Shoemaker Moldflow Design Guide
1. Auflage 2013
ISBN: 978-3-446-41854-7
Verlag: Carl Hanser
Format: PDF
Kopierschutz: 1 - PDF Watermark
A Resource for Plastics Engineers
E-Book, Englisch, 348 Seiten
ISBN: 978-3-446-41854-7
Verlag: Carl Hanser
Format: PDF
Kopierschutz: 1 - PDF Watermark
The origins of this book not only include Moldflow Design Principles, but also includes Warpage Design Principles published by Moldflow, and C-Mold Design Guide. Collectively, these documents are based on years of experience in the research, theory and practice of injection molding. These documents are now combined into one book, the Moldflow Design Principles. This book is intended to help practicing engineers solve problems they encounter frequently in the design of parts and molds, as will as during production. This book can also be used as a reference for training purpose at industrial, as well as educational institutions.
Contents:
- Polymer Flow Behaviour in Injection Molds
- Molding Conditions and Injection Pressure
- Filling Pattern
- Moldflow Design Principles
- Meshes used in Moldflow
- Product Design
- Gate Design
- Runner System Design
- Cooling System Design
- Shrinkage and Warpage
- Moldflow Design Procedure
- Part Defects
- Injection Molding
- Injection Molding Machine, System, and Operations
- Injection Molding Process Control
- Plastics Materials
Autoren/Hrsg.
Fachgebiete
Weitere Infos & Material
1;Foreword;6
2;Preface;8
3;Acknowledgements;10
4;Contents;12
5;1 Polymer Flow Behavior in Injection Molds;22
5.1;1.1 Phases of Injection Molding;22
5.1.1;1.1.1 How Plastic Fills a Mold;22
5.1.2;1.1.2 The Filling Phase;24
5.1.3;1.1.3 The Pressurization Phase;27
5.1.4;1.1.4 The Compensation Phase;27
5.2;1.2 How Do Plastics Flow?;28
5.2.1;1.2.1 Material Behavior;28
5.2.2;1.2.2 Deformation;29
5.2.3;1.2.3 Viscoelastic Behavior;29
5.2.4;1.2.4 Melt Shear Viscosity;30
5.2.5;1.2.5 Newtonian Fluid vs. Non-Newtonian Fluid;31
5.2.6;1.2.6 Shear-thinning Behavior;31
5.2.7;1.2.7 Shear Rate Distribution;32
5.2.8;1.2.8 Pressure-driven Flow;32
5.2.9;1.2.9 Pressure Gradient and Injection Times;34
5.2.10;1.2.10 Melt Flow Length;34
5.2.11;1.2.11 Injection Pressure vs. Fill Time;34
5.2.12;1.2.12 Flow Instability;36
6;2 Molding Conditions and Injection Pressure;38
6.1;2.1 Injection-pressure Overview;38
6.1.1;2.1.1 Pressure Drives the Flow Front;39
6.2;2.2 Factors Influencing Injection-pressure Requirements;39
6.3;2.3 Equations;41
6.3.1;2.3.1 Circular Channel Flow;41
6.3.2;2.3.2 Strip Channel Flow;41
6.4;2.4 Effect of Molding Conditions;42
6.4.1;2.4.1 Part Quality;42
6.4.2;2.4.2 Melt Temperature;43
6.4.3;2.4.3 Mold Temperature;43
6.4.4;2.4.4 Fill Time;44
6.4.5;2.4.5 Shear Stress Variation;44
6.4.6;2.4.6 Packing Pressure and Time;45
6.4.7;2.4.7 Summary;46
6.4.8;2.4.8 Back Flow;47
6.5;2.5 Using Moldflow to Determine Optimum Molding Conditions;47
6.5.1;2.5.1 Part;48
