Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment
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
Sawing
A process to cut components, stock, etc.
Process character: Precision: [very low,, very high]; MRR: low
Sawing
Shaping
A process to plane the surface of a workpiece (or to reduce part thickness
Process character: High MRR, medium Surface finish, dimension control
(a)
tool-post
(b)
pivot
slide
(c)
chip
chip
tool-post rotates as
slide returns;
workpiece shifted;
next stroke
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
Drilling, Reaming, Boring
Processes to make holes
Process character: High MRR, Cheap, Medium-high surface, dimension control
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
Tapping
Processes to make threads in holes
Process character: low MRR, Cheap, good surface, dimension control
Manual tap and die set
Automated tapping
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
Abrasive tools and Machines
abrasive wheels, paper, tools
diamond grinding wheel for slicing silicon wafers
Grinding wheels
 Grinding machine
Centerless grinding 
diamond dicing wheel for silicon
Turning
Processes to cut cylindrical stock into revolved shapes
Process character: high MRR, high surface, dimension control
spindle
chuck
tool-post
tail-stock
tail-stock wheel
depth of cut, d
feed, f
lead-screw
carriage wheel
carriage
cross-slide wheel
Turning operations
depth of cut, d
feed, f
turning
taper
profile cut
groove cut
cut-off
thread cut
knurling
facing
face groove
boring, internal groove
drilling
Fixturing parts for turning
steps
part in a 3-jaw chuck
4-jaw chuck holding a non-rotational part A long part held between live center (at spindle)
and dead center (at tailstock)
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.
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: Kalpakjian & Schmid]]
Common vertical milling cutters
Flat
Ballnose
Bullnose
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
Fixtures for Milling: Vise
V-slot vise jaws hold cylindrical parts horizontally/vertically
 Vise fixed to a milling table, holding rectangular part
Universal angle vise can index parts along any direction 
Vise on sine-bar to hold part at an angle
relative to the spindle
Fixtures for Milling: Clamps
Clamp support
(clamp and support have teeth)
Workpiece
Strap clamp
Parallel bars raise the part
above table surface – allow
making through holes
Bolt (bolt-head is inserted into T-slot in table)
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]
ve
vf
v
Geometry of the cutting tool
end cutting edge angle
lead cutting edge angle
back rake angle
side rake angle
side clearance angle
front clearance angle
depth of cut
Modeling: Mechanism of cutting
Chip
Friction between
tool, chip in this
region
Chip forms by
shear in this region
Tool
Old model: crack propagation
Current model: shear
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.
Tool wear, Tool failure, Tool life criteria
chip
crater wear
tool
workpiece
flank wear
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).
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)
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.
Process modeling: empirical results
Experimental chart showing relation of tool wear with f and V
[source: Boothroyd]
Modeling: surface finish
Relation of feed and surface finish
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
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
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
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
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]
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
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:
C pr
Nt
Nt
 Mt l  Mt m  M
tc 
Ct
Nb
Nb
Process parameters optimization: Speed
Average cost per item:
C pr
Nt
Nt
 Mt l  Mt m  M
tc 
Ct
Nb
Nb
Let: total length of the tool path = L
tm 
L
V
M
L
 MLV 1
V
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
Nt
tm
L V (1n ) / n
L V 1/ n



Nb
t
V C
C
Process parameters optimization: Speed
Average cost per item:
C pr
Nt
Nt
 Mt l  Mt m  M
tc 
Ct
Nb
Nb
L
M  MLV 1
V
Nt
L V (1 n ) / n

Nb
C
C pr  Mt l  MLV
1
L
 ( M t c  Ct ) V (1 n ) / n
C
Process parameters optimization: Speed
C pr  Mt l  MLV
1
L
 ( M t c  Ct ) V (1 n ) / n
C
Optimum speed (to minimize costs)
dC pr
dV
 0   MLV
2
L
(1  n) (12 n ) / n
 ( M t c  Ct )
V
C
n

MC
n 


V * 
 ( M tc  Ct ) (1  n) 
n
Optimum speed (to minimize time)
Average time to produce part:
t pr
Nt
 tl  t m 
tc
Nb
Process parameters optimization: Speed
Optimum speed (to minimize costs)

MC
n 

V *  
(
M
t

C
)
(
1

n
)
c
t


n
Optimum speed (to minimize time)
Average time to produce part:
t pr
load/unload time
Nt
 tl  t m 
tc
Nb
tool change time
machining time
t pr
Nt
 tl  t m 
tc
Nb
L
tm 
V
Nt
L V (1 n ) / n

Nb
C
Substitute, differentiate, solve for V*
Process Planning
The process plan specifies:
operations
tools, path plan and operation conditions
setups
sequences
possible machine routings
fixtures
S4
S3
4 x counterbored holes
S10
S5
S6
S2
S1
S7
S9
S8
groove 5mmX5mm
Process Planning
Job # :
Stock: bar stock diameter: 105
Batch size= N pieces
Fixture: 3-jaw chuck on lathe; Strap clamp + parallel bars on drill-press
Legend:
4 x counterbored holes
Description
Setup 1: Part in chuck
[HSS 1-pt tool] turn S4 to 104
[HSS 1-pt tool] turn S2 to 55
groove 5mmX5mm
[HSS 1-pt tool] face S1
[HSS 1-pt tool] face S3
S4
S3
[Drill in tailstock] Center drill
S10
S5
S6
[Drill in tailstock] Drill 32
S2
Setup 2: Chuck part on S4
[HSS 1-pt tool] turn S5 to 60,
face S10, fillet edge on S4
S1
S7
[HSS 1-pt tool] Face S6
[5mm groove cutter] Groove S9
Setup 3: Clamp part on Drill press,
Locate using: S3, S7
[Center drill] mark, center-drill 4 holes
S9
S8
[7.5mm Drill] drill 4 holes 7.5
[10mm counterbore] Counterbore 5mm
V
f
S
d
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
L
Tc
Ts
Operation sequencing examples (Milling)
step  hole
or
hole  step
big-hole  step  small hole
or
small hole  step  big-hole
or
…
Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment
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
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.
Fusion 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
Fusion 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
Solid state welding
Diffusion welds between very clean, smooth pieces of metal, at 0.3~0.5Tm
Cold welding (roll bonding)
coins, bimetal strips
Solid state welding..
Ultrasonic welding
Ultrasonic wire bonder
25mm Al wire on IC Chip
Medical, Packaging, IC chips, Toys
Materials: metal, plastic
- clean, fast, cheap
Resistance welding
Welding metal strips: clamp together, heat by current
Spot welding
Spot welding
Spot welds on a pan
Robotic Spot welding on auto body
Seam welding
resistance seam welding
resistance welded petrol tank
Brazing
Tm of Filler material < Tm of the metals being joined
Torch 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
Furnace brazing
Gluing
Adhesive type
Acrylic
Anaerobic
Notes
two component thermoplastic; quick
setting; impact resistant, strong impact
and peel strength
thermoset; slow, no-air curing – cures in
presence of metal ions
Applications
fiberglass, steel, plastics, motor
magnets, tennis racquets
sealing of nut-and-bolts, closefitting holes and shafts, casting
micro-porosities etc.
Epoxy
strongest adhesive; thermoset; high tensile metal parts (especially Nickel),
strength; low peel strength
ceramic parts, rigid plastics
Cyanoacrylate
thermoplastic; high strength; rapid aerobic [common brand: Crazy glue™]
curing in presence of humidity
plastics, rubber, ceramics, metals
Hot melt
thermoplastic polymers; rigid or flexible; footwear, cartons and other
applied in molten state, cure on cooling
packaging boxes, book-binding
Polyacrylate esters Pressure sensitive adhesives
all types of tapes, labels, stickers,
(PSA)
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
Mechanical fasteners
(a) Screws
(b) Bolts, nuts and washers
(a) pneumatic carton stapler
(b) Clips
(c) Rivets
(c) A circlip in the gear drive of a kitchen mixer
Plastic wire clips
Plastic snap-fasteners
Wire  conductor: crimping
Traditional Manufacturing Processes
Casting
Forming
Sheet metal processing
Powder- and Ceramics Processing
Plastics processing
Cutting
Joining
Surface treatment
Surface treatment, Coating, Painting
Post-production processes
Only affect the surface, not the bulk of the material
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
Mechanical hardening
Shot peening
Shot peening precision auto gears
[source: www.vacu-blast.co.uk]
Laser peening
[source: www.uwinint.co.kr]
Case hardening
Process
Dopant
Procedure
Notes
Applications
Carburizing
C
Low-carbon steel part in 0.5 ~ 1.5mm case gets
oven at 870-950C with to 65 HRC; poor
excess CO2
dimension control
Gears,
cams,
shafts, bearings
CarboNitriding
C and N
Low-carbon steel part in 0.07~0.5mm case, up
oven at 800-900C with to 62 HRC, lower
excess CO2 and NH3
distortion
Nuts,
gears
Cyaniding
C and N
Low-carbon steel part in 0.025~0.25mm
bath of cyanide salts with up to 65 HRC
30% NaCN
Nitriding
N
Low-carbon steel part in 0.1~0.6mm case, up tools,
oven at 500-600C with to 1100 HV
shafts
excess NH3
Boronizing
B
Part heated in oven with Very
hard,
wear Tool and
Boron containing gas
resistant
case, steels
0.025~0.075mm
bolts,
case, nuts,
bolts,
gears, screws
gears,
die
Vapor deposition
Deposition of thin film (1~10 mm) of metal
Sputtering: important process in IC Chip manufacture
Thermal spraying
High velocity oxy-fuel spraying
Thermal metal powder spray
Tungsten Carbide / Cobalt Chromium Coating
on roll for Paper Manufacturing Industry
Plasma spray
[source: www.fst.nl/process.htm]
Electroplating
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
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
Painting
Electrostatic Spray Painting
Spray Painting in BMW plant
Silk screening
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