1. Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment

2. Cutting
Processes that involve removal of material from solid workpiece
Sawing
Shaping (or planing),
Broaching, drilling,
Grinding,
Turning
Milling
Important concept: PROCESS PLANNING
Fixturing and Location
Operations sequencing
Setup planning
Operations planning

3. Sawing A process to cut components, stock, etc.
Process character: Precision: [very low,, very high]; MRR: low

4. Sawing

5. Shaping
A process to plane the surface of a workpiece (or to reduce part thickness
Process character: High MRR, medium Surface finish, dimension control

6. Broaching
Precise process for mass-production of complex geometry parts
(complicated hole-shapes)
Process character: High MRR, Very good surface, dimension control, Expensive

7. Drilling, Reaming, Boring
Processes to make holes
Process character: High MRR, Cheap, Medium-high surface, dimension control

8. Drilling basics
- softer materials  small point angle; hard, brittle material: larger point angle
- Length/Diameter ratio is large  gun-drilling (L/D ratio ~ 300)
- Very small diameter holes (e.g. < 0.5 mm): can’t drill (why?)
- F drilled hole > F drill: vibrations, misalignments, …
- Tight dimension control: drill  ream
- Spade drills: large, deep holes
- Coutersink/counterbore drills: multiple diameter hole  screws/bolts heads

9. Tapping Processes to make threads in holes
Process character: low MRR, Cheap, good surface, dimension control
Automated tapping
Manual tap and die set

10. Grinding, Abrasive Machining
Processes to finish and smooth surfaces
Process character: very low MRR, very high surface, dimension control
1. To improve the surface finish of a manufactured part
(a) Injection molding die: milling manual grinding/electro-grinding.
(b) Cylinders of engine: turning  grinding  honing  lapping
2. To improve the dimensional tolerance of a manufactured part
(a) ball-bearings: forging  grinding [control: < 15 mm]
(b) Knives: forged steel  hardened  grinding
3. To cut hard brittle materials
(a) Semiconductor IC chips: slicing and dicing
4. To remove unwanted materials of a cutting process
(a) Deburring parts made by drilling, milling

11. Abrasive tools and Machines

12. Turning Processes to cut cylindrical stock into revolved shapes
Process character: high MRR, high surface, dimension control

13. Turning operations

14. Fixturing parts for turning

15. Milling Versatile process to cut arbitrary 3D shapes
Process character: high MRR, high surface, dimension control
[source:
Kalpakjian
&
Schmid ]

16. Common vertical milling cutters
Flat
Ballnose
Bullnose

17. Up and Down milling

18. Fixtures for Milling: Vise

19. Fixtures for Milling: Clamps

20. Process Analysis
Fundamental understanding of the process  improve, control, optimize
Method: Observation  modeling  verification
Every process must be analyzed; [we only look at orthogonal 1-pt cutting]

21. Geometry of the cutting tool

22. Modeling: Mechanism of cutting
Old model: crack propagation
Current model: shear

23. Tool wear: observations and models
High stresses, High friction, High temp (1000C)  tool damage
Adhesion wear:
fragments of the workpiece get welded to the tool surface at high temperatures;
eventually, they break off, tearing small parts of the tool with them.
Abrasion:
hard particles, microscopic variations on the bottom surface of the chips
rub against the tool surface
Diffusion wear:
at high temperatures, atoms from tool diffuse across to the chip;
the rate of diffusion increases exponentially with temperature;
this reduces the fracture strength of the crystals.

24. Tool wear, Tool failure, Tool life criteria
Catastrophic failure (e.g. tool is broken completely)
VB = 0.3 mm (uniform wear in Zone B), or VBmax = 0.6 mm (non-uniform flank wear)
KT = f, (where f = feed in mm/revolution).

25. Built-up edge (BUE)
Deposition, work hardening of a thin layer of the workpiece material
on the surface of the tool.
BUE  poor surface finish
Likelihood of BUE decreases with
(i) decrease in depth of cut,
(ii) increase in rake angle,
(iii) use of proper cutting fluid during machining.