6.5.2;2.5.2 Molding Window Size;48
6.5.3;2.5.3 Injection Pressure;49
6.5.4;2.5.4 Flow Front Temperature;50
6.5.5;2.5.5 Cooling Time;51
6.5.6;2.5.6 Summary;52
7;3 Filling Pattern;54
7.1;3.1 Filling Pattern Overview;54
7.1.1;3.1.1 What Is the Filling Pattern?;54
7.2;3.2 Flow in Complex Molds;55
7.2.1;3.2.1 Overpack;55
7.2.2;3.2.2 Racetrack Effect;56
7.2.3;3.2.3 Varying Injection Rate;56
7.2.4;3.2.4 Underflow Effect;57
7.2.5;3.2.5 Hesitation Effect;58
7.2.6;3.2.6 Weld Lines;59
7.2.7;3.2.7 Meld Lines;59
7.2.8;3.2.8 Sink Marks;59
7.2.9;3.2.9 Multidirectional Flow;60
7.2.10;3.2.10 Unstable Flow;61
7.2.11;3.2.11 Simple Flow Pattern;62
7.3;3.3 Flow-front Velocity and Flow-front Area;62
7.3.1;3.3.1 What are FFV and FFA?;62
7.3.2;3.3.2 Flow-front Velocity Influences Filling Pattern;62
7.3.3;3.3.3 Equation;63
7.4;3.4 Using Moldflow to Determine the Filling Pattern;64
7.4.1;3.4.1 Computer Simulation Can Eliminate Molding Trials;64
7.4.2;3.4.2 Using a Flow Analysis;64
7.5;3.5 Using Moldflow to Achieve Constant FFV;65
7.5.1;3.5.1 Controlling the FFV Through Ram Speed;65
8;4 Moldflow Design Principles;68
8.1;4.1 Product Design and Moldflow;68
8.2;4.2 Sequence of Analysis;68
8.2.1;4.2.1 Part Filling Optimization;69
8.2.2;4.2.2 Molding Conditions;69
8.2.3;4.2.3 Runner Design;69
8.2.4;4.2.4 Cooling Optimization;70
8.2.5;4.2.5 Packing Optimization;70
8.2.6;4.2.6 Warpage Optimization;70
8.3;4.3 Moldflow Flow Concepts;70
8.3.1;4.3.1 Unidirectional and Controlled Flow Pattern;71
8.3.2;4.3.2 Flow Balancing;72
8.3.3;4.3.3 Constant Pressure Gradient;73
8.3.4;4.3.4 Maximum Shear Stress;74
8.3.5;4.3.5 Uniform Cooling;75
8.3.6;4.3.6 Positioning Weld and Meld Lines;76
8.3.7;4.3.7 Avoid Hesitation Effects;76
8.3.8;4.3.8 Avoid Underflow;76
8.3.9;4.3.9 Balancing with Flow Leaders and Flow Deflectors;78
8.3.10;4.3.10 Controlled Frictional Heat;79
8.3.11;4.3.11 Thermal Shutoff of Runners;79
8.3.12;4.3.12 Acceptable Runner/Cavity Ratio;80
9;5 Meshes Used In Moldflow Analyses;82
9.1;5.1 Mesh Types Used by Moldflow;82
9.1.1;5.1.1 Finite Elements Used in Moldflow;82
9.1.2;5.1.2 Mesh Types;83
9.1.3;5.1.3 Solver Assumptions;84
9.2;5.2 Mesh Requirements;85
9.2.1;5.2.1 Mesh Density Considerations;85
9.2.2;5.2.2 Part Details;88
9.3;5.3 Geometry Creation;89
9.4;5.4 Importing Geometry;90
9.5;5.5 Using Different Mesh Types;90
9.5.1;5.5.1 Door Panel;90
9.5.2;5.5.2 Manifold;91
10;6 Product Design;92
10.1;6.1 Material Properties for Product Design;92
10.1.1;6.1.1 Plastics Are Sensitive to Operating Conditions;92
10.1.2;6.1.2 Stress-Strain Behavior;93
10.1.3;6.1.3 Creep and Stress Relaxation;98
10.1.4;6.1.4 Fatigue;100
10.1.5;6.1.5 Impact strength;101
10.1.6;6.1.6 Thermal Mechanical Behavior;101
10.2;6.2 Design for Strength;103
10.2.1;6.2.1 Predicting Part Strength;103
10.2.2;6.2.2 Loading/Operating Conditions;103
10.3;6.3 Part Thickness;107
10.3.1;6.3.1 Part Thickness Drives Quality and Cost;107
