The Complete Part Design Handbook

E. Alfredo Campo The Complete Part Design Handbook

E. Alfredo Campo

The Complete Part Design Handbook For Injection Molding of Thermoplastics

Hanser Publishers, Munich • Hanser Gardner Publications, Cincinnati

The Author: E. Alfredo Campo, 1213 Cerrito Perdido Lane , El Paso, TX 79912,USA Distributed in the USA and in Canada by Hanser Gardner Publications, Inc. 6915 Valley Avenue, Cincinnati, Ohio 45244-3029, USA Fax: (513) 527-8801 Phone: (513) 527-8977 or 1-800-950-8977 www.hansergardner.com Distributed in all other countries by Carl Hanser Verlag Postfach 86 04 20, 81631 München, Germany Fax: +49 (89) 98 48 09 www.hanser.de The use of general descriptive names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. While the advice and information in this book are believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Library of Congress Cataloging-in-Publication Data Campo, E. Alfredo. The complete part design handbook : for injection molding of thermoplastics / E. Alfredo Campo. p. cm. Includes index. ISBN-13: 978-1-56990-375-9 ISBN-10: 1-56990-375-1 1. Injection molding of plastics--Handbooks, manuals, etc. 2. Thermoplastics--Design--Handbooks, manuals, etc. 3. Plastics--Handbooks, manuals, etc. I. Title. TP1150.C36 2006 668.4‘23--dc22 2006010219 Bibliografische Information Der Deutschen Bibliothek Die Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie; detaillierte biblio-grafische Daten sind im Internet über abrufbar. ISBN-10: 3-446-40309-4 ISBN-13: 978-3-446-40309-3 All rights reserved.No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying or by any information storage and retrieval system, without permission in writing from the publisher. © Carl Hanser Verlag, Munich 2006 Production Management: Oswald Immel Typeset by Manuela Treindl, Laaber, Germany Coverconcept: Marc Müller-Bremer, Rebranding, München, Germany Coverdesign: MCP • Susanne Kraus GbR, Holzkirchen, Germany Printed and bound by Druckhaus “Thomas Müntzer” GmbH, B. Langensalza, Germany

V

Dedication To my wife Sandy, my son Jaime, and my daughter Michelle for the love and understanding they gave me during the six long years that it took me to produce all the original drawings, calculate examples and write this comprehensive handbook. For my uncle, Captain Jaime Merchán and my aunt Ruth Reichman for the assistance provided while attending the University of Miami. For my great grand uncle Rafael Ramirez who paid for my elementary and high school education after I lost my father at the age of five. In honor of my beloved departed brother, Leoncio, and sister in-law Becky. For my grand nephew, Alfredo Campo V. for winning the BMX world championship and the sportsman of the year in my native country Ecuador. For Richard Scott, Bob Rackley and Bill Hawkins from the Du Pont Film Department for their leadership, teaching and guidance in how to be successful in the engineering technical research and development fields. For Larry Gillespie, Director of Du Pont Engineering Polymers for providing me the opportunity to work in most of the technical positions in plastics, such as development of new compounds, economic project analysis, designs of international compounding facilities and laboratories in Japan, Mexico and Brazil. For the Du Pont Film Department, Textile Fibers Department, Engineering Polymers Department, and Du Pont do Brazil that provided me several technical assignments in Plastics during thirty years of service to the company. For all the Du Pont Plastics Customers that gave me the opportunity to improve their plastic products and optimize their injection molding manufacturing processes. E. Alfredo Campo

VII

Preface This handbook was written for the injection molding product designer who has a limited knowledge of engineering polymers. It is a guide for the designer to decide which resin and design geometries to use for the design of plastic parts. It can also offer knowledgeable advice for resin and machine selection and processing parameters. Manufacturer and end user satisfaction is the ultimate goal. This book is an indispensable, all inclusive, reference guide that can be used by any plastic product designer. There is no need to search through many books and catalogs for needed information. New illustrations, graphs and equations have been included to provide additional clarity for complex ideas. The equations have been verified to ensure correctness and not just copied from another source. Thousands of hours of research and cross referencing have gone into the completion of this work. In addition, more than 35 years of the “hands-on” experience of a plastics expert have been incorporated in this handbook. The following topics are covered: Chapter 1

Plastic Materials Selection Guide: Includes an introduction to plastic materials, the beginning of plastics, classification of polymer families. Each resin is discussed by its basic chemistry, properties, processing characteristics, advantages, disadvantages and limitations, typical applications and several product illustrations. Thermoplastic materials (35 generic families), thermoplastic elastomer materials (8 generic families), liquid injection molding of silicone, thermoset materials (16 generic families).

Chapter 2

Engineering Product Design: Starts with the introduction to structural product design principles, mechanical strength properties of thermoplastics. Centroid, section area, moment of inertia equations and tables. Beam deflection analysis methods. Structure analysis of beams, columns, flat circular plates, and torsion.

Chapter 3

Structural Design for Thermoplastics: Discusses the product wall thickness, structural rib design, sharp corners, bosses, threads, undercuts, integral life hinges, pin hinges. Encapsulation of inserts, types of metal inserts and anchorage, and electrical lead inserts.

Chapter 4

Thermoplastic Gearing Design: An introduction to and classification of gears. Standard spur, helical, bevel, and worm gears; properties required for thermoplastic molded spur gears, mounting gears on metal shafts, tolerances and mold shrinkage of gears. Plastic spur and helical gearing technology design, strength, horsepower rating, equations, tables, analysis examples and gear specification illustrations.

Chapter 5

Plastic Journal Bearing Design: An introduction to types of materials for journal bearings. Theory and design for lubrication. Design principles, performances, dimensions, clearances, molding effects, PV limits and surface finishing. Self-lubricated thermoplastic bearings. Equations, tables, and analysis examples.

VIII

Preface Chapter 6

Thermoplastic Spring Design: Introduces cantilever beam spring design, applications, and analysis examples. Locating, fixing clip, flexible hinges, and torsional spring applications. Belleville spring washers’ equations, tables, and analysis examples.

Chapter 7

Thermoplastic Pressure Vessel Design: Discusses thin- and thick-walled pressure vessels’ basic principles, equations, tables, analysis examples, design guidelines, applications, and pressure vessel regulations.

Chapter 8

Thermoplastic Assembly Methods: Joining two or more components together: assembly method is selected based on product design geometry, size, end use requirements, thermoplastic material characteristics, automatic or manual assembly operation, and manufacturing costs. Each assembly method provides a description, process sequence, advantages and limitations, typical applications, equipment, product joint design, and its variations.

Chapter 9

Thermoplastic Effects on Design: Starts discussing the polymer melt behavior, reinforcement, degradation, moisture characteristics, mold shrinkage and critical properties. The molding process effects caused by molding cycle, melt/mold temperature, injection pressure and speed, etc. on product design dimensions, surface finishing, weld line strength and impact resistance and other molding problems.

