Injection mold design handbook / Bruce Catoen, Herbert Rees.

Format:

Book

Author/Creator:

Catoen, Bruce, author.

Rees, Herbert, 1915- author.

Language:

English

Subjects (All):

Injection molding of plastics--Handbooks, manuals, etc.

Injection molding of plastics.

Genre:

Handbooks and manuals.

Physical Description:

1 online resource (818 pages)

Place of Publication:

Munich, Germany : Hanser Publishers, [2021]

Summary:

Injection Mold Design Handbook will take the reader through the process of conceptualizing and designing an injection mold that will produce the desired plastic part. Since it all starts with the plastic part, the book will first focus on key features and details of the plastic part which are necessary for good mold design. The design of the main components of an injection mold will be discussed and good design practices will be shared. Finally the process of testing and gaining customer acceptance of the mold for production will be detailed. A comprehensive appendix and detailed drawings will provide the required detail for completing a mold design.

Contents:

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.

Notes:

Description based on print version record.

ISBN:

1-5231-4500-5

1-56990-816-8

OCLC:

1273974356