كتاب Handbook of Molded Part Shrinkage and Warpage
منتدى هندسة الإنتاج والتصميم الميكانيكى
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منتدى هندسة الإنتاج والتصميم الميكانيكى
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 كتاب Handbook of Molded Part Shrinkage and Warpage

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كتاب Handbook of Molded Part Shrinkage and Warpage  Empty
مُساهمةموضوع: كتاب Handbook of Molded Part Shrinkage and Warpage    كتاب Handbook of Molded Part Shrinkage and Warpage  Emptyالثلاثاء 03 أكتوبر 2023, 2:18 am

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أحضرت لكم كتاب
Handbook of Molded Part Shrinkage and Warpage
Jerry M. Fischer

كتاب Handbook of Molded Part Shrinkage and Warpage  H_b_o_29
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Table of Contents
1 Introduction to Plastics Processing . 1
1.0 Introduction 1
1.1 Interactivity Basics 1
1.2 Thermodynamic Principles Governing Injection Molding . 3
1.2.1 Filling 4
1.2.2 Holding 5
1.2.3 Cooling 6
2 Shrinkage and Warpage . 9
2.1 In-Mold Shrinkage 9
2.1.1 Determination of Shrinkage 10
2.1.2 Molded-in Stress 11
2.2 Warpage 12
2.2.1 Common Causes of Nonuniform Shrinkage . 13
2.2.2 Principles of Minimizing Warpage . 14
2.3 Post-Mold Shrinkage . 16
3 Causes of Molded-Part Variation: Part Design . 17
3.1 Wall Thickness 17
3.2 Ribs 18
3.3 Bosses 21
3.4 Example of Proper Part Design . 21
3.5 Other Design Considerations . 22
4 Causes of Molded-Part Variation: Material . 23
4.1 Amorphous and Semicrystalline Resins 23
4.1.1 Amorphous Polymers 25
4.1.2 Semicrystalline Materials . 26
4.2 Effects of Fillers, Reinforcements, Pigments, Time, and Stress 29
4.2.1 Effects of Fillers and Fibers 29
4.2.2 Minimizing the Effects of Fiber Reinforcements 32
4.2.3 Effects of Pigments . 34
4.2.4 The Effects of Time and Stress on Dimensional Stability 36
4.3 Shrinkage Predictions: Using Pressure-Volume-Temperature (PVT) Relationships . 37
4.3.1 PVT System Properties . 37
4.3.2 Predicting Mold Shrinkage . 43
4.3.3 Predicting Mold Warpage . 46
4.3.4 Accuracy of Shrinkage Predictions 48
5 Causes of Molded-Part Variation: Mold Design 51
5.1 Cavity Dimensions and Design Factors 51Table of Contents © Plastics Design Library
viii
5.2 Gate Types 53
5.2.1 Pin, Pinpoint, Tunnel, and Submarine Gates 54
5.2.2 Edge and Straight-Edge Gates 55
5.2.3 Fan Gates 55
5.2.4 Film, Diaphragm, and Ring Gates 55
5.2.5 Tab Gates 56
5.2.6 Multiple Gates 56
5.3 Gate Location 57
5.3.1 Side, End, and Center Gates . 58
5.3.2 Determining Gate Position 60
5.4 Gate Size 62
5.5 Gate-Design Systems . 62
5.6 Runner Design 63
5.6.1 Multiple-Cavity Molds . 64
5.6.2 Ejection 70
5.7 Mold-Cooling Design 70
5.7.1 Cooling Channels 70
5.7.2 Effects of Corners . 74
5.7.3 Thickness Variations . 75
5.7.4 Runnerless Molds . 75
5.7.5 Slides 75
5.7.6 Venting 75
5.8 Mold Construction Materials 76
5.9 Prototype Molding with SLA or Similar Type Molds . 76
5.10 Pitfalls to Avoid . 77
6 Causes of Molded-Part Variation: Processing 79
6.1 Molding Conditions . 79
6.2 Injection Melt Temperature . 83
6.3 Injection Rate and Pressure . 83
6.3.1 Injection Speed 83
6.3.2 Injection Pressure 84
6.4 Holding Pressure and Time . 85
6.4.1 Holding Pressure . 85
6.4.2 Holding-Pressure Time . 87
6.5 Mold Temperature . 88
6.5.1 Predicting Mold Temperature Effects . 89
6.5.2 Relationship Between Mold Temperature and Shrinkage . 90
6.5.3 Relationship Between Wall Thickness and Shrinkage 90
6.6 Demolding Temperature 91
6.7 Molded-In Stresses 92
6.8 Other Molding Processes . 93
6.8.1 Lost Core Process . 93
6.8.2 Gas Assist Processing . 93
6.8.2.1 Foaming 94
6.8.2.2 Shrinkage of Gas-Assisted Processes . 95© Plastics Design Library Table of Contents
ix
7 Factors Affecting Post-Mold Shrinkage and Warpage . 97
7.1 Effects of Temperature on Dimensions . 97
7.2 Effects of Moisture on Dimensions . 98
7.3 Creep 103
8 Controlling Mold and Post-Mold Shrinkage and Warpage 105
8.1 Finding the Cause 105