Chapter 10

Thermoplastic Injection Mold Design: Provides an introduction of injection molds, classification and effects on product design. Types of steels, chemical composition, effects of alloying, heat treatment, properties and characteristics. Types of steels used for mold bases and mold components. Cavity surfaces finish procedures and specifications. Types of injection mold designs. Cold runners (two- and three-plate molds, interchangeable mold inserts and vertical insert encapsulation mold). Hot runner molds (internally and externally heated, insulated). Mold design system and other considerations, such as number of cavities, parting line, ejection, cooling, cold runner, gating, venting, cavity inserts sidewall strength, support pillars, molded parts tolerances, mold designer check list, general specifications for mold construction are covered.

Chapter 11

Performance Testing of Thermoplastics: It introduces various tests to which thermoplastic polymers are subjected, describes their properties (statistical analysis), such as mechanical, thermal, chemical resistance, rheometer melt viscosity, soldering heat resistance, electrical, flammability, smoke generation, weathering and micro-organism resistance. Test description, procedures, apparatus, test specimen and conditioning, and their significance are discussed here.

Chapter 12

Thermoplastic Product Cost Analysis: It discusses molding process variables and capital equipment cost. Three cost analysis methods are used to estimate the molded product user’s price.

IX

Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII 1 Polymeric Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Introduction to Plastic Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.1 Beginning of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.2 Polymer Families . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Thermoplastic Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2.1 Classification of Polymers by Performance . . . . . . . . . . . . . 4 1.2.2 Molecular Structure of Plastic Materials . . . . . . . . . . . . . . . 6 1.2.3 Acrylonitrile-Butadiene-Styrene (ABS) . . . . . . . . . . . . . . . . 6 1.2.4 Acetal (POM, Polyacetal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.2.5 Polymethyl Metacrylate (Acrylic, PMMA) . . . . . . . . . . . . 12 1.2.6 High Temperature Nylon (HTN) . . . . . . . . . . . . . . . . . . . . 14 1.2.7 Ionomer Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.2.8 Liquid Crystal Polymer (LCP) . . . . . . . . . . . . . . . . . . . . . . . 18 1.2.9 Polyamide (PA, Nylon) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.2.10 Polyetherimide (PEI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1.2.11 Polyarylate (PAR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.2.12 Polyetherether Ketone (PEEK). . . . . . . . . . . . . . . . . . . . . . . 27 1.2.13 Polycarbonate (PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 1.2.14 Modified Polyphenylene Oxide (PPO). . . . . . . . . . . . . . . . 31 1.2.15 Polybutylene Terephthalate (PBT) . . . . . . . . . . . . . . . . . . . 33 1.2.16 Polyethylene Terephthalate (PET) . . . . . . . . . . . . . . . . . . . . 34 1.2.17 Polyethylene (PE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 1.2.18 Polytetrafluoroethylene (PTFE) . . . . . . . . . . . . . . . . . . . . . 39 1.2.19 Polyphenylene Sulfide (PPS) . . . . . . . . . . . . . . . . . . . . . . . . 44 1.2.20 Polypropylene (PP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 1.2.21 Polystyrene (PS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 1.2.22 Polysulfone (PSU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 1.2.23 Polyvinyl Chloride (PVC) . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 1.2.24 Styrene Acrylonitrile (SAN) . . . . . . . . . . . . . . . . . . . . . . . . . 53 1.3 Thermoplastic Elastomers (TPE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 1.3.1 Thermoplastic Elastomer Families . . . . . . . . . . . . . . . . . . . 56 1.3.2 Thermoplastic Polyurethane Elastomer (TPU) . . . . . . . . 57 1.3.3 Styrenic Block Copolymer (SBS). . . . . . . . . . . . . . . . . . . . . 60 1.3.4 Polyolefin Thermoplastic Elastomer (TPO) . . . . . . . . . . . 62 1.3.5 Elastomeric Alloy Thermoplastic Vulcanized (TPV). . . . 65 1.3.6 Melt Processible Rubber (MPR) . . . . . . . . . . . . . . . . . . . . . 69 1.3.7 Copolyester Thermoplastic Elastomer . . . . . . . . . . . . . . . 71 1.3.8 Polyamide Thermoplastic Elastomer . . . . . . . . . . . . . . . . . 75 1.4 Liquid Injection Molding Silicone (LIM®) . . . . . . . . . . . . . . . . . . . . 77 1.4.1 LIM® Silicone Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 1.5 Thermoset Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 1.5.1 Polyester Alkyd (PAK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 1.5.2 Diallyl Phthalate/Isophthalate (DAP, DAIP) . . . . . . . . . . . 85 1.5.3 Melamine Formaldehyde (MF) . . . . . . . . . . . . . . . . . . . . . . 87 1.5.4 Cellulosic Ester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 1.5.5 Cyanate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 1.5.6 Epoxy (EP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 1.5.7 Phenol Formaldehyde (Phenolic, PF). . . . . . . . . . . . . . . . . 94

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Contents 1.5.8 1.5.9 1.5.10 1.5.11 1.5.12 1.5.13 1.5.14 1.5.15 1.5.16

Polybutadiene (PB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Bismaleimide (BMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Unsaturated Polyester (UP) . . . . . . . . . . . . . . . . . . . . . . . . . 98 Polyimide (PI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Polyxylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Polyurethane (PUR). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Silicone (SI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Urethane Hybrid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Vinyl Ester (BPA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

2 Engineering Product Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Understanding the Properties of Materials . . . . . . . . . . . . . . . . . . . 2.1.1 Plastics Selection Guidelines . . . . . . . . . . . . . . . . . . . . . . . 2.2 Structural Design of Thermoplastic Components . . . . . . . . . . . . . 2.2.1 Stress-Strain Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.2 Tensile Testing of Viscoelastic Materials. . . . . . . . . . . . . . 2.3 Mechanical Properties of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Tension and Compression Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 Modulus of Elasticity (E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 Stress and Strain Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 Thermoplastics Elastic Design Method . . . . . . . . . . . . . . . . . . . . . . 2.7.1 Working Stress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7.2 Compressive Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7.3 Flexural Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7.4 Coefficient of Linear Thermal Expansion (α) . . . . . . . . 2.7.5 Poisson’s Ratio (υ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7.6 Moisture Effects on Nylon . . . . . . . . . . . . . . . . . . . . . . . . . 2.7.7 Effects of Temperature on the Behavior of Thermoplastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 Stress-Strain Recovery (Hysteresis) . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8.1 Creep Behavior of Thermoplastics . . . . . . . . . . . . . . . . . . 2.8.2 Creep and Rupture Under Long-Term Load . . . . . . . . . . 2.8.3 Creep and Relaxation of Thermoplastics. . . . . . . . . . . . . 2.9 Flexural Beam Stress Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.10 Viscoelastic Modulus Design Method . . . . . . . . . . . . . . . . . . . . . . . . 2.11 Centroid, Section Area, and Moment of Inertia . . . . . . . . . . . . . . . 2.12 Radius of Gyration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13 Stress Analysis of Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13.1 Types of Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13.2 Normal Stresses in Beams . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13.3 Shearing Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.14 Beam Deflection Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.14.1 Beam Deflection by Double Integration Method . . . . . 2.14.2 Beam Deflection Moment Area Method . . . . . . . . . . . . . 2.14.3 Applications of Moment Area and Double Integration Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.14.4 Beam Deflection Superposition Method . . . . . . . . . . . . . 2.15 Column Structural Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.15.1 Long Slender Column Critical Load (PCr) . . . . . . . . . . . . 2.15.2 Column Slenderness Ratio (L / r) . . . . . . . . . . . . . . . . . . . 2.15.3 Eccentrically Loaded Columns . . . . . . . . . . . . . . . . . . . . . 2.16 Flat Circular Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16.1 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16.2 Stress Analysis Methods . . . . . . . . . . . . . . . . . . . . . . . . . . .

