Injection Mold Design Engineering

2. Auflage 2016
ISBN: 978-1-56990-665-1
Verlag: Carl Hanser Fachbuchverlag
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 553 Seiten

This book provides a structured methodology and scientific basis for engineering injection molds. The topics are presented in a top-down manner, beginning with introductory definitions and the big picture before proceeding to layout and detailed design of molds. The book provides very pragmatic analysis with worked examples that can be readily adapted to real-world product design applications. It will help students and practitioners to understand the inner workings of injection molds and encourage them to think outside the box in developing innovative and highly functional mold designs.
This new edition has been extensively revised with new content that includes more than 80 new and revised figures and tables, coverage of development strategy, 3D printing, in-mold sensors, and practical worksheets, as well as a completely new chapter on the mold commissioning process, part approval, and mold maintenance.

David O. Kazmer (Ph.D. Mechanical Engineering, Stanford University) is the Dandeneau Professor for Sustainable Manufacturing in the Department of Plastics Engineering at the University of Massachusetts Lowell. He performs research and teaches courses related to plastics product and process development.
Prior to his current appointment, he was an Applications Engineer at General Electric and Director of Research and Development at Synventive HotRunners. He is a licensed professional manufacturing engineer, and is a fellow of the American Society of Mechanical Engineers and the Society of Plastics Engineers. He is also the recipient of the ASME Kos Ishii-Toshiba Award for sustained, meritorious contributions to the field of design for manufacturing.

Autoren/Hrsg.

