vapours of metals on a surface)
Elementary processes that use thermal energy
30/09/2015 Manufacturing [email protected]
29
• 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
30/09/2015 Manufacturing [email protected]
30
Factors that contribute to a transformation
• Material
• Energy
• Information
• Resources
30/09/2015 Manufacturing [email protected]
31
INFORMATION
Transformation
Information
InformationFeedback from the process
Feedback from the part
Information Technolocal
Managerial
30/09/2015 Manufacturing [email protected]
32
• 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).
30/09/2015 Manufacturing [email protected]
33
Factors that contribute to a transformation
• Material
• Energy
• Information
• Resources
30/09/2015 Manufacturing [email protected]
34
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.
30/09/2015 Manufacturing [email protected]
36
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
30/09/2015 Manufacturing [email protected]
37
Coconut(Raw material)
Stone(Tool)
Man(Machine)
Hand(Fixture)
Example of of a technological transformation systemTo break a coconut
30/09/2015 Manufacturing [email protected]
38
Example of technological transformation systemDrilling of a part
Drilling Press(Machine)
Part(Raw/Semimanufactured part)
Drill(Tool)
Work tableClamps(Fixture)
30/09/2015 Manufacturing [email protected]
39
Example of technological transformation system Mold Polishing
Robot(Machine)
Stamp(Semimanufactured part)
Abrasive Brush.(Tool)
Work TableClamps.(Fixture)
30/09/2015 Manufacturing [email protected]
40
CLOSED TECHNOLOGICAL TRANSFORMATION SYSTEM
CLOSED SYSTEM:The force loop closes inside the machine’s structure
30/09/2015 Manufacturing [email protected]
41
OPEN TECHNOLOGICAL TRANSFORMATION SYSTEM
OPEN SYSTEM:The force loop is external to the machine’s structure and closes with the ground.
30/09/2015 Manufacturing [email protected]
42
Example of closed technological transformation system.MACHINING CENTRE FOR BURRS REMOVAL.
Tool
Raw part Fixture
Machine
30/09/2015 Manufacturing [email protected]
43
Example of open technological transformation system.ANTHROPOMORPHIC ROBOT FOR TRIMMING
Tool
Raw part Fixture
Machine
30/09/2015 Manufacturing [email protected]
44
Example of open loop techological transformation system.
Welding Robot
Laser cutting Robot
WJ cutting Robot
tagliolaser3d_2.mov
30/09/2015 Manufacturing [email protected]
45
Manufacturing processes
Sequence of processes ( trasformations) thatmodify the shape, size, surface conditions
of single parts
30/09/2015 Manufacturing [email protected]
46
30/09/2015 Manufacturing Processes [email protected]
4830/09/2015 [email protected] 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
…….
30/09/2015 Manufacturing [email protected]
49
30/09/2015 Manufacturing [email protected]
50
Deformation processes1. Bulk deformation
RollingForgingExtrusionWire and bar drawing
2. Sheet metalworkingBendingDeep drawingCuttingMiscellaneous processes
30/09/2015 Manufacturing [email protected]
52
30/09/2015 Manufacturing [email protected]
53
30/09/2015 [email protected] 5630/09/2015 Manufacturing [email protected]
56
30/09/2015 Manufacturing [email protected]
57
30/09/2015 Manufacturing [email protected]
59
Turning DrillingMillingMaterial removal processes
BroachingGrinding
AwjcEcm
30/09/2015 Manufacturing [email protected]
60
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
30/09/2015 Manufacturing [email protected]
62
30/09/2015 Manufacturing [email protected]
63
30/09/2015 Manufacturing [email protected]
64
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
30/09/2015 Manufacturing [email protected]
65
30/09/2015 Manufacturing [email protected]
66
30/09/2015 Manufacturing [email protected]
67
30/09/2015 Manufacturing [email protected]
68
30/09/2015 Manufacturing [email protected]
69
30/09/2015 Manufacturing [email protected]
70
Scales in Manufacturing
Illustration of the range ofcommon sizes of parts and thecapabilities of manufacturingprocesses in producing theseparts.