115 115 117 120 121 122 126 129 129 130 131 132 133 134 135 136 136 137 138 138 139 139 145 147 150 158 158 158 159 164 168 169 178 179 183 188 188 188 188 194 195 195

XI

Contents 2.16.3 2.16.4 2.16.5 2.16.6

Flat Circular Plate Equations . . . . . . . . . . . . . . . . . . . . . . . Flat Circular Plate Stresses . . . . . . . . . . . . . . . . . . . . . . . . . Theory of Flexure Comparison . . . . . . . . . . . . . . . . . . . . . Circular Plates Simply Supported, Concentrated Center Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16.7 Flat Circular Plate under Concentrated Center Load . . 2.16.8 Flat Circular Plate with Fixed Edge . . . . . . . . . . . . . . . . . . 2.16.9 Flat Circular Plate Compensation Factor for Deflection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16.10 Flat Circular Plate Bending under Edge Boundaries . . . 2.17 Torsion Structural Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

196 197 198

3 Structural Designs for Thermoplastics . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Uniform and Symmetrical Wall Thickness . . . . . . . . . . . . . . . . . . . 3.1.1 Part Geometries Difficult to Mold . . . . . . . . . . . . . . . . . . 3.1.2 Wall Draft Angle per Side . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Structural Rib Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Rib Strength Analysis Method . . . . . . . . . . . . . . . . . . . . . . 3.3 Internal Sharp Corners and Notches . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Injection Molded Thermoplastic Bosses. . . . . . . . . . . . . . . . . . . . . . 3.5 Injection Molded Thermoplastic Threads . . . . . . . . . . . . . . . . . . . . 3.6 Collapsible Core for Molding Internal Threads . . . . . . . . . . . . . . . 3.7 Preferred Standard Thread Forms for Thermoplastics . . . . . . . . . 3.7.1 Thermoplastic Threads Creep Effects. . . . . . . . . . . . . . . . 3.8 Injection Molded Products with Undercuts. . . . . . . . . . . . . . . . . . . 3.9 Injection Molded Integral Life Hinges . . . . . . . . . . . . . . . . . . . . . . . 3.9.1 Injection Molded Integral Life Hinge Design . . . . . . . . . 3.9.2 Mold Design Considerations for Hinges . . . . . . . . . . . . . 3.9.3 Proper Gate Design for Life Hinges . . . . . . . . . . . . . . . . . 3.10 Conventional Types of Pin Hinges. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11 Metal Inserts for Thermoplastic Encapsulation . . . . . . . . . . . . . . . 3.11.1 Machined Metal Threaded Insert Tolerances . . . . . . . . . 3.11.2 Thermoplastic Boss Wall Thickness for Metal Inserts. . 3.11.3 Press/Lock Slotted Metal Insert Installation After Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11.4 Cold Forged Metal Inserts for Encapsulation . . . . . . . . . 3.11.5 Threaded Female Metal Inserts . . . . . . . . . . . . . . . . . . . . . 3.11.6 Metal Inserts Anchorage for Thermoplastic Encapsulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11.7 Metal Insert Encapsulating Process Problems . . . . . . . . 3.11.8 Special Metal Inserts Anchorage for Encapsulation . . . 3.11.9 Electrical Lead Inserts for Encapsulation. . . . . . . . . . . . . 3.11.10 Inserts Preparation for Molding Encapsulation . . . . . . .

211 211 212 213 213 215 222 222 224 224 225 227 227 232 233 235 236 237 239 240 240

4 Thermoplastic Gearing Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Classification of Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 Gears Parallel to the Shaft Axis . . . . . . . . . . . . . . . . . . . . . 4.1.2 Bevel Gears, Nonparallel and Intersecting Shafts . . . . . . 4.1.3 Hypoid Gears, Nonparallel and Nonintersecting Shafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.4 Gears for Straight Linear Motion . . . . . . . . . . . . . . . . . . . 4.2 Standard Injection Molded Thermoplastic Gears . . . . . . . . . . . . . 4.2.1 Selection of Thermoplastic Resins for Gears . . . . . . . . . 4.2.2 Horsepower Equations for Gears . . . . . . . . . . . . . . . . . . .

198 199 199 200 200 207

242 243 244 246 249 250 253 255 257 258 258 259 261 262 263 264 266

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Contents

4.3 4.4

4.5 4.6 4.7 4.8 4.10

4.11 4.12 4.13

4.2.3 Spur Gear Terminology and Definitions . . . . . . . . . . . . . Properties Required for Injection Molded Thermoplastic Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thermoplastic Spur Gear Design Requirements . . . . . . . . . . . . . . 4.4.1 Gating Effects on Thermoplastic Gear Roundness Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.2 Multifunction Designs with Thermoplastic Gears. . . . . 4.4.3 Mounting Thermoplastic Gears on Metal Shafts . . . . . . 4.4.4 Standard Spur Gears, Equations, and Calculations . . . . 4.4.5 Spur Gear Pitch Backlash . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.6 Standard Spur Gear Tooth Size Selection . . . . . . . . . . . . 4.4.7 Standard Gear Total Composite Tolerances . . . . . . . . . . Tolerances and Mold Shrinkage of Thermoplastic Gears . . . . . . . Standard Helical Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standard Straight Bevel Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standard Worm Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.1 Standard Worm Gear Analysis . . . . . . . . . . . . . . . . . . . . . . Plastic Gearing Technology Designs . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.1 Spur and Helical Gears PGT-1 Tooth Design . . . . . . . . . 4.10.2 Spur and Helical Gears PGT-2 Tooth Design . . . . . . . . . 4.10.3 Spur and Helical Gears PGT-3 Tooth Design . . . . . . . . . 4.10.4 Spur and Helical Gears PGT-4 Tooth Design . . . . . . . . . 4.10.5 Plastic Gearing Technology Tooth Form Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.6 Maximum Allowable Outside Diameter DO (Max.) . . . 4.10.7 Spur Gear Tooth Form Comparison. . . . . . . . . . . . . . . . . 4.10.8 Mating Spur Gears Tooth Form Comparison . . . . . . . . . 4.10.9 PGT Spur Mating Gears Strength Balance . . . . . . . . . . . 4.10.10 PGT Close Mesh Center Distance Between Spur Gears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.11 Maximum Close Mesh Center Distance . . . . . . . . . . . . . PGT Helical Thermoplastic Gearing . . . . . . . . . . . . . . . . . . . . . . . . . 4.11.1 PGT-1 Helical Mating Gears Strength Balance . . . . . . . . 4.11.2 PGT-1 Helical Mating Gears Center Distance . . . . . . . . PGT Spur and Helical Gears Horsepower Rating . . . . . . . . . . . . . . 4.12.1 PGT Gear Horsepower Equation Basic Parameters . . . . PGT Spur and Helical Gear Specifications. . . . . . . . . . . . . . . . . . . .