8.2 Processing Considerations . 106
8.2.1 Melt Temperatures and Uniformity 106
8.2.2 Mold Temperatures and Uniformity . 107
8.2.3 Filling, Packing, and Holding Pressures . 108
8.2.4 Filling, Packing, and Holding Times 108
8.2.5 Part Temperature at Ejection 109
8.2.6 Clamp Tonnage . 109
8.2.7 Post-Mold Fixturing and Annealing . 109
8.2.8 Special Problems With Thick Walls and Sink Marks . 109
8.2.9 Nozzles .110
8.2.10 Excessive or Insufficient Shrinkage . 111
8.2.11 Secondary Machining 111
8.2.12 Quality Control 111
8.3 Material Considerations .112
8.3.1 Filler or Reinforcement Content 114
8.3.2 Degree of Liquid Absorption .114
8.3.3 Regrind .114
8.4 Tooling Considerations .114
8.4.1 Gate Locations .114
8.4.2 Types and Sizes of Gates .115
8.4.3 Runner Systems .115
8.4.4 Mold-Cooling Layout 116
8.4.5 Tool Tolerances 116
8.4.6 Draft Angles 117
8.4.7 Ejection-System Design .117
8.4.8 Elastic Deformation of a Mold 118
8.4.9 Mold Wear .118
8.4.10 Mold Contamination .118
8.4.11 Position Deviations of Movable Mold Components .119
8.4.12 Special Issues With Gears 119
8.5 Part Geometry 121
8.5.1 Overall Part Dimensions . 122
8.5.2 Wall Thickness 122
8.5.3 Shrinkage-Restricting Features . 124
8.6 Controlling Warpage . 124
9 Computer-Aided Analysis 127
9.1 Capabilities of CAA 127
9.2 Limitations of CAA . 128
9.3 Selecting a CAA Program . 129Table of Contents © Plastics Design Library
x
9.4 Customer Requirements 131
9.5 Management Tools 132
9.6 Filling Analysis . 133
9.7 Packing and Holding Simulation . 136
9.8 Shrinkage/Warpage Simulation . 136
9.9 Cooling Analysis . 136
9.10 Costs 137
9.11 Conclusions 138
10 Case Studies 139
10.1 Unexpected Housing Shrink 139
10.2 Changing Materials Triggers Warpage . 140
10.3 Creep in a Water Heater Stand . 141
10.4 Oversize Part Injection-Molding Alkyd Thermoset 141
10.5 Inadequate Baby Dish Mold . 142
10.6 Gas Entrapment in Baby Dish Mold . 144
10.7 Warpage in a Molded Spool 145
10.8 Daisy-Wheel Breakage . 147
10.9 PVC Part-Flashing Problems 147
10.10 Polycarbonate Switch Failure 148
10.11 Square Poker Chip Tray, Inadequate Shot Size . 149
10.12 Problem Ejecting Square Poker Chips . 149
10.13 Military Cup Material “Shrinkage” . 150
10.14 Core-Deflection Problems 151
10.15 Elevator Gib Warpage 152
10.16 Sucker-Rod Guide Brittleness 153
10.17 Bottle-Cap Thread Distortion . 153
10.18 Plastic Post Creep 154
10.19 Excessive Shrinkage of Glass-Filled Nylon . 154
10.20 Preventing Warpage in Thin Molded Lids 155
11 Data 157
11.1 Unfilled Materials . 158
11.2 Effects of Fillers 159
11.3 Shrinkage vs Various Parameters . 164
11.3.1 Shrinkage vs Injection Temperature 164
11.3.2 Shrinkage vs Melt Temperature 165
11.3.3 Shrinkage vs Mold Temperature . 166
11.3.4 Shrinkage vs Density (Polyethylene) . 166
11.3.5 Shrinkage vs Holding Pressure 167
11.3.6 Shrinkage vs Thickness . 169
11.4 Moisture Absorption Curves . 171
11.5 Pressure Volume Temperature (PVT) Curves . 172
11.6 Shrinkage and Warpage of Molded Disks . 186
11.7 Angular Warpage 188
11.8 General Shrinkage Characteristics for Various Plastics . 193© Plastics Design Library Table of Contents
xi
11.9 Material-Specific Shrinkage Characteristics 198
11.9.1 Polybutylene Terephthalate (PBT) (Crastin®) (DuPont) . 198
11.9.2 Polyoxymethylene: Acetal (POM) (Delrin® ) (DuPont) 200
11.9.3 Polycarbonate (PC) . 203
11.9.4 Polyphenylene Sulfide (Fortron®) (PPS) . 204
11.9.5 Thermoplastic Elastomer Ether Ester Block Copolymer (TEEE) (Hytrel®) (DuPont) . 206
11.9.6 Polypropylene (PP) 207
11.9.7 Polyethylene Terephthalate (PET) (Rynite®) (DuPont) . 215
11.9.8 Polyetherimide (PEI) (Ultem®) (GE Plastics) 215
11.9.9 Liquid Crystal Polymer (LCP) (Zenite®) (DuPont) . 216
11.9.10 Polyamide: Nylon (PA) (Zytel®) (DuPont) . 217
Appendix A: Conversion Factors and Equivalents . 221
Appendix B: Abbreviations, Acronyms, and Material Names . 223
B.1 Abbreviations and Acronyms 223
B.2 Material Names . 228
Glossary 233
References and Bibliography . 237
References (cited in text) 237
Bibliography 239