Inhaltsverzeichnis

1;Preface to the2nd Edition;9
2;Preface to the 1st Edition;10
3;Contents;11
4;Nomenclature;21
5;1 Introduction;27
5.1;1.1 Overview of the Injection Molding Process;27
5.2;1.2 Mold Functions;30
5.3;1.3 Mold Structures;32
5.3.1;1.3.1 External View of Mold;32
5.3.2;1.3.2 View of Mold during Part Ejection;34
5.3.3;1.3.3 Mold Cross-Section and Function;35
5.4;1.4 Other Common Mold Types;37
5.4.1;1.4.1 Three-Plate, Multicavity Family Mold;38
5.4.2;1.4.2 Hot Runner, Multigated, Single Cavity Mold;40
5.4.3;1.4.3 Comparison;41
5.5;1.5 The Mold Development Process;42
5.6;1.6 Mold Standards;44
5.7;1.7 Chapter Review;46
5.8;1.8 References;46
6;2 Plastic Part Design;47
6.1;2.1 The Product Development Process;47
6.1.1;2.1.1 Product Definition;48
6.1.2;2.1.2 Product Design;49
6.1.3;2.1.3 Development;49
6.1.4;2.1.4 Scale-Up and Launch;50
6.1.5;2.1.5 Role of Mold Design;50
6.2;2.2 Design Requirements;51
6.2.1;2.2.1 Application Engineering Information;52
6.2.2;2.2.2 Production Planning;53
6.2.3;2.2.3 End-Use Requirements;54
6.2.4;2.2.4 Design for Manufacturing and Assembly;56
6.2.5;2.2.5 Plastic Material Properties;56
6.3;2.3 Design for Injection Molding;57
6.3.1;2.3.1 Uniform Wall Thickness;57
6.3.2;2.3.2 Rib Design;59
6.3.3;2.3.3 Boss Design;60
6.3.4;2.3.4 Corner Design;60
6.3.5;2.3.5 Surface Finish and Textures;62
6.3.6;2.3.6 Draft;64
6.3.7;2.3.7 Undercuts;65
6.4;2.4 Chapter Review;67
6.5;2.5 References;68
7;3 Mold Cost Estimation;69
7.1;3.1 The Mold Quoting Process;69
7.2;3.2 Cost Overview for Molded Parts;71
7.2.1;3.2.1 Mold Cost per Part;73
7.2.2;3.2.2 Material Cost per Part;74
7.2.3;3.2.3 Processing Cost per Part;75
7.2.4;3.2.4 Defect Cost per Part;78
7.3;3.3 Mold Cost Estimation;79
7.3.1;3.3.1 Mold Base Cost Estimation;80
7.3.2;3.3.2 Cavity Cost Estimation;81
7.3.2.1;3.3.2.1 Cavity Set Cost;82
7.3.2.2;3.3.2.2 Cavity Materials Cost;82
7.3.2.3;3.3.2.3 Cavity Machining Cost;84
7.3.2.4;3.3.2.4 Cavity Discount Factor;88
7.3.2.5;3.3.2.5 Cavity Finishing Cost;89
7.3.3;3.3.3 Mold Customization;90
7.4;3.4 Manufacturing Strategy;95
7.4.1;3.4.1 Breakeven Analysis;95
7.4.2;3.4.2 Prototyping Strategy;98
7.5;3.5 Chapter Review;102
7.6;3.6 References;103
8;4 Mold Layout Design;105
8.1;4.1 Parting Plane Design;105
8.1.1;4.1.1 Determine Mold Opening Direction;106
8.1.2;4.1.2 Determine Parting Line;109
8.1.3;4.1.3 Parting Plane;110
8.1.4;4.1.4 Shut-Offs;112
8.2;4.2 Cavity and Core Insert Creation;113
8.2.1;4.2.1 Height Dimension;113
8.2.2;4.2.2 Length and Width Dimensions;114
8.2.3;4.2.3 Adjustments;115
8.3;4.3 Mold Base Selection;117
8.3.1;4.3.1 Cavity Layouts;117
8.3.2;4.3.2 Mold Base Sizing;119
8.3.3;4.3.3 Molding Machine Compatibility;121
8.3.4;4.3.4 Mold Base Suppliers;123
8.4;4.4 Material Selection;124
8.4.1;4.4.1 Strength vs. Heat Transfer;126
8.4.2;4.4.2 Hardness vs. Machinability;127
8.4.3;4.4.3 Material Summary;128
8.4.4;4.4.4 Surface Treatments;129
8.5;4.5 Chapter Review;131
8.6;4.6 References;133
9;5 Cavity Filling Analysis and Design;135
9.1;5.1 Overview;135
9.2;5.2 Objectives in Cavity Filling;136
9.2.1;5.2.1 Complete Filling of Mold Cavities;136
9.2.2;5.2.2 Avoid Uneven Filling or Over-Packing;137
9.2.3;5.2.3 Control the Melt Flow;138
9.3;5.3 Viscous Flow;138
9.3.1;5.3.1 Shear Stress, Shear Rate, and Viscosity;138
9.3.2;5.3.2 Pressure Drop;139
9.3.3;5.3.3 Rheological Behavior;141
9.3.4;5.3.4 Newtonian Model;143
9.3.5;5.3.5 Power Law Model;145