5 Plastic Journal Bearing Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Materials Used for Journal Bearings . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.1 Babbitt Journal Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.2 Bronze Journal Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.3 Sintered Porous Metal Journal Bearings . . . . . . . . . . . . . 5.2.4 Plugged Bronze Journal Bearings . . . . . . . . . . . . . . . . . . . 5.2.5 Carbon-Graphite Journal Bearings . . . . . . . . . . . . . . . . . . 5.2.6 Cast-iron Journal Bearings . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.7 Wooden Journal Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.8 Rubber Journal Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.9 Self-Lubricated Thermoplastic Journal Bearings . . . . . . 5.3 Hydrodynamics of Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Journal Bearings Design for Lubrication . . . . . . . . . . . . . . . . . . . . . 5.5 Journal Bearing Design Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.1 Journal Bearing Nomenclature and Equations . . . . . . . .

268 272 273 275 277 279 279 281 282 283 287 289 290 292 293 294 295 297 298 299 300 302 303 304 305 308 309 314 319 322 323 324 328 335 335 335 336 336 336 336 337 337 337 337 338 339 342 345 345

XIII

Contents

5.6 5.7 5.8 5.9 5.10 5.11 5.12

5.13

5.14 5.15

5.16

5.17

5.5.2 Thermoplastic Journal Bearing Axial Wall Thickness . . 5.5.3 Mounting Thermoplastic Journal Bearings . . . . . . . . . . Split Bushing Thermoplastic Journal Bearings . . . . . . . . . . . . . . . . Self-Centering Thermoplastic Journal Bearings . . . . . . . . . . . . . . . Journal Bearing Load Carrying Contact Surface (C) . . . . . . . . . . . Load Reaction Across the Length of Thermoplastic Bearing . . . . Injection Molded Journal Bearings Process Defects . . . . . . . . . . . . Factors Affecting Journal Bearing Performance . . . . . . . . . . . . . . . Factors Affecting Journal Bearing Dimensions . . . . . . . . . . . . . . . . 5.12.1 Length-to-Inside Diameter Ratio of Journal Bearings . 5.12.2 Types of Service and Motion of Journal Bearings . . . . . 5.12.3 Thermoplastic Journal Bearing Annealing Effects . . . . . 5.12.4 Acetal Homopolymer Moisture Absorption Effects . . . 5.12.5 TFE and Nylon 6/6 Moisture Absorption Effects . . . . . . 5.12.6 Temperature Effects on Thermoplastic Journal Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.12.7 Thermal Effects on Thermoplastic Journal Bearing Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Journal Bearing Pressure-Velocity (PV) Limits . . . . . . . . . . . . . . . . 5.13.1 Methods to Determine the PV Limits of Plastics . . . . . . 5.13.2 Journal Bearing Coefficient of Friction . . . . . . . . . . . . . . 5.13.3 Journal Bearing Failures Due to Small Clearances. . . . . 5.13.4 Definition of Different Types of Wear . . . . . . . . . . . . . . . Mating Material Hardness and Surface Finishing. . . . . . . . . . . . . . Self-Lubricated Thermoplastic Journal Bearings . . . . . . . . . . . . . . 5.15.1 Vespel® Polyimide Bearings . . . . . . . . . . . . . . . . . . . . . . . . 5.15.2 Journal Bearing Pressure Equation . . . . . . . . . . . . . . . . . . 5.15.3 Vespel® Wear Factor Effects Caused by Temperature . . 5.15.4 Vespel® Wear Transition Temperature . . . . . . . . . . . . . . . 5.15.5 Frictional Behavior of Vespel® . . . . . . . . . . . . . . . . . . . . . . 5.15.6 Vespel® Journal Bearings Length to Inside Diameter Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.15.7 Vespel® Thrust Bearing Ratio Between Diameters . . . . 5.15.8 Vespel® Journal Bearing Initial Clearance (cI) . . . . . . . . 5.15.9 Vespel® Journal Bearing Inside Diameter (dB) . . . . . . . . Teflon® (TFE) Fabric Composite Bearings . . . . . . . . . . . . . . . . . . . 5.16.1 Bearing Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . 5.16.2 Bearing PV Limit Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.16.3 Journal Bearing Clearances (c) . . . . . . . . . . . . . . . . . . . . . Thermoplastic Kevlar® Reinforced Bearings . . . . . . . . . . . . . . . . . .

6 Thermoplastic Molded Spring Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Thermoplastic Molded Spring Design Considerations . . . . . . . . . 6.3 Thermoplastic Helical Compression Springs . . . . . . . . . . . . . . . . . 6.4 Thermoplastic Molded Cantilever Beam Springs . . . . . . . . . . . . . . 6.5 Cantilever Beam Spring Design Analysis . . . . . . . . . . . . . . . . . . . . . 6.5.1 Initial Modulus of Elasticity Cantilever Beam Analysis Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5.2 Stress-Strain Curve Cantilever Beam Analysis Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5.3 Empirical Data Cantilever Spring Analysis Method . . . 6.6 Thermoplastic Cantilever Spring Applications . . . . . . . . . . . . . . . . 6.7 Thermoplastic Belleville Spring Washers . . . . . . . . . . . . . . . . . . . . .

347 347 348 348 350 350 351 352 353 354 354 354 355 355 356 357 358 359 359 360 361 362 363 366 367 368 369 369 370 370 370 371 373 374 374 375 375 377 377 378 378 379 381 381 381 382 385 388

XIV

Contents 6.7.1 6.7.2 6.7.3

Acetal Homopolymer Belleville Spring Washer Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 Belleville Spring Washer Loading Rate. . . . . . . . . . . . . . . 392 Belleville Spring Washer Long-Term Loading Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392

7 Thermoplastic Pressure Vessel Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Thermoplastic Thin-Walled Pressure Vessels . . . . . . . . . . . . . . . . . 7.2 Thin-Walled Cylinder Basic Principles . . . . . . . . . . . . . . . . . . . . . . . 7.3 Thick-Walled Pressure Vessels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.1 Lame’s Equation for Thick-Walled Cylinders . . . . . . . . . 7.3.2 Maximum Stresses with Internal and External Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.3 Maximum Stresses for Internal Pressure Only . . . . . . . . 7.4 Designing Cylinders for Cost Reduction . . . . . . . . . . . . . . . . . . . . . 7.5 Thermoplastic Pressure Vessels Design Guidelines . . . . . . . . . . . . 7.5.1 Preliminary Pressure Vessel Design. . . . . . . . . . . . . . . . . . 7.6 Testing Prototype Thermoplastic Pressure Vessels . . . . . . . . . . . . . 7.6.1 Redesign and Retesting the Pressure Vessels . . . . . . . . . . 7.7 Pressure Vessel Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7.1 ASME Pressure Vessel Code . . . . . . . . . . . . . . . . . . . . . . . .

