Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Polymer PropertiesElongation Poisson’sin 50 mm ratio
Material UTS (MPa) E (GPa) (%) (!)ABS 28–55 1.4–2.8 75–5 –ABS (reinforced) 100 7.5 – 0.35Acetals 55–70 1.4–3.5 75–25 –Acetals (reinforced) 135 10 – 0.35–0.40Acrylics 40–75 1.4–3.5 50–5 –Cellulosics 10–48 0.4–1.4 100–5 –Epoxies 35–140 3.5–17 10–1 –Epoxies (reinforced) 70–1400 21–52 4–2 –Fluorocarbons 7–48 0.7–2 300–100 0.46–0.48Nylon 55–83 1.4–2.8 200–60 0.32–0.40Nylon (reinforced) 70–210 2–10 10–1 –Phenolics 28–70 2.8–21 2–0 –Polycarbonates 55–70 2.5–3 125–10 0.38Polycarbonates (reinforced) 110 6 6–4 –Polyesters 55 2 300–5 0.38Polyesters (reinforced) 110–160 8.3–12 3–1 –Polyethylenes 7–40 0.1–0.14 1000–15 0.46Polypropylenes 20–35 0.7–1.2 500–10 –Polypropylenes (reinforced) 40–100 3.6–6 4–2 –Polystyrenes 14–83 1.4–4 60–1 0.35Polyvinyl chloride 7–55 0.014–4 450–40 –
TABLE 10.1 Approximate range of mechanical properties for various engineering plastics at room temperature.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Polymer Structure
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
FIGURE 10.1 Basic structure of some polymer molecules: (a) ethylene molecule; (b) polyethylene, a linear chain of many ethylene molecules; (c) molecular structure of various polymers. These molecules are examples of the basic building blocks for plastics.
Polypropylene
Polystyrene
Polyvinyl chloride
Polytetrafluoroethylene(Teflon)
Polyethylene
H
C
H
H
C
H
Fl
C
Fl
Fl
C
Fl
H
C
H
H
C
Cl
CH3
H
C
H
H
C
C6H5
H
C
H
H
C
n
H
C
H
H
C
H
nCH3
H
C
H
H
C
n
H
C
H
H
C
Cl
nC6H5
H
C
H
H
C
n
Fl
C
Fl
Fl
C
Fl
H
C
H
H
C
H
(a) (b)
Polyethylene
Mer
n
Heat, pressure,
catalyst
(c)
H H H H
C C C C
H H H HHH
C
HH
C
Polymer repeating unitMonomer
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Effect of Molecular Weight
FIGURE 10.2 Effect of molecular weight and degree of polymerization on the strength and viscosity of polymers.
104 107
Molecular weight, degreeof polymerization
Pro
pert
y
Tensile andimpact strength
Commercial
polymers
Viscosity
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Polymer Chains
FIGURE 10.3 Schematic illustration of polymer chains. (a) Linear structure; thermoplastics such as acrylics, nylons, polyethylene, and polyvinyl chloride have linear structures. (b) Branched structure, such as polyethylene. (c) Cross-linked structure; many rubbers and elastomers have this structure. Vulcanization of rubber produces this structure. (d) Network structure, which is basically highly cross-linked; examples include thermosetting plastics such as epoxies and phenolics.
(a) Linear (b) Branched
(c) Cross-linked (d) Network
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Effect of Temperature
FIGURE 10.4 Behavior of polymers as a function of temperature and (a) degree of crystallinity and (b) cross-linking. The combined elastic and viscous behavior of polymers is known as viscoelasticity.
(a) (b)
Amorphous
Glassy
Increasingcrystallinity
Ela
stic m
odulu
s (
log s
cale
)
Temperature
Tg Tm
100% crystalline
Leathery
Rubbery
Viscous
No cross-linking
Increasingcross-linking
Ela
stic m
odulu
s (
log s
cale
)
Temperature
Tm
Leathery
Rubbery
Viscous
Glassy
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Crystallinity
FIGURE 10.5 Amorphous and crystalline regions in a polymer. Note that the crystalline region (crystallite) has an orderly arrangement of molecules. The higher the crystallinity, the harder, stiffer, and less ductile is the polymer.
Amorphous region
Crystalline region
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Glass-Transition Temperature
FIGURE 10.6 Specific volume of polymers as a function of temperature. Amorphous polymers, such as acrylic and polycarbonate, have a glass-transition temperature, Tg, but do not have a specific melting point, Tm. Partly crystalline polymers, such as polyethylene and nylons, contract sharply at their melting points during cooling.