10.3.2;6.3.2 Cycle Time Increases with Thickness;107
10.3.3;6.3.3 Thick Parts Tend to Warp;107
10.3.4;6.3.4 Thin, Uniform Parts Improve Surface Quality;108
10.3.5;6.3.5 Reducing Part Thickness;108
10.4;6.4 Boosting Structural Integrity with Ribs;109
10.4.1;6.4.1 Structural Integrity: the Goal of Every Design;109
10.4.2;6.4.2 Designing Ribs;109
10.5;6.5 Design for Assembly;111
10.5.1;6.5.1 Molding One Part vs. Separate Components;111
10.5.2;6.5.2 Tolerances: Fit between Parts;111
10.5.3;6.5.3 Press-fit Joints;112
10.5.4;6.5.4 Snap-fit Joints;114
10.5.5;6.5.5 Cantilever Snap Joints;116
10.5.6;6.5.6 Torsion Snap-fit Joints;117
10.5.7;6.5.7 Fasteners;119
10.5.8;6.5.8 Inserts;122
10.5.9;6.5.9 Welding Processes;122
11;7 Gate Design;124
11.1;7.1 Gate Design Overview;124
11.1.1;7.1.1 What Is a Gate?;124
11.1.2;7.1.2 Single vs. Multiple Gates;124
11.1.3;7.1.3 Gate Dimensions;124
11.1.4;7.1.4 Gate Location;125
11.2;7.2 Gate Types;125
11.2.1;7.2.1 Manually Trimmed Gates;125
11.2.2;7.2.2 Automatically Trimmed Gates;131
11.3;7.3 Design Rules;134
11.3.1;7.3.1 Determining the Number of Gates;134
11.3.2;7.3.2 Flow Patterns;136
11.3.3;7.3.3 Gate Position;137
11.3.4;7.3.4 Avoiding Common Problems;143
11.3.5;7.3.5 Gate Length;143
11.3.6;7.3.6 Gate Thickness;143
11.3.7;7.3.7 Freeze-off Time;144
11.4;7.4 Using Moldflow for Gate Design;144
11.4.1;7.4.1 Gate Location;144
11.4.2;7.4.2 Molding Window Size for the Three Gate Locations;145
11.4.3;7.4.3 Filling Pattern;146
11.4.4;7.4.4 Gate Size Based on Shear Rate;146
12;8 Runner System Design;148
12.1;8.1 Definitions;148
12.1.1;8.1.1 Feed System;148
12.1.2;8.1.2 Runner System;148
12.1.3;8.1.3 Cold Runner;148
12.1.4;8.1.4 Hot Runner;149
12.1.5;8.1.5 Hot Manifold;149
12.1.6;8.1.6 Hot Drop;149
12.1.7;8.1.7 Sprue;149
12.2;8.2 Runner System Design Principles;150
12.2.1;8.2.1 Benefits of Good Runner Design;150
12.2.2;8.2.2 Runner Design Philosophy;150
12.2.3;8.2.3 Flow Balancing;151
12.2.4;8.2.4 Flow Control;151
12.2.5;8.2.5 Frictional Heating in Runners;153
12.2.6;8.2.6 Thermal Shutoff;153
12.2.7;8.2.7 System and Runner Pressures;153
12.2.8;8.2.8 Constant Pressure Gradient;154
12.2.9;8.2.9 Cold Slug Wells;154
12.2.10;8.2.10 Easy Ejection;155
12.3;8.3 Runner Types;155
12.3.1;8.3.1 Cold Runners;155
12.3.2;8.3.2 Hot Runner Systems;156
12.4;8.4 Runner Layout;157
12.4.1;8.4.1 Determining the Number of Cavities;157
12.4.2;8.4.2 Planning the Runner System Layout;159
12.4.3;8.4.3 Partially Balanced Runners;160
12.4.4;8.4.4 Geometrically Balanced Runners;162
12.5;8.5 Initial Runner Sizing;162
12.5.1;8.5.1 Determining Sprue Dimensions;162
12.5.2;8.5.2 Designing Runner Cross Sections;163
12.5.3;8.5.3 Determining Runner Diameters;166
12.6;8.6 Runner Balancing;168
12.6.1;8.6.1 How Runner Balancing Works;168
12.6.2;8.6.2 When Are the Runner Sizes Optimized?;168
12.6.3;8.6.3 Validating the Balance;168