General References 239
Index 241
© Plastics Design Library Index
Index
A
Abrasive wear 118
ABS 25, 36
PVT curves 172, 173
Absorption
of fluids 100
of water 101
Absorption curves
moisture 171
Accurate parts 80
Acetal 26, 31, 36
post-mold shrinkage 16, 97
Air escape
runner 75
Air movement
effect on shrinkage 9
Alignment devices 125
Ambient air condition 107
Amorphous materials
2, 4, 13, 14, 25, 36, 88, 112
Analysis
computer 127
costs 138
displays 134
filling 133
purpose 127, 131
Analysis programs
cooling 136
holding and packing 136
shrinkage/warpage 136
simplified 132
Analysis software 138
Analysis tools 137
Angular warpage 188
Anisotropic shrinkage 13, 26, 29
Anisotropy 34
Annealing 89, 93, 98, 109, 217
lost-core process 93
Antifreeze
in coolant 71
Apec® (Bayer Corp. Plastics Div.) 92
Applications 1
Aromatic hydrocarbons 113, 149
ASTM D955-89 157
ASTM testing technique 115
Asymmetric shrinkage analysis 35
B
Baby dish 142
Backpressure 106, 129
Baffles
heat transfer 74
Balanced runner 64
Barrel temperature 148
Bayblend® (Bayer Corp. Plastics Div.) 92
Beaumont melt-rotation system 70
Bending moment 35
Bending stresses 47, 71, 84
Biaxial orientation 11
Bi-lobe cross section 32
Blowing agent 110
BO. See Biaxial orientation
Bonds
with adjacent molecules 7
Bosses 21, 123
Bottle cap 153
Bow angles 189
Branched polymers 27
Branching flow 130
Bubblers 146
heat transfer 74
Bubbles 110
causing streaks 10
Burned spots 76
C
CAE (computer-aided engineering) 47
analysis 127
design 127
simulation 33
software 49
Carbon 31
Cascades
heat transfer 74
Cavity
area 109
for measuring 11
pressure 83, 85, 108, 112
Cellulosics 16
Center-gating 59
Chain folding 26
Channels
cooling 97
Checklist
troubleshooting 105
Chemical absorption 113
Chemical resistance 113
of plastic 16
of polycarbonate 149
Circuit loops 136
Circular fibers 32
Circumferential shrinkage 63Index © Plastics Design Library
242
Clamp pressure 131
Clamp tonnage 94, 109
Clamping force 134
Clamping pressure 82, 84
effect on shrinkage 9
Coefficient of friction 113
Coefficient of thermal expansion 37, 113
Cold molds 79
Colorants 107
Combustion
in-mold 76
Compressibility 79
Compression
exceeds shrink 85
Computer programs
as management tools 132
selecting 129
Computer-aided engineering. See CAE (Computeraided engineering)
Conditioning the parts 51
Conductivity 114
Cone gates 56
Conformable cooling 116
Connectivity 133
Consultant
hiring 137
Container-closure lids 155
Control system
closed-loop 112
Converging flow 13
Coolant
with antifreeze 71
Coolant temperature
vs shrinkage 210
Cooling 106
analysis modules 136
cavity and core 73
conformable 116
of the core 146
differential 6
halves separately 125
influences quality 2
of molds 70, 107
slow 90
uneven 13, 98
uniformly 73
Cooling capacity 72
Cooling channels 107, 116
conforming 76
locations 72, 97
Cooling efficiency 97
Cooling fixtures 109
Cooling kinetics 42
Cooling phase 43
Cooling rate 14, 88
Cooling-related shrinkage 14
Cooling time 6, 79, 134
calculation 72
effect on shrinkage 9
shorter 124
Cooling tower 107
Cooling zones 107
Copolymers
resist warpage 13
Core pins
cooling 73, 79, 98
Cores 143
cause warpage 14
copper or aluminum 53
draft requirements 117
Corners
cooling 74
differential shrinkage 73
rounded 18
Costs 137
estimation 127
software 137
Cracking 93
Crastin® (DuPont) 198, 199
Creep 2, 16, 36, 141
charts 36
failure 121
rate 36
rupture 36
Cross-flow
shrinkage 5, 33, 114, 157
vs in-flow direction 35
Crystal lamellae 36
Crystal nucleation 41
Crystalline bonds 7
Crystalline lamellae 26
Crystalline materials
unfilled 62
Crystalline morphology 14
Crystalline nuclei 34
Crystalline plastics 2, 88
differential shrinkage 29
Crystalline structure 5
Crystallinity 34, 146
degree of 42
Crystallization 5, 86
kinetically driven 27
rapid 27
slow rate 27
temperatures 40, 41
Crystals
higher percentage of 90
CTE (coefficient of thermal expansion) 37, 38
Cushion 107
Cycle time 10
and demolding 91
variations 97