393 393 394 396 396

8 Thermoplastic Assembly Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 Cold Heading Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 Cold Heading Procedure and Equipment . . . . . . . . . . . . 8.3 Electro Fusion Fitting System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.1 The SEF-System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 Hot Plate Welding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.1 Hot Plate Welding Joint Design . . . . . . . . . . . . . . . . . . . . . 8.4.2 Flash or Weld Bead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 Solvent and Adhesive Bonding Methods . . . . . . . . . . . . . . . . . . . . . 8.5.1 Solvents Used to Bond Thermoplastic Polymers . . . . . . 8.6 Adhesive Bonding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.1 Adhesive Families . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.2 Adhesive Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.3 Adhesives Bonding Selection . . . . . . . . . . . . . . . . . . . . . . . 8.6.4 Ultra Violet Curable Adhesives . . . . . . . . . . . . . . . . . . . . . 8.6.5 Adhesive Surface Preparation. . . . . . . . . . . . . . . . . . . . . . . 8.6.6 Adhesive Application and Curing Methods . . . . . . . . . . 8.6.7 Joint Design for Adhesive Bonding . . . . . . . . . . . . . . . . . . 8.7 Metal Fasteners Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.1 Thermoplastic Bosses and Self-Tapping Screws . . . . . . . 8.7.2 Thread Forming and Thread Cutting Screws . . . . . . . . . 8.8 Press Fitting Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.1 Press Fitting Interference . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.2 Circular Press Fitting Assembly Method . . . . . . . . . . . . . 8.9 Snap Fitting Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9.1 Circular Undercut Snap Fitting Joints . . . . . . . . . . . . . . . 8.9.2 Suggestions for Stripping Circular Undercut Snap Fitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9.3 Cantilevered Latch Snap Fitting Joint. . . . . . . . . . . . . . . . 8.9.4 Cantilever Snap Fit Latch Design Guidelines . . . . . . . . . 8.9.5 Cantilever Latch Snap Fit Mathematical Model . . . . . . .

405 405 405 406 408 409 410 412 413 413 414 416 416 419 420 421 424 425 425 427 429 430 437 439 441 444 445

398 398 400 400 400 402 402 402 403

446 447 449 450

XV

Contents 8.9.6

8.10

8.11

8.12

8.13

8.14

8.15 8.16 8.17

Cantilever Snap Latch Beam Permissible Deflection (δ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9.7 Cantilever Latch Beam Assembly Force (W) . . . . . . . . . . 8.9.8 Design and Material Considerations . . . . . . . . . . . . . . . . 8.9.9 Uniform Cross Section Cantilever Beam . . . . . . . . . . . . . 8.9.10 Tapered Cross Section Cantilever Beam . . . . . . . . . . . . . Electromagnetic Welding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.10.1 Electromagnetic Welding Process . . . . . . . . . . . . . . . . . . . 8.10.2 Electromagnetic Welding Coil Design . . . . . . . . . . . . . . . 8.10.3 Electromagnetic Welding Joint Design . . . . . . . . . . . . . . 8.10.4 Available Welding Gasket Shapes and Forms . . . . . . . . . Vibration Welding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.11.1 High Frequency Vibration Welding . . . . . . . . . . . . . . . . . 8.11.2 Vibration Welding Modes . . . . . . . . . . . . . . . . . . . . . . . . . . 8.11.3 Comparing Vibration Welding to Other Assembly Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.11.4 Vibration Welding Equipment . . . . . . . . . . . . . . . . . . . . . . 8.11.5 Vibration Welding Joint Design. . . . . . . . . . . . . . . . . . . . . 8.11.6 Vibration Welding Aligning and Fixturing . . . . . . . . . . . 8.11.7 Vibration Welding Tolerances . . . . . . . . . . . . . . . . . . . . . . 8.11.8 Vibration Welding Equipment . . . . . . . . . . . . . . . . . . . . . . Spin Welding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.12.1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.12.2 Basic Spin Welding Equipment . . . . . . . . . . . . . . . . . . . . . 8.12.3 Spin Welding Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.12.4 Types of Spin Welding Processes . . . . . . . . . . . . . . . . . . . . 8.12.5 Spin Welding Joint Designs . . . . . . . . . . . . . . . . . . . . . . . . 8.12.6 Spin Welding Process Suggestions. . . . . . . . . . . . . . . . . . . Ultrasonic Welding Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.13.1 Ultrasonic Welding Basic Principles . . . . . . . . . . . . . . . . . 8.13.2 Ultrasonic Welding Basic Components . . . . . . . . . . . . . . 8.13.3 Ultrasonic Welding Equipment . . . . . . . . . . . . . . . . . . . . . 8.13.4 Ultrasonic Welding Process Variables . . . . . . . . . . . . . . . . 8.13.5 Ultrasonic Welding Joint Designs . . . . . . . . . . . . . . . . . . . 8.13.6 Ultrasonic Welding Energy Director Butt Joint . . . . . . . 8.13.7 Ultrasonic Welding Method Design Limitations . . . . . . 8.13.8 Weldability of Thermoplastic Materials . . . . . . . . . . . . . . 8.13.9 Effects Caused by Thermoplastic Additives on Ultrasonic Welding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ultrasonic Insertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.14.1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.14.2 Ultrasonic Insertion Configurations . . . . . . . . . . . . . . . . 8.14.3 Ultrasonic Insertion Product Design . . . . . . . . . . . . . . . . 8.14.4 Ultrasonic Insertion Equipment Requirements . . . . . . . 8.14.5 Ultrasonic Insertion Process Guidelines . . . . . . . . . . . . . Ultrasonic Stud Staking Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.15.1 Ultrasonic Stud Staking Joint Design . . . . . . . . . . . . . . . . Ultrasonic Stud Heading Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.16.1 Thermoplastic Stud Profiles for Ultrasonic Heading . . Ultrasonic Spot Welding Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.17.1 Hand-Held Ultrasonic Spot Welder . . . . . . . . . . . . . . . . .

