12566 toc

Contents Preface to the 3rd Edition v The Following Contributors Helped to Revise and Update This New Edition vi Materials for Injection Molds 1.1 Steels 1.1.1 Summary 1.1.2 Case-Hardening Steels 1.1.3 Nitriding Steels 1.1.4 Through-Hardening Steels 1.1.5 Heat-Treated Steels 1.1.6 Martensitic Steels 10 1.1.7 Hard Mold Alloys 10 1.1.8 Corrosion-Resistant Steels 10 1.1.9 Refined Steels 11 1.2 Cast Steel 12 1.3 Nonferrous Metallics 12 1.3.1 Copper Alloys 1.3.1.1 Beryllium-Copper Alloys 12 13 1.3.2 Zinc and Its Alloys 14 1.3.3 Aluminum Alloys 16 1.3.4 Bismuth-Tin Alloys 18 1.4 Materials for Electrolytic Deposition 19 1.5 Surface Treatment of Steels for Injection Molds 20 1.5.1 General Information 20 1.5.2 Heat Treatment of Steels 21 This page has been reformatted by Knovel to provide easier navigation vii viii Contents 1.5.3 Thermochemical Treatment Methods 1.5.3.1 Carburizing 1.5.3.2 Nitriding 1.5.3.3 Bonding 21 21 22 22 1.5.4 Electrochemical Treatments 1.5.4.1 Chrome Plating 1.5.4.2 Nickel Plating 1.5.4.3 NYE-CARD Process 1.5.4.4 Hard Alloy Coating 23 23 23 24 24 1.5.5 Coating at Reduced Pressure 1.5.5.1 CVD Process 1.5.5.2 PVD Process 24 24 25 Laser Surface Treatment 26 1.6.1 Laser Hardening and Re-Melting 27 1.6.2 Laser Alloying, Dispersing, and Coating 27 1.7 Electron Beam Hardening 28 1.8 Lamcoat Coating 28 References 28 Mold Making Techniques 31 2.1 Production of Metallic Injection Molds and Mold Inserts by Casting 32 2.1.1 Casting Methods and Cast Alloys 32 2.1.2 Sand Casting 33 2.1.3 Precision Casting Techniques 35 Rapid Tooling for Injection Molds 35 2.2.1 State of the Art 37 2.2.2 Direct Rapid Tooling 2.2.2.1 Direct Fabrication of Metallic Molds 2.2.2.1.1 Generative Methods 2.2.2.1.2 Direct Fabrication of Nonmetallic Molds 39 39 39 1.6 2.2 This page has been reformatted by Knovel to provide easier navigation 42 Contents 2.2.3 ix Indirect Rapid Tooling (Multistage Process Chains) 2.2.3.1 Process Chains Involving a Positive Pattern 2.2.3.2 Process Chains Involving a Negative Pattern 43 Outlook 50 2.3 Hobbing 50 2.4 Machining and Other Material Removing Operations 54 2.4.1 Machining Production Methods 54 2.4.2 Surface Treatment (Finishing) 2.4.2.1 Grinding and Polishing (Manual or Assisted) 2.4.2.2 Vibratory Grinding 2.4.2.3 Sand Blasting (Jet Lapping) 2.4.2.4 Pressure Lapping 2.4.2.5 Electrochemical Polishing 2.4.2.6 Electric-Discharge Polishing 55 55 56 56 57 57 57 Electric-Discharge Forming Processes 59 2.5.1 Electric-Discharge Machining (EDM) 59 2.5.2 Cutting by Spark Erosion with Traveling-Wire Electrodes 62 2.6 Electrochemical Machining (ECM) 63 2.7 Electrochemical Material Removal-Etching 63 2.8 Surfaces Processed by Spark Erosion or Chemical Dissolution (Etching) 65 Laser Carving 67 2.9.1 Rapid Tooling with LASERCAV 68 2.10 Molds for the Fusible-Core Technique 68 2.10.1 Molds for Sheathing the Fusible Cores 2.10.1.1 Gating the Molding 2.10.1.2 Thermal Considerations Concerning Mold Design 2.10.1.3 Core Shifting 2.10.1.4 Venting 71 74 2.2.4 2.5 2.9 This page has been reformatted by Knovel to provide easier navigation 44 46 74 75 75 x Contents 2.10.2 Molds for Making the Fusible Cores 2.10.2.1 Core Material 2.10.2.2 Construction of a Casting Mold 2.10.2.3 Gating Systems 2.10.2.4 Thermal Considerations Concerning the Core-Casting Mold 2.10.2.5 Demolding Cast Fusible Cores 77 78 78 78 References 81 Procedure for Estimating Mold Costs 85 3.1 General Outline 85 3.2 Procedures for