Cycolac® (GE Plastics) 172, 173© Plastics Design Library Index
243
D
Daisy-wheel 147
Decision support programs 127, 129, 132
Decomposition products 119
Deflection 118
Deformation
elastic 118
Degradation 147
heat history 9
of thermoplastics 1
Delamination 62
Delays
in cycle time 97
Delrin® (DuPont) 35, 86, 87, 88, 91, 97, 98, 99,
100, 171, 200, 201, 202
acetal resin 201
resins grades 91
shrinkage 202
water absorption 171
Demolding temperature 92
Density 38
Deposits
in molds 119
Design
example 21
for dimensional stability 17
and molding factors 33
Designers
of parts 121
Diaphragm gates 56
Differential cooling
creates stresses 6
Differential crystallinity 13
Differential orientation 13
Differential shrinkage 45, 47, 48, 73, 79, 140
Dimensional change
non-recoverable 36
Dimensional control 105
Dimensional specifications 51
Dimensional stability 17, 22
effects of time 36
Dimensional tolerances 23, 112
Dimensions 122
Directional properties 11
Directional shrinkage 35
Discoloration 148
Disks
for measurements 186
Displays
analysis results 134
Distortion
out-of-plane 113
Diverging flow 13
Dome-like warpage 63
Double domain equation 40
Double Domain Tait Equation 40
Draft 117
Draft allowance 51
Drool 110, 146
Dual Domain FEA 134
Ductility 11
Durethan® (Bayer Corp. Plastics Div.) 92
E
Edge gate 55
Edge stiffeners and ribs 33
Eject phase 43
Ejection 70
problems 149
temperature 109
Ejector pins 117
and tunnel gate 54
Ejector plates 117
Ejectors 143
Elastic memory 124
Electrical conductivity 114
Elevators 152
Elongation 11
End-gating 58
End-use temperatures 131
Environmental conditions 107
Environmental fluids 101
Escorene® (Exxon) 85
Estimating shrinkage 48
complex parts 48
Examples
molding case studies 139
Expert system 133
F
faBest® (Plastics & Computer) 133, 134
Falling weight 81
Fan gates 32, 55
faSolid® (Plastics & Computer) 134
Fiber concentration 139
Fiber fillers 48, 103
Fiber orientation 14
and gate location 57
multiple gates 57
significant factors 30
Fiber reinforcements 22, 32
Fiber-reinforced materials 14
Fiber-reinforced polymers 31, 33
anisotropic shrinkage 30
regrind or recycled 31
Fiberous fillers 114
Fibers 29
oriented 155
Field variables 134
Fill rate 83, 84Index © Plastics Design Library
244
Fillers 29, 47, 103, 114
abrasive 118
concentrations 205
deposits buildup 119
effect on shrinkage 9
effects of 159
inorganic 29
lubricant 15
orientation 47
shape studies 32
Filling analysis 131, 133, 134
programs 135
Filling and packing time 108
Filling patterns 61, 125, 135
Filling problem 141
Film gates 55, 56
Final part shrinkage 23
Finite-element analysis 127, 128, 133
Fixturing 98, 109
Flake fillers 114
Flake-filled materials 140
Flake-type reinforcements 32
Flakes 29
Flames in the mold 76
Flash problems 105
Flashing 82, 109
Flow
branching 130
converging 13
diverging 13
hesitation 75
patterns 86
Flow aids 125
Flow analysis 137
lay-flat 133
Flow-direction shrinkage 157
Flow fronts 60, 61
analysis 134
Flow paths 82, 140
Flow rates 130
coolant 71
Flow restrictions 125
Flow tab 85
Fluid state 5
Fluids
absorption 100
affect size change 98
environmental 16, 101
Foaming agent 94, 149
Fortron® (Hoechst Celanese)
effect of fillers 205
Fountain flow 128
Free shrinkage 25
Freeze line 40, 44
Friction 4, 113
bonds 7
heating 4, 83, 106
Frozen skin 134
Full-shot molding 93
G
Gas assist process 94
Gas injection molding 93
Gate
dimensions 62
Gate design 145
Gate freeze 25, 136
Gate restriction heating 83
Gate smear 84
Gates 106, 149
cashew 55
cone 56
cross-section 55
design 63, 79
diaphragm 56
dimensions 62, 86
disk 56
edge 55
effect on shrinkage 9, 62, 81
fan 55
film 55
locations 57, 60, 86, 114, 115
material near 124
minimum dimensions 146
models 128
multiple 56, 114
pin 54
pinpoint 54
ring 56
size 115
small 115
small vs large 81
sprue 54
straight-edge 55
submarine 54
tab 56
tunnel 54
types 53
valve 57
winkle 55
Gating 9
Gears 119
molded 119
Geometric effects
cause stress 14
Glass fiber
fillers 118
migration 101
reinforced plastics 114
reinforcements 12
