ppt

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

2. Cutting
Sawing
Shaping (or planing),
Broaching, drilling,
Grinding,
Turning
Milling
Processes that involve removal of material from solid workpiece
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
chip
slide
tool-post pivot
chip
tool-post rotates as
slide returns;
workpiece shifted;
next stroke
(a) (b) (c)
chip
chip
slide
tool-post pivot
slide
tool-post pivot
chip
tool-post rotates as
slide returns;
workpiece shifted;
next stroke
chip
tool-post rotates as
slide returns;
workpiece shifted;
next stroke
(a) (b) (c)
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
Broaching machine
Broaching tools
Complex hole shapes cut by broaching
Broaching machine
Broaching tools
Complex hole shapes cut by broaching

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
Manual tap and die set
Automated tapping

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
abrasive wheels, paper, tools diamond grinding wheel for slicing silicon wafers diamond dicing wheel for silicon
abrasive wheels, paper, tools diamond grinding wheel for slicing silicon wafers diamond dicing wheel for silicon
 Grinding machine
Grinding wheels
Centerless grinding 
 Grinding machine
Grinding wheels
Centerless grinding 

12. Turning
Processes to cut cylindrical stock into revolved shapes
Process character: high MRR, high surface, dimension control
feed, f
depth of cut, d
feed, f
depth of cut, d
spindle chuck tool-post
carriage
tail-stock
carriage wheel cross-slide wheel
tail-stock wheel
lead-screw
spindle chuck tool-post
carriage
tail-stock
carriage wheel cross-slide wheel
tail-stock wheel
lead-screw

13. Turning operations
turning taper profile cut groove cut cut-off thread cut
facing face groove boring, internal groove drilling
knurling
turning taper profile cut groove cut cut-off thread cut
facing face groove boring, internal groove drilling
knurling
feed, f
depth of cut, d
feed, f
depth of cut, d

14. Fixturing parts for turning
part in a 3-jaw chuck 4-jaw chuck holding a non-rotational part
A collet type work-holder; collets are common in
automatic feeding lathes – the workpiece is a long
bar; each short part is machined and then cut-off;
the collet is released, enough bar is pushed out to
make the next part, and the collet is pulled back to
grip the bar; the next part is machined, and so on.
A long part held between live center (at spindle)
and dead center (at tailstock)
steps
part in a 3-jaw chuck 4-jaw chuck holding a non-rotational part
A collet type work-holder; collets are common in
automatic feeding lathes – the workpiece is a long
bar; each short part is machined and then cut-off;
the collet is released, enough bar is pushed out to
make the next part, and the collet is pulled back to
grip the bar; the next part is machined, and so on.
A long part held between live center (at spindle)
and dead center (at tailstock)
steps

15. Milling
Versatile process to cut arbitrary 3D shapes
Process character: high MRR, high surface, dimension control
[source: www.hitachi-tool.com.jp]
[source: www.phorn.co.uk]
[source: www.hitachi-tool.com.jp]
[source: www.hitachi-tool.com.jp]
[source: www.phorn.co.uk]
[source: www.phorn.co.uk]
[source: Kalpakjian & Schmid]
]
]

16. Common vertical milling cutters
Flat
Ballnose
Bullnose

17. Up and Down milling
(a) Conventional, or Up milling
- chip thickness goes UP;
- cutting dynamics: smoother
(b) Climb, or Down milling
- chip thickness goes DOWN;
- cutting dynamics: bad for forged/cast
parts with brittle, hard scales on surface
(a) Conventional, or Up milling
- chip thickness goes UP;
- cutting dynamics: smoother
(b) Climb, or Down milling
- chip thickness goes DOWN;
- cutting dynamics: bad for forged/cast
parts with brittle, hard scales on surface

18. Fixtures for Milling: Vise
 Vise fixed to a milling table, holding rectangular part
V-slot vise jaws hold cylindrical parts horizontally/vertically
 Vise fixed to a milling table, holding rectangular part
V-slot vise jaws hold cylindrical parts horizontally/vertically
Vise on sine-bar to hold part at an angle
relative to the spindle
Universal angle vise can index parts along any direction 
Vise on sine-bar to hold part at an angle
relative to the spindle
Universal angle vise can index parts along any direction 

19. Strap clamp
Clamp support
(clamp and support have teeth)
Parallel bars raise the part
above table surface – allow
making through holes
Bolt (bolt-head is inserted into T-slot in table)
Workpiece
Strap clamp
Clamp support
(clamp and support have teeth)
Parallel bars raise the part
above table surface – allow
making through holes
Bolt (bolt-head is inserted into T-slot in table)
Workpiece
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]
v
ve
vf
v
ve
vf

21. Geometry of the cutting tool
end cutting edge angle
side rake angle
side clearance angle front clearance angle
back rake angle
lead cutting edge angle
end cutting edge angle
side rake angle
side clearance angle front clearance angle
back rake angle
lead cutting edge angle