12.6.4;8.6.4 Processing Window;169
12.7;8.7 Using Moldflow for Runner Balancing;170
12.7.1;8.7.1 Runner Balancing a 48-cavity Tool;170
12.7.2;8.7.2 Runner Balancing for a Family Mold;172
12.7.3;8.7.3 Runner Balancing for a Multigated Part;173
13;9 Cooling System Design;174
13.1;9.1 Mold Cooling System Overview;174
13.1.1;9.1.1 Importance of Cooling System Design;174
13.1.2;9.1.2 Mold Cooling System Components;175
13.2;9.2 Cooling-channel Configuration;177
13.2.1;9.2.1 Types of Cooling Channels;177
13.3;9.3 Alternative Cooling Devices;178
13.3.1;9.3.1 What Do They Do?;178
13.3.2;9.3.2 Baffles;179
13.3.3;9.3.3 Bubblers;180
13.3.4;9.3.4 Thermal Pins;180
13.3.5;9.3.5 Cooling Slender Cores;181
13.3.6;9.3.6 Cooling Large Cores;182
13.3.7;9.3.7 Cooling Cylinder Cores;183
13.4;9.4 Cooling System Equations;183
13.4.1;9.4.1 Cooling Time;183
13.4.2;9.4.2 Reynolds Number and Coolant Flow;184
13.5;9.5 Design Rules;184
13.5.1;9.5.1 Mold Cooling Design Considerations;184
13.5.2;9.5.2 Location and Size of Channels;185
13.5.3;9.5.3 Flow Rate and Heat Transfer;187
13.6;9.6 Using Moldflow for Cooling System Design;188
13.6.1;9.6.1 Example Setup;189
13.6.2;9.6.2 Cycle Time Determined by Design and Processing Parameters;190
14;10 Shrinkage and Warpage;194
14.1;10.1 Injection Molding and Shrinkage;194
14.1.1;10.1.1 What Are Shrinkage and Warpage?;194
14.1.2;10.1.2 Shrinkage and Machine Settings;194
14.1.3;10.1.3 Mold Filling and Packing;195
14.1.4;10.1.4 How Pressure and Time Affect Shrinkage;196
14.1.5;10.1.5 Thermally Unstable Flow;197
14.2;10.2 Basic Causes of Shrinkage and Warpage;198
14.2.1;10.2.1 Causes of Shrinkage;198
14.2.2;10.2.2 Causes of Warpage;202
14.2.3;10.2.3 Relating Orientation and Area Shrinkage to Warpage;203
14.3;10.3 Designing Accurate Parts Considering Warpage;204
14.3.1;10.3.1 Material Selection;205
14.3.2;10.3.2 Wall Thickness Variation;205
14.3.3;10.3.3 Gate Position and Runner Dimensions;206
14.3.4;10.3.4 Molding Conditions;208
14.3.5;10.3.5 Cooling Line Layout;211
15;11 Moldflow Design Procedure;212
15.1;11.1 Determine Analysis Objectives;212
15.2;11.2 Moldflow Analysis Steps Framework;213
15.2.1;11.2.1 The Whole Process;213
15.2.2;11.2.2 Optimize Fill;213
15.2.3;11.2.3 Balance and Size the Runners;218
15.2.4;11.2.4 Optimize Cooling;220
15.2.5;11.2.5 Optimize the Packing Profile;221
15.2.6;11.2.6 Optimize Warpage;222
15.3;11.3 Using Moldflow to Evaluate an Initial Design;226
15.3.1;11.3.1 Description of this Example;226
15.3.2;11.3.2 Molding Window;226
15.3.3;11.3.3 Filling Analysis;227
15.3.4;11.3.4 Gate and Runner Design;227
15.3.5;11.3.5 Cooling System Design;228
15.3.6;11.3.6 Packing Analysis;230
15.3.7;11.3.7 Warpage Analysis;230
15.4;11.4 Using Moldflow to Optimize the Design;231
15.4.1;11.4.1 Determine the Cause of Warpage;231
15.4.2;11.4.2 Investigating Different Gate Locations;231