Glass filled nylon 154
Glass filled polypropylene 15
Glass reinforcement 161© Plastics Design Library Index
245
Glass slide test 147
Glass transition temperature 25, 26
Gussets 189
H
Heat deflection temperature 92
Heat exchangers 107
Heat generation 63
Heat history 3, 9, 81
Heat loads 79, 146
Heat pipe 146
Heat stability 22
Heat transfer
from core 73
rate 97
Heating
localized 71
nonuniform 107
secondary 83
Heating channels
location 72
Heating cylinder 105
Hesitation
flow front 60
in flow 75
High-density polyethylene 27
Hinge
integral 81
Hoechst Celanese test plaque 190, 192
Hold pressure 26, 27
Hold time 136
Holding and packing analysis programs 136
Holding phase 86, 108
Holding pressure 5, 79, 85, 86, 106, 108, 167
effect on shrinkage 9
effective 139
vs shrinkage 167
Holding pressure time 86, 87
effect on shrinkage 9
Holding time 5, 79, 86, 108
Hollow injection molding 93
Hollow parts
lost-core process 93
Hot molds 79
Hot runner 146
Hot spots
localized 98
Hot sprue 146
Humidity
affects efficiency 107
effect on shrinkage 9
Hybrid composite materials
mold shrinkage values 32
Hydraulic cylinder 106
Hydrocarbons 113, 149
environment 101
Hygroscopic materials 7, 16, 98
Hygroscopic polymers 51
Hytrel® (DuPont) 87, 88
injection pressure 206
mold temperature 206
I
Ignition
of plastic 119
Impact loads 113
Impact strength 11, 81
In-flow direction
restricted shrink 29
vs cross-flow shrinkage 31, 35
In-flow-direction
shrinkage values 25
In-mold shrinkage 97
Injection hold pressure 26
Injection molded composite 29
Injection molded parts
estimating shrinkage 37
Injection molding 13, 23, 26
machine 3
model 43
process 1, 106
of thermoplastics 2
Injection phases 44
Injection pressures 4, 6, 43, 83, 84, 111,
125, 148, 167, 206
effect on shrinkage 9
excessive 13
limits 82
Injection process 44
Injection rate 83
effect on shrinkage 9
Injection speed 83
vs shrinkage 213
Injection temperature
vs shrinkage 164
Injection time 124
Inorganic fibers 29
Inorganic pigments 35
Internal stresses 124
Isochrone 134
Isotropic shrinkage 25, 32
J
Jetting 54, 55, 56, 84, 115, 146
K
Kinematic viscosity 71
Kinetic process 26Index © Plastics Design Library
246
L
Laminar flow
during injection molding 12
Lay-flat flow analysis 133
Leader pins 125, 144
Length
change 13
Lexan® (GE Plastics) 37, 174, 175, 176, 177, 178
Lids
container-closure 155
Linear expansion 38
Linear polymers 27
Linear shrinkage 51
Linen-reinforced melamine 150
Liquid absorption 114
Living hinge 81
Local shrinkage 48
Locked-in stresses 15
Long-term shrinkage 124
Lost-core process 93
Low-aspect ratio fillers 29
Lubricant 95
antifreeze 71
Lubricant filler 15
Lubricate for filling 142
Lubricating fillers 114
Lubricity
of semicrystalline materials 15
M
Makrolon® (Bayer) 92
Manually operated molding machines 97
Mass
entering 136
vs melt temperature 211
Materials 112
MDPE 27
Mean demolding temperatures 91
Measurements
indirectly controlled 112
of shrinkage and warpage 186
standard procedure 11
Mechanical properties
depend on orientation 11
Medical devices 1
Medium-density polyethylene 27
Melamine 150
Melt
uniformity 106
Melt flow rate
effect on shrinkage 9
Melt rotation 70
Melt temperatures 79, 83, 106, 124, 211
effect on shrinkage 9
limits 82
too low 13
vs shrinkage 165, 211, 214
of thermoplastics 1
Melt transition 40
Mid-cavity pressure 45
Midplane analysis 128
Midplane FEA 133
Migration
moisture 101
Military dinnerware 150
Mixing of the melt 106
Model problems 137
Modulus
effect of orientation 11
Moisture 147
causes surface imperfections 99
Moisture absorption 101, 171, 219
by nylon 16
Moisture content
plastic pellets 107
Moisture migration 101
Moisture reabsorption 51
Moisture-treated 153
Mold construction materials
thermal conductivity 76
Mold cooling 107
Mold design 23, 51
considerations 51
Mold designers 12
Mold dimensions
tolerances 51
Mold filling 10
Mold-open time
effect on shrinkage 9
Mold rigidity 118
Mold shrinkage values 197
Mold-surface temperature
vs shrinkage 210