26. Experimental chart showing relation of tool wear with f and V
Process modeling: empirical results
Experimental chart showing relation of tool wear with f and V
[source: Boothroyd]

27. Modeling: surface finish
Relation of feed and surface finish

28. Analysis: Machining Economics
How can we optimize the machining of a part ?
Identify the objective, formulate a model, solve for optimality
Typical objectives: maximum production rate, and/or minimum cost
Are these objectives compatible (satisfied simultaneously) ?
Formulating model: observations  hypothesis  theory  model

29. Analysis: Machining Economics..
Formulating model: observations  hypothesis  theory  model
Observation:
A given machine, tool, workpiece combination has finite max MRR
Hypothesis:
Total volume to cut is minimum  Maximum production rate
Model objective:
Find minimum volume stock for a given part
-- Near-net shape stocks (use casting, forging, …)
-- Minimum enclosing volumes of 3D shapes
Models:
- minimum enclosing cylinder for a rotational part
- minimum enclosing rectangular box for a milled part
Solving:
-- requires some knowledge of computational geometry

30. Analysis: Machining Economics..
Model objective:
Find optimum operations plan and tools for a given part 
Example: or  or ??
Model: Process Planning
- Machining volume, tool selection, operations sequencing
Solving:
- in general, difficult to optimize

31. Analysis: process parameters optimization
Model objective:
Find optimum feed, cutting speed to [maximize MRR]/[minimize cost]/…
Feed:
Higher feed  higher MRR
Finish cutting:
surface finish  feed
 Given surface finish, we can find maximum allowed feed rate

32. Process parameters optimization: feed
Rough cutting:
MRR  cutting speed, V
MRR  feed, f
 cannot increase V and f arbitrarily
↑ V  ↑ MRR; surface finish ≠ f(V); energy per unit volume MRR ≠ f(V)
Friction wear: increase in V increases relative speed of tool and chip; however, increase in Feed increases area of contact of chip and tool – rate of tool wear
is not affected, just the area of wear is larger.
Tool temperature  V, f; Friction wear  V; Friction wear ≠ f
For a given increase in MRR: ↑ V  lower tool life than ↑ f
Optimum feed: maximum allowed for tool [given machine power, tool strength]

33. Process parameters optimization: Speed
Model objective:
Given optimum feed, what is the optimum cutting speed
 provided upper limits, but not optimum
Need a relation between tool life and cutting speed (other parameters being constant)
Taylor’s model (empirically based): V tn = constant

34. Process parameters optimization: Speed
One batch of large number, Nb, of identical parts
Replace tool by a new one whenever it is worn
Total non-productive time = Nbtl
tl = time to (load the stock + position the tool + unload the part)
Nb be the total number of parts in the batch.
Total machining time = Nbtm
tm = time to machine the part
Total tool change time = Nttc
tc = time to replace the worn tool with a new one
Nt = total number tools used to machine the entire batch.
Avg cost = Non-productive cost + Machining time cost + Tool change time cost + Tool cost
Cost of each tool = Ct,
Cost per unit time for machine and operator = M.
Average cost per item:

35. Process parameters optimization: Speed
Average cost per item:
Let: total length of the tool path = L
t = tool life  Nt = (Nb tm)/t  Nt / Nb = tm / t
We need to replace all time components in terms of Velocity
Taylor’s model Vtn = C’  t = C’ 1/n / V1/n = C/V1/n

36. Process parameters optimization: Speed
Average cost per item:
This gives us cost per unit as a function of Velocity.

37. Process parameters optimization: Speed
Optimum speed (to minimize costs)
Optimum speed (to minimize time)
Average time to produce part:

38. Process parameters optimization: Speed
Optimum speed (to minimize costs)
Optimum speed (to minimize time)
Average time to produce part:
load/unload time
tool change time
Note: the solution is different.
machining time
Substitute, differentiate, solve for V*

39. Process Planning The process plan specifies: operations
tools, path plan and operation conditions
setups
sequences
possible machine routings
fixtures

40. Process Planning

41. Operation sequencing examples (Milling)
big-hole  step  small hole or
small hole  step  big-hole …
step  hole or
hole  step

42. Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment

43. Joining Processes Types of Joints:
1. Joints that allow relative motion (kinematic joints)
2. Joints that disallow any relative motion (rigid joints)
Uses of Joints:
1. To restrict some degrees of freedom of motion
2. If complex part shape is impossible/expensive to manufacture
3. To allow assembled product be disassembled for maintenance.
4. Transporting a disassembled product is sometimes easier/feasible

44. Joining Processes
Fusion welding: joining metals by melting  solidification
Solid state welding: joining metals without melting
Brazing: joining metals with a lower mp metal
Soldering: joining metals with solder (very low mp)
Gluing: joining with glue
Mechanical joining: screws, rivets etc.