22. Modeling: Mechanism of cutting
Chip
Tool
Chip forms by
shear in this region
depth
of
cut
Friction between
tool, chip in this
region
Chip
Tool
Chip forms by
shear in this region
depth
of
cut
Friction between
tool, chip in this
region
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
1. Catastrophic failure (e.g. tool is broken completely)
2. VB = 0.3 mm (uniform wear in Zone B), or VBmax = 0.6 mm (non-uniform flank wear)
3. KT = 0.06 + 0.3f, (where f = feed in mm/revolution).
workpiece
tool
crater wear
flank wear
chip
workpiece
tool
crater wear
flank wear
chip

25. Built-up edge (BUE)
Deposition, work hardening of a thin layer of the workpiece material
on the surface of the tool.
negative rake angle
(for cutting hard, brittle materials)
negative rake angle
(for cutting hard, brittle materials)
negative rake angle
(for cutting hard, brittle materials)
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. 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
Model: Process Planning
- Machining volume, tool selection, operations sequencing
Solving:
- in general, difficult to optimize
Example:


or
or
??

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)
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
 provided upper limits, but not optimum
Need a relation between tool life and cutting speed (other parameters being constant)
Model objective:
Given optimum feed, what is the optimum cutting speed
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.
Cost of each tool = Ct,
Cost per unit time for machine and operator = M.
Average cost per item:
t
b
t
c
b
t
m
l
pr C
N
N
t
N
N
M
Mt
Mt
C 




35. Process parameters optimization: Speed
Average cost per item: t
b
t
c
b
t
m
l
pr C
N
N
t
N
N
M
Mt
Mt
C 



Let: total length of the tool path = L
V
L
tm  1

 MLV
V
L
M
t = tool life  Nt = (Nb tm)/t  Nt / Nb = tm / t
Taylor’s model Vtn = C’ t = C’1/n / V1/n = C/V1/n
C
V
L
C
V
V
L
t
t
N
N n
n
n
m
b
t
/
)
1
(
/
1 




36. Process parameters optimization: Speed
Average cost per item: t
b
t
c
b
t
m
l
pr C
N
N
t
N
N
M
Mt
Mt
C 



1

 MLV
V
L
M
C
V
L
N
N n
n
b
t
/
)
1
( 

n
n
t
c
l
pr V
C
t
M
C
L
MLV
Mt
C /
)
1
(
1
)
( 






37. Process parameters optimization: Speed
n
n
t
c
l
pr V
C
t
M
C
L
MLV
Mt
C /
)
1
(
1
)
( 





n
n
t
c
pr
V
n
n
C
t
M
C
L
MLV
dV
dC /
)
2
1
(
2 )
1
(
)
(
0 
 





Optimum speed (to minimize costs)
n
t
c n
n
C
t
M
MC
V 










)
1
(
)
(
*
Optimum speed (to minimize time)
c
b
t
m
l
pr t
N
N
t
t
t 


Average time to produce part:

38. Process parameters optimization: Speed
Optimum speed (to minimize costs)
n
t
c n
n
C
t
M
MC
V 










)
1
(
)
(
*
Optimum speed (to minimize time)
c
b
t
m
l
pr t
N
N
t
t
t 


Average time to produce part:
load/unload time
machining time
tool change time
V
L
tm 
c
b
t
m
l
pr t
N
N
t
t
t 


C
V
L
N
N n
n
b
t
/
)
1
( 

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
4 x counterbored holes
groove 5mmX5mm
4 x counterbored holes
groove 5mmX5mm
S1
S2
S3
S4
S5 S6
S7
S8
S9
S10
S1
S2
S3
S4
S5 S6
S7
S8
S9
S10