30/09/2015 Manufacturing [email protected]
71
30/09/2015 Manufacturing [email protected]
72
30/09/2015 Manufacturing [email protected]
73
30/09/2015 Manufacturing [email protected]
74
30/09/2015 Manufacturing [email protected]
75
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.
f
i
30/09/2015 Manufacturing [email protected]
76
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
i
t (time)
(Part’s properties)
Final State 2
Finale State 3f3
f1
f2 Variability of the results
30/09/2015 Manufacturing [email protected]
77
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
i1
i2
Variability of the result
Variability of the starting state
30/09/2015 Manufacturing [email protected]
78
Energy
Material
Energy
Information
Semimanufactured/Finished
chips/scraps
Heat
Feedback from the process
Feedback from the part
Transformation
Resources
Information
MaterialRaw/Semimanufactured
Further Materials
TechnologicalManagerial
MachinesToolsFixtures
Troules
Disturbances
Disturbances
Disturbances
Disturbances
Every transformation is subjected to disturbances of different origin
30/09/2015 Manufacturing [email protected]
79
REAL TRANSFORMATIONS
• 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.– …..
30/09/2015 Manufacturing [email protected]
80
t
t
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
30/09/2015 Manufacturing [email protected]
81
REAL TRANSFORMATIONS
t
t
t
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
Tool Wear
30/09/2015 Manufacturing [email protected]
82
• 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?
30/09/2015 Manufacturing [email protected]
83
t (time)
Part’s property)
Variability of starting state
Tolerance interval
Starting state 1
Starting state 2
i1
i2
OK
Variability of the result
Variability of output and tolerances (capability)
30/09/2015 Manufacturing [email protected]
84
t (time)
Part’s property)
Variability of starting state
Variability of the result
Starting state 1
Starting state 2
i1
i2
Variability of the output and tolerances (capability)
Variability of the output
NO !!!!
30/09/2015 Manufacturing [email protected]
85
REDUCTION OF OUTPUT’S VARIABILITY
When the variability of the output is higher than thespecified tolerance we may:
– Improve the process
– Change the process
30/09/2015 Manufacturing [email protected]
86
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
30/09/2015 Manufacturing [email protected]
87
t (time)
d(mm)Position of hole axis)
Tolerance interval
INTERVAL OF SPECIFIED TOLERANCE
10 - 0.1
10 + 0.1
30/09/2015 Manufacturing [email protected]
88
1st CASE Drilling with standard drill
Variability of hole’s position : + 0.18 mm
Helicoidal drill
30/09/2015 Manufacturing [email protected]
89
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
30/09/2015 Manufacturing [email protected]
90
2nd CASEDrilling after a center drilling
Position variability of the axis: + 0.1 mm
2. Standard drill1. Center drill
30/09/2015 Manufacturing [email protected]
91
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
30/09/2015 Manufacturing [email protected]
92
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
30/09/2015 Manufacturing [email protected]
93
t (time)
d(mm)Posiotion of hole’s axis)
10 - 0.1
10 + 0.1
OK
10 - 0.05
10 + 0.05 Variability of result
Tolerance interval
Drilling with a guide bushing after center drilling
30/09/2015 Manufacturing [email protected]
94
CHOICE OF PRODUCTION PROCESS
Production Process
Technical practicability Economical practicability
30/09/2015 Manufacturing [email protected]
95
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.
30/09/2015 Manufacturing [email protected]
96
• 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
30/09/2015 Manufacturing [email protected]
97
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
30/09/2015 Manufacturing [email protected]
98
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
30/09/2015 Manufacturing [email protected]
99
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…)
30/09/2015 Manufacturing [email protected]
100
CHOICE OF PRODUCTION PROCESS
Production Process
Technical practicability Economical practicability
30/09/2015 Manufacturing [email protected]
101
chap 1and chap 40
Manufacturing Engineering and Technology Kalpakjian
30/09/2015 Manufacturing [email protected]
102