15.4.3;11.4.3 Validating the Best Gate Location;232
16;12 Part Defects;236
16.1;12.1 Air Traps;236
16.1.1;12.1.1 What Is an Air Trap?;236
16.1.2;12.1.2 Problems Caused by Air Traps;237
16.1.3;12.1.3 Remedies;237
16.2;12.2 Black Specks and Black Streaks;238
16.2.1;12.2.1 What Are Black Specks and Black Streaks?;238
16.2.2;12.2.2 Causes of Black Specks and Black Streaks;238
16.2.3;12.2.3 Remedies;239
16.3;12.3 Brittleness;240
16.3.1;12.3.1 What Is Brittleness?;240
16.3.2;12.3.2 Causes of Brittleness;240
16.3.3;12.3.3 Remedies;240
16.4;12.4 Burn Marks;241
16.4.1;12.4.1 What Is a Burn Mark?;241
16.4.2;12.4.2 Causes of Burn Marks;242
16.4.3;12.4.3 Remedies;243
16.5;12.5 Delamination;243
16.5.1;12.5.1 What Is Delamination?;243
16.5.2;12.5.2 Causes of Delamination;244
16.5.3;12.5.3 Remedies;244
16.6;12.6 Dimensional Variation;245
16.6.1;12.6.1 What Is Dimensional Variation?;245
16.6.2;12.6.2 Causes of Dimensional Variation;245
16.6.3;12.6.3 Remedies;245
16.7;12.7 Discoloration;246
16.7.1;12.7.1 What Is Discoloration?;246
16.7.2;12.7.2 Causes of Discoloration;246
16.7.3;12.7.3 Remedies;247
16.8;12.8 Fish Eyes;248
16.8.1;12.8.1 What Are Fish Eyes?;248
16.8.2;12.8.2 Causes of Fish Eyes;248
16.8.3;12.8.3 Remedies;248
16.9;12.9 Flash;249
16.9.1;12.9.1 What Is Flash?;249
16.9.2;12.9.2 Causes of Flash;249
16.9.3;12.9.3 Remedies;250
16.10;12.10 Flow Marks;251
16.10.1;12.10.1 What Is A Flow Mark?;251
16.10.2;12.10.2 Causes of Flow Marks;251
16.10.3;12.10.3 Remedies;251
16.11;12.11 Hesitation;252
16.11.1;12.11.1 What Is Hesitation?;252
16.11.2;12.11.2 Problems Caused by Hesitation;252
16.11.3;12.11.3 Remedies;253
16.12;12.12 Jetting;253
16.12.1;12.12.1 What Is Jetting?;253
16.12.2;12.12.2 Problems Caused by Jetting;254
16.12.3;12.12.3 Remedies;254
16.13;12.13 Ripples;256
16.13.1;12.13.1 What Are Ripples?;256
16.13.2;12.13.2 Cause of Ripples;256
16.13.3;12.13.3 Remedies;257
16.14;12.14 Short Shots;257
16.14.1;12.14.1 What Is a Short Shot?;257
16.14.2;12.14.2 Causes of Short Shots;258
16.14.3;12.14.3 Remedies;258
16.15;12.15 Silver Streaks;259
16.15.1;12.15.1 What Are Silver Streaks?;259
16.15.2;12.15.2 Causes of Silver Streaks;260
16.15.3;12.15.3 Remedies;260
16.16;12.16 Sink Marks and Voids;261
16.16.1;12.16.1 What Are Sink Marks and Voids?;261
16.16.2;12.16.2 Causes of Sink Marks and Voids;261
16.16.3;12.16.3 Remedies;262
16.17;12.17 Weld Lines and Meld Lines;264
16.17.1;12.17.1 What Are Weld Lines and Meld Lines?;264
16.17.2;12.17.2 Problems Caused by Weld Lines;264
16.17.3;12.17.3 Strength of Weld Lines;265
16.17.4;12.17.4 Remedies;266
17;Appendix A: Injection Molding;268
17.1;A.1 Injection-molding Overview;268
17.1.1;A.1.1 Process;268
17.1.2;A.1.2 Applications;269
17.2;A.2 Development of the Injection-molding Machine;269
17.2.1;A.2.1 Benefits of the Reciprocating Screw;269
17.3;A.3 Development of the Injection-molding Process;270
17.4;A.4 Alternative Injection-molding Processes;270
17.4.1;A.4.1 Co-injection (Sandwich) Molding;270
17.4.2;A.4.2 Fusible Core Injection Molding;271
17.4.3;A.4.3 Gas-assisted Injection Molding;272
17.4.4;A.4.4 Injection-compression Molding;273
17.4.5;A.4.5 Lamellar (Microlayer) Injection Molding;274
17.4.6;A.4.6 Live-feed Injection Molding;274
17.4.7;A.4.7 Low-pressure Injection Molding;275
17.4.8;A.4.8 Push-pull Injection Molding;275
17.4.9;A.4.9 Reactive Molding;276
17.4.10;A.4.10 Structural Foam Injection Molding;277
17.4.11;A.4.11 Thin-wall Molding;277
18;Appendix B: Injection-molding Machine: System and Operations;280
18.1;B.1 Injection-molding Machine;280
18.1.1;B.1.1 Components;280
18.1.2;B.1.2 Machine Specification;281
18.1.3;B.1.3 Machine Function;281
18.1.4;B.1.4 Auxiliary Equipment;281
18.2;B.2 Machine Components;282
18.2.1;B.2.1 Injection System;282
18.2.2;B.2.2 Mold System;284
18.2.3;B.2.3 Hydraulic System;285
18.2.4;B.2.4 Control System;285
18.2.5;B.2.5 Clamping System;285
18.3;B.3 Molded System;286
18.3.1;B.3.1 The Delivery System;286
18.4;B.4 Machine Operating Sequence;287
18.4.1;B.4.1 Process Cycle;287
18.5;B.5 Screw Operation;289
18.5.1;B.5.1 Back Pressure;289
18.5.2;B.5.2 Injection Speed;289
18.5.3;B.5.3 Screw Rotation Speed;289
18.5.4;B.5.4 Cushion;290
18.6;B.6 Secondary Operations;290
18.6.1;B.6.1 Assembly;290
18.6.2;B.6.2 Decoration;290
18.6.3;B.6.3 Other Secondary Operations;291
19;Appendix C: Injection-molding Process Control;292
19.1;C.1 Importance of Process Conditions;292
19.1.1;C.1.1 Setting Machine Process Conditions;292
20;Appendix D: Plastic Materials;302
20.1;D.1 What Are Plastics?;302
20.1.1;D.1.1 Polymerization Process;302
20.1.2;D.1.2 Structure of Polymers;302
20.1.3;D.1.3 Polymer Alloys and Blends;304
20.1.4;D.1.4 Polymer Composites;304
20.2;D.2 Classification of Plastics;304
20.2.1;D.2.1 Classes of Plastics;305
20.2.2;D.2.2 Structures and Properties of Plastics;305
20.3;D.3 Thermoplastics;306
20.3.1;D.3.1 Market Share Distribution of Thermoplastics;306
20.3.2;D.3.2 Structures and Properties of Thermoplastics;307
20.3.3;D.3.3 Amorphous Polymers;307
20.3.4;D.3.4 Semicrystalline Polymers;308
20.4;D.4 Thermosets;309
20.5;D.5 Properties and Applications of Thermoplastics;310
20.5.1;D.5.1 ABS;311
20.5.2;D.5.2 PA 12;312
20.5.3;D.5.3 PA 6;314
20.5.4;D.5.4 PA 66;315
20.5.5;D.5.5 PBT;317
20.5.6;D.5.6 PC;318
20.5.7;D.5.7 PC/ABS;320
20.5.8;D.5.8 PC/PBT;321
20.5.9;D.5.9 HDPE;322
20.5.10;D.5.10 LDPE;324
20.5.11;D.5.11 PEI;325
20.5.12;D.5.12 PET;326
20.5.13;D.5.13 PETG;327
20.5.14;D.5.14 PMMA;328
20.5.15;D.5.15 POM;330
20.5.16;D.5.16 PP;331
20.5.17;D.5.17 PPE/PPO;333
20.5.18;D.5.18 PS;334
20.5.19;D.5.19 PVC;335
20.5.20;D.5.20 SAN;337
20.5.21;D.5.21 Additives, Fillers, and Reinforcements;338
20.5.22;D.5.22 Modifying Polymer Properties;339
20.5.23;D.5.23 Low-aspect Fillers;340
20.5.24;D.5.24 High-aspect Fillers: Fibers;340
21;Index;342