9.4;5.4 Process Simulation;147
9.5;5.5 Cavity Filling Analyses and Designs;150
9.5.1;5.5.1 Estimating the Processing Conditions;150
9.5.2;5.5.2 Estimating the Filling Pressure and Minimum Wall Thickness;153
9.5.3;5.5.3 Estimating Clamp Tonnage;156
9.5.4;5.5.4 Predicting Filling Patterns;159
9.5.5;5.5.5 Designing Flow Leaders;161
9.6;5.6 Chapter Review;164
9.7;5.7 References;165
10;6 Feed System Design;167
10.1;6.1 Overview;167
10.2;6.2 Objectives in Feed System Design;167
10.2.1;6.2.1 Conveying the Polymer Melt from Machine to Cavities;167
10.2.2;6.2.2 Impose Minimal Pressure Drop;168
10.2.3;6.2.3 Consume Minimal Material;169
10.2.4;6.2.4 Control Flow Rates;171
10.3;6.3 Feed System Types;171
10.3.1;6.3.1 Two-Plate Mold;172
10.3.2;6.3.2 Three-Plate Mold;174
10.3.3;6.3.3 Hot Runner Molds;179
10.4;6.4 Feed System Analysis;182
10.4.1;6.4.1 Determine Type of Feed System;184
10.4.2;6.4.2 Determine Feed System Layout;185
10.4.3;6.4.3 Estimate Pressure Drops;189
10.4.4;6.4.4 Calculate Runner Volume;191
10.4.5;6.4.5 Optimize Runner Diameters;192
10.4.6;6.4.6 Balance Flow Rates;196
10.4.7;6.4.7 Estimate Runner Cooling Times;199
10.4.8;6.4.8 Estimate Residence Time;201
10.5;6.5 Practical Issues;202
10.5.1;6.5.1 Runner Cross-Sections;202
10.5.2;6.5.2 Sucker Pins;206
10.5.3;6.5.3 Runner Shut-Offs;208
10.5.4;6.5.4 Standard Runner Sizes;209
10.5.5;6.5.5 Steel Safe Designs;210
10.6;6.6 Advanced Feed Systems;211
10.6.1;6.6.1 Insulated Runner;211
10.6.2;6.6.2 Stack Molds;212
10.6.3;6.6.3 Branched Runners;214
10.6.4;6.6.4 Dynamic Melt Control;216
10.7;6.7 Chapter Review;218
10.8;6.8 References;220
11;7 Gating Design;223
11.1;7.1 Objectives of Gating Design;223
11.1.1;7.1.1 Connecting the Runner to the Mold Cavity;223
11.1.2;7.1.2 Provide Automatic De-gating;223
11.1.3;7.1.3 Maintain Part Aesthetics;224
11.1.4;7.1.4 Avoid Excessive Shear or Pressure Drop;224
11.1.5;7.1.5 Control Pack Times;225
11.2;7.2 Common Gate Designs;226
11.2.1;7.2.1 Sprue Gate;226
11.2.2;7.2.2 Pin-Point Gate;227
11.2.3;7.2.3 Edge Gate;228
11.2.4;7.2.4 Tab Gate;229
11.2.5;7.2.5 Fan Gate;230
11.2.6;7.2.6 Flash/Diaphragm Gate;231
11.2.7;7.2.7 Tunnel/Submarine Gate;232
11.2.8;7.2.8 Thermal Gate;235
11.2.9;7.2.9 Valve Gate;238
11.3;7.3 The Gating Design Process;239
11.3.1;7.3.1 Determine Gate Location(s);239
11.3.2;7.3.2 Determine Type of Gate;241
11.3.3;7.3.3 Calculate Shear Rates;243
11.3.4;7.3.4 Calculate Pressure Drop;245
11.3.5;7.3.5 Calculate Gate Freeze Time;247
11.3.6;7.3.6 Adjust Dimensions;250
11.4;7.4 Chapter Review;251
11.5;7.5 References;252
12;8 Venting;253
12.1;8.1 Venting Design Objectives;253
12.1.1;8.1.1 Release Compressed Air;253
12.1.2;8.1.2 Contain Plastic Melt;254
12.1.3;8.1.3 Minimize Maintenance;254
12.2;8.2 Venting Analysis;254
12.2.1;8.2.1 Estimate Air Displacement and Rate;254
12.2.2;8.2.2 Identify Number and Location of Vents;255
12.2.3;8.2.3 Specify Vent Dimensions;258
12.3;8.3 Venting Designs;262
12.3.1;8.3.1 Vents on Parting Plane;262
12.3.2;8.3.2 Vents around Ejector Pins;264
12.3.3;8.3.3 Vents in Dead Pockets;265
12.4;8.4 Chapter Review;267
12.5;8.5 References;268
13;9 Cooling System Design;269
13.1;9.1.1 Objectives in Cooling System Design;269
13.1.1;9.1.2 Maximize Heat Transfer Rates;269
13.1.2;9.1.3 Maintain Uniform Wall Temperature;270
13.1.3;9.1.4 Minimize Mold Cost;270
13.1.4;9.1.5 Minimize Volume and Complexity;271