Estimating Mold Costs 85 3.3 Cost Group I: Cavity 88 3.3.1 Computation of Working Hours for Cavities 89 3.3.2 Time Factor for Machining Procedure 90 3.3.3 Machine Time for Cavity Depth 90 3.3.4 Time Consumption for Cavity Surface 91 3.3.5 Time Factor for Parting Line 92 3.3.6 Time Factor for Surface Quality 92 3.3.7 Machining Time for Fixed Cores 92 3.3.8 Time Factor for Tolerances 93 3.3.9 Time Factor for Degree of Difficulty and Multifariousness 93 3.3.10 Time Factor for Number of Cavities 94 3.3.11 Computation of Working Hours for EDM Electrodes 94 3.4 Cost Group II: Basic Molds 95 3.5 Cost Group III: Basic Functional Components 96 3.5.1 Sprue and Runner System 96 3.5.2 Runner System 98 3.5.3 Hot-Runner Systems 98 3.5.4 Heat-Exchange System 98 3.5.5 Ejector System 99 This page has been reformatted by Knovel to provide easier navigation 80 81 Contents xi 3.6 Cost Group IV: Special Functions 99 3.7 Other Cost Calculation Methods 100 3.7.1 Costs Based on Similarity Considerations 100 3.7.2 The Principle behind Hierarchical Similarity Searching 103 References 103 The Injection Molding Process 105 4.1 Cycle Sequence in Injection Molding 105 4.1.1 Injection Molding of Thermoplastics 107 4.1.2 Injection Molding of Crosslinkable Plastics 107 4.1.2.1 Injection Molding of Elastomers 108 4.1.2.2 Injection Molding of Thermosets 108 4.2 Terms Used in Connection with Injection Molds 109 4.3 Classification of Molds 109 4.4 Functions of the Injection Mold 110 4.5 4.4.1 Criteria for Classification of Molds 111 4.4.2 Basic Procedure for Mold Design 115 4.4.3 Determination of Mold Size 4.4.3.1 Maximum Number of Cavities 4.4.3.2 Clamping Force 4.4.3.3 Maximum Clamping Area 4.4.3.4 Required Opening Stroke 4.4.4 The Flow Length/Wall Thickness Ratio 122 4.4.5 Computation of Number of Cavities 123 4.4.5.1 Algorithm for the Determination of the Technically and Economically Optimum Number of Cavities 127 4.4.5.2 Costs for Sampling, Setup, and Maintenance 136 115 115 121 121 121 Cavity Layouts 138 4.5.1 General Requirements 138 4.5.2 Presentation of Possible Solutions 139 This page has been reformatted by Knovel to provide easier navigation xii Contents 4.5.3 Equilibrium of Forces in a Mold During Injection 139 4.5.4 Number of Parting Lines 140 References 141 Design of Runner Systems 143 5.1 Characterization of the Complete Runner System 143 5.2 Concept and Definition of Various Types of Runners 144 5.2.1 Standard Runner Systems 144 5.2.2 Hot-Runner Systems 144 5.2.3 Cold-Runner Systems 144 5.3 Demands on the Runner System 145 5.4 Classification of Runner Systems 146 5.5 The Sprue 146 5.6 Design of Runners 151 5.7 Design of Gates 152 5.7.1 5.8 5.9 Position of the Gate at the Part 156 Runners and Gates for Reactive Materials 161 5.8.1 Elastomers 161 5.8.2 Thermosets 162 5.8.3 Effect of Gate Position for Elastomers 162 5.8.4 Runners for Highly-Filled Melts 163 Qualitative (Flow Pattern) and Quantitative Computation of the Filling Process of a Mold (Simulation Models) 164 5.9.1 Introduction 164 5.9.2 The Flow Pattern and Its Significance 165 5.9.3 Using the Flow Pattern for Preparing a Simulation of the Filling Process 166 5.9.4 Theoretical Basis for Producing a Flow Pattern 168 5.9.5 Practical Procedure for Graphically Producing a Flow Pattern 169 5.9.5.1 Drawing the Flow Fronts 169 5.9.5.2 Radius Vectors for the Presentation of Shadow Regions 169 This page has been reformatted by Knovel to provide easier navigation Contents 5.9.5.3 5.9.5.4 5.9.5.5 5.9.5.6 5.9.5.7 Areas with Differences in Thickness Flow Patterns of Ribs Flow Patterns of Box-Shaped Moldings Analysis of Critical Areas Final Comments xiii 172 175 176 176 179 5.9.6 Quantitative Analysis of Filling 179 5.9.7 Analytical Design of Runners and Gates 5.9.7.1 Rheological Principles 5.9.7.2 Determining Viscous Flow Behavior under Shear with the Aid of a Capillary Viscometer 5.9.7.3 Elongational Viscosity 5.9.7.4 Simple Equations for Calculating Loss of Pressure in Gates and Runners 180 180 186 189 189 5.10 Special Phenomena Associated with Multiple Gating 192 5.11 Design of Gates and Runners for Crosslinking Compounds 194 5.11.1 Elastomers 5.11.1.1 Calculation of Filling Process 5.11.1.2 Effect of Processing Characteristics on the Basis of Processing Windows 5.11.1.3 Criticism and Examples Concerning the Processing-Window Model 194 194 195 196 5.11.2 Thermosets 198 5.11.2.1 Flow-Curing Behavior of Thermosets 198 References 200 Design of Gates 205 6.1 The Sprue Gate 205 6.2 The Edge or Fan Gate 206 6.3 The Disk Gate 208 6.4 The Ring Gate 208 6.5 The Tunnel Gate (Submarine Gate) 210 This page has been reformatted by Knovel to provide easier navigation xiv Contents 6.6 The Pinpoint Gate in Three-Platen Molds 212 6.7 Reversed Sprue with Pinpoint Gate 214 6.8 Runnerless Molding 215 6.9 Molds with Insulated Runners 217 6.10 Temperature-Controlled Runner Systems – Hot Runners 220 6.10.1 Hot-Runner Systems 6.10.1.1 Economic Advantages and Disadvantages of Hot-Runner Systems 6.10.1.2 Hot Runners for Various Applications and New Possibilities 6.10.1.3 Design of a Hot-Runner System and Its Components 6.10.1.3.1 Sprue Bushing 6.10.1.3.2 Melt Filters 6.10.1.3.3 Manifold Blocks 6.10.1.3.4 Manifold Beams 6.10.1.4 Nozzles for Hot-Runner Molds 6.10.1.5 Data Concerning the Design of Hot Runner Manifolds 6.10.1.5.1 Manifold Beams 6.10.1.5.2 Nozzle Design 6.10.1.5.3 Notes on Operating Hot Runners 6.10.1.6 Heating of Hot Runner Systems 6.10.1.6.1 Heating of Nozzles 6.10.1.6.2 Heating of Manifolds 6.10.1.6.3 Computing of Power Output 6.10.1.6.4 Temperature Control in Hot Manifolds 6.10.1.6.5 Placement of Thermocouples 221 221 222 223 227 228 228 229 231 234 234 237 238 238 238 239 240 241 241 6.10.2 Cold Runners 242 6.10.2.1 Cold-Runner Systems for Elastomer Injection Molds 242 This page has been reformatted by Knovel to provide easier navigation Contents xv 6.10.2.2 Cold-Runner Molds for Thermosets 248 6.11 Special Mold Concepts 249 6.11.1 Stack Molds 249 6.11.2 Molds for Multicomponent Injection Molding 6.11.2.1 Combination Molds 6.11.2.2 Two-Component Sandwich Injection Molds 6.11.2.3 Bi-Injection Molds 252 253 256 256 References 256 Venting of Molds 259 7.1 Passive Venting 260 7.2 Active Venting 265 7.3 Venting of Gas Counter-Pressure Injection Molds 266 References 268 The Heat Exchange System 271 8.1 Cooling Time 272 8.2 Thermal Diffusivity of Several Important Materials 275 8.3 8.4 8.2.1 Thermal Diffusivity of Elastomers 276 8.2.2 Thermal Diffusivity of Thermosets 276 Computation of Cooling Time of Thermoplastics 277 8.3.1 Estimation 277 8.3.2 Computation of Cooling Time with Nomograms 277 8.3.3 Cooling Time with Asymmetrical Wall Temperatures 279 8.3.4 Cooling Time for Other Geometries 280 Heat Flux and Heat-Exchange Capacity 283 8.4.1 Heat Flux 8.4.1.1 Thermoplastics 8.4.1.2 Reactive Materials 8.4.1.2.1 Thermosets This page has been reformatted by Knovel to provide easier navigation 