Injection Mold Design Engineering

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Contents : PrefaceNomenclature 1. Introduction 1.1 Overview of the Injection Molding Process1.2 Mold Functions 1.3 Mold Structures 1.3.1 External View of Mold 1.3.2 View of Mold during Part Ejection 1.3.3 Mold Section and Function 1.4 Other Common Mold Types 1.4.1 Three Plate, Multi-Cavity Family Mold1.4.2 Hot Runner, Multi-Gated, Single Cavity Mold 1.4.3 Comparison 1.5 The Mold Development Process 1.6 Chapter Review 2. Plastic Part Design2.1 The Product Development Process 2.1.1 Product Definition2.1.2 Product Design2.1.3 Business and Production Development 2.1.4 Scale-Up and Launch 2.1.5 Role of Mold Design 2.2 Design Requirements 2.2.1 Application Engineering Information2.2.2 Production Data2.2.3 End Use Requirements 2.2.4 Product Design Methodology 2.2.5 Plastic Material Properties 2.3 Design for Injection Molding 2.3.1 Uniform Wall Thickness2.3.2 Rib Design2.3.3 Boss Design2.3.4 Corner Design 2.3.5 Surface Finish and Textures2.3.6 Draft 2.3.7 Undercuts 2.4 Chapter Review 3. Mold Cost Estimation 3.1 The Mold Quoting Process 3.2 Cost Drivers for Molded Parts3.2.1 Effect of Production Quantity3.2.2 Break-Even Analysis 3.3 Mold Cost Estimation3.3.1 Cavity Cost Estimation3.3.1.1 Cavity Set Cost 3.3.1.2 Cavity Materials Cost3.3.1.3 Cavity Machining Cost 3.3.1.4 Cavity Discount Factor 3.3.1.5 Cavity Finishing Cost 3.3.2 Mold Base Cost Estimation 3.3.3 Mold Customization 3.4 Part Cost Estimation 3.4.1 Mold Cost per Part 3.4.2 Material Cost per Part3.4.3 Processing Cost per Part3.4.4 Defect Cost per Part 3.5 Chapter Review 4. Mold Layout Design4.1 Parting Plane Design 4.1.1 Determine Mold Opening Direction 4.1.2 Determine Parting Line 4.1.3 Parting Plane4.1.4 Shut-Offs 4.2 Cavity and Core Insert Creation 4.2.1 Height Dimension 4.2.2 Length and Width Dimensions4.2.3 Adjustments 4.3 Mold Base Selection4.3.1 Cavity Layouts 4.3.2 Mold Base Sizing 4.3.3 Molding Machine Compatibility 4.3.4 Mold Base Suppliers 4.4 Mold Material Selection 4.4.1 Strength vs. Heat Transfer 4.4.2 Hardness vs. Machinability 4.4.3 Mold-Maker’s Cost vs. Molder’s Cost 4.4.4 Material Summary4.5 Chapter Review 5. Cavity Filling Analysis and Design 5.1 Overview 5.2 Objectives in Cavity Filling 5.2.1 Complete Filling of Mold Cavities 5.2.2 Avoid Uneven Filling or Over-Packing 5.2.3 Control the Melt Flow5.3 Viscous Flow5.3.1 Shear Stress, Shear Rate, and Viscosity 5.3.2 Pressure Drop 5.3.3 Theological Behavior 5.3.4 Newtonian Model 5.3.5 Power Law Model5.4 Validation5.5 Cavity Filling Analyses and Designs5.5.1 Estimating the Processing Conditions5.5.2 Estimating the Filling Pressure and Minimum Wall Thickness 5.5.3 Estimating Clamp Tonnage 5.5.4 Predicting Filling Patterns 5.5.5 Designing Flow Leaders 5.6 Chapter Review 6. Feed System Design 6.1 Overview 6.2 Objectives in Feed System Design6.2.1 Conveying the Polymer Melt from Machine to Cavities 6.2.2 Impose Minimal Pressure Drop 6.2.3 Consume