13.1.5;9.1.6 Maximize Reliability;271
13.1.6;9.1.7 Facilitate Mold Usage;271
13.2;9.2 The Cooling System Design Process;272
13.2.1;9.2.1 Calculate the Required Cooling Time;272
13.2.2;9.2.2 Evaluate Required Heat Transfer Rate;278
13.2.3;9.2.3 Assess Coolant Flow Rate;279
13.2.4;9.2.4 Assess Cooling Line Diameter;280
13.2.5;9.2.5 Select Cooling Line Depth;283
13.2.6;9.2.6 Select Cooling Line Pitch;286
13.2.7;9.2.7 Cooling Line Routing;288
13.3;9.3 Cooling System Designs;292
13.3.1;9.3.1 Cooling Line Networks;292
13.3.2;9.3.2 Cooling Inserts;295
13.3.3;9.3.3 Conformal Cooling;295
13.3.4;9.3.4 Highly Conductive Inserts;296
13.3.5;9.3.5 Cooling of Slender Cores;298
13.3.5.1;9.3.5.1 Cooling Insert;299
13.3.5.2;9.3.5.2 Baffles;300
13.3.5.3;9.3.5.3Bubblers;301
13.3.5.4;9.3.5.4 Heat Pipes;301
13.3.5.5;9.3.5.5 Conductive Pin;302
13.3.5.6;9.3.5.6 Interlocking Core with Air Channel;303
13.3.6;9.3.6 One-Sided Heat Flow;304
13.4;9.4 Mold Wall Temperature Control;307
13.4.1;9.4.1 Pulsed Cooling;307
13.4.2;9.4.2 Conduction Heating;310
13.4.3;9.4.3 Induction Heating;311
13.4.4;9.4.4 Managed Heat Transfer;312
13.5;9.5 Chapter Review;314
13.6;9.6 References;315
14;10 Shrinkage and Warpage;317
14.1;10.1 The Shrinkage Analysis Process;319
14.1.1;10.1.1 Estimate Process Conditions;320
14.1.2;10.1.2 Model Compressibility Behavior;320
14.1.3;10.1.3 Assess Volumetric Shrinkage;323
14.1.4;10.1.4 Evaluate Isotropic Linear Shrinkage;326
14.1.5;10.1.5 Evaluate Anisotropic Shrinkage;327
14.1.6;10.1.6 Numerical Simulation;329
14.1.7;10.1.7 Shrinkage Analysis Validation;332
14.2;10.2 Shrinkage Design Practices;336
14.2.1;10.2.1 “Steel Safe” Mold Design;336
14.2.2;10.2.2 Processing Dependence;337
14.2.3;10.2.3 Semicrystalline Plastics;339
14.2.4;10.2.4 Effect of Fillers;340
14.2.5;10.2.5 Shrinkage Range Estimation;340
14.2.6;10.2.6 Final Shrinkage Recommendations;341
14.3;10.3 Warpage;343
14.3.1;10.3.1 Sources of Warpage;344
14.3.2;10.3.2 Warpage Avoidance Strategies;349
14.4;10.4 Chapter Review;350
14.5;10.5 References;350
15;11 Ejection System Design;353
15.1;11.1 Objectives in Ejection System Design;356
15.1.1;11.1.1 Allow Mold to Open;356
15.1.2;11.1.2 Transmit Ejection Forces to Moldings;356
15.1.3;11.1.3 Minimize Distortion of Moldings;357
15.1.4;11.1.4 Maximize Ejection Speed;357
15.1.5;11.1.5 Minimize Cooling Interference;358
15.1.6;11.1.6 Minimize Impact on Part Surfaces;358
15.1.7;11.1.7 Minimize Complexity and Cost;359
15.2;11.2 The Ejector System Design Process;359
15.2.1;11.2.1 Identify Mold Parting Surfaces;360
15.2.2;11.2.2 Estimate Ejection Forces;360
15.2.3;11.2.3 Determine Ejector Push Area and Perimeter;366
15.2.4;11.2.4 Specify Type, Number, and Size of Ejectors;369
15.2.5;11.2.5 Layout Ejectors;371
15.2.6;11.2.6 Detail Ejectors and Related Components;374
15.3;11.3 Ejector System Analyses and Designs;376
15.3.1;11.3.1 Ejector Pins;376
15.3.2;11.3.2 Ejector Blades;379
15.3.3;11.3.3 Ejector Sleeves;381
15.3.4;11.3.4 Stripper Plates;382
15.3.5;11.3.5 Elastic Deformation around Undercuts;385
15.3.6;Core Pulls;387
15.3.7;11.3.6 Slides;392
15.3.8;11.3.7 Early Ejector Return Systems;395
15.4;11.4 Advanced Ejection Systems;397
15.4.1;11.4.1 Split Cavity Molds;397
15.4.2;11.4.2 Collapsible Cores;399
15.4.3;11.4.3 Rotating Cores;401
15.4.4;11.4.4 Reverse Ejection;403
15.5;11.5 Chapter Review;404
15.6;11.6 References;406
16;12 Structural System Design;407
