1、technology profiles Engineering Plastics and Plastic Composites In Automotive Applications Kalyan SehanobishEngineering Plastics and Plastic Composites in Automotive Applications Kalyan Sehanobish Warrendale, Pa. Copyright 2009 SAE International eISBN: 978-0-7680-5646-4All rights reserved. No part o
2、f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. For permission and licensing requests, contact: SAE Permissions 400 Commonwealt
3、h Drive Warrendale, PA 15096-0001 USA E-mail: permissionssae.org Tel: 724-772-4028 Fax: 724-772-4891 Library of Congress Cataloging-in-Publication Data Sehanobish, Kalyan. Engineering plastics and plastic composites in automotive applications/Kalyan Sehanobish. p. cm. Includes bibliographical refere
4、nces. ISBN 978-0-7680-1933-9 1. Plastics in automobiles. 2. Automobiles-Design and construction. I. Society of Automotive Engineers. II. Title. TL154.S383 2009 629.232-dc22 2008053079 For multiple print copies, contact: SAE Customer Service E-mail: CustomerServicesae.org Tel: 877-606-7323 (inside US
5、A and Canada) 724-776-4970 (outside USA) Fax: 724-776-1615 ISBN 978-0-7680-1933-9 Copyright 2009 SAE International Positions and opinions expressed in this book are entirely those of the authors and do not necessarily represent those of the organizations to which the authors are affiliated or SAE. T
6、he authors are solely responsible for the content of this book. SAE Order No. T-122 Printed in the United States of America.Contents Introduction v Executive Summary ix Chapter One 1 Why Choose Plastics for Automotive Applications? Chapter Two 3 Plastics in the Interior of the Vehicle Chapter Three
7、15 Plastics in Horizontal and Vertical Body Panels Chapter Four 19 Plastics in the Exterior of the Vehicle Chapter Five 23 Plastics in the Powertrain Chapter Six 25 Plastics in Fuel Systems Chapter Seven 29 Plastics in Lighting and Wheel Systems Chapter Eight 31 The Future of Plastics in Automotive
8、Applications References 37 List of Acronyms 41 About the Author 45 iiiIntroduction B efore the 1970s, plastics were considered primarily as non-engineering materials and were used in applications such as belts, hoses, gaskets, carpet backing, sealing, adhesives, tires, and so forth as a part of an e
9、ngineering solution. Those individuals who are not materials scientists presumably wont classify elastomers (i.e., natural and synthetic rubbers) and adhesives used in these applications as engineering plastics, although those materials have enabled the engineering function since their inception. It
10、 wasnt until plastics started to replace metals that they began to be considered as engineering materials. Today, plastics have penetrated into engineering applications within the automotive industry, replacing traditional materials at a significant rate in only the past 30 years. By themselves, pla
11、stics are poor choices for engineering applications because of their poor strength-to-density ratio.1 The introduction of plastics containing inorganic fillers and of plastic composite systems with cross-linkable resins as binders advanced the growth of plastics as structural materials in engineerin
12、g applications. This book will not only cover some of the current applications of plastics and their advantages but also will address what may be foreseen in terms of new applications for plastics in automotive engineering. However, before going any further, lets share some actual data (Table 1) com
13、piled from various sources on the penetration of plastics and plastic composites into passenger vehicles.2,3 From Table 1, it is evident that the use of plastics in engineering applications has crept upward from approximately 4.6% of the overall vehicle body weight in 1977 to approximately 7.6% in 2
14、003. At first glance, this may not seem impressive, until you consider the increases in the variety of equipment and accessories added to vehicles during the past 30 years. In fact, these lightweight materials have allowed the industry to maintain the overall weight of vehicles at the same level as
15、a basic new car in 1977. Today, plastics comprise almost 50% of the material volume in most new cars. Studies show that each 100 pounds of plastics can replace approximately 200 to 300 pounds of mass from traditional material.2,3 vTABLE 1 PLASTICS IN A TYPICAL PASSENGER VEHICLE* Lets start by classi
16、fying the plastics found in various segments of an automobile. (The use of plastics as foams and fabrics for noise absorption and comfort will not be addressed here.) To begin, we find examples of plastics primarily in decorative, safety, noise, vibration, and harshness applications for the interior
17、 parts of the vehicle. These applications include the cockpit systems (e.g., instrument panels IPs, structural portions of IPs, and dashmats), headliners, seat systems (e.g., seat backs and seat bases), soft and hard trim (e.g., door trim and pillars), interior door handles, gloveboxes, and packagin
18、g trays. Steering wheels, door handles, and mirror housings are other interior items that are built from plastics. Plastics vihave even entered critical safety-oriented applications such as airbags and airbag covers. Plastics are making modest advances in all horizontal and vertical body panel parts
19、 in the exterior of the vehicle or behind the cockpit, thereby replacing metals. These applications include door panels, roofs, floors, fenders, back panels, hoods, and mud plates often used as part of the firewall. Greater penetration of plastics into these parts is expected to occur in the future.