Mold temperature 81, 88, 97, 106, 206
effect on shrinkage 9
limits 82
and shrinkage 90
vs shrinkage 166, 217
and uniformity 107
Mold volume 44
Molded parts
quality 112
Molded-in stresses 6, 11, 13, 17, 21, 81,
89, 92, 95
minimizing 14
Molding conditions 79, 91, 207, 208
Molding cycle
effect on shrinkage 9
Molding experiences 139
Molding machine 3
Molding machine platens 118© Plastics Design Library Index
247
Molding processes 93
Molding window 82
Moldings
warp-free 124
Molds
alignment devices 125
cleaning sprays 119
contamination 118
cooling 124
cooling system 136
damage 105
deposits 119
functions 76
for gears 119
hot vs cold 90
maintenance 127
movable 119
multiple-cavity 63
runnerless 75
small vs large 207
vented 119
venting 75
Molecular chain damage 62
Molecular migration 82
Molecular orientation 10, 81
and gate location 57
Molecular relaxations 25
Molecular weight 27
effect on shrinkage 13
Monitors
closed-loop 112
Movable mold components 119
Multiple-cavity molds 63, 64, 116
Multiple gates 57
for round parts 56
N
Negative feedback 152
Negative shrinkage values 216
Nitrogen assisted 94
No-flow temperature 130, 134
No-flow time 134
Nomograph for estimating mold shrinkage 201
Non-fibrous reinforcements 32
Non-return valve 107
Nonuniform shrinkage 12, 13
warpage 46
Noryl® (GE Plastics) 38, 179
Novodur® (Bayer AG Plastics Div.) 92
Novolen® (BASF)
shrinkage 168
Nozzles 110
molding problems 111
Nucleating agents 107
pigments 35
Nucleation agents
effect on crystallization 87
Nylon 26, 36, 64, 67, 98
absorbs moisture 16
carbon fiber 162
fiber-filled 159
glass-fiber filled 162, 217
glass-filled 140, 154
holding pressure time 87
hygroscopic 7, 16, 101
moisture content 171
post-mold shrinkage 16
O
Off-center shrinkage 35
Oil-well pumps 153
Opening force 134
Organic pigments 34, 35
Orientation 135
affects mechanical properties 11
at gates 12
by injection molding 12
during mold filling 10
fill-direction induced 13
and flow fronts 60
and gate location 57
is increased 13
molecular 10, 81
of polymer molecules 4
Oriented fibers 155
Overpacking 135
effect on shrinkage 48
P
Pack time 136
Packing
of the cavity 84
inadequate 111
uneven 125
Packing phase 106, 108
Packing pressure 43, 44, 79, 86
Packing-rate differences 13
Packing stage 46
Packing stress 14
Packing time 81, 88
Part design 17
Part modification 105
Part thickness
vs shrinkage 210
Part wall thickness 145
Part warpage 29
Partial shot molding 93
Particulate fillers 29, 114, 159, 160
Parting line
damage 76, 109, 118Index © Plastics Design Library
248
Parting line gates 149
Pellets
unmelted 106
Petroleum 149
Pigments 34, 35
Pin gates 54
Pinpoint gates 54
Plaque-type test molds 115
Plastic materials 1
Plastic pellets
moisture content 107
unmelted 106
Plastic processing methods 39
Plastic-property degradation 99
Plasticizers 16, 98
migration 101
Plasticizing capacity 9
Platelet fillers 47
Platens 84, 118
Pocan® (Bayer AG Plastics Div.) 92
Poker chips 149
Polyacetal
glass-fiber filled 217
Polyacetal (POM) disks
for measurement 187
Polyamides
water absorption 99
Polybutadiene-terephthalate 198
natural vs pigment 34
post-mold shrinkage 97
PVT curves 183, 184
Polybutylene
post-mold shrinkage 97
Polycarbonate 25, 36, 148
amorphous 38
carbon fiber 160
chemical resistance 149
compressibility 39
filled and unfilled 160
glass fibers 160, 203
PTFE fibers 160
PVT curves 174, 178
resin 23
SLA vs steel molds 76
warpage 203
warpage measurement 187
Polyethylene 26, 27
grades 27
in-mold shrinkage 193
Polymer crystallization 26
Polymers
shrinkage behaviors 14
Polyphenylene oxide
PVT curves 179
Polyphenylene sulfide 204
effect of fillers 205
injection pressure 205
warpage 190
Polypropylene 26, 207
30%-glass-reinforced 32
glass-filled 15
impact-strength 81
in-mold shrinkage 193
molding 30
Polystyrenacrylo-nitrile (SAN)
warpage 187
Polystyrene 25
dimensional changes 51
in-mold shrinkage 193
Polyvinyl chloride
degradation 147
Post-mold shrinkage 9, 16, 92, 97
Post-molding problems 2
Potassium acetate solution 220