16.1;12.1 Objectives in Structural System Design;408
16.1.1;12.1.1 Minimize Stress;408
16.1.2;12.1.2 Minimize Mold Deflection;413
16.1.3;12.1.3 Minimize Mold Size;414
16.2;12.2 Analysis and Design of Plates;414
16.2.1;12.2.1 Plate Compression;415
16.2.2;12.2.2 Plate Bending;418
16.2.3;12.2.3 Support Pillars;421
16.2.4;12.2.4 Shear Stress in Side Walls;428
16.2.5;12.2.5 Interlocks;430
16.2.6;12.2.6 Stress Concentrations;433
16.3;12.3 Analysis and Design of Cores;436
16.3.1;12.3.1 Axial Compression;436
16.3.2;12.3.2 Compressive Hoop Stresses;438
16.3.3;12.3.3 Core Deflection;440
16.4;12.4 Fasteners;443
16.4.1;12.4.1 Fits;443
16.4.2;12.4.2 Socket Head Cap Screws;448
16.4.3;12.4.3 Dowels;450
16.5;12.5 Review;452
16.6;12.6 References;454
17;13 Mold Technologies;455
17.1;13.1 Introduction;455
17.2;13.2 Coinjection Molds;457
17.2.1;13.2.1 Coinjection Process;457
17.2.2;13.2.2 Coinjection Mold Design;459
17.3;13.3 Gas Assist/Water Assist Molding;460
17.4;13.4 Insert Molds;463
17.4.1;13.4.1 Low Pressure Compression Molding;463
17.4.2;13.4.2 Insert Mold with Wall Temperature Control;465
17.4.3;13.4.3 Lost Core Molding;467
17.5;13.5 Injection Blow Molds;469
17.5.1;13.5.1 Injection Blow Molding;469
17.5.2;13.5.2 Multilayer Injection Blow Molding;471
17.6;13.6 Multishot Molds;473
17.6.1;13.6.1 Overmolding;473
17.6.2;13.6.2 Core-Back Molding;475
17.6.3;13.6.3 Multi-Station Mold;477
17.7;13.7 In-Mold Labeling;479
17.7.1;13.7.1 Statically Charged Film;480
17.7.2;13.7.2 Indexed Film;481
17.8;13.8 Review;482
17.9;13.9 References;483
18;14 Mold Commissioning;485
18.1;14.1 Mold Commissioning Objectives;485
18.1.1;14.1.1 Certify Mold Acceptability;485
18.1.2;14.1.2 Optimize Molding Process and Quality;487
18.1.3;14.1.3 Develop Mold Operation and Maintenance Plans;487
18.2;14.2 Commissioning Process;488
18.2.1;14.2.1 Mold Design Checklist;491
18.2.2;14.2.2 Component Verification;491
18.2.3;14.2.3 Mold Assembly;492
18.2.4;14.2.4 Mold Final Test;492
18.2.5;14.2.5 Preliminary Molding Recommendations;493
18.3;14.3 Molding Trials;496
18.3.1;14.3.1 Filling Stage;497
18.3.2;14.3.2 Packing Stage;499
18.3.3;14.3.3 Cooling Stage;501
18.4;14.4 Production Part Approval;502
18.4.1;14.4.1 Quality Assurance;502
18.4.2;14.4.2 Gauge and Process Repeatability & Reproducibility;503
18.4.3;14.4.3 Image-Based Dimensional Metrology;505
18.4.4;14.4.4 Process Capability Evaluation;507
18.5;14.5 Mold Maintenance;511
18.5.1;14.5.1 Pre-Molding Maintenance;513
18.5.2;14.5.2 Molding Observation and Mold Map;514
18.5.3;14.5.3 Post-Molding Maintenance;515
18.5.4;14.5.4 Scheduled Regular Maintenance;515
18.5.5;14.5.5 Mold Rebuilding;516
18.6;14.6 Summary;517
18.7;14.7 References;519
19;Appendix;521
19.1;Appendix A: Plastic Material Properties;523
19.2;Appendix B: Mold Material Properties;528
19.2.1;B.1 Nonferrous Metals;528
19.2.2;B.2 Common Mold Steels;529
19.2.3;B.3 Other Mold Steels;530
19.3;Appendix C: Properties of Coolants;531
19.4;Appendix D: Statistical Labor Data;532
19.4.1;D.1 United States Occupational Labor Rates;532
19.4.2;D.2 International Labor Rate Comparison;532
19.5;Appendix E: Unit Conversions;534
19.5.1;E.1 Length Conversions;534
19.5.2;E.2 Mass/Force Conversions;535
19.5.3;E.3 Pressure Conversions;535
19.5.4;E.4 Flow Rate Conversions;535
19.5.5;E.5 Viscosity Conversions;536
19.5.6;E.6 Energy Conversions;536
19.6;Appendix F: Estimation of Melt Velocity;536
20;Index;543
21;Leere Seite;4