Temperature
Tg Tm
Amorphous polymers
Cooling:
rapid
slow
Sp
ecific
vo
lum
e
Partly crystalline polymers
Material Tg (!C) Tm (!C)Nylon 6,6 57 265Polycarbonate 150 265Polyester 73 265Polyethylene
High density -90 137Low density -110 115
Polymethylmethacrylate 105 –Polypropylene -14 176Polystyrene 100 239Polytetrafluoroethylene (Teflon) -90 327Polyvinyl chloride 87 212Rubber -73 –
TABLE 10.2 Glass-Transition and Melting Temperatures of Selected Polymers
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Deformation of Polymers
FIGURE 10.7 Various deformation modes for polymers.: (a) elastic; (b) viscous; (c) viscoelastic (Maxwell model); and (d) viscoelastic (Voigt or Kelvin model). In all cases, an instantaneously applied load occurs at time to, resulting in the strain paths shown.
(a) (b)
(c) (d)
Str
ain
Time
t0 t1
Increasing viscosityS
tra
in
Time
t0 t1
Recoveredstrain
Str
ain
Time
t0 t1
Str
ain
Time
t0 t1
Recovered strain
FIGURE 10.8 General terminology describing the behavior of three types of plastics. PTFE is polytetrafluoroethylene (Teflon, a trade name). Source: After R.L.E. Brown.
Rigid andbrittle(melamine,phenolic)
Soft and flexible(polyethylene, PTFE)
Tough and ductile(ABS, nylon)
0
Str
ess
Strain
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Temperature Effects
FIGURE 10.9 Effect of temperature on the stress-strain curve for cellulose acetate, a thermoplastic. Note the large drop in strength and increase in ductility with a relatively small increase in temperature. Source: After T.S. Carswell and H.K. Nason.
00 0
10
20
30
40
50
60
70225°C
25°
50°
65°
80°
0°10
8
6
4
2
5 10 15 20 25 30
Str
ess (
psi x 1
03)
MP
aStrain (%)
FIGURE 10.10 Effect of temperature on the impact strength of various plastics. Note that small changes in temperature can have a significant effect on impact strength. Source: P.C. Powell.
Impact str
ength
Low-densitypolyethylene
High-impactpolypropylene
Polyvinyl chloride
Polymethylmethacrylate
Temperature (°F)
°C
0 32 90
218 0 32
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Viscosity of Melted Polymers
FIGURE 10.11 Parameters used to describe viscosity; see Eq. (10.3).
v
y
t
t
FIGURE 10.12 Viscosity of some thermoplastics as a function of (a) temperature and (b) shear rate. Source: After D.H. Morton-Jones.
Low density polyethylene
Polypropylene
Rigid P
VC
Acrylic
Nylon
140 160 180 200 220 240 260 280 300 320
Vis
co
sity (
Ns/m
2)
10
102
103
104
Temperature (°C)
(a)
1 10 102 103 10410
102
103
104
Ap
pa
ren
t vis
co
sity (
Ns/m
2)
Shear rate, ! (s-1)
Polycarbonate
Rigid PV
C (190°C
)
Acrylic (240°C) LDPE (170°C)
Nylon (285°C)
Polypropylene (230°C)
(b)
! = 1000 s-1
Viscous behavior:
τ= η
!dvdy
"= ηγ̇
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Polymer Behavior in Tension
FIGURE 10.13 (a) Load-elongation curve for polycarbonate, a thermoplastic. Source: After R.P. Kambour and R.E. Robertson. (b) High-density polyethylene tension-test specimen, showing uniform elongation (the long, narrow region in the specimen).
(a) (b)
0 25 50 75 100 125
mm
16
14
12
10
8
6
4
2
0
(psi x
10
3)
100
80
60
40
20
0
Str
ess (
MP
a)
0 1 2 3 4 5
Elongation (in.)
Molecules arebeing oriented
FIGURE 10.14 Typical load-elongation curve for elastomers. The area within the clockwise loop, indicating loading and unloading paths, is the hysteresis loss. Hysteresis gives rubbers the capacity to dissipate energy, damp vibration, and absorb shock loading, as in automobile tires and v i b r a t ion dampener s fo r machinery.
Loading
Unloading
Load
Elongation
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Applications for PlasticsDesignRequirement
Typical Applications Plastics
Mechanicalstrength
Gears, cams, rollers, valves, fanblades, impellers, pistons.
Acetals, nylon, phenolics, polycarbonates,polyesters, polypropylenes, epoxies, poly-imides.
Wearresistance
Gears, wear strips and liners, bear-ings, bushings, roller-skate wheels.
Acetals, nylon, phenolics, polyimides,polyurethane, ultrahigh-molecular-weightpolyethylene.
Frictional prop-erties
High Tires, nonskid surfaces, footware,flooring.