Powders 29
Pre-holding phase 134
Premature freeze-off 46
Pressure
and rib width 18
differential 9
distribution 135
during injection 43
effect on shrinkage 9
excessive 13
gradients 106
histories 43
holding 79, 85
injection 4, 6, 108, 124
limits 82
packing 79
rapid increase 119
step-up ratio 105
traces 44
Pressure vs shrinkage 45
Pressure vs time 43
Pressure-volume-temperature 23, 37, 128
Primary creep 36
Process conditions 106
Process simulation software 12
Process variables 79
Processing
conditions 23, 25
history 38
packing phase 23
temperatures 1
Prototype moldings 76
Puddling 115
Pumps
oil-well 153
PVT 23, 37
behavior 37
curves 172© Plastics Design Library Index
249
diagram 38, 45
relationships 40
semicrystalline polymer 40
test equipment limitation 41
Q
Quality
of molded parts 112
Quality assurance 112
R
Radial shrinkage 63
Rate of crystallization 41
Redesign
part 105
Regrind 107, 114
Regrinding process 31
Reinforced plastics
fillers 48
mechanical properties 11
Reinforced thermoplastics
greatest influence 33
Reinforcements 22, 189
orientation of 12
Reinforcing ribs 15, 110
Repeatability
of molding process 106
Reprocessing
of thermoplastics 1
Resin composition 23
Rib design 19
Ribbing
problems 18
Ribs 110
designs 110
effect on shrinkage 35
reinforcing 15
Rigidity 118
design for 18
Ring gates 56
Ripple 97
River delta effect 86
Robotic systems 115
Rod guides 153
Rods
sucker 153
Room temperature
effect on shrinkage 9
Rotor
molding of 139
Round-off errors 129
Runnerless molds 75
Runners 106, 115
air escape 75
balanced 64
balancing 133
branched 68
length 68
models 128
sizes 63, 133, 146
systems 63, 79
temperature gradient 69
temperature profile 68
trapezoid 70
Rynite® (DuPont) 215
S
Saddle-type shrinkage 63
Saturated nylon 7
Scrap plastic 154
Scrap rubber 154
Screw-forward time 87
Secondary crystallization 26
Segregation
temperature 69
Semicrystalline materials 5, 13, 86, 87, 97, 146
higher shrinkage 29
Semicrystalline parts 90
Semicrystalline plastics 5, 26, 112
Semicrystalline polymer
PVT data 40
Semicrystalline polymers 14, 26, 31, 36, 37
dimensional changes 51
“real” behavior 41
shrinkage values 27
Semicrystalline resins 23
Semicrystalline thermoplastics
cooling rate 79
Shear
excessive 62
Shear flow 30
Shear heating 65, 68, 146
Shear rates 69, 119, 130, 135
at gates 12
Shear stress 135
Shear-modulus curve 91
Shear-sensitive materials 119
Short shot 82, 107, 125
molding 93
process 94
Shrink behavior
isotropic 114
Shrink fixture 152
Shrink rates 15
vs part thickness 90
Shrink sections 21
Shrinkage 9
anisotropic 113
data 157, 194
flow direction 157
vs holding pressure 167
vs injection speed 213Index © Plastics Design Library
250
vs injection temperature 164
insufficient 111
measurement 186
vs melt temperature 165, 211
minimum 14
vs mold temperature 166, 210, 213, 217
negative 216
non-uniform 12
vs part thickness 210
post-mold 16, 89
vs pressure 209, 212
saddle-type 63
vs thickness 169
vs time 209
uneven 106
volumetric 108
Shrinkage estimates 42
Shrinkage measurement
procedure 11
Shrinkage predictions 45, 48
Shrinkage rates 194
ASTM test specimens 193
Shrinkage restricting features 124
Shrinkage variation 9
Shrinkage/warpage
analysis modules 136
Side-gating 58
Sidewalls 152
Sink marks 110, 123
Skin
forming 83
SLA mold 76
Slides
cooling 75
Society of the Plastics Industry 23
Software
computer-assisted engineering 18
process simulation 12
Software licenses 137
Solid element flow analysis 133
Solidification 27, 97
Solidification line 42
Specific volume 38, 42, 44
Specifications
dimensional 51
tolerance 122
Spherical fillers 47
Spherulite 26
Sprue
heated 54
hot 146
shear heating 68
Sprue gate 54
Stability
dimensional 17
Standards
for determining shrinkage 10
Static charge 114
Steel 151
Steel rods 153
Steel safe 49
Step-up ratio 105
Stereolithography (SLA) technique 76
Stick-slip skin folding 129
Stiffness 103
effect of orientation 11
Straight-edge gate 55
Strain analysis 136
Streaking
surface 10
Strength