Leseproben

Nomenclature

Mold engineering requires analysis, and so an extensive nomenclature has been developed. , , and refer to the length, width, and height dimensions as shown in Figure 1.

Figure 1 Length, width, and height nomenclature

Variable names have been selected and consistently used as expected (e. g., for temperature, for cost, for pressure, etc.). refers to rate-related constants (with time dependence) and refers to monetary constants (with cost dependence). To provide clarity, variable subscripts are unabbreviated throughout most of the book. The nomenclature for many of the variables and their units are as follows.

Table 1 Nomenclature

Variable

Meaning

Thermal diffusivity [m2/s]

Compressibility [1/MPa]

Deflection [m]

bending

Deflection due to bending [m]

compression

Deflection due to compression [m]

total

Deflection due to bending and compression [m]

Strain [m/m]

Plastic's strain to failure [%]

Shear rate [1/s]

Maximum allowable shear rate for a plastic melt being molded [1/s]

Viscosity [Pa s]

Thermal conductivity [W/m°C]

insert

Cost per unit volume of core and cavity insert materials [$/m3]

mold	Cost of mold metal per kilogram [$/kg]

plastic

Cost of plastic per kilogram [$/kg]

Tolerance limit [m]

Apparent viscosity for Newtonian model [Pa]

static

Coefficient of static friction [?]

Density [kg/m3]

insert

Density of core and cavity insert materials [kg/m3]

plastic

Density of plastic [kg/m3]

Draft angle [°]

Draft angle [°]

buckling

Stress level at which column buckles [MPa]

cyclic

Imposed cyclic stress [MPa]

endurance

Maximum allowable stress given cyclic loading [MPa]

hoop	Hoop stress [MPa]

limit

Maximum allowable stress given cyclic loading or yielding [MPa]

yield

Maximum allowable stress given yield failure [MPa]

Shear stress [Pa]

Specific volume [?]

?ejectors

Total perimeter of all ejectors [m]

cavity_Projected

Projected area of the mold cavity [m2]

compression

Area exposed to compressive stress [m2]

eff	Effective area under stress [m2]

ejectors

Total area of all ejectors [m2]

part	Total surface area of the molded part

shear

Area exposed to shear stress [m2]

Tolerance coefficient for a standard fit [m2/3]

auxiliaries

Total cost of all auxiliaries [$]

inserts

Total cost of all cavities [$]

insert_finishing

Cost of finishing one set of core and cavity inserts [$]

insert_machining

Cost of machining one set of core and cavity inserts [$]

insert_materials

Cost of materials for one set of core and cavity inserts [$]

mold	Total cost of purchasing mold [$]

mold/part

Cost of purchasing mold amortized across total production quantity [$]

mold_base

Total cost of mold base and modifications [$]

mold_customization

Total cost of all customizations of mold base [$]

mold_steel

Initial purchase cost of mold base or steel [$]

part	Total cost per molded part [$]

plastic/part

Cost of material used in molding one part [$]

process/part

Cost of machinery and labor used to mold one part [$]

plastic

Plastic's specific heat [J/kg °C]

...