Elastomers, rubbers.
Low Sliding surfaces, artificial joints. Fluorocarbons, polyesters, polyethylene, poly-imides.
Electricalresistance
All types of electrical components andequipment, appliances, electrical fix-tures.
Polymethylmethacrylate, ABS, fluorocarbons,nylon, polycarbonate, polyester, polypropy-lenes, ureas, phenolics, silicones, rubbers.
Chemicalresistance
Containers for chemicals, laboratoryequipment, components for chemicalindustry, food and beverage contain-ers.
Acetals, ABS, epoxies, polymethylmethacry-late, fluorocarbons, nylon, polycarbonate,polyester, polypropylene, ureas, silicones.
Heat resistance Appliances, cookware, electrical com-ponents.
Fluorocarbons, polyimides, silicones, acetals,polysulfones, phenolics, epoxies.
Functional anddecorativefeatures
Handles, knobs, camera and batterycases, trim moldings, pipe fittings.
ABS, acrylics, cellulosics, phenolics,polyethylenes, polpropylenes, polystyrenes,polyvinyl chloride.
Functional andtransparent fea-tures
Lenses, goggles, safety glazing, signs,food-processing equipment
Acrylics, polycarbonates, polystyrenes, poly-sulfones. laboratory hardware.
Housings andhollow shapes
Power tools, housings, sport helmets,telephone cases.
ABS, cellulosics, phenolics, polycarbonates,polyethylenes, polypropylene, polystyrenes.
TA B L E 1 0 . 3 G e n e r a l recommendations for plastic products.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Reinforced Polymers
FIGURE 10.15 Schematic illustration of types of reinforcing plastics. (a) Matrix with particles; (b) matrix with short or long fibers or flakes; (c) continuous fibers; and (d) and (e) laminate or sandwich composite structures using a foam or honeycomb core (see also Fig. 7.48 on making of honeycombs).
Particles
Continuous fibers
(a)
(c) (b)
Short or long fibers, or flakes
Laminate
Foam
Honeycomb
(d)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Properties of Reinforcing Fibers
FIGURE 10.16 Specific tensile strength (ratio of tensile strength-to-density) and specific tensile modulus (ratio of modulus of elasticity-to-density) for various fibers used in reinforced plastics. Note the wide range of specific strength and stiffness available.
Kevlar 49
S-glass
Boron
High-modulus
graphite
E-glass
Celion 3000
Thornel
P-55
Titanium
Steel Aluminum
Kevlar 29
Kevlar 129 Spectra 900
Spectra 2000
Str
ength
/density (
m x
10
4)
40
30
20
10
0
Stiffness/density (m x 106)
0 105 15 20
Thornel P-100
High-tensilegraphite
Tensile Elastic Density RelativeType Strength (MPa) Modulus (GPa) (kg/m3) CostBoron 3500 380 2600 HighestCarbon
High strength 3000 275 1900 LowHigh modulus 2000 415 1900 Low
GlassE type 3500 73 2480 LowestS type 4600 85 2540 Lowest
Kevlar29 2800 62 1440 High49 2800 117 1440 High129 3200 85 1440 High
Nextel312 1630 135 2700 High610 2770 328 3960 High
Spectra900 2270 64 970 High1000 2670 90 970 High
Note: These properties vary significantly, depending on the material and methodof preparation. Strain to failure for these fibers is typically in the range of 1.5% to5.5%.
TABLE 10.4 Typical properties of reinforcing fibers.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Metal and Ceramic Matrix Composites
Material CharacteristicsFIBER
Glass High strength, low sti!ness, high density; E (calcium aluminoborosilicate) andS (magnesiaaluminosilicate) types are commonly used; lowest cost.
Graphite Available typically as high modulus or high strength; less dense than glass; lowcost.
Boron High strength and sti!ness; has tungsten filament at its center (coaxial); highestdensity; highest cost.
Aramids (Kevlar) Highest strength-to-weight ratio of all fibers; high cost.Other Nylon, silicon carbide, silicon nitride, aluminum oxide, boron carbide, boron
nitride, tantalum carbide, steel, tungsten, and molybdenum; see Chapters 3, 8,9, and 10.
MATRIXThermosets Epoxy and polyester, with the former most commonly used; others are pheno-
lics, fluorocarbons, polyethersulfone, silicon, and polyimides.Thermoplastics Polyetheretherketone; tougher than thermosets, but lower resistance to temper-
ature.Metals Aluminum, aluminumlithium alloy, magnesium, and titanium; fibers used are
graphite, aluminum oxide, silicon carbide, and boron.Ceramics Silicon carbide, silicon nitride, aluminum oxide, and mullite; fibers used are
various ceramics.