452 453 454 454 455 458 459 460 463 464 465 465 466 469 471 472 473 474 474 476 476 476 477 477 480 480 482 482 483 483 487 489 492 494 496 497 500 500 501 502 502 503 503 503 506 506 509 510

9 Thermoplastic Effects on Product Design . . . . . . . . . . . . . . . . . . . . . . . . . 511 9.1 Polymer Melt Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511

XVI

Contents 9.1.1 Thermoplastics Glass Transition Temperature . . . . . . . . General Characteristics of Polymers . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.1 Critical Properties of Thermoplastics. . . . . . . . . . . . . . . . Polymer Reinforcements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3.1 Types of Fiber Reinforcements . . . . . . . . . . . . . . . . . . . . . 9.3.2 Isotropic Warpage of Fiber Reinforced Resins . . . . . . . . 9.3.3 Fiber Glass Reinforcement Limitations . . . . . . . . . . . . . . 9.3.4 Injection Molding Process Effects on Fiber Glass Orientation . . . . . . . . . . . . . . . . . . . . . . . . . 9.3.5 Tensile Stress Effects Caused by Fiber Glass Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3.6 Flexural Modulus Effects Caused by Fiber Glass Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical and Environmental Resistance . . . . . . . . . . . . . . . . . . . . . 9.4.1 Effects of the Environment . . . . . . . . . . . . . . . . . . . . . . . . . Types of Degradations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5.1 Oxidative Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5.2 Radiation Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5.3 Photo Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5.4 Mechanical Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5.5 Microbial Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . Moisture Effects on Nylon Molded Parts . . . . . . . . . . . . . . . . . . . . . Aqueous Potassium Acetate for Moisture Conditioning Nylon . . Injection Molding Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mold Cavity Surface Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . Mold Cavity Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . 9.10.1 Mold and Post-Mold Shrinkage. . . . . . . . . . . . . . . . . . . . . Process Condition Effects on Mold Shrinkage . . . . . . . . . . . . . . . . Post-Mold Shrinkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Weld Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

519 520 521 522 522 522 522 522 523 523 527 528 529 530 531 533 538 541

10 Injection Mold Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1 Classification of Injection Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2 Effects of Product Design on the Injection Molding Process . . . . 10.2.1 Uniform Wall Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.2 Balance Geometrical Configuration . . . . . . . . . . . . . . . . . 10.2.3 Smooth Internal Sharp Corners . . . . . . . . . . . . . . . . . . . . 10.2.4 Draft Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.5 Feather Edges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.6 Proportional Boss Geometries . . . . . . . . . . . . . . . . . . . . . . 10.2.7 Gate Type and Location . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2.8 Molded Product Ejection Surface Area . . . . . . . . . . . . . . 10.2.9 Molded Product Tolerances . . . . . . . . . . . . . . . . . . . . . . . . 10.2.10 Surface Finish of Molded Product . . . . . . . . . . . . . . . . . . 10.3 Effects of Mold Design on the Injection Molding Process . . . . . . 10.3.1 Runner System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.2 Mold Cooling System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.3 Ejector System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.4 Mold Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.5 Other Mold Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4 Design Considerations for Injection Molds . . . . . . . . . . . . . . . . . . . 10.4.1 Preliminary Mold Design . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.2 Detailed Mold Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5 Types of Steels Required for Injection Molds . . . . . . . . . . . . . . . . .

545 545 546 547 547 547 547 547 548 548 548 548 549 549 549 549 550 550 550 550 551 552 553

9.2 9.3

9.4 9.5

9.6 9.7 9.8 9.9 9.10 9.11 9.12 9.13

513 513 514 515 516 517 517 517 518

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Contents 10.5.1 Major Steel Families . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.6 Steels for Thermoplastic Injection Molds . . . . . . . . . . . . . . . . . . . . 10.6.1 General Steel Selection Procedures . . . . . . . . . . . . . . . . . . 10.6.2 Properties and Characteristics of Tool Steels . . . . . . . . . 10.6.3 Effects of Alloying Elements on Tool Steel Properties. . 10.6.4 Chemical Composition of Steels Used for Molds . . . . . 10.6.5 Effects of Alloying on Tool Steels . . . . . . . . . . . . . . . . . . . 10.6.6 Effects of Heat Treatment on Tool Steel Properties . . . . 10.6.7 Prehardened Tool Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.6.8 Carburizing Tool Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.6.9 Oil and Air Hardening Tool Steels. . . . . . . . . . . . . . . . . . . 10.6.10 Stainless Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.6.11 Steels Used in Thermoplastic Injection Mold Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7 Mold Cavity Surface Finishing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7.1 Mold Surface Finishing Process Procedures . . . . . . . . . . 10.8 Thermoplastic Injection Mold Bases . . . . . . . . . . . . . . . . . . . . . . . . . 10.8.1 Standard Mold Base Components. . . . . . . . . . . . . . . . . . . 10.8.2 Functions of the Mold Base Components . . . . . . . . . . . . 10.8.3 Types of Standard Mold Bases . . . . . . . . . . . . . . . . . . . . . . 10.9 Types of Thermoplastic Injection Molds . . . . . . . . . . . . . . . . . . . . . 10.9.1 Two-Plate Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9.2 Round Mate® Interchangeable Insert Molds . . . . . . . . . 10.9.3 Master Unit Die Interchangeable Insert Molds . . . . . . . 10.9.4 Three-Plate Mold Cold Runner System . . . . . . . . . . . . . . 10.9.5 Vertical Insert Mold for Thermoplastic Encapsulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9.6 Hot Runner Molding Systems . . . . . . . . . . . . . . . . . . . . . . 10.9.7 Hot Runner Mold Temperature Control Systems . . . . . 10.9.8 Hot Runner Mold Gates (Drops) . . . . . . . . . . . . . . . . . . . 10.9.9 Types of Hot Runner Molding Systems . . . . . . . . . . . . . . 10.9.10 Thermoplastic Stack Injection Molds. . . . . . . . . . . . . . . . 10.9.11 Lost Core Thermoplastic Injection Molds. . . . . . . . . . . . 10.10 Number of Mold Cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.10.1 Cavity Number Limitations . . . . . . . . . . . . . . . . . . . . . . . . 10.10.2 Number of Mold Cavities Equation . . . . . . . . . . . . . . . . . 10.11 Mold Parting Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.11.1 Flat Mold Parting Line. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.11.2 Non-Flat Mold Parting Line . . . . . . . . . . . . . . . . . . . . . . . . 10.11.3 Balancing of Mold Parting Line Surfaces . . . . . . . . . . . . . 10.12 Mold Ejection Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.12.1 Ejector Plate Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.12.2 Ejector Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.12.3 Retaining Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.12.4 Ejector Sleeves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.12.5 Types of Mold Ejection Systems . . . . . . . . . . . . . . . . . . . . 10.13 Injection Mold Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.13.1 Mold Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . 10.13.2 Factors Affecting Mold Cooling. . . . . . . . . . . . . . . . . . . . . 10.13.3 Effects Caused by Elevated Mold Temperature . . . . . . . 10.13.4 Effects Caused by Too Low a Mold Temperature . . . . . . 10.13.5 Mold Heat Transfer Methods . . . . . . . . . . . . . . . . . . . . . . . 10.13.6 Mold Cavity Insert Cooling . . . . . . . . . . . . . . . . . . . . . . . . 10.14 Injection Molding Machine Nozzle . . . . . . . . . . . . . . . . . . . . . . . . . .