45. Fusion welding Oxy-acetylene welding Arc welding
Flame: 3000C
Oxy-acetylene welding
Arc welding
robotic
manual
arc: 30,000C
Gas shielded arc welding
MIG
TIG
Argon Al
Ti, Mg,
Thin sections

46. Fusion welding.. Plasma arc welding Laser beam welding
Deep, narrow welds
Aerospace, medical, automobile body panels
Plasma arc welding
Faster than TIW, slower than Laser
Nd:YAG and CO2 lasers, power ~ 100kW
Laser beam welding
Fast, high quality, deep, narrow welds
deep, narrow welds, expensive
Electron beam welding

47. Solid state welding
Diffusion welds between very clean, smooth pieces of metal, at 0.3~0.5Tm
Cold welding (roll bonding)
coins, bimetal strips

48. Solid state welding.. Ultrasonic welding Ultrasonic wire bonder
25mm Al wire on IC Chip
Ultrasonic wire bonder
Medical, Packaging, IC chips, Toys
Materials: metal, plastic
- clean, fast, cheap

49. Resistance welding Spot welding Seam welding
Welding metal strips: clamp together, heat by current
Spot welding
Seam welding

50. Brazing
Tm of Filler material < Tm of the metals being joined
Torch brazing
Furnace brazing
Common Filler materials: copper-alloys, e.g. bronze
Common applications: pipe joint seals, ship-construction
Soldering
Tin + Lead alloy, very low Tm (~ 200C)
Main application: electronic circuits

51. Gluing

52. Mechanical fasteners (a) Screws (b) Bolts, nuts and washers (c) Rivets
(a) pneumatic carton stapler (b) Clips (c) A circlip in the gear drive of a kitchen mixer
Plastic wire clips
Plastic snap-fasteners
Wire  conductor: crimping

53. Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment

54. Surface treatment, Coating, Painting
Post-production processes
Only affect the surface, not the bulk of the material
Improving the hardness
Improving the wear resistance
Controlling friction, Reduction of adhesion, improving the lubrication, etc.
Improving corrosion resistance
Improving aesthetics

55. Mechanical hardening Shot peening Laser peening
Shot peening precision auto gears
[source:
Laser peening
[source:

56. Case hardening Process Dopant Procedure Notes Applications Carburizing
Low-carbon steel part in oven at C with excess CO2
0.5 ~ 1.5mm case gets to 65 HRC; poor dimension control
Gears, cams, shafts, bearings
CarboNitriding
C and N
Low-carbon steel part in oven at C with excess CO2 and NH3
0.07~0.5mm case, up to 62 HRC, lower distortion
Nuts, bolts, gears
Cyaniding
Low-carbon steel part in bath of cyanide salts with 30% NaCN
0.025~0.25mm case, up to 65 HRC
nuts, bolts, gears, screws
Nitriding N
Low-carbon steel part in oven at C with excess NH3
0.1~0.6mm case, up to 1100 HV
tools, gears, shafts
Boronizing B
Part heated in oven with Boron containing gas
Very hard, wear resistant case, 0.025~0.075mm
Tool and die steels

57. Vapor deposition Deposition of thin film (1~10 mm) of metal
Sputtering: important process in IC Chip manufacture

58. Thermal spraying High velocity oxy-fuel spraying
Tungsten Carbide / Cobalt Chromium Coating
on roll for Paper Manufacturing Industry
Thermal metal powder spray
Plasma spray
[source:

59. Electroplating Anodizing
Deposit metal on cathode, sacrifice from anode
chrome-plated auto parts
copper-plating
Anodizing
Metal part on anode: oxide+coloring-dye deposited using electrolytic process

60. Painting Type of paints: Enamel: oil-based; smooth, glossy surface
Lacquers: resin based; dry as solvent evaporates out; e.g. wood varnish
Water-based paints: e.g. wall paints, home-interior paints
Painting methods
Dip coating: part is dipped into a container of paint, and pulled out.
Spray coating:  most common industrial painting method
Electrostatic spraying: charged paint particles sprayed to part using voltage
Silk-screening: very important method in IC electronics mfg

61. Painting Electrostatic Spray Painting Spray Painting in BMW plant
Silk screening

62. Summary
These notes covered processes: cutting, joining and surface treatment
We studied one method of modeling a process, in order to optimize it
We introduced the importance and difficulties of process planning.
Further reading: Chapters 24, 21, 30-32: Kalpajian & Schmid