TABLE 10.4 Types and General Characteristics of Reinforced Plastics and Metal-Matrix and Ceramic-Matrix Composites
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Fiber Spinning
FIGURE 10.1 The melt spinning process for producing polymer fibers. The fibers are used in a variety of applications, including fabrics and as reinforcements for composite materials.
Polymerchips
Feedhopper
Cold air
Spinneret
Meltspinning
Melter/extruder
Bobbin
Stretching
Twisting andwinding
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Composite Material Microstructure
FIGURE 10.18 (a) Cross-section of a tennis racket, showing graphite and aramid (Kevlar) reinforcing fibers. Source: After J. Dvorak and F. Garrett. (b) Cross-section of boron-fiber-reinforced composite material.
(b)(a)
Kevlar fibers
Graphite fibers
Matrix
Matrix
Borondiameter 0.1 mm
Tungstendiameter 0.012 mm
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Effect of Fibers
FIGURE 10.19 Effect of the percentage of reinforcing fibers and fiber length on the mechanical properties of reinforced nylon. Note the significant improvement with increasing percentage of fiber reinforcement. Source: Courtesy of Wilson Fiberfill International.
Short glass fibers
Carbon fibers
Long glass fib
ers
Short glass fibers
Carbon fibers
Long glass fibers
Reinforcement (%)
Impact energ
y (
ft-lb/in.)
J/m
0
1
2
3
4
5
6
0 10 20 30 40
10 0 40 20 30
0
100
200
300
Reinforcement (%)
Fle
xura
l m
odulu
s (
psi x 1
06)
Long and short
glass fibers
0
1
2
3
4
5
6
10
0
30
40
20 GP
a
Short glass fibers
Long glass fibers
Carbon fib
ers
10 0 30 40 20
Reinforcement (%)
Fle
xura
l str
ength
(psi x
10
3)
0
10
20
30
40
50
60
100
0
200
300
400
MP
a
Carbon fibers
Reinforcement (%)
(b)
(c) (d)
(a)
Tensile
str
ength
(psi x 1
03)
MP
a
0
10
20
30
40
50
60
0 10 20 30 40 0
100
200
300
400
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Strength and Fracture of Composites
FIGURE 10.20 (a) Fracture surface of glass-fiber-reinforced epoxy composite. The fibers are 10 µm (400 µin.) in diameter and have random orientation. (b) Fracture surface of a graphite-fiber-reinforced epoxy composite. The fibers are 9-11 µm in diameter. Note that the fibers are in bundles and are all aligned in the same direction. Source: Courtesy of L.J. Broutman.
(a) (b)
FIGURE 10.21 Tensile strength of glass-reinforced polyester as a function of fiber content and fiber direction in the matrix. Source: After R.M. Ogorkiewicz.
Te
nsile
str
en
gth
(p
si x 1
05)
20 40 60 80
Unidirectional
Orthogonal
Random
Glass content (% by weight)
MP
a
10001.5
2.0
1.0
0.5
0
500
0
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Plastics ProcessesProcess CharacteristicsExtrusion Long, uniform, solid or hollow, simple or complex cross-sections; wide range
of dimensional tolerances; high production rates; low tooling cost.Injection molding Complex shapes of various sizes and with fine detail; good dimensional
accuracy; high production rates; high tooling cost.Structural foam
moldingLarge parts with high stiffness-to-weight ratio; low production rates; lessexpensive tooling than in injection molding.
Blow molding Hollow thin-walled parts of various sizes; high production rates and lowcost for making beverage and food containers.
Rotational molding Large hollow shapes of relatively simple design; low production rates; lowtooling cost.
Thermoforming Shallow or deep cavities; medium production rates; low tooling costs.Compression molding Parts similar to impression-die forging; medium production rates; relatively
inexpensive tooling.Transfer molding More complex parts than in compression molding, and higher production
rates; some scrap loss; medium tooling cost.Casting Simple or intricate shapes, made with flexible molds; low production rates.Processing of
reinforced plasticsLong cycle times; dimensional tolerances and tooling costs depend on thespecific process.
TABLE 10.6 Characteristics of processing plastics and reinforced plastics.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Extrusion
FIGURE 10.22 Schematic illustration of a typical extruder.
Thrust bearing
Hopper
Throat
Screw
Barrelliner
Barrel
Barrelheater/cooler
Thermocouples
Wire filterscreen
Breakerplate
Die
Melt-pumping sectionMelt sectionFeed section
Throat-coolingchannel
Gear reducerbox
Motor
Adapter
Meltthermocouple
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Extrusion Mechanics
FIGURE 10.23 Geometry of the pumping section of an extruder screw.
W
w
H
D
!
