Kooperativer Bibliotheksverbund

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Format: 1 online resource (818 pages)

ISBN: 1-5231-4500-5 , 1-56990-816-8

Note: Intro -- Preface -- Acknowledgments -- The Author -- Contents -- 1 Introduction -- 1.1 Benefits of Injection Molding -- 1.2 The Injection Mold -- 1.2.1 The Role of the Injection Mold -- 1.3 What Is an Injection Mold? -- 1.3.1 Elements of an Injection Mold -- 1.4 Classification of Molds -- 1.5 Continued Innovation in Molds and Hot Runners -- 1.6 The Injection Molding Machine -- 2 Overview of Plastics for Mold Design -- 2.1 What Is Plastic? -- 2.2 Plastics Terminology -- 2.3 Polymer Orientation -- 2.3.1 Shrinkage -- 2.3.2 Multiple Shrinkages -- 2.4 Additives -- 2.5 Mechanical Properties of Plastics -- 2.6 How Molten Plastics Behave -- 2.6.1 How Plastics Flow -- 2.6.2 Plastic Flow in Runners and Cavities -- 2.7 Degradation -- 2.8 Selection and Requirements for Plastic Materials -- 3 Plastic Part Design for Mold Designers -- 3.1 Plastic Part Drawing -- 3.2 Product Shape: How Can the Product Best Be Molded? -- 3.3 Parting Line (P/L) -- 3.4 Uniform Wall Thickness -- 3.5 L/t Ratio (Length of Flow Divided by Wall Thickness) -- 3.6 Drafts -- 3.7 Corners, Fillets, and Chamfers -- 3.8 Ribs and Bosses -- 3.9 Rim Designs -- 3.10 Stripped Undercuts -- 3.11 Sidewall Windows in the Part -- 3.12 Gate Location and Number of Gates -- 3.12.1 CAE Filling Analysis for Gate Location Optimization -- 3.12.2 Two or More Gates per Cavity - Large Products -- 3.12.3 Gate Dimple -- 3.12.4 Recessed Gate -- 3.12.5 Deep Undercuts and Mold Design Complexity -- 3.13 Re-Design of the Product to Avoid the Need for Side Cores -- 3.13.1 Selecting Other than the Conventional Parting Line -- 3.14 Shape of Threads and Undercuts -- 3.15 Need for Multi-Stage Ejection -- 3.16 Post-Molding Operations versus Mold Complexity -- 3.17 Plastic Part Tolerances and Effect on Mold Design -- 3.17.1 General and Specific Plastic Part Tolerances. , 3.17.2 Are Special Fits with Matching Products Required? -- 3.17.3 Tolerances for the Filling Volume -- 3.18 Stacking of Products and Free Dispensing -- 3.19 Deliberate Mismatches for Easy Mold Design -- 3.19.1 Mismatch at the Parting Line -- 3.19.2 Mismatch between Two Matching Pieces, such as Box and Lid -- 3.20 Surface Finish -- 3.20.1 Finish of Molding Surfaces -- 3.20.2 Texturing of Surfaces -- 3.21 Fitting Surfaces of Mold Parts -- 3.22 Engravings -- 3.22.1 Engravings versus Applied Labels -- 3.22.2 Two-Color and Two-Material Engraving -- 3.22.3 Depth of Engravings -- 3.22.4 Font Style and Size of Artwork -- 3.22.5 Polarity of Engraving -- 3.22.6 Are the Locations Selected for Engraving Practical? -- 3.22.7 Engravings in the Walls and Bottoms of Products -- 3.23 General Appearance of the Product -- 3.23.1 Flatness -- 3.23.2 Sinks and Voids -- 3.23.3 Witness Lines -- 3.23.4 Weld Lines -- 3.23.5 Surface Defects (Flow Marks, Splay, Record Grooves, Haze, Jetting, Hooks, and Ripples) -- 3.24 Identification of the Molded Piece -- 3.25 Product Strength Requirements -- 3.25.1 The Role of Gate Location in Increasing Product Strength -- 3.26 Special Features -- 3.26.1 Holes and Counter-Bores for Assembly