20、 Other panels that will be considered here as exterior parts include the bumper fascia, quarter panels, underbody shields, drag panels, exterior door handles, and mirror housings. Improved performance and lightness of weight will drive more plastics in these applications. The powertrain segment is t
21、he most complicated and challenging application of plastics. As modern plastics meet these challenges, the presence of plastics will continue to grow. Plastics have already found their way into air induction systems (e.g., intake manifolds, ducts, air cleaners, air filters, and snorkels), cooling sy
22、stems (e.g., hoses), side and front engine covers, engine fans, turbo systems (e.g., turbo impellers and housings), valve covers, oil pans, oil filters, and belly pans. Fuel systems have already experienced an invasion by plastics. The use of plastics can be seen in fuel tanks, fuel rails, fuel pump
23、 parts, connectors, hoses, and fuel filters. Furthermore, external and internal lighting systems have already gone primarily to plastics. Wheel systems have adopted plastics much earlier in the construction of tires, wheel covers, and wheel house liners, although wheel systems remain primarily the d
24、omain of metals. In spite of such frequent use of plastics, the automobile remains largely a metal play with sheet metal, cast iron, aluminum, magnesium, and so forth. According to the Society of the Plastics Industrys 1998 edition of Facts and Figures, the land transportation industry consumes only
25、 approximately 5% of the total plastics consumed in millions of pounds and remained unchanged between 1993 and 2008. The packaging industry consumes approximately 25% of all plastics made today. Although more new applications for plastics will be introduced in the transportation industry, a similar
26、increase in the use of plastics in other industries will tend to maintain the ratio of plastics consumed as fairly constant. A dramatic change in this ratio can occur only if regulatory mandates for lowering the weight of vehicles pushes plastics viifurther into the horizontal and vertical body part
27、s of vehicles, coupled with innovation in plastic composites that addresses both the temperature-related expansion issues and the high-temperature baking issues of plastics. The use of plastics as structural beams and rails remains far from reality and only a dream for the plastics industry and fabr
28、icators within that industry. Although the field of plastics and plastic composites in the transportation industry is vast, this book will focus on plastics that have already made entry into the automotive segments mentioned in the preceding paragraphs. It will conclude by projecting the future of p
29、lastics in the automotive industry in light of predicted global trends. viiiExecutive Summary P lastics have entered engineering applications within the automotive industry at a significant rate during the last 30 years. Although plastics have a poor strength-to-density ratio by themselves, plastics
30、 with inorganic fillers and plastic composite systems have advanced as structural materials while offering many advantages over metal. This book focuses on some of the various types of plastics and plastic composites and their applications within passenger vehicles. It also discusses the future of p
31、lastics in the automotive industry. Plastics are classified as thermoplastics, rubbers, or thermosets. Available in a variety of forms and blends, their advantages include durability, strength, lightness of weight, and excellent thermal and electrical insulating properties. Progress made in the recy
32、cling of plastics has added to the acceptance of plastics. Interior components make up the largest use of plastics in automotive vehicles, in applications such as instrument panels (IPs), body panels, door panels, dashmats, seat backs, seat bases, steering wheels, and airbag covers. The use of plast
33、ics in exterior horizontal and vertical body panels of vehicles has been difficult, but some have found their way into the body panels, hoods, and especially fenders of vehicles. Plastics are commonly used in bumpers and are appearing as underbody shields and exterior door handles. Environmental con
34、ditions and stresses have limited the use of plastics in the exterior parts of vehicles. While once viewed as unsuitable for the extreme environment found near engines, plastics now are being used under the hood as replacements for metal parts. These plastics meet the requirements for strength, high
35、 temperatures, and even flame resistance needed for powertrain applications while offering the advantages of lower weight and cost, improved air flow, and corrosion resistance. Plastics also are used in fuel systems, with the largest application being fuel tanks. They are the predominant material to