553 557 558 559 559 559 560 562 564 566 567 568 569 571 573 578 578 579 582 583 584 585 585 586 587 588 589 590 593 601 602 606 606 606 607 607 608 610 610 611 611 611 611 612 615 616 617 617 618 618 631 639

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Contents 10.14.1 Mold Cold Runner System . . . . . . . . . . . . . . . . . . . . . . . . . 10.14.2 Determining the Injection Pressure Needed . . . . . . . . . . 10.14.3 Cold Runner Flow Tab. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mold Cavity Gating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.15.1 Types of Mold Cavity Gates . . . . . . . . . . . . . . . . . . . . . . . . 10.15.2 Different Types of Hot Runner Gates . . . . . . . . . . . . . . . . Gate Molding Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mold Venting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.17.1 Product Design for Venting . . . . . . . . . . . . . . . . . . . . . . . . 10.17.2 Venting Characteristics of Thermoplastic Polymers . . . 10.17.3 Mold Deposit Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.17.4 How to Avoid Venting Problems . . . . . . . . . . . . . . . . . . . . 10.17.5 Planning Mold Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.17.6 Mold Venting Process Problems . . . . . . . . . . . . . . . . . . . . 10.17.7 Mold Venting Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.17.8 Mold Venting Using Sintered Porous Insert Plugs . . . . . 10.17.9 Logic Seal (Negative Coolant Pressure) Mold Venting . 10.17.10 Mold Cavity Vacuum Venting System . . . . . . . . . . . . . . . Mold Cavity Insert Contact Area Strength . . . . . . . . . . . . . . . . . . . . 10.18.1 Cavity Insert Sidewall Strength . . . . . . . . . . . . . . . . . . . . . 10.18.2 Methods to Calculate the Strength of Cavity Insert Sidewall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mold Layout Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mold Support Pillars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tolerances for Thermoplastic Molded Parts . . . . . . . . . . . . . . . . . . 10.21.1 Factors Affecting Dimensional Control Tolerances . . . . General Specifications for Mold Construction for Thermoplastic Injection Molding Resins . . . . . . . . . . . . . . . . . . . . . 10.22.1 Mold Design Requirements . . . . . . . . . . . . . . . . . . . . . . . . 10.22.2 Mold Drawing Standards . . . . . . . . . . . . . . . . . . . . . . . . . . 10.22.3 Required Types of Tool Steels for Mold Construction . 10.22.4 Mold Construction Requirements . . . . . . . . . . . . . . . . . . Mold Tryout – Debug – Approvals – “MQ1” Requirements. . . . . 10.23.1 Mold Tryout or Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 10.23.2 Mold Debug Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.23.3 Approval of Molded Parts and Pre-Production Molding Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.23.4 Mold Cavity and Core Surface Temperatures . . . . . . . . . 10.23.5 “MQ1” Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

639 653 654 655 656 663 664 666 667 669 669 670 671 672 674 690 691 693 698 699

11 Performance Testing of Thermoplastics . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Property Data Sheet for Thermoplastics . . . . . . . . . . . . . . . . . . . . . 11.2 Tensile Testing (ASTM D-638) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.1 Tensile Testing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.2 Tensile Test Specimen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.3 Specimen Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.4 Tensile Strength Test Procedures . . . . . . . . . . . . . . . . . . . . 11.2.5 Tensile Modulus and Elongation . . . . . . . . . . . . . . . . . . . . 11.2.6 Molecular Orientation Effects . . . . . . . . . . . . . . . . . . . . . . 11.2.7 Crosshead Speed Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.8 Temperature Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2.9 Moisture Absorption Effects. . . . . . . . . . . . . . . . . . . . . . . . 11.2.10 Stress-Strain Effects Caused by Creep . . . . . . . . . . . . . . . 11.3 Flexural Testing (ASTM D-790) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

723 724 725 725 726 726 726 727 728 729 729 729 730 730

10.15 10.16 10.17

10.18

10.19 10.20 10.21 10.22

10.23

700 704 705 705 707 709 709 709 711 713 720 720 720 720 720 721

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Contents

11.4

11.5

11.6

11.7 11.8 11.9

11.10 11.11 11.12 11.13

11.14

11.15 11.16 11.17 11.18

11.3.1 Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.2 Test Procedures and Equations . . . . . . . . . . . . . . . . . . . . . 11.3.3 Modulus of Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Compressive Strength Testing (ASTM D-695) . . . . . . . . . . . . . . . . 11.4.1 Compressive Testing Apparatus . . . . . . . . . . . . . . . . . . . . . 11.4.2 Test Specimens and Conditioning. . . . . . . . . . . . . . . . . . . 11.4.3 Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4.4 Stress-Strain Tension and Compression Curves. . . . . . . Shear Strength Testing (ASTM D-732) . . . . . . . . . . . . . . . . . . . . . . . 11.5.1 Test Specimen and Apparatus . . . . . . . . . . . . . . . . . . . . . . 11.5.2 Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.5.3 Significance and Limitations . . . . . . . . . . . . . . . . . . . . . . . Surface Hardness Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.1 Rockwell Hardness Testing (ASTM D-785-60T) . . . . . . 11.6.2 Barcol Hardness Testing (ASTM D-2583) . . . . . . . . . . . . 11.6.3 Factors Affecting the Test Results . . . . . . . . . . . . . . . . . . . Abrasion Resistance Testing (ASTM D-1044) . . . . . . . . . . . . . . . . . 11.7.1 Taber Abrasion Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.7.2 Theoretical Analysis of Wear . . . . . . . . . . . . . . . . . . . . . . . Coefficient of Friction (ASTM D-1894) . . . . . . . . . . . . . . . . . . . . . . 11.8.1 Coefficient of Friction of Thermoplastic Materials . . . . 11.8.3 Effects of Lubricants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mold Shrinkage Test (ASTM D-955) . . . . . . . . . . . . . . . . . . . . . . . . 11.9.1 Purpose of the Mold Shrinkage Test . . . . . . . . . . . . . . . . . 11.9.2 Factors Affecting Mold Shrinkage . . . . . . . . . . . . . . . . . . . 11.9.3 Injection Molding Effects on Shrinkage. . . . . . . . . . . . . . 11.9.4 Requirements for Sampling . . . . . . . . . . . . . . . . . . . . . . . . 11.9.5 Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific Gravity Testing (ASTM D-792) . . . . . . . . . . . . . . . . . . . . . . 11.10.1 Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Density Gradient Testing (ASTM D-1505) . . . . . . . . . . . . . . . . . . . Water Absorption Testing (ASTM D-570) . . . . . . . . . . . . . . . . . . . . 11.12.1 Test Specimen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.12.2 Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Impact Resistance Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.13.1 Pendulum Impact Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.13.2 Charpy Impact Testing (ASTM D-256) . . . . . . . . . . . . . . 11.13.3 Chip Impact Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.13.4 Tensile Impact Testing (ASTM D-1822) . . . . . . . . . . . . . 11.13.5 Drop Weight Impact Testing (ASTM D-3029) . . . . . . . . 11.13.6 Falling Weight Impact Testing . . . . . . . . . . . . . . . . . . . . . . 11.13.7 Instrumented Impact Testing . . . . . . . . . . . . . . . . . . . . . . . Creep, Rupture, Relaxation, and Fatigue . . . . . . . . . . . . . . . . . . . . . 11.14.1 Tensile Creep Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.14.2 Flexural Creep Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.14.3 Procedure for Applying Creep Modulus . . . . . . . . . . . . . Melting Point Test (ASTM D-795) . . . . . . . . . . . . . . . . . . . . . . . . . . Vicat Softening Point (ASTM D-1525) . . . . . . . . . . . . . . . . . . . . . . . 11.16.1 Melting Point, Glass Transition Temperature . . . . . . . . . Brittleness Temperature (ASTM D-746) . . . . . . . . . . . . . . . . . . . . . 11.17.1 Test Apparatus and Procedures . . . . . . . . . . . . . . . . . . . . . UL – Temperature Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.18.1 Relative Thermal Indices . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.18.2 Long Term Thermal Aging Index . . . . . . . . . . . . . . . . . . .

731 732 733 733 734 734 734 735 735 735 736 736 736 737 739 740 740 741 741 742 743 744 744 744 745 745 745 746 748 749 750 750 751 751 751 753 755 755 755 756 757 758 761 761 762 764 767 767 768 768 768 770 770 772

XX

Contents 11.18.3 Creep Modulus/Creep Rupture Tests . . . . . . . . . . . . . . . . 11.19 Heat Deflection Temperature (ASTM D-648). . . . . . . . . . . . . . . . . 11.19.1 Apparatus and Test Specimens . . . . . . . . . . . . . . . . . . . . . 11.19.2 Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.19.3 Test Variables and Limitations . . . . . . . . . . . . . . . . . . . . . . 11.20 Soldering Heat Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.21 Coefficient of Linear Thermal Expansion Testing . . . . . . . . . . . . . 11.21.1 Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.22 Thermal Conductivity Testing (ASTM C-177) . . . . . . . . . . . . . . . . 11.23 Melt Flow Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.23.1 Moisture Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.24 Melt Index Testing (ASTM D-1238) . . . . . . . . . . . . . . . . . . . . . . . . . 11.24.1 Melt Flow Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.25 Capillary Rheometer Melt Viscosity Testing (ASTM D-1703) . . . 11.25.1 Melt Viscosity vs. Shear Rate Curves. . . . . . . . . . . . . . . . . 11.26 Electrical Properties Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.26.1 Underwriter’s Laboratories (UL) Yellow Cards . . . . . . . 11.26.2 How to Read and Interpret the “UL Yellow Card” . . . . . 11.26.3 “UL Insulation Systems Recognition” . . . . . . . . . . . . . . . 11.27 Electrical Insulation Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.28 Electrical Resistance Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.28.1 Volume Resistivity Testing (ASTM D-257) . . . . . . . . . . . 11.28.2 Surface Resistivity Testing (ASTM D-257) . . . . . . . . . . . 11.28.3 Dielectric Strength Testing (ASTM D-149) . . . . . . . . . . . 11.28.4 Dielectric Constant Testing (ASTM D-150) . . . . . . . . . . 11.28.5 Dissipation Factor Testing (ASTM D-150) . . . . . . . . . . . 11.28.6 Arc Resistance Testing (ASTM D-495) . . . . . . . . . . . . . . . 11.28.7 High Voltage Arc Tracking Rate (UL-746 A) . . . . . . . . . . 11.28.8 Comparative Track Index Testing (ASTM D-3638/ UL 746 A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.29 Self and Flash Ignition Temperature Testing (ASTM D-1929) . . 11.29.1 Test Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.29.2 High Current Arc Ignition Testing (UL 746A) . . . . . . . . 11.29.3 Hot Wire Coil Ignition Testing (UL 746A/ASTM D-3874) . . . . . . . . . . . . . . . . . . . . . . . . . 11.29.4 Hot Mandrel Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.29.5 Glow Wire Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.30 Flammability Characteristics of Polymers . . . . . . . . . . . . . . . . . . . . 11.30.1 Inherently Flame Retardant Polymers . . . . . . . . . . . . . . . 11.30.2 Less Flame Retardant Polymers . . . . . . . . . . . . . . . . . . . . . 11.30.3 Flammable Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.31 UL 94 Flammability Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.31.1 Horizontal Burning Testing, UL 94HB. . . . . . . . . . . . . . . 11.31.2 Vertical Burning Testing, UL 94-V0, UL 94-V1, UL 94-V2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.31.3 Vertical Burning Testing, UL 94-5V, UL 94-5VA, UL 94-5VB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.31.4 Factors Affecting UL 94 Flammability Testing . . . . . . . . 11.32 Limited Oxygen Index Testing (ASTM D-2863) . . . . . . . . . . . . . . . 11.32.1 Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.32.2 Factors Affecting the Test Results . . . . . . . . . . . . . . . . . . . 11.33 Smoke Generation Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.33.1 Smoke Density Testing (ASTM D-2843) . . . . . . . . . . . . . 11.34 Weathering Tests for Thermoplastic Materials . . . . . . . . . . . . . . . .

773 774 774 775 775 775 776 777 777 779 780 780 781 782 783 784 785 786 791 792 792 793 794 795 797 800 801 803 804 805 805 806 807 807 807 809 810 810 810 811 811 812 813 815 815 816 816 817 817 818

XXI

Contents 11.34.1 Weathering Creep Factors (Degradation) . . . . . . . . . . . . 11.34.2 Ultraviolet (UV) Radiation . . . . . . . . . . . . . . . . . . . . . . . . 11.34.3 Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.34.4 Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.34.5 Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.34.6 Micro-Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Accelerated Weathering Testing (ASTM G 23) . . . . . . . . . . . . . . . . 11.35.1 Exposure to Fluorescent UV Lamp, Condensation (ASTM G 53) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.35.2 Accelerated Weather Testing, Weather-Ometer® . . . . . . 11.35.3 Exposure to Carbon Arc Light and Water Testing (ASTM D-1499) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.35.4 Exposure to Xenon Arc Light and Water Testing (ASTM D-2565) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.35.5 Outdoor Weathering Testing of Thermoplastics (ASTM D-1435) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fungi Resistance Testing of Thermoplastics (ASTM G 21) . . . . . Bacteria Resistance Testing of Thermoplastics (ASTM G 22) . . . Fungi and Bacteria Outdoor Exposure Resistance Limitations . .

827 828 829 829

12 Thermoplastic Product Cost Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 Injection Molding Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Molding Cycle Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3 Material Handling (Regrinds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4 Capital Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5 Injection Molding Machine Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6 Injection Molding Machine Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7 Machine Installation and Safety Considerations . . . . . . . . . . . . . . 12.8 Auxiliary Equipment and Automation . . . . . . . . . . . . . . . . . . . . . . . 12.9 Mold Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.10 Molded Products Cost Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.10.1 Cost Analysis Basic Method . . . . . . . . . . . . . . . . . . . . . . . . 12.10.2 Cost Analysis Graph Method . . . . . . . . . . . . . . . . . . . . . . . 12.10.3 Advanced Cost Analysis Method . . . . . . . . . . . . . . . . . . . . 12.11 Secondary Molding Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.12 Additional Manufacturing Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . .

831 832 832 833 833 833 836 837 837 838 841 841 842 843 848 848

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acronyms for Polymeric Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Common Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Process Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reinforcement and Filler Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . English and Metric Units Conversion Guide. . . . . . . . . . . . . . . . . . . . . . . .

849 849 850 851 851 852 853

11.35

11.36 11.37 11.38

818 819 819 820 820 820 821 821 822 823 825

Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855 About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869