Barrel
Pitch
Flight
Barrel
FIGURE 10.1 Extruder and die characteristics for Example 10.5.
Extruder characteristic
Die characteristic
Operating point
3
2
1
0
Flo
w r
ate
, q
x 1
0-5
(m3/s
)
0 5 10 15
Pressure (MPa)
Drag flow:
Pressure flow:
Die characteristic
K for circular cross-sections:
Qd =π2HD2N sinθcosθ
2
Qp =WH3p
12η(l/sinθ)=pπDH3 sin2θ
12ηl
Qdie = Kp
K =πD4d128ηld
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Blown-Film Manufacture
FIGURE 10.25 (a) Schematic illustration of production of thin film and plastic bags from a tube produced by an extruder, and then blown by air. (b) A blown-film operation. Source: Courtesy of Windmoeller & Hoelscher Corp.
(a) (b)
Wind-up
Pinch rolls
Guide rolls
Blowntube
Mandrel
Die
Extruder
Air
(a)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Tube Extrusion
FIGURE 10.26 Extrusion of plastic tubes. (a) Extrusion using a spider die (see also Fig.6.59) and pressurized air; (b) coextrusion of tube for producing a bottle.
(b)
(a)
Breaker plate
Spider die
Co-extrusion blow molding
Extruder barrel
Extruder 1
Extruder 2
Screen pack
Melt flowdirection
MandrelA
v
A
B
B
Polymer melt
Spider legs (3)
Spider legs (3)
Air channel
Mandrel
Plastic melt:two or more layers
Parison
Air in
SectionB–B
Section A–A
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Injection Molding
FIGURE 10.27 Injection molding with (a) a plunger and (b) a reciprocating rotating screw. Telephone receivers, plumbing fittings, tool handles, and housings are examples of parts made by injection molding.
Powder,Pellets
Hopper
Heatingzones Nozzle Mold
Vent
Ejector pins
Cylinder(barrel)Cooling
zone
Piston(ram)
Injectionchamber Torpedo
(spreader) Sprue
Moldedpart Vent
Press(clamp)force
Rotating and reciprocatingscrew
(b)
(a)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Mold Features
FIGURE 10.28 Illustration of mold features for injection molding. (a) Two-plate mold, with important features identified; (b) injection molding of four parts, showing details and the volume of material involved. Source: Courtesy of Tooling Molds West, Inc.
(b)
Mainrunner
Gate
Cavity Guidepin
Guide pinSprue
Cavity
Branchrunner
(a)
Gate
Sprue
Part
Mainrunner
Cold slug wellBranchrunner
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Mold Types
FIGURE 10.29 Types of molds used in injection molding. (a) Two-plate mold, (b) three-plate mold, and (c) hot-runner mold.
(c)
Parts
Sprue
bushing
Plate
Plate
Hot plate;Runner stays molten
Ejectorpins
(a) (b)
Parts
Sprue
bushing Sprue
Runner
GatePlate
Part
Plate
Ejectorpins
Part
Ejectorpins
Sprue
bushing
Plate Plate
Stripper
plate
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Insert Molding
FIGURE 10.30 Products made by insert injection molding. Metallic components are embedded in these parts during molding. Source: (a) Courtesy of Plainfield Molding, Inc., and (b) Courtesy of Rayco Mold and Mfg. LLC.
(a) (b)
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Reaction-Injection Molding
FIGURE 10.31 Schematic illustration of the reaction-injection-molding process.
Mixinghead
Recirculationloop
Pump
Monomer 2
Stirrer
Pump
Heatexchanger
Heatexchanger
Recirculationloop
Displacementcylinders
Mold
Monomer 1
Stirrer
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Blow Molding
FIGURE 10.32 Schematic illustrations of (a) the blow-molding process for making plastic beverage bottles and (b) a three-station injection-blow-molding machine.
(c)
(a)
(b)
Heatingpassages
Mold closedand bottle blown
Tail
Blown bottle
Extrudedparison
Knife
Bottlemold
Blow pin
Extruder
Injection-moldingmachine
Parison
Coolingpassages
Parison transferredto blow mold
Blow pin
Blow pinremoved
Blownbottle
Parison mold
Blown-mold station
Blown bottle
Stripper station3
Bottle
Reciprocating-screw extruder
Transferhead
Blow mold
Preformneck ring
Parison
Preformmold
Preformmold station
Core-pin opening(Blown air passage)
Blow-moldneck ring
Indexingdirection
Blow-moldbottom plug
1
2
Stripper plate
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Rotational Molding
FIGURE 10.33 The rotational molding (rotomolding or rotocasting) process. Trash cans, buckets, carousel horses and plastic footballs can be made by this process.