Minimal Material 6.2.4 Control Flow Rates 6.3 Feed System Types 6.3.1 Two-Plate Mold 6.3.2 Three-Plate Mold6.3.3 Hot Runner Molds6.4 Feed System Analysis6.4.1 Determine Type of Feed System 6.4.2 Determine Feed System Layout6.4.3 Estimate Pressure Drops 6.4.4 Calculate Runner Volume 6.4.5 Optimize Runner Diameters 6.4.6 Balance Flow Rates 6.4.7 Estimate Runner Cooling Times6.4.8 Estimate Residence Time 6.5 Practical Issues 6.5.1 Runner Cross-Sections 6.5.2 Sucker Pins 6.5.3 Runner Shut-Offs6.5.4 Standard Runner Sizes 6.5.5 Steel Safe Designs6.6 Chapter Review 7. Gating Design 7.1 Objectives of Gating Design 7.1.1 Connecting the Runner to the Mold Cavity 7.1.2 Provide Automatic De-Gating7.1.3 Provide Aesthetic De-Gating 7.1.4 Avoid Excessive Shear or Pressure Drop 7.1.5 Control Pack Times7.2 Common Gate Designs7.2.1 Sprue Gate7.2.2 Pin-Point Gate 7.2.3 Edge Gate7.2.4 Tab Gate7.2.5 Fan Gate7.2.6 Flash/Diaphragm Gate 7.2.7 Tunnel/Submarine Gate 7.2.8 Thermal Gate 7.2.9 Valve Gate 7.3 The Gating Design Process7.3.1 Determine Type of Gate 7.3.2 Calculate Shear Rates 7.3.3 Calculate Pressure Drop 7.3.4 Calculate Gate Freeze Time 7.3.5 Adjust Dimensions 7.4 Chapter Review 8. Venting 8.1 Venting Design Objectives 8.1.1 Release Compressed Air 8.1.2 Contain Plastic Melt 8.1.3 Minimize Maintenance8.2 Venting Analysis 8.2.1 Estimate Air Displacement and Rate 8.2.2 Identify Number and Location of Vents 8.2.3 Specify Vent Dimensions 8.3 Venting Designs 8.3.1 Vents on Parting Plane 8.3.2 Vents around Ejector Pins 8.3.3 Vents in Dead Pockets8.4 Chapter Review 9. Cooling System Design 9.1 Objectives in Cooling System Design 9.1.1 Maximize Heat Transfer Rates9.1.2 Maintain Uniform Wall Temperature 9.1.3 Minimize Mold Cost 9.1.4 Minimize Volume and Complexity 9.1.5 Minimize Stress and Corrosion 9.1.6 Facilitate Mold Usage 9.2 The Cooling System Design Process9.2.1 Calculate the Required Cooling Time 9.2.2 Evaluate Required Heat Transfer Rate 9.2.3 Assess Coolant Flow Rate9.2.4 Assess Cooling Line Diameter9.2.5 Select Cooling Line Depth 9.2.6 Select Cooling Line Pitch 9.2.7 Cooling Line Routing 9.3 Cooling System Designs 9.3.1 Cooling Line Networks9.3.2 Cooling Inserts 9.3.3 Conformal Cooling 9.3.4 Highly Conductive Inserts 9.3.5 Cooling of Slender Cores 9.3.5.1 Cooling Insert 9.3.5.2 Baffles 9.3.5.3 Bubblers 9.3.5.4 Heat Pipes 9.3.5.5 Conductive Pin 9.3.5.6 Interlocking Core with Air Channel9.3.6 One-Sided Heat Flow 9.4 Chapter Review 10. Shrinkage and War page 10.1 The Shrinkage Analysis Process10.1.1 Estimate Process Conditions 10.1.2 Model Compressibility Behavior 10.1.3 Assess Volumetric Shrinkage 10.1.4 Evaluate Isotropic Linear Shrinkage 10.1.5 Evaluate Anisotropic Shrinkage 10.1.6 Assess Shrinkage Range 10.1.7 Establishing Final Shrinkage Recommendations 10.2 Shrinkage Analysis and Validation 10.2.1 Numerical Simulation10.2.2 “Steel Safe” Mold Design 10.2.3 Processing Dependence 10.2.4 Semi-Crystalline Plastics 10.2.5 Effect of Fillers 10.3 Warp age 10.3.1 Sources of War page 10.3.2 War page Avoidance Strategies10.4 Chapter Review 11. Ejection System Design11.1 Objectives in Ejection System Design 11.1.1 Allow Mold to Open 11.1.2 Transmit Ejection Forces to Moldings11.1.3 Minimize Distortion of Moldings 11.1.4 Actuate Quickly and Reliably 11.1.5 Minimize Cooling Interference11.1.6 Minimize Impact on Part Surfaces11.1.7 Minimize Complexity and Cost 11.2 The Ejector System Design Process 11.2.1 Identify Mold Parting Surfaces 11.2.2 Estimate Ejection Forces11.2.3 Determine Ejector Push Area and Perimeter 11.2.4 Specify Type, Number, and Size of Ejectors 11.2.5 Layout Ejectors11.2.6 Detail Ejectors and Related Components 11.3 Ejector System Analyses and Designs11.3.1 Ejector Pins 11.3.2 Ejector Blades 11.3.3 Ejector Sleeves 11.3.4 Stripper Plates11.3.5 Elastic Deformation around Undercuts 11.3.6 Core Pulls 11.3.7 Slides 11.3.8 Early Ejector Return Systems 11.3.9 Advanced Ejection Systems 11.4 Chapter Review 12. Structural System Design 12.1 Objectives in Structural System Design. 12.1.1 Minimize Stress 12.1.2 Minimize Mold Deflection 12.1.3 Minimize Mold Size 12.2 Analysis and Design of Plates 12.2.1 Plate Compression12.2.2 Plate Bending 12.2.3 Support Pillars 12.2.4 Shear Stress in Side Walls 12.2.5 Interlocks12.2.6 Stress Concentrations 12.3 Analysis and Design of Cores 12.3.1 Axial Compression 12.3.2 Compressive Hoop Stresses 12.3.3 Core Deflection 12.4 Fasteners 12.4.1 Fits 12.4.2 Socket Head Cap Screws12.4.3 Dowels 12.5 Review 13. Mold Technologies 13.1 Introduction 13.2 Coinjection Molds 13.2.1 Co injection Process 13.2.2 Co injection Mold Design 13.2.3 Gas Assist/Water Assist Molding 13.3 Insert Molds 13.3.1 Low Pressure Compression Molding 13.3.2 Insert Mold with Wall Temperature Control 13.3.3 Lost Core Molding 13.4 Injection Blow Molds 13.4.1 Injection Blow Molding 13.4.2 Multilayer Injection Blow Molding 13.5 Multi-Shot Molds13.5.1 Over molding13.5.2 Core-Back Molding 13.5.3 Multi-Station Mold 13.6 Feed Systems 13.6.1 Insulated Runner 13.6.2 Stack Molds13.6.3 Branched Runners 13.6.4 Dynamic Melt Control 13.7 Mold Wall Temperature Control13.7.1 Pulsed Cooling 13.7.2 Conduction Heating 13.7.3 Induction Heating 13.7.4 Managed Heat Transfer 13.8 In-Mold Labeling 13.8.1 Statically Charged Film13.8.2 Indexed Film13.9 Ejection 13.9.1 Split Cavity Molds 13.9.2 Collapsible Cores 13.9.3 Rotating Cores 13.9.4 Reverse Ejection 13.10 Review Appendix Appendix A: Plastic Material PropertiesAppendix B: Mold Material PropertiesB.1 Non-Ferrous Metals B.2 Common Mold Steels B.3 Other Mold Steels B.4 NotesAppendix C: Properties of CoolantsAppendix D: Statistical Labor DataD.1 United States Labor RatesD.2 International Labor RatesD.3 Trends in International Manufacturing Costs Appendix E: Unit Conversions E.1 Length Conversions E.2 Mass/Force ConversionsE.3 Pressure Conversions E.4 Flow Rate Conversions E.5 Viscosity Conversions E.6 Energy ConversionsAppendix F: Advanced Derivations BibliographySubject Index