Plastic Forming Processes

Plastic Forming Processes

Plastic Forming Processes Maurice Reyne

First published in France in 2006 by Hermes Science/Lavoisier entitled: Transformations, assemblages et traitements des plastiques First published in Great Britain and the United States in 2008 by ISTE Ltd and John Wiley & Sons, Inc. Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address: ISTE Ltd John Wiley & Sons, Inc. 27-37 St George s Road 111 River Street London SW19 4EU Hoboken, NJ 07030 UK USA www.iste.co.uk ISTE Ltd, 2008 LAVOISIER, 2006 www.wiley.com The rights of Maurice Reyne to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988. Library of Congress Cataloging-in-Publication Data Reyne, Maurice. [Transformations, assemblages et traitements des plastiques. English] Plastic forming processes / Maurice Reyne. p. cm. ISBN 978-1-84821-066-0 1. Plastics--Molding I. Title. TP1150.R48 2008 668.4'12--dc22 2008033359 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN: 978-1-84821-066-0 Printed and bound in Great Britain by CPI Antony Rowe Ltd, Chippenham, Wiltshire.

Table of Contents Preface... ix Chapter 1. Introduction... 1 Chapter 2. Polymers.... 3 2.1. Definitions... 3 2.1.1. Synthetic materials... 4 2.1.2. Thermoplastics and thermosets... 5 2.1.3. Abbreviations for plastics... 6 2.2. Plastics classification... 6 2.2.1. Classification by price/quality... 6 2.2.2. Classification by molecular structure... 8 2.2.3. Division between amorphous and crystalline structures... 8 2.3. General properties... 10 2.3.1. Average mechanical, thermal and chemical properties for virgin polymers... 10 2.3.2. Main qualitative characteristics.... 12 2.4. Further reading... 22 Chapter 3. Converting Processes.... 23 3.1. Manufacture of molded parts in 3D... 24 3.1.1. Standard injection molding... 24 3.1.2. Specific injection molding processes... 36 3.1.3. Compression and transfer... 59 3.1.4. Pressing between hot plates... 62 3.1.5. Reaction injection molding (RIM)... 64

vi Plastic Forming Processes 3.1.6. Casting and inclusion... 67 3.2. Manufacture of long products... 70 3.2.1. Standard extrusion... 70 3.2.2. Extrusion with shaped die... 75 3.2.3. Specificities of extrusion... 92 3.2.4. Calendering...110 3.2.5. Coating (flexible PVC or PUR)...114 3.3. Manufacture of hollow products...117 3.3.1. Blow molding...117 3.3.2. Specificities of blow molding...123 3.3.3. Injection-blow molding...128 3.3.4. Rotomolding...132 3.3.5. Dip molding...141 3.4. Manufacture of thermoformed parts...143 3.4.1. Standard thermoforming...143 3.4.2. Specificities of thermoforming...154 3.5. Manufacture of foamed products...159 3.5.1. Expandable polystyrene molding...159 3.5.2. Polyurethane molding...166 3.5.3. Other types of foams...173 3.6. Machining and cutting...174 3.6.1. Operation...175 3.6.2. Cutting...175 3.6.3. Sanding and polishing...175 3.6.4. Applications...175 Chapter 4. Assembly and Fixations...177 4.1. Undemountable processes...177 4.1.1. Adhesive bonding...177 4.1.2. Welding...178 4.1.3. Riveting...193 4.2. Demountable assemblies...195 4.2.1. Ratchet assembly...195 4.2.2. Screwing...197 4.2.3. Assembly with flexible hinge...197 4.2.4. Insert...198 Chapter 5. Finishing Treatments....199 5.1. Plastics deposition on metal (or metal coating)....199 5.1.1. Torch gun spray...200 5.1.2. Fluidized bed...201 5.1.3. Electrostatic powder coating...203

Table of Contents vii 5.1.4. Dip coating, suspension or aerosol...204 5.1.5. Powder selection...204 5.2. Metal deposition on plastics...205 5.2.1. Vacuum metallizing...205 5.2.2. Sputtering...209 5.2.3. Electroplating...210 5.2.4. Advantages and disadvantages of the various processes...212 5.3. Printing and decorating...213 5.3.1. Preliminary treatments...213 5.3.2. Printing or decoration on a rigid substrate...215 Chapter 6. Ecology and Recycling...231 6.1. Nuisance and pollution...231 6.1.1. Ecological appearances (waste built-up)...231 6.1.2. Biological appearances (contamination of the atmosphere)...232 6.1.3. Positive appearances...233 6.2. Solid waste treatment...233 6.2.1. Regenerating plastics...234 6.2.2. Energy enrichment...236 6.2.3. Planned degradation...237 6.2.4. Conditions for success...238 Chapter 7. Mold Making....239 7.1. Standard molds...239 7.1.1. Base components...239 7.1.2. Materials and heat transfer systems...241 7.1.3. Fabrication processes...242 7.1.4. Calculation of mold costs...243 7.2. New mold concepts...244 7.2.1. Shorter mold making time...244 7.2.2. Thermal appearances of molding...247 Chapter 8. Economic Data....251 8.1. Costs and prices...251 8.1.1. Polymer prices...251 8.1.2. Conversion costs...253 8.1.3. Productivity...255 8.1.4. Cost and sales price...256 8.2. Structure of the plastics industry...257 8.3. Markets...257

viii Plastic Forming Processes Chapter 9. Trends...259 9.1. Polymers...259 9.2. Conversion processes...262 Appendix. Symbols Used...269 Index...271

Preface Most books about plastics are written by professors who explain the behavior of these materials through their chemical contents and their mechanical properties from mathematical concepts. These approaches are of interest for research, but they are far removed from the daily problems of converters or users who need practical advice. There are few books offering a complete technical analysis of converting processes. The books that exist generally mention only the standard processes of injection molding or extrusion. There are actually more than 20 basic techniques, most of them with specific derivative developments, which are increasingly functional. Unfortunately, the trade experts are too busy and they fail to describe their practices, or they do so only for their own techniques. Therefore, many processes are simply ignored by potential users. The purpose of this book is thus to analyze in an almost fully exhaustive way, the many processes now practiced, or under development, covering both the assembling and the specific treatments. In order to do so, this book covers, for each of the major converting process techniques: the polymers used; the process principle, with its advantages and limitations; the description of the manufacturing equipment, molds, machines and all accompanying devices; characteristics of the converting process, pressure, temperature, vacuum;

x Plastic Forming Processes current operational characteristics, dimensions, output rate, waste, runs; typical or specific applications; and development trends. In order to describe this in a practical way, the book contains 400 drawings and pictures to describe the various processes.