Plastics in the Automotive Industry

195 Pages·1994·39.964 MB·English

by  J. Maxwell (Auth.)

Plastics
in the
automotive industrv
JAMES MAXWELL
WOODHEAD
PUBLISHING LIMITED
CAMBRIDGE, ENGLAND
Published by Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB1 6AH,
England
Published in North America by the Society of Automotive Engineers, Inc, 400 Commonwealth
Drive, Warrendale, PA 15096-0001, USA
First published 1994, Woodhead Publishing Ltd and Society of Automotive Engineers, Inc
0 1994, Woodhead Publishing Ltd
Conditions of sale
All rights reserved. No part of this publication may be reproduced or transmitted in any form
or by any means, electronic or mechanical, including photocopy, recording, or any information
storage and retrieval system, without permission in writing from the publisher.
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication Data
A catalogue record for this book is available from the Library of Congress
Woodhead Publishing ISBN I 85573 039 1
Society of Automotive Engineers ISBN 1 56091 527 7
SAE order number: R-147
Designed by Geoff Green (text) and Chris Feely (jacket).
Typeset by Best-set Typesetter Ltd, Hong Kong.
Printed by Galliard (Printers) Ltd. Great Yarmouth, Norfolk, England
The Plastic Age
Like us on a graph it will break or burn if it strays
Into the frost or flame where the axis looms.
Like us itS no better or worse than the endless ways
Its maker makes in his beautiful living rooms.
Glyn Maxwell
Preface
This book is not only a survey of the role and reach of plastics in auto-
mobiles, but is an attempt to build a bridge between two different but
interdependent industries. It describes the application of plastics to each
sector of automotive engineering, and identifies the factors involved in
their selection. It reviews key historical developments and assesses future
opportunities and constraints.
Primarily, the book is aimed at automotive engineers, designers and
specifiers. Many are working with plastics materials and designing plastic
components, having had no formal training in polymers, and using data
sources which can be confusing and unhelpful. Experiences lecturing to
graduate engineers have taught me that mechanical engineering and polymer
science are cultures which are largely alien to each other. In spite of some
brave attempts to combat over-specialization, the problem is still very wide-
spread, particularly (but by no means exclusively) in Great Britain. In
deference to engineers, therefore, no chemical formulae appear in this
book. No specialized knowledge of plastics is assumed; merely a willingness
to understand, and to work with (rather than against!) the essential physics
and chemistry of these materials.
Secondly, the book attempts to steer polymer people towards an under-
standing of the needs and problems of automotive engineers. Awareness has
been growing among polymer chemists and physicists in recent years, but in
the past the plastics industry has shown an extraordinary reluctance to relate
to the pressures of the assembly line, or even to present data in a relevant
way.
The book consists of nine chapters. The first three constitute a com-
prehensive ‘user’s guide’ to plastics, covering materials and processes
generally, but with an automotive focus. The first chapter includes an his-
torical summary of automotive plastics, and examines the problems as
well as the benefits of the materials. The second chapter (‘Understanding
plastics’) includes sections on composites, processes and functional design,
and the third (‘Choosing plastics’) offers routes to material selection in
X
Preface xi
the individual application sectors. The next four chapters address these
application areas systematically, under the headings, respectively, of ‘In-
teriors’, ‘Exteriors’, ‘Engine, power train and chassis’ and ‘Electrics’. The
two final chapters examine the global problems generating much comment
and concern at the time of writing; Chapter 8 is devoted entirely to that
most pressing (but not necessarily most serious) problem - recycling.
Because of the high profile of global environmental issues, this book
should interest anyone concerned about the future of the motor industry and
the plastics industry. Already both industries are being targeted by well-
intentioned but ill-informed legislation. It is important that policy-makers
(in the boardroom as well as the legislature) are aware of the realities: that
deep-seated changes, like designing and proving new cars or new recovery
processes, take a long time; and that, if the energy factors are properly
assessed, the benefits that plastics can provide far exceed the disadvantages.
Acknowledgements
I would like to record my appreciation of the help received from many
sources. Generally, for their opinion-forming input received over many
years, I thank my colleagues from the former ICI Plastics Division, whose
concentrated polymer wisdom and experience has now been scattered over
many fields, perhaps sadly, but certainly fruitfully. Specifically, for helpful
discussions and the provision of photographs, I thank Albert Adams (Lotus
Engineering), Tony Bardsley (Du Pont), Jan Czerski and Alfred Pirker
(BASF), Kevin Dunn (ICI Polyurethanes) and Leo Morelli (Communication
Systems, Brussels), Mehmet Sonmez (ICI Materials), Dick Thomas (ICI
Acrylics), Laurent Rotival (Dow Plastics), John Whittaker (The Bird
Group), Chris Wakley (Chris Wakley PR, for GE Plastics), S van Buijtenen
and E Baeten (DSM Polymers) and D Westaway (DSM Resins).
Most importantly, I thank my wife for her sustained forbearance and
support.
xii
1
Materials for cars
Plastics usage
Materials and their conversion into comp\ ents account for more than half
the cost of a car. The materials mix is changing continually, and the fastest
growing category is plastics. In 1993 a typical car contained some 100 kg of
plastics, constituting around 11% of its total weight. Globally, this represents
a market of over 4 million tonnes of plastics, with a value of over &5 billion.
Plastics usage in cars has been rising steadily since the 1950s, as Fig. 1.1
shows. When expressed in terms of percentage of car weight (see Fig. 1.2)
the rate of growth appears to be increasing more dramatically; this is
deceptive because over most of this period cars were becoming lighter.
Average car weights fell by more than 15% between 1973 (when the cost of
oil first became a major factor in automotive design) and the end of the
1980s. The highest growth rate for automotive plastics was in this period. It
became evident that any new problems arising from the supply of oil-based
plastics could be more than adequately compensated by fuel economies from
plastics-based design changes and weight-saving techniques. Furthermore,
greater cost consciousness highlighted the potential advantages of plastics in
component consolidation and simplified assembly.
Some extravagant predictions have been made in the past for the un-
stoppable growth of automotive plastics. There are clear signs now however
that the growth curve is beginning to flatten out. An ultimate levelling out is
inevitable in any case, because of the irreplaceable metal parts. Excessive
weight reduction would lead to unacceptable handling characteristics; how-
ever, the current trend towards stronger body structures is once more
increasing the average weight of cars. Increasing competition and prolonged
recession are encouraging a cool appraisal of the cost and performance of all
materials. In this chapter both the benefits and the limitations of plastics are
examined in a general context, with a look at the historical background and
at the very significant changes in the types and qualities of the plastics which
the motor industry selects. Table 1.1 summarizes the classes of materials to
1
2 Plastics in the automotive industry
a
150 -
/
140 - /
/
130 - /
/
120 -
110 -
100 -
Y
L- 90 -
m0
z 80-
n
70 -
m
$ !
60:
50
40 -
.Toyota Crown
0 Peugeot 504
I I
I I I I I 1 I I I 1 I l l I
1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990
1.1 Growth of plastics content in cars, by
weight.
14
13 -
12 -
11 - Citroen BX 0
10 -
9 -
T 8 -
5
3 7 -
6 - Citroen CX 0
5 -
4 - Citroen GSO
3 -1
2 ORenault 4 I
I
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t I I I I I I I 1 I I I I I I
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990
1.2 Growth of plastics content in cars, by
weight percentage.
Materials for cars 3
Table 1.1. Material content of a typical car by weight (%)
Steel sheet 55
Cast iron 10
Plastics 10
Non-ferrous metals I
Liquids 5
Elastomers 4
Glass 3
Textiles and cellulose products 2
Insulating materials 2
Paints and adhesives -2
100
Table 1.2. Typical figures for plastics consumption by type (Yo)
Polypropylene (PP) 23
Polyurethane (PUR) 21
Polyvinyl chloride (PVC) 12
Acrylonitrile-butadiene-styrene( ABS) 10
Thermosetting polymers 8
Polyamides (PA, nylon) 8
Polyethylene (high and low density, HDPE and LDPE) 5
Polycarbonate (PC) and blends 4
Polyphenylene ether/oxide (PPE/PPO) and blends 3
Polyformaldehyde (POM, acetal) 2
Polymethyl methacrylate (PMMA) 2
Thermoplastic polyesters (PET and PBT) 1
Others 1
-
100
be found in a modern car; Table 1.2 provides a similar summary of the types
of plastics used by the motor industry. These are very general figures; there
are considerable differences between models, and regional differences be-
tween Europe, America and Japan.
History of automotive plastics
The motor industry was using plastics long before the Second World War, in
such items as electrical components and interior fittings. They were used
whenever they were available as a convenient low cost alternative to tradi-
tional materials. These were direct replacement applications; the concept of
redesigning around the essential merits of plastics came much later, following
some fundamental changes on the world scene.
The first major change was the development of low cost oil in the post-war
years, providing a reliable and consistent raw material for cheap plastics.
4 Plastics in the automotive industry
Prices of bulk plastics fell, and continued to fall during the 1950s and most
of the 1960s. The second big factor was the appearance, in this same period,
of a seemingly endless flow of exciting new materials. Most of the materials
now classed as engineering plastics were in volume production in their basic
formulations before the end of the 1960s. The spectacular growth in the
plastics market since the early 1970s has resulted not so much from the
discovery of new plastics as from the refining and targeting of the established
ones. In Fig. 1.3 the major discoveries in plastics are plotted against a
background of the growth in the total world plastics market.
From the beginning, much of the development work on engineering
plastics was directed towards the motor industry. These materials (together
with reinforced composite versions of some bulk plastics) gradually acquired
respectability in the automotive industry, as it came to be seen that they
could be produced to consistent formulations, and held to precise engineering
specifications. The development of a proper understanding between the
automotive and plastics industries did not happen overnight; in fact it is an
ongoing process, and there is still room for improvement. Nevertheless. it is
1
70
60
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al
C
C
0 lEpoxy
50
C
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I
E
Oil crisis
1
lo
I I I 1
1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990
1.3 Milestones in polymer development, and
growth of total plastics market.