Screws or Rivets -- 3.26.2 Hinges and Snaps -- 4 Specifying the Right Machine for the Mold -- 4.1 Required Clamp Size (Tonnage) -- 4.2 Required Opening Stroke and Shut-Height -- 4.3 Platen Mounting Pattern and Ejector Positions -- 4.4 Locating Ring Size and Machine Nozzle Size -- 4.5 Extruder Sizing and Specification -- 4.5.1 Extruder Shot Size Calculation -- 4.5.2 Requirements for Machine Plasticizing Capacity -- 4.5.3 Screw Selection -- 4.6 Machine Nozzle Selection -- 4.6.1 Open Nozzles -- 4.6.2 Shut-off Nozzles -- 4.7 Injection Unit Selection -- 4.7.1 Reciprocating Screw versus Two-Stage Injection Units. , 4.7.2 Injection Speed and Pressure Requirements -- 5 Factors Affecting the Design of an Injection Mold -- 5.1 Total Equipment Productivity (TEP) Objectives -- 5.2 Cycle Time -- 5.3 Projected Annual Requirements -- 5.4 Purpose of the Mold -- 5.4.1 Prototype Mold -- 5.4.2 Experimental Mold -- 5.4.3 Combination of Prototype and Experimental Mold -- 5.4.4 Production Mold -- 5.4.5 New Products -- 5.4.6 Existing Product, Large Quantities -- 5.4.7 Limited Quantities, Limited Product Lifecycle -- 5.4.8 Short Runs, Small Production Requirements -- 5.5 The Injection Molding Machine -- 5.6 The Plant Environment -- 5.6.1 Condition of Ambient (Shop) Air -- 5.7 Coolant Supply -- 5.7.1 Is the Cooling Water Clean? -- 5.7.2 Chiller Sizing Guidelines -- 5.8 Power Supply -- 6 Cycle Time Estimation -- 6.1 Factors Impacting Cycle Time -- 6.1.1 Type of Plastic -- 6.1.2 Wall Thickness of Product -- 6.1.3 Mold Materials -- 6.1.4 Efficiency of Cooling -- 6.1.5 Venting -- 6.1.6 Ejection -- 6.1.7 Molding Machine -- 6.1.8 Impact of Cold Runners versus Hot Runners on Cycle Time -- 6.2 Estimating Cycle Time -- 7 Product Cost Estimation -- 7.1 Machine Hour Cost per Unit Molded -- 7.2 Mold Cost per Unit Molded -- 7.3 Labor Costs -- 7.4 Estimating Product Cost -- 8 Mold Layout, Drawings, and Inspection -- 8.1 Steps to Designing the Mold -- 8.2 Information and Documentation -- 8.2.1 Machine Specifications -- 8.2.2 Productivity Features -- 8.2.3 Additional Requirements -- 8.3 Determining the Mold Cavitation -- 8.3.1 Minimum Number of Cavities -- 8.3.2 Preferred (Practical) Number of Cavities -- 8.4 Assembly and Detail Drawings -- 8.4.1 Drawings and Views -- 8.4.2 Arrangement of Views -- 8.4.3 Notes on Drawings -- 8.4.4 Additional Information on the Drawings -- 8.5 Mold Layout and Assembly Drawings -- 8.5.1 Machine Platen Layout -- 8.5.2 Symmetry of Layout, Balancing of Clamp. , 8.5.3 The Views -- 8.5.4 Completing the Assembly Drawing -- 8.5.5 Bill of Materials (BOM) and "Ballooning" -- 8.5.6 Finishing Touches -- 8.6 Inspection Features on Drawings -- 8.6.1 Rollers or Roller Balls -- 8.6.2 How to Inspect Tapers -- 8.7 Chamfers and Radii -- 8.7.1 General Information -- 8.7.2 Specifying Chamfers -- 8.7.3 Radii in Corners -- 9 Mold Shoe Design -- 9.1 Mold Plates -- 9.2 Mold Hardware -- 9.3 Location of Fittings, Hoses, and Cables -- 9.4 Forces Affecting Mold Shoes -- 9.4.1 Deflection of Mold Plates -- 9.4.2 Calculation of Plate Deflection and Stress -- 9.5 Selection of Materials for Mold Plates -- 9.6 Guiding of Moving Plates -- 9.6.1 Gibs -- 9.7 Mounting Holes and Clamp Slots -- 9.8 Locating Rings -- 9.9 Mold Handling - Lift Holes, Lift Bars, and Latches -- 9.9.1 Lift Bars -- 9.9.2 Latches -- 9.10 Mold Identification Nameplates -- 10 Cavity and Core Design Overview -- 10.1 Mold Cavity Space -- 10.2 Plastic versus Steel Part Drawing -- 10.3 The Preliminary Stack Layout -- 10.3.1 Where Should the Parting Line Be Located? -- 10.3.2 Will the Product Pull out of the Cavity and Stay on the Core? -- 10.3.3 Will the Product Eject Easily from the Core? -- 10.3.4  Is the Cavity Balanced? -- 10.4 Determining the Method of Cavity Construction -- 10.4.1 Cavity and/or Core Are Cut Right into the Mold Plate -- 10.4.2 Individual Cavities and Cores -- 10.5 Stack Sizing and Total Area of the Stack -- 10.6 Forces on the Cores and Cavities -- 10.6.1 Checking for Sufficient Steel Shut-off Area in Stack -- 10.6.2 Checking for Stack Compression due to Clamp Tonnage -- 10.6.3 Checking for Acceptable Hoop Stress in the Cavity -- 10.7 Core and Cavity Material Selection -- 10.8 Determining the Stack Construction -- 10.9 Venting -- 10.9.1 Parting Line (P/L) Venting -- 10.9.2 Vent Grooves and Channels -- 10.9.3 Vent Pins -- 10.9.4 Venting of Ribs. , 10.9.5 Venting the Bottom of a Cavity -- 10.9.6 Core Cap and Core Sidewall Venting -- 11 Ejection -- 11.1 Manual or Semi-Automatic Ejection -- 11.2 Automatic Ejection -- 11.3 Basic Requirements for Ejection -- 11.3.1 Machine Opening Stroke for Ejection -- 11.3.2 Venting for Ease of Ejection -- 11.3.3 Surface Finish Forces on Ejection -- 11.4 Force Required for Ejection -- 11.5 Where to Eject the Product -- 11.5.1 Ejection of Deep Cup-Shaped Parts -- 11.5.2 Ejection of Parts with Deep Ribs -- 11.5.3 Ejection of Bosses -- 11.5.4 Ejection of Shallow Parts -- 11.5.5 Ejection of Rim Shapes -- 11.5.6 Ejection of Cold Runners -- 11.6 Ejector Pins, Blade Ejectors, and Sleeves -- 11.6.1 Ejector Pin Clearance (Fit) and Length of Land -- 11.6.2 Blade Ejectors -- 11.6.3 Number, Size, and Location of Ejector Pins -- 11.6.4 Finish of Ejector Pins and Bores -- 11.6.5 Preventing Ejector Pins from Turning -- 11.7 Ejector and Ejector Retainer Plates -- 11.7.1 Ejection Forces -- 11.7.2 Injection Forces -- 11.7.3 Number and Location of Machine Ejectors to Be Used -- 11.7.4 Calculation of Ejector Plate Deflection -- 11.7.5 Ejector Pin Retainer Plate -- 11.7.6 Ejector Return Pins -- 11.7.7 Ejector Box -- 11.7.8 Returning the Ejector Plate -- 11.8 Stripper Ejection -- 11.8.1 General Rules for Stripper Ejection -- 11.8.2 Guiding the Stripper Plate -- 11.8.3 Stripper Rings -- 11.8.4 Stripper Bars -- 11.8.5 Stripper Ring Ejection of Lids -- 11.8.6 Stripping from the Injection (Cavity) Side -- 11.9 Air Ejection -- 11.9.1 Requirements and Timing for Air Ejection -- 11.9.2 Poppet Air Ejection -- 11.9.3 Core Air -- 11.9.4 Blow-off Jets -- 11.9.5 Blow-down Jets -- 11.9.6 Air Ejection from the Cavity Side -- 11.10 Ejection of Significant Undercuts -- 11.10.1 Cam Ejection (Internal and External) Using Neck Rings -- 11.10.2 Core Pull Ejection -- 11.10.3 Collapsible Cores. , 11.10.4 Lifter Ejection.

Additional Edition: ISBN 1-56990-815-X

Language: English

Keywords: Handbooks and manuals. ; Handbooks and manuals. ; Handbooks and manuals.