36、day for headlight lenses and ixother automotive lighting. However, wheel systems remain primarily metal, except for decorative uses of plastics such as found on hubcaps. Plastics will continue to permeate automotive applications, and hybrid polymermetal technologies are expected to be developed in t
37、he years ahead. Increased use of airbags also will translate into the need for more plastic solutions. Acceptance of plastics engineering into vehicles will be driven by the need for lightness of weight, fuel efficiency, freedom from petroleum dependence, and improved methods of reuse and recycling
38、of plastics. The future of plastics in the automotive industry depends largely on technological and manufacturing innovation, as well as economic and environmental factors. xChapter One Why Choose Plastics for Automotive Applications? “Plastics“ is a broad term utilized primarily by the end users of
39、 these materials. In technical terms, the scientific nomenclature that more commonly defines plastics is that they are polymers composed of long covalent-bonded molecules. Plastics often are classified into three groups: 1. Thermoplastics 2. Rubbers 3. Thermosets Thermoplastics can be melted or soft
40、ened and then reformed, and they demonstrate very little elastic recovery below their glass transition temperature. By comparison, rubbers exhibit large extensions and will spring back easily upon release. Thermosets are heavily cross-linked polymers that normally are rigid and intractable. The use
41、of both thermosets and thermoplastics in passenger vehicles has grown to the point where a wide variety of plastics now are used in vehicles. Figure 1 shows the top ten types of plastics used in automotive applications in North America.4 Figure 1 The use of plastics in automotive applications in Nor
42、th America. 1Plastics offer several advantages in terms of their performance characteristics when used individually, as highly formulated filled plastic blends, and as reinforced plastic composites. For example, plastics are durable, strong, and lightweight, and they can be made transparent, translu
43、cent, or opaque. Likewise, plastics can be soft, flexible, or hard, and they can be formed into almost any shape, size, or color. Plastics can provide resistance to heat, chemicals, and corrosion, depending on how they are formulated. Furthermore, plastics are excellent thermal and electrical insula
44、tors and can be formulated to impart both thermal and electrical conductivity to a certain extent. In most cases, plastics are cost effective while providing automakers with the design freedom to incorporate safety, styling, and comfort into vehicles. Over the past decade, significant progress has b
45、een made in the recovery and recycling capabilities for automotive plastics, but much more remains to be done. Thus, there are many good reasons that automotive engineers find plastics to be an attractive and beneficial material for use in the design of vehicles. As concerns about safety and lightne
46、ss of weight unfold, plastics will continue to be a key player in the automotive industry. 2Chapter Two Plastics in the Interior of the Vehicle T oday, interior components account for the largest share of plastics in vehicles. This fact is not expected to change dramatically as plastics continue to
47、gain acceptance for use elsewhere in vehicles. Traditionally, instrument panels (IPs) were made from several metal components that had to be painted and were held together by a steel supporting structure. Plastics initially entered the IP market to improve aesthetics on top of the steel structure. W
48、ith the progression of time, thermoplastics have been expanding further into this application segment, facilitating complex designs and a reduction in both cost and weight. These thermoplastics include the following: Acrylonitrile-butadiene-styrene (ABS) High-heat ABS (HHABS) Blends of polycarbonate
49、 (PC) and ABS Modified polyphenylene ether (PPE) Modified polypropylene (thermoplastic polyolefin TPO) Long-glass-filled polypropylene (LGF PP) and ABS Styrene maleic anhydride (SMA) Designs that utilize thermoplastics could enable the integration of airbag housings, instrument housings, and so forth with structural needs (i.e., structural portions of IPs), allowing for the elimination of steel beams. However, the cost advantages remain debatable. Lets take a closer look at some of the plastics in interior applications and their performance characteristics. Fi
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