283 283 287 287 xvi Contents 8.5 Analytical, Thermal Calculation of the Heat-Exchange System Based on the Specific Heat Flux (Overall Design) 293 8.5.1 8.6 8.7 Analytical Thermal Calculation 8.5.1.1 Calculating the Cooling Time 8.5.1.2 Heat Flux Balance 8.5.1.3 Coolant Throughput 8.5.1.4 Temperature of the Cooling Channel 8.5.1.5 Position of the Cooling Channels 8.5.1.6 Design of Cooling Circuit 8.5.1.6.1 Flow Rate of Coolant 8.5.1.6.2 Pressure Drop 294 296 296 298 300 302 307 307 308 Numerical Computation for Thermal Design of Molded Parts 308 8.6.1 Two-Dimensional Computation 309 8.6.2 Three-Dimensional Computation 309 8.6.3 Simple Estimation of the Heat Flow at Critical Points 310 8.6.4 Empirical Correction for Cooling a Corner 311 Practical Design of Cooling Systems 312 8.7.1 Heat-Exchange Systems for Cores and Parts with Circular Cross-Section 312 8.7.2 Cooling Systems for Flat Parts 316 8.7.3 Sealing of Cooling Systems 318 8.7.4 Dynamic Mold Cooling 320 8.7.5 Empirical Compensation of Corner Distortion in Thermoplastic Parts from Heat-Flux Differences 8.7.5.1 Cold Core and Warm Cavity 8.7.5.2 Modification of Corner Configuration 8.7.5.3 Local Adjustment of Heat Fluxes 322 323 323 324 8.8 Calculation for Heated Molds for Reactive Materials 325 8.9 Heat Exchange in Molds for Reactive Materials 325 8.9.1 8.9.2 Heat Balance 325 Temperature Distribution 328 This page has been reformatted by Knovel to provide easier navigation Contents xvii 8.10 Practical Design of the Electric Heating for Thermoset Molds 329 References 331 Shrinkage 335 9.1 Introduction 335 9.2 Definition of Shrinkage 335 9.3 Tolerances 337 9.4 Causes of Shrinkage 342 9.5 Causes of Anisotropic Shrinkage 343 9.6 Causes of Distortion 345 9.7 Effect of Processing on Shrinkage 346 9.8 Supplementary Means for Predicting Shrinkage 348 References 349 10 Mechanical Design of Injection Molds 351 10.1 Mold Deformation 351 10.2 Analysis and Evaluation of Loads and Deformations 351 10.2.1 Evaluation of the Acting Forces 352 10.3 Basis for Describing the Deformation 353 10.3.1 Simple Calculation for Estimating Gap Formation 353 10.3.2 More Accurate Calculation for Estimating Gap Formation and Preventing Flash 354 10.4 The Superimposition Procedure 356 10.4.1 Coupled Springs as Equivalent Elements 356 10.4.1.1 Parallel Coupling of Elements 357 10.4.1.2 Elements Coupled in Series 358 10.5 Computation of the Wall Thickness of Cavities and Their Deformation 358 10.5.1 Presentation of Individual Cases of Loading and the Resulting Deformations 359 10.5.2 Computing the Dimensions of Cylindrical Cavities 360 This page has been reformatted by Knovel to provide easier navigation xviii Contents 10.5.3 Computing the Dimensions of Non-Circular Cavity Contours 362 10.5.4 Computing the Dimensions of Mold Plates 363 10.6 Procedure for Computing Dimensions of Cavity Walls under Internal Pressure 364 10.7 Deformation of Splits and Slides under Cavity Pressure 364 10.7.1 Split Molds 364 10.8 Preparing for the Deformation Calculations 370 10.8.1 Geometrical Simplifications 372 10.8.2 Tips on Choosing Boundary Conditions 374 10.9 Sample Calculations 376 10.10 Other Loads 385 10.10.1 Estimating Additional Loading 385 References 386 11 Shifting of Cores 387 11.1 Estimating the Maximum Shifting of a Core 387 11.2 Shifting of Circular Cores with Lateral Pinpoint Gate at the Base (Rigid Mount) 388 11.3 Shifting of Circular Cores with Disk Gates (Rigid Mount) 390 11.3.1 Basic Examination of the Problem 391 11.3.2 Results of the Calculations 392 11.4 Shifting of Cores with Various Types of Gating (Rigid Mount) 394 11.5 Shifting of Inserts 395 11.5.1 Analytical Calculation of Deformation of Metal Inserts Using a Cylindrical Roll Shell as an Example 395 11.5.1.1 Evaluation of the Deflection Line for Different Part Geometries 396 11.6 Design Examples for Core Mounting and Alignment of Deep Cavities 399 References 400 This page has been reformatted by Knovel to provide easier navigation Contents 12 xix Ejection 401 12.1 Summary of Ejection Systems 401 12.2 Design of the Ejection System – Ejection and Opening Forces 405 12.2.1 General Discussion 405 12.2.2 Methods for Computing the Release Forces 12.2.2.1 Coefficients of Static Friction for Determining Demolding and Opening Forces 12.2.2.2 The Estimation Method for Cylindrical Sleeves 12.2.2.3 Rectangular Sleeves 12.2.2.4 Tapered Sleeves 12.2.2.5 Summary of Some Basic Cases 407 407 410 413 413 413 12.2.3 The Release Forces for Complex Parts Exemplified with a Fan 414 12.2.4 Numerical Computation of Demolding Processes (for Elastomer Parts) 420 12.2.5 Estimating the Opening Forces 12.2.5.1 Changes of State in a p-v-T Diagram for Molds with Different Rigidities 12.2.5.2 Indirect Opening Forces 12.2.5.3 Total Opening Force 424 425 426 426 12.3 Types of Ejectors 426 12.3.1 Design and Dimensions of Ejector Pins 426 12.3.2 Points of Action of Ejector Pins and Other Elements of Demolding 429 12.3.3 Ejector Assembly 433 12.4 Actuation of the Ejector Assembly 434 12.4.1 Means of Actuation and Selection of Places of Action 434 12.4.2 Means of Actuation 434 12.5 Special Release Systems 437 12.5.1 Double-Stage Ejection 437 This page has been reformatted by Knovel to provide easier navigation xx Contents 12.5.2 Combined Ejection 437 12.5.3 Three-Plate Molds 12.5.3.1 Ejector Movement by Stripper Bolt 12.5.3.2 Ejector Movement by Latch 12.5.3.3 Reversed Ejection from the Stationary Side 440 440 440 441 12.6 Ejector Return 443 12.7 Ejection of Parts with Undercuts 446 12.7.1 Demolding of Parts with Undercuts by Pushing Them Off 446 12.7.2 Permissible Depth of Undercuts for Snap Fits 447 12.8 Demolding of Threads 449 12.8.1 Demolding of Parts with Internal Threads 12.8.1.1 Stripper Molds 12.8.1.2 Collapsible Cores 12.8.1.3 Molds with Interchangeable Cores 449 449 449 450 12.8.2 Molds with Unscrewing Equipment 451 12.8.2.1 Semiautomatic Molds 452 12.8.2.2 Fully Automatic Molds 453 12.8.3 Demolding of Parts with External Threads 460 12.9 Undercuts in Noncylindrical Parts 461 12.9.1 Internal Undercuts 461 12.9.2 External Undercuts 461 12.9.2.1 Slide Molds 462 12.9.2.2 Split-Cavity Molds 467 12.9.3 Molds with Core-Pulling Devices 471 References 472 13 Alignment and Changing of Molds 475 13.1 Function of Alignment 475 13.2 Alignment with the Axis of the Plasticating Unit 475 13.3 Internal Alignment and Interlocking 476 13.4 Alignment of Large Molds 480 This page has been reformatted by Knovel to provide easier navigation Contents xxi 13.5 Changing Molds 482 13.5.1 Systems for a Quick Change of Molds for Thermoplastics 482 13.5.2 Mold Exchanger for Elastomer Molds 489 References 490 14 Computer-Aided Mold Design and the Use of CAD in Mold Construction 493 14.1 Introduction 493 14.1.1 The Flow Pattern Method Pointed the Way Forward 493 14.1.2 Geometry Processing Marks the Key to Success 494 14.1.3 Complex Algorithms Mastered 495 14.1.4 Simulation Techniques Still Used Too Infrequently 495 14.1.5 Simpler and Less Expensive 495 14.1.6 The Next Steps Already Carved Out 496 14.2 CAD Use in Mold Design 498 14.2.1 Introduction 498 14.2.2 Principles of CAD 14.2.2.1 2D/3D Model Representation 14.2.2.2 Enhancing the Performance of CAD Models by Associativity, Parametrics, and Features 14.2.2.3 Interfaces and Use of Integrated CAD 14.2.2.4 Data Administration and Flow of Information 14.2.3 CAD Application in Mold-Making 14.2.3.1 Modeling 14.2.3.2 Integrated Functions for Mold-Making 14.2.3.3 Application-Specific Function Extension 14.2.3.4 Possibilities Afforded to Concurrent Engineering through the Use of CAD This page has been reformatted by Knovel to provide easier navigation 498 498 501 502 506 507 507 511 514 515 xxii Contents 14.2.4 Selection and Introduction of CAD Systems 14.2.4.1 Phases in System Selection 14.2.4.2 Formulating the CAD Concept 14.2.4.3 Benchmarking 14.2.4.4 CAD Introduction 517 518 520 521 522 References 523 15 Maintenance of Injection Molds 527 15.1 Advantages of Maintenance Schedules 529 15.2 Scheduling Mold Maintenance 530 15.2.1 Data Acquisition 530 15.2.2 Data Evaluation and Weak-Point Analysis 532 15.2.3 Computer-Based Support 534 15.3 Storage and Care of Injection Molds 534 15.4 Repairs and Alterations of Injection Molds 538 References 541 16 Measuring in Injection Molds 543 16.1 Sensors in Molds 543 16.2 Temperature Measurement 543 16.2.1 Measuring Melt Temperatures in Molds Using IR Sensors 543 16.3 Pressure Measurement 544 16.3.1 Purpose of Pressure Measurement 544 16.3.2 Sensors for Measuring Melt Pressures in Molds 544 16.3.2.1 Direct Pressure Measurement 545 16.3.2.2 Indirect Pressure Measurement 546 16.4 Use of Sensor-Transducer Probes 547 16.5 Process Optimization 547 16.6 Monitoring Quality 548 References 550 This page has been reformatted by Knovel to provide easier navigation Contents 17 xxiii Mold Standards 553 References 559 18 Temperature Controllers for Injection and Compression Molds 561 18.1 Function, Method, Classification 561 18.2 Control 563 18.2.1 Control Methods 563 18.2.2 Preconditions for Good Control Results 18.2.2.1 Controllers 18.2.2.2 Heating, Cooling, and Pump Capacity 18.2.2.3 Temperature Sensors 18.2.2.4 Installation of Temperature Sensors in the Mold 18.2.2.5 Heat-Exchange System in the Mold 18.2.2.6 Keeping the Temperature as Stable as Possible 565 565 565 566 566 567 568 18.3 Selection of Equipment 569 18.4 Connection of Mold and Equipment – Safety Measures 569 18.5 Heat Carrier 570 18.6 Maintenance and Cleaning 571 References 571 19 Steps for the Correction of Molding Defects during Injection Molding 573 References 576 20 Special Processes – Special Molds 577 20.1 Injection Molding of Microstructures 577 20.1.1 Molding Technology and Process Control 577 20.1.2 Production Processes for Microcavities 20.1.2.1 Silicon Technology 20.1.2.2 The LiGA Technique 20.1.2.3 Laser LiGA This page has been reformatted by Knovel to provide easier navigation 579 581 583 584 xxiv Contents 20.1.2.4 Laser Removal 584 20.1.2.5 Electric-Discharge Removal 585 20.1.2.6 Micromachining 587 20.2 In-Mold Decoration 587 20.3 Processing of Liquid Silicone 591 20.3.1 Evacuation 591 20.3.2 Gate 592 20.3.3 Demolding 592 20.3.4 Temperature Control 592 20.3.5 Cold-Runner Technique 593 20.4 Injection-Compression Molding 593 References 596 Index 601 This page has been reformatted by Knovel to provide easier navigation