40. Process Planning
4 x counterbored holes
groove 5mmX5mm
4 x counterbored holes
groove 5mmX5mm
S1
S2
S3
S4
S5 S6
S7
S8
S9
S10
S1
S2
S3
S4
S5 S6
S7
S8
S9
S10
[7.5mm Drill] drill 4 holes 7.5
[HSS 1-pt tool] Face S6
[5mm groove cutter] Groove S9
Setup 3: Clamp part on Drill press,
Locate using: S3, S7
[HSS 1-pt tool] turn S5 to 60,
face S10, fillet edge on S4
[Center drill] mark, center-drill 4 holes
[HSS 1-pt tool] face S1
[HSS 1-pt tool] face S3
[Drill in tailstock] Center drill
[Drill in tailstock] Drill 32
Setup 2: Chuck part on S4
[10mm counterbore] Counterbore 5mm
[HSS 1-pt tool] turn S2 to 55
[HSS 1-pt tool] turn S4 to 104
Setup 1: Part in chuck
Ts
Tc
L
d
S
f
V
Description
Fixture: 3-jaw chuck on lathe; Strap clamp + parallel bars on drill-press
Legend:
Batch size= N pieces
Stock: bar stock diameter: 105
Job # :
[7.5mm Drill] drill 4 holes 7.5
[HSS 1-pt tool] Face S6
[5mm groove cutter] Groove S9
Setup 3: Clamp part on Drill press,
Locate using: S3, S7
[HSS 1-pt tool] turn S5 to 60,
face S10, fillet edge on S4
[Center drill] mark, center-drill 4 holes
[HSS 1-pt tool] face S1
[HSS 1-pt tool] face S3
[Drill in tailstock] Center drill
[Drill in tailstock] Drill 32
Setup 2: Chuck part on S4
[10mm counterbore] Counterbore 5mm
[HSS 1-pt tool] turn S2 to 55
[HSS 1-pt tool] turn S4 to 104
Setup 1: Part in chuck
Ts
Tc
L
d
S
f
V
Description
Fixture: 3-jaw chuck on lathe; Strap clamp + parallel bars on drill-press
Legend:
Batch size= N pieces
Stock: bar stock diameter: 105
Job # :
V: cutting speed m/min
f : feed mm/rev
S: spindle rpm
d: depth of cut mm
L: Tool path length, min
Tc: cutting time, min
Ts: setup time, min

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

42. Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Cutting
Joining
Powder- and Ceramics Processing
Plastics processing
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. Arc welding
Oxy-acetylene welding
Flame: 3000C
arc: 30,000C
manual
robotic
Gas shielded arc welding
Argon
MIG TIG
Al Ti, Mg,
Thin sections
Fusion welding

46. Plasma arc welding
Electron beam welding
Laser beam welding
Deep, narrow welds
Aerospace, medical, automobile body panels
Faster than TIW, slower than Laser
Nd:YAG and CO2 lasers, power ~ 100kW
Fast, high quality, deep, narrow welds
deep, narrow welds, expensive
Fusion 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
25mm Al wire on IC Chip
Ultrasonic wire bonder
Medical, Packaging, IC chips, Toys
Materials: metal, plastic
- clean, fast, cheap

49. Resistance welding
Welding metal strips: clamp together, heat by current
Spot welds on a pan
Spot welding Robotic Spot welding on auto body
Spot welds on a pan
Spot welding Robotic Spot welding on auto body
Spot welding
Seam welding
resistance seam welding
resistance welded petrol tank
resistance seam welding
resistance welded petrol tank

50. Brazing
Torch brazing Furnace brazing
Tm of Filler material < Tm of the metals being joined
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
Adhesive type Notes Applications
Acrylic two component thermoplastic; quick
setting; impact resistant, strong impact
and peel strength
fiberglass, steel, plastics, motor
magnets, tennis racquets
Anaerobic thermoset; slow, no-air curing – cures in
presence of metal ions
sealing of nut-and-bolts, close-
fitting holes and shafts, casting
micro-porosities etc.
Epoxy strongest adhesive; thermoset; high tensile
strength; low peel strength
metal parts (especially Nickel),
ceramic parts, rigid plastics
Cyanoacrylate thermoplastic; high strength; rapid aerobic
curing in presence of humidity
[common brand: Crazy glue™]
plastics, rubber, ceramics, metals
Hot melt thermoplastic polymers; rigid or flexible;
applied in molten state, cure on cooling
footwear, cartons and other
packaging boxes, book-binding
Polyacrylate esters
(PSA)
Pressure sensitive adhesives all types of tapes, labels, stickers,
decals, envelops, etc.
Phenolic thermoset, oven curing, strong but brittle acoustic padding, brake lining,
clutch pads, abrasive grain bonding
Silicone thermoset, slow curing, flexible gaskets and sealants
Formaldehyde thermoset joining wood, making plywood
Urethane thermoset, strong at large thickness fiberglass body parts, concrete gap
filling, mold repairs
Water-based cheap, non-toxic, safe wood, paper, fabric, leather

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
Wire  conductor: crimping
Plastic snap-fasteners

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

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

55. Mechanical hardening
Shot peening precision auto gears [source: www.vacu-blast.co.uk]
[source: www.uwinint.co.kr]
Shot peening
Laser peening

56. Case hardening
Process Dopant Procedure Notes Applications
Carburizing C Low-carbon steel part in
oven at 870-950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 800-900C with
excess CO2 and NH3
0.07~0.5mm case, up
to 62 HRC, lower
distortion
Nuts, bolts,
gears
Cyaniding C and N 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 500-600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
Thermal metal powder spray
Plasma spray
Tungsten Carbide / Cobalt Chromium Coating
on roll for Paper Manufacturing Industry
[source: www.fst.nl/process.htm]

59. Electroplating
Deposit metal on cathode, sacrifice from anode
Anodizing
chrome-plated auto parts
copper-plating
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. 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.
Summary
Further reading: Chapters 24, 21, 30-32: Kalpajian & Schmid