Secondaryaxis
Spindle
Pressurizingfluid
Inlet
Outletvent
Mold
Primaryaxis
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Thermoforming
FIGURE 10.35 Various thermoforming processes for thermoplastic sheet. These processes are commonly used in making advertising signs, cookie and candy trays, panels for shower stalls, and packaging.
(a) Straight vacuumforming
(b) Drape vacuumforming
(c) Force above sheet (d) Plug and ring forming
RingClamp
Plasticsheet
Ram
Mold
Mold
Vacuum line
Vacuumline
Plasticsheet
Clamp
Heater
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Compression Molding
FIGURE 10.35 Types of compression molding, a process similar to forging: (a) positive, (b) semipositive, and (c) flash. The flash in part (c) is trimmed off. (d) Die design for making a compression-molded part with undercuts. Such designs also are used in other molding and shaping operations.
(a) (b) (c)
Open
OverlapLand
Knockout(ejector pin)
(d)
Part
Plug
Heatingelements
Punch
Mold
Charge
Moldedpart
ClosedFlash
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Transfer Molding
FIGURE 10.36 Sequence of operations in transfer molding of thermosetting plastics. This process is particularly suitable for making intricate parts with varying wall thicknesses.
Transfer plunger
Transfer pot andmolding powder
2. Mold closed and cavities filled
Knockout(ejector) pin
3. Mold open and molded parts ejected
1. Insert polymer in mold
Sprue
Punch
Moldedparts
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Casting, Potting, Encapsulation & Calendering
FIGURE 10.38 Schematic illustration of calendering. Sheets produced by this process are subsequently used in processes such as thermoforming.
Liquid plastic
Mold
Electrical coil
Housing or case
Coil Mold Mold
1. 2. 3.
FIGURE 10.37 Schematic illustration of (a) casting, (b) potting, and (c) encapsulation of plastics.
Finished film
Rubber feed
Calender rolls
Takeoff orstripper roll
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Reinforced Plastic Components
FIGURE 10.39 Reinforced-plastic components for a Honda motorcycle. The parts shown are front and rear forks, a rear swing arm, a wheel, and brake disks.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Manufacture of Prepregs
FIGURE 10.40 (a) Manufacturing process for polymer-matrix composite. Source: After T.-W. Chou, R.L. McCullough, and R.B. Pipes. (b) Boron-epoxy prepreg tape. Source: Textron Systems.
(a) (b)
Continuousstrands
Spools
Surfacetreatment
Resin
Backing paper
Continuousstrands
ChopperResinpaste
Resinpaste
Compactionbelt
Carrierfilm
Carrierfilm
FIGURE 10.41 Manufacturing process for producing reinforced-plastic sheets. The sheet is still viscous at this stage and can later be shaped into various products. Source: After T.-W. Chou, R. L. McCullough, and R. B. Pipes.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Vacuum and Pressure Molding
FIGURE 10.42 (a) Vacuum-bag forming. (b) Pressure-bag forming. Source: After T. H. Meister.
Atmosphericpressure
Flexible bag
Gasket
Vacuumtrap
Vacuumtrap
Resinand glass
Gelcoat
Mold
Clampingbar
Moldrelease
Moldrelease
Room-temperature or oven cureHand or spray lay-up
Air pressure345 kPa (50 psi)Clamp
Gelcoat
Resin andglass
Metal orplastic mold
Steam orhot water
Hand or spray lay-up
(a) (b)
Flexible bag
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Open Mold Processing
FIGURE 10.43 Manual methods of processing reinforced plastics: (a) hand lay-up and (b) spray-up. These methods are also called open-mold processing. (c) A boat hull made by these processes. Source: Courtesy of Genmar Holdings, Inc.
(c)
(a) (b)
Mold
Boat hull
Mold
Gantry crane
Lay-up ofresin and
reinforcement
Mold
Roller Brush
(a) (b)
Mold
Roving Resin
Chopped glassroving
Spray
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Filament Winding
FIGURE 10.44 (a) Schematic illustration of the filament-winding process. (b) Fiberglass being wound over aluminum liners for slide-raft inflation vessels for the Boeing 767 aircraft. Source: Advanced Technical Products Group, Inc., Lincoln Composites.
(a) (b)
Rotating mandrel
Traversing resin bath
Continuous roving
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Pultrusion
FIGURE 10.45 (a) Schematic illustration of the pultrusion process. (b) Examples of parts made by pultrusion. Source: Courtesy of Strongwell Corporation.
(b)(a)
Infiltration tank
Preforming die
Heated die
PullerCured
pultrusion
Pultrusioncut to length
Prepregfeed system
Saw
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Processing of RP Parts
FIGURE 10.46 The computational steps involved in producing a stereolithography file. (a) Three-dimensional description of the part. (b) The part is divided into slices. (Only 1 in 10 is shown.) (c) Support material is planned. (d) A set of tool directions is determined for manufacturing each slice. Shown is the extruder path at section A-A from (c), for a fused-deposition modeling operation.
(a) (b)
(c) (d)
A
A
Model
Support
Model
Support
Side view
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Rapid Prototyping Processes
TABLE 10.7 Characteristics of rapid-prototyping processes.
SupplyPhase
Process Layer CreationTechnique
Phase-ChangeType
Materials
Liquid Stereolithography Liquid-layer cur-ing
Photopoly-merization
Photopolymers (acrylates,epoxies, colorable resins, andfilled resins)
Polyjet Liquid-layer cur-ing
Photopoly-merization
Photopolymers
Fused-depositionmodeling
Extrusion ofmelted plastic
Solidification bycooling
Thermoplastics (ABS, poly-carbonate, and polysulfone)
Powder Three-dimensionalprinting
Binder-dropletdeposition ontopowderlayer
No phasechange
Polymer, ceramic and metalpowder with binder
Selectivelaser sinter-ing
Layer of powder Laser-driven Sintering ormelting
Polymers, metals withbinder, metals, ceramics,and sand with binder
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
RP MaterialsTensile Elastic Elongation
Strength Modulus in 50 mmProcess Material (MPa) (GPa) (%) NotesStereo-lithography
Somos 7120a 63 2.59 2.3-4.1 Transparent amber; good generalpurpose material for rapid prototyp-ing.
Somos 9120a 32 1.14-1.55 15-25 Transparent amber; good chemicalresistance; good fatigue properties;used for producing patterns in rub-ber molding.
WaterShed 11120 47.1-53.6 2.65-2.88 3.3-3.5 Optically clear with a slight greentinge; similar mechanical propertiesas ABS; used for rapid tooling.
Prototool 20Lb 72-79 10.1-11.2 1.2-1.3 Opaque beige; higher strength poly-mer suitable for automotive com-ponents, housings, and injectionmolds.
Polyjet FC 700 42.3 2.0 15-25 Transparent amber; good impactstrength, good paint absorption andmachinability.
FC800 49.9-55.1 2.5-2.7 15-25 White, blue or black; good humidityresistance; suitable for general pur-pose applications.
FC900 2.0-4.6 – 47 Gray or black; very flexible mate-rial, simulates the feel of rubber orsilicone.
Fused-depositionmodeling
Polycarbonate 52 2.0 3 White; high-strength polymer suit-able for rapid prototyping and gen-eral use.
ABS 22 1.63 6 Available in multiple colors, mostcommonly white; a strong anddurable material suitable for generaluse.
PC-ABS 34.8 1.83 4.3 Black; good combination of mechan-ical properties and heat resistance.
Selectivelaser sinter-ing
Duraform PA 44 1.6 9 White; produces durable heat- andchemical-resistant parts; suitable forsnap-fit assemblies and sandcastingor silicone tooling.
Duraform GF 38.1 5.9 2 White; glass-filled form of DuraformPA, has increased sti!ness and issuitable for higher temperature ap-plications.
SOMOS 201 17.3 14 130 Multiple colors available; mimicsrubber mechanical properties
ST-100c 305 137 10 Bronze-infiltrated steel powder.
TABLE 10.8 Mechanical properties of selected materials for rapid prototyping.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Stereolithography and FDM
FIGURE 10.47 Schematic illustration of the stereolithography process. Source: Courtesy of 3D Systems.
UV light source
Liquid surface
Vat
c
b
a
Platform
UV curable liquid
Formed part
(a) (b)
Filament supply
Plastic modelcreated inminutes
Thermoplasticor wax filament
Heated FDM headmoves in x–y plane
Tablemoves in
z-direction
z
y
x
Fixturelessfoundation
FIGURE 10.48 (a) Schematic illustration of the fused-deposition modeling process. (b) The FDM Vantage X rapid prototyping machine. Source: Courtesy of Stratasys, Inc.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Support Structures
FIGURE 10.49 (a) A part with a protruding section that requires support material. (b) Common support structures used in rapid-prototyping machines. Source: After P.F. Jacobs.
(a) (b)
Gussets Island Ceiling within an arch Ceiling
a
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Selective Laser Sintering
FIGURE 10.50 Schematic illustration of the selective-laser-sintering process. Source: After C. Deckard and P.F. McClure.
Motor
Laser Optics
Motor
Process-controlcomputer
Part-buildcylinder
Powder-feed
cylinder
Roller mechanism
Galvanometers
Process chamber
Environmental-control unit
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Three-Dimensional Printing
FIGURE 10.51 Schematic illustration of the three-dimensional-printing process. Source: After E. Sachs and M. Cima.
1. Spread powder 2. Print layer 3. Piston movement
4. Intermediate stage 5. Last layer printed 6. Finished part
Powder Binder
(a) (b)
FIGURE 10.52 (a) Examples of parts produced through three-dimensional printing. Full color parts also are possible, and the colors can be blended throughout the volume. Source: Courtesy ZCorp, Inc.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
3D Printing of Metal Parts
Binder
Metalpowder
powder
Binder deposition
Particles are loosely sinteredBinder is burned off
(a)
Infiltrated bylower-melting-point metal
(c)(b)
Infiltrating metal, permeates into P/M part
Microstructure detail
Unfused
FIGURE 10.53 The three-dimensional printing process: (a) part build; (b) sintering, and (c) infiltration steps to produce metal parts. Source: Courtesy of the ProMetal Division of Ex One Corporation.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Rapid Manufacturing: Investment Casting
1. Pattern creation
5. Wax meltout/burnout
Heat
2. Tree assembly
6. Fill mold with metal
Moltenmetal
Crucible
3. Insert into flask
7. Cool
4. Fill with investment
8. Finish
FIGURE 10.54 Manufacturing steps for investment casting that uses rapid-prototyped wax parts as patterns. This approach uses a flask for the investment, but a shell method can also be used. Source: 3D Systems, Inc.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Sprayed Metal Tooling Process
Pattern
Base plate
Alignment tabs
Metalspray
Coating
Aluminum-filledepoxy
Flask
Finished mold half
Pattern
Base plate
Molded part
Second mold half
(a) (b) (c)
(d) (e)
FIGURE 10.55 Production of tooling for injection molding by the sprayed-metal tooling process. (a) A pattern and base plate are prepared through a rapid-prototyping operation; (b) a zinc-aluminum alloy is sprayed onto the pattern (See Section 4.5.1); (c) the coated base plate and pattern assembly is placed in a flask and back-filled with aluminum-impregnated epoxy; (d) after curing, the base plate is removed from the finished mold; and (e) a second mold half suitable for injection molding is prepared.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Example: RP Injection Manifold
FIGURE 10.56 Rapid prototyped model of an injection-manifold design, produced through stereolithography. Source: 3D Systems.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Design of Polymer Parts
(b) (c) (d)
Extruded product
Die shape
Originaldesign
Distortion Modifieddesign
(a)
Thick
Pull-in (sink mark)
Thin
FIGURE 10.57 Examples of design modifications to eliminate or minimize distortion of plastic parts. (a) Suggested design changes to minimize distortion. Source: After F. Strasser. (b) Die design (exaggerated) for extrusion of square sections. Without this design modification, product cross-sections would not have the desired shape because of the recovery of the material, known as die swell. (c) Design change in a rib to minimize pull-in caused by shrinkage during cooling. (d) Stiffening of the bottom of thin plastic containers by doming, similar to the process used to make the bottoms of aluminum beverage cans and similar containers.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Costs and Production VolumesTypical Production Volume,
Equipment Production Tooling Number of PartsProcess Capital Cost Rate Cost 10 102 103 104 105 106 107
Machining Med Med LowCompression molding High Med HighTransfer molding High Med HighInjection molding High High HighExtrusion Med High Low *Rotational molding Low Low LowBlow molding Med Med MedThermoforming Low Low LowCasting Low Very low LowForging High Low MedFoam molding High Med Med*Continuous process.Source: After R. L. E. Brown, Design and Manufacture of Plastic Parts. Copyright c!1980 by John Wiley& Sons, Inc. Reprinted by permission of John Wiley & Sons, Inc.
TABLE 10.9 Comparative costs and production volumes for processing of plastics.
Manufacturing Processes for Engineering Materials, 5th ed. Kalpakjian • Schmid© 2008, Pearson EducationISBN No. 0-13-227271-7
Case Study: Invisalign Orthodontic Aligners
(a) (b)
FIGURE 10.58 (a) An aligner for orthodontic use, manufactured using a combination of rapid tooling and thermoforming; (b) comparison of conventional orthodontic braces to the use of transparent aligners. Source: Courtesy Align Technologies, Inc.
(a)
(b) (c)
FIGURE 10.59 Manufacturing sequence for Invisalign orthodontic aligners. (a) Creation of a polymer impression of the patient's teeth; (b) computer modeling to produce CAD representations of desired tooth profiles; (c) production of incremental models of desired tooth movement. An aligner is produced by thermoforming a transparent plastic sheet against this model. Source: Courtesy Align Technologies, Inc.