design for 18
load support 113
orientation 11
Stress concentrations 11
Stress relaxation 7, 26, 88
Stresses 11
cause orientation 81
effect of orientation 11
in gate area 86
internal 63, 71
locked-in. See Molded-in stresses
long-term exposure 36
long-term shrinkage 124
minimizing 14
molded-in 6, 11, 13, 17, 21, 92
orientation 11
Submarine gates 54
Sucker rods 153
Support pillars 143
Surface compression 111
Surface defects 110
Surface finish 129
and fill rate 84
rough 95
Surface imperfections 99
Surface temperature 97
Symmetry of molded parts 14
System properties 38
T
Tab gates 56
Tait Equation 40
Talc-filled material 140
Temperature
demolding 91
effect on shrinkage 9
at ejection 109
end-use 131
inside heating cylinder 105
melt 83
of melt 106
of mold halves 35© Plastics Design Library Index
251
processing 1
segregation 69
vs shrinkage 210
Temperature control system 2
Temperature displays 135
Temperature limits 82
Temperature profiles 91, 130
of flowing plastic 5
predictions 130
Temperature settings
barrel 148
Temperature variations 97
causes 35
Tensile modulus 114
Tensile strength 82
ultimate 11
Tensile stresses 93
Test bars 35, 157
Test molds
design 32
plaque-type 115
Test plaque 188, 189, 190
Test specimens
for measuring shrink 11
Textured surfaces 117
Tg
38, 40
Thermal conductivity
of mold materials 76
Thermal contraction 7
Thermal expansion 113
rate 37
Thermal strain 14, 51
vs temperature 37
Thermal transition 37
Thermally induced warping 71
Thermodynamic principles 1
governing molding 3
Thermodynamic process 26
Thermofoam® (Thermofil) 93
Thermolube® (Thermofil) 93
Thermoplastics 1
applications 1
crystalline and amorphous 2
Thermosets 1, 141, 150
applications 1
Thick and thin
transition regions 18
Thick wall sections 109
Thickness
abrupt change 18
change 93
of part 101
vs shrinkage 169, 193
variations 14, 75, 106
of walls 122
Thread profile 153
Time
injection 124
TMconcept® (Plastics & Computer)
127, 128, 132, 137
Tolerances 106, 121, 122
acceptable range 23
application 23
chart 23
mold dimension 51
tight 112
Tool design 12
Tooling
changes 105
effect on shrinkage 48
Tooth profile predictions 120
Toughness 113
Trimming 115
Troubleshooting
checklist 105
Tunnel gates 54, 115, 149
with flexible plastics 55
Turbulent flow 107
coolant 70
Two-phase behavior
of amorphous polymers 40
U “U
”-shaped flange 18
Ultem® (GE Plastics) 215
Undercooling 42
Undercutting 48
Unfilled material 158
V
V/P change 134
Vacuum
as insulator 98
Valox® (GE Plastics) 40, 182, 183, 184, 185
PVT curves 184, 185
Valve gates 57
Valves
non-return 107
Vent runner 75
Venting 129
of molds 75
Vents 119
Visco-elastic characteristic 113
Viscosity
kinematic 71
Voids 110, 123, 146
Volume 38
Volume expansion on heating 38
Volume-reduction process 26
Volume shrinkage 44
Volume vs. temperature 5
Volumetric shrinkage 108Index © Plastics Design Library
252
W
Waiting period 209
Wall thickness 12, 14, 31, 109, 122, 161
effect on shrinkage 9
and shrinkage 17
transitions 122
variable 15
warpage 106
Walls
thick 93
thickness 88, 90
Warp 47
effect of cycle time 10
Warp index 47
Warpage 9, 12, 79, 124
analysis modules 136
angular 188
bow-shaped 100
dome-like 63
measurement 186
minimizing 14
semicrystalline materials 13
thermally induced 71
Warpage factors 53
Water
flow rate 107
Water absorption 99, 113, 171
Water channels 97, 146
Water heater stand 141
Water needle 94
Water pressure assist 94
Wear
abrasive 118
Wear-resistant materials 76
Weight
of finished part 112
Weld-line location 129
prediction 134
Weld lines 57
cause warpage 14
Weld tensile strength 82
Wood-fiber
directional properties 11
Woven fabrics
directional properties 12
Wrinkles
in skin 83
Z
Zenite® (DuPont) 88, 216
Zinc sterate
as lubricant 142
Zytel® (DuPont) 89, 90, 91, 98, 101, 180,
181, 217
humidity effect 218, 219, 220
PVT curves 180, 181
water content 171


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» كتاب The Complete Part Design Handbook
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