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Plastics in automotive.

The rollout of the one-millionth Chevrolet Corvette from GM's Bowling Green, Ky., assembly plant in July 1992 was a major milestone for the plastic-bodied sports car that will be 40 years young next year. Many other, frequently unobserved, milestones are further testaments to the acceptance of plastics in the automotive industry.

"There are more composite bumper beams in 1993 models than in years past, and more under-the-hood plastic applications than ever before," asserts Robert D. Albert, vice president, Automotive Materials Group, Dow Plastics. "Automotive interiors are dominated by plastics, worldwide. Many of these uses may not be new or unique, but they represent major sales of plastics for the 1993 cars and are indicators of the designs of future years."

This has not been a year with many plastics-intensive new platforms, but there was some major redesign in the 1992 models, and some exciting new uses are slated for 1994 and 1995, Albert says. However, given the state of the world economy, most automakers are not making sweeping changes for 1993. "With a three- to six-year design cycle," Albert continues, "breakthrough technology is the exception, not the rule."

FEWER BARRIERS

Allan Murray, manager, Advanced Technology Office, Plastics and Trim Products Division, Ford Motor Co., underscores the pattern of steady, if unrevolutionary, progress of plastics in new cars. "We are seeing fewer radical applications, but significant improvements in existing ideas," he says. "We have broken through barriers of the past, regarding the fit and finish of plastic body panels; structural composite front ends; integrated radiator supports; and plastic instrument panel carriers that replace metal, to mention only a few examples. Over the years, we have identified the benefits of plastics, and have learned how to produce and assemble them.

"But," Murray emphasizes, "we must now bear in mind what will be done with the vehicle at the end of its useful life, and still get best value out of the product. Recyclability, from the manufacturing and post-consumer standpoints, will increasingly affect how we do our jobs. It will change the way materials are mixed in assemblies and how they are attached. Solutions will involve taking the 'big chunks' and designing them to be compatible, with low labor and disassembly costs. Recycling, coupled with incorporation of subtle improvements in design and manufacturing, is becoming a powerful driver within the automotive industry, relative to future plastics applications."

PACE TOO SLOW

"Among some advanced automotive engineers and designers, the pace of change is too slow to effectively rescue an ailing industry," says Charles Haddad, manager, Advanced Engineering, Design Staff, Ford Motor Co. Haddad characterizes these advanced technologists as corporate "fortune-tellers" who evaluate how new science and technology could satisfy the market needs of their products. Charged with determining which technologies offer the best opportunities to improve quality, cost, weight, and feasibility of application to the automobile, they must develop convincing sales plans for their proposed designs and must facilitate their acceptance by the product and manufacturing offices.

In recent years, Haddad concedes, advanced engineers have been experiencing some success in promoting innovative products. "But," he insists, "much more must be done, requiring major breakthroughs on many fronts, to put us back in the role of world leaders in automotive innovation."

Haddad points out that a great many ideas have been kicking around in the industry for years, looking for a home. "Current automotive technologies have become archaic and costly," he adds, "contributing to a crisis in the industry. An abundance of new materials and design concepts is ready for development and application to the vehicle's structure, chassis, and body, to produce profitable low-cost cars that maintain comfort and performance and improve fuel economy."

As opposed to the high-cost, old technology of stamped steel, and even more costly stamped aluminum, Haddad cites a number of available and potentially more cost-efficient and major weight-saving choices. These alternatives include low-cost composite structure and exterior; medium-cost, roll-formed steel space-frame structure, or low-cost extruded aluminum structure, with thermoplastic neat or composite exterior. "The U.S. auto industry," Haddad comments, "has for many years been piecemealing these new architectures. But it is not moving the technology sufficiently to provide enough information to persuade the manufacturers, or myself for that matter, to adopt the new technologies for production vehicles. It is important at some point to invest in all three proposals and to develop them so that rational decisions can be made.

"Based on my 36 years in the automotive industry, I think we can improve our worldwide competitive position by designing composite, roll-formed, or extruded aluminum-based cars. It is time we start moving the technical needle a little faster for American industry."

A GROWING ROSTER

Nevertheless, while decisions on major innovations continue to percolate, new value-added designs lengthen the roster of plastic components in cars. A PCV valve for the 1993 Chrysler LH series (Chrysler Concorde, Dodge Intrepid, and Eagle Vision) screws onto the engine intake manifold, eliminating a nipple and interconnecting hose. Made of Amoco Performance Products, Inc.'s A model 1145HS polyphthalamide (PPA) resin, the 300|degrees~F material resists oil splashes and has torque capability of 500 inch-lbs.

A model A-1133 HS PPA improves strength and stiffness on the end-plate of the engine-cooling blower designed by the Delco Chassis Division of GM Corp. J.K. Doty, automotive industry manager, says the resin meets long-term stability requirements to 176|degrees~C.

Ford Motor Co.'s Transmission Division selected Amodel PPA for two transmission stub tube configurations: a current model automatic four-speed overdrive small truck and larger car transmissions, and a design relating to transmission fluid level sensing.

FOAM BUMPER SYSTEMS

Bumper systems of Arco Chemical Co.'s expanded polypropylene bead foam now include the 1993 Chrysler LeBaron, Dodge Spirit, Plymouth Acclaim, Toyota Corolla, Geo Prizm, Chevrolet Corvette, Pontiac Firebird and TransAm, and Nissan Stanza Altima.

Dylark styrene-maleic anhydride (SMA) substrates are specified for the 1993 Ford Taurus and Mercury Sable instrument panels, which have passenger-side air bags. An integral air bag door for the '92 Pontiac Bonneville SSEi's instrument panel, which makes use of Dylark's stiffness and thermal stability, is extended to the Bonneville's entire 1994 line.

Arco has programs with two automakers to demonstrate the recyclability of Dylark SMA substrates, which typically are urethane-foam-padded and vinyl-skinned. By use of an air separation or solvent process, 98% to 99.9% Dylark has been reclaimed for reuse with virgin resin in a 20:80 ratio. One European automaker approved the recycled SMA for instrument-panel components.

SMC APPLICATIONS

The GM Saturn station wagon's liftgate and roof are now made of Ashland Chemical Co.'s Phase Alpha sheet molding compound (SMC).

Following its acquisition of Olin Corp.'s Uralloy low-profile additives in 1992, Ashland is for the first time selling additive systems. Also, Arotran low-profile resin transfer molding (RTM) materials are used for several truck hoods and specialty automotive body parts. Recently introduced Arotran 6530 improves thermal resistivity and hardness. New Arotran parts, especially for lower volumes in Europe, include body panels, roofs, and fenders for buses; truck-roof and cab parts for a European bus and truck manufacturer; and components for a Hyundai bus.

Arotech 2000, 2001, and 2002 thickenable vinyl ester resins are being considered for under-the-hood applications in 1994 models; and vinyl esters are being considered for use in a liquid molding process, for a structural underbody program.

TPO FASCIAS

AutoAlliance International, Inc., chose D&S Plastics International's new highflow Dexflex D162HF thermoplastic olefin (TPO) for front and rear fascias on all new Mazda 626 and MX-6 models and Ford's Probe GT and LX. Chrysler selected Dexflex 880 for front and rear fascias on its LH line. Integral-colored Dexflex 480 is used for high-gloss wheel-lip moldings. Although retaining a grained surface, the material appears clear-coated. D&S is developing TPO skins, to go over polyurethane foam, to provide improved scratch resistance and a soft touch.

A Florida/Arizona weatherability-tested, molded-in color/clearcoat system increases mar resistance and gloss levels. Additionally, molded-in-color/partial paint, with the part half-painted for a two-tone look, is specified for some 1994 vehicles.

NUMEROUS ENTRIES

Other 1993 entries are Du Pont Co.'s melt-recyclable Bexloy K 550 glass-reinforced PET fenders for Chrysler's LH; and Bexloy W ionomer resin for a high-gloss, molded-in-color air baffle in the Pontiac Bonneville; for wheel-arch supports in Nissan's Pathfinder; and for a climate-control system bracket in the Ford full-size Econoline van.

Du Pont's XTC long-glass-reinforced PET polyester is being evaluated by a number of automakers for horizontal or vertical panels, using SMC compression-molding equipment.

Du Pont sees near-term plastics volume being affected most by under-the-hood uses for fuel, air management, and safety. Air-intake manifolds of Zytel nylon in GM cars with the 3800 tuned port injection V-6 engine cut parts and weight, vs. aluminum, by nearly 50%.

Metal heat shields in Dodge's Viper and Ram Van are replaced by Nomex aramid pressboard. Also, disc-brake pads in the Ford Thunderbird, Crown Victoria, and Mustang, and the Lincoln Continental, Mark VIII, and Town Car have converted to Kevlar aramid fiber.

Pontiac SSEi's and Chrysler LH's air bags have protective covers of Du Pont's Tyvek spunbonded olefin. Ford has extended bag deployment doors of DYM 100 thermoplastic elastomer to a number of its full-size cars.

ABOVE THE BELT LINE

Eastman Performance Plastics, Eastman Chemical Co., is focusing on its high-crystalline, unfilled (HDT to 210|degrees~F) and high-performance, talc-filled polypropylenes (HDT to 235|degrees~F) for temperature-upgraded "above the belt line" applications. The unfilled, high-crystalline grade's melt flow of 35 offers potential for thinner wall sections and faster cycles. The joint venture Ford/Nissan VX54 minivan now includes interior parts of the high-performance polypropylene.

The Eastman/Thermocolor Corp. business alliance to enhance color quality has established a clearer path of accountability for meeting color specifications. If questions arise on maintaining quality levels in polypropylene colors, customers can now expect a timely response.

Ektar polyester-based materials are targeted for under-the-hood and electronics uses, including surface mounting. With HDTs of over 500|degrees~F at 264 psi, the resins compete with materials such as polyphenylene sulfide, polyphthalamide, and nylon.

ALL-POLYOLEFIN SYSTEMS

Exxon Chemical's Mytex polypropylene is selected for the rear bumper fascia of the 1993 Nissan Sentra and Stanza Altima. The Altima also has an instrument panel, map pocket, and cowl top molded of Exxon Chemical polypropylenes. An all-polyolefin instrument panel system is under development, as is an all-polyolefin bumper system, that exceeds industry impact requirements. Molded of Taffen structural thermoplastic composite (STC), the beam weighs less than 10 lbs and withstands both the industry standard 5-mph barrier test and a more stringent 5-mph pole impact test, equivalent to the force of a 3000-lb vehicle hitting a 7-inch-diameter stationary pole. Chrysler's LH series features a knee bolster of Taffen STC that eliminates steel, combining four parts into one 11-lb unit.

Ron Price, development and planning manager, foresees growth of 25 to 30 lb integrated polypropylene bumper systems (including beam, energy absorber, fascia and supports, air dam, and trim) from 75 million lbs/yr in 1991 to 95 million in 1993, 166 million in 1996, and to 250 million in the year 2000. For instrument panel/console systems (which would include elements such as air-conditioning ductwork, exterior skin, air bag housing and cover, steering wheel column cover, and knee bolster), Price foresees growth from 15 million lbs/yr in 1990, to 30 million in 1993, 95 million in 1996, and 185 million in 2000.

CHANGING REQUIREMENTS

With dual air bags expected in all cars within a few years, Kevin Smith, director, Automotive Technology, GE Plastics, points out that the instrument panel will require design changes to cope not only with impact forces, but also with the explosive stresses of bag deployment. The upper part of Chrysler LH's two-piece instrument panel now uses glass-filled Noryl modified polyphenylene oxide (PPO) for strength and toughness to handle air bag deployment. Steel is basically replaced in the lower part, except for brackets, with thermoplastic composite.

The 1993 Jeep Grand Cherokee's upper instrument panel is made of vinyl-wrapped Gecet expandable, modified PPO bead, providing efficient resistance to knee impact loads. In the same vehicle, the first blow-molded glove-box door in production, including an integral hinge, is molded of Cycolac ABS. Inner and outer panels and numerous fasteners are eliminated.

Larry Berkowski, GE Plastics' industry manager, Underhood Components, sees the beginning of a movement to under-the-hood "beautification" for mid-scale to luxury cars. Already implemented in 1993 is an unfilled, 3-mm-thick, two-piece cover of Noryl GTX for the Lincoln Mercury Mark VIII that meets maximum 300|degrees~F requirements. Molded in black or foil-stamped, "the cover helps avoid the intimidating effect on some people who are confronted by the complexity of today's automobile engines," Berkowski says. More such covers are coming in 1994 and 1995.

Easy-flow, mineral-filled Supec polyphenylene sulfide, heat-resistant to 500|degrees~F, is used for very thin (2-mm-thick) fog-lamp reflectors on the Ford Taurus and Mercury Sable. Lomod HG 3015A, retaining good processing in spite of extensive use of a proprietary filler, is selected for an HVAC motor shroud for noise abatement.

The grille-opening reinforcement for the new Jeep Grand Cherokee, 5 ft wide by 8 inches high and molded of Valox 508 polybutylene terephthalate, has molded-in supports for both headlamp lights with one assembly. Development for late 1990s vehicles includes fully modular front ends, which support radiator/condensor, lights, fans, and other structural parts. Also, an air-intake resonator that smooths acceleration is made of blow-moldable GTX 625. Now in production on the Grand Marquis and Lincoln Town Car, the design will be extended to the Mark VIII, with other models in the offing.

Azdel polypropylene/glass-mat bumper beams have been on some American vehicles (Ford Mustang and Chevrolet Corvette) since the late 1980s, and are on the current GM APV and transnationals such as the Honda Accord. Ken Anderson, industry manager, Bumper Systems, GE Plastics, says that a 1993 Chrysler minivan uses the thermoplastic composite structural beam for weight reduction and parts integration. Early beams used random glass, and Honda Accord's 1990 bumper improved performance with random and unidirectional glass. For 1994, five more transnational vehicles, besides Honda, are targeted for front and rear Azdel beams.

GE has approached the bumper beam market with the Azdel beam and the Xenoy polycarbonate/PBT bonded system that combined the beam and fascia. New Xenoy designs do not incorporate a bonded fascia, to permit more fascia styling flexibility, and to provide the energy management in a single, structurally and functionally enhanced injection-molded part. Dubbed the "Solitary Beam" and being developed for 1995 and beyond, the Xenoy beam features high strain-to-failure and is an evolution of the Ford box-beam design that initially appeared on the 1984 Escort GT and then was scaled up to the 1986 Taurus and Sable. The shockless energy management system eliminates cost, weight, and assembly of hydraulic or foam shock absorbers.

HIGH GROWTH AREA

"Consumption of TPOs in automotive applications, including bumper fascias, instrument panels, and interior trim, will experience an annual growth of as much as 30% through the decade," predicts John R. Harvey, marketing manager, Transportation, Himont Advanced Materials. Harvey says the fascia market represents the greatest growth area. He cites TPO usage for bumper fascias by North American manufacturers (including the transplants) of 40 million lbs on the 1993 models, and predicts a doubling of that consumption by 1996. By the year 2000, the continuing trend could result in TPO fascias' accounting for 125 to 130 million lbs.

Harvey foresees polypropylene instrument panel growth, including elements such as the structural carrier, air ducting, knee bolsters, and glove box, to 15 to 18 million lbs in 1995 models, and to 25 to 35 million lbs in the 2000 model year.

CARRYING THE LOAD

A spring spacer strut of Celanese glass-reinforced nylon 6/6, replacing a metal/rubber component, is the first injection-molded plastic part to carry the load requirements of an automobile chassis/suspension, says Hoechst Celanese Corp.'s Stuart Cohen, technical manager, Automotive Development Center. Also, a stub-shaft bearing, molded of Fortron PPS, replaces a metal roller bearing. PPS also is used for corrosion-resistant waterpump impellers in cooling systems.

A motor housing of a windshield washer pump; a UV-stabilized grade with inherent gloss that eliminates a painting step; and a long bracket that replaces individual clips for attachment of body sidemoldings are current Celcon acetal resin applications that reduce parts and assembly. An integrated Fortron PPS fuel rail-air intake manifold, using the lost-core method, combines 22 parts, cuts costs by 25% and weight by 56%, compared to a die-cast aluminum unit.

Hoechst Celanese is working with customers to develop sensors made from heat- and chemical-resistant thermoplastics for anti-lock braking systems, electronic ignitions, air bags, and fluid monitoring; and is improving its nylon and polyester grades to meet higher heat requirements of fuel-vapor canisters. Also, resins with colorants are being formulated to meet 10-yr-life exterior weatherability standards.

Company efforts include developing automotive applications for its Celazole polybenzimidazole (PBI) material's high compressive and flexural strengths, low coefficient of friction, and HDT of 619|degrees~F. Four melt-processable grades are undergoing evaluation; a possible use is in piston rings. A cooperative venture with KMC, Inc., a subsidiary of Cookson America, aims at developing Celadyne PBI bearings based on KMC designs.

IMPROVED MELT FLOW

A new instrument panel component of Makrolon DP-1-1416 polycarbonate resin from Miles Inc.'s Polymer Division is debuting on several 1993 models. The material combines improved low-temperature impact strength and a melt-flow rate of 17.5 g/10 min at 300|degrees~C. Joseph P. Backes, vice president in charge of the Automotive Products Center, adds that a Baydur structural reaction injection-molded polyurethane system with internal mold release is replacing metal for the bumper beam of a Big Three sports car.

The company's new line of Apec HT polycarbonate resins, being applied for lenses, reflectors, and other lighting devices, responds to the need for high-heat-resistant materials for compact, high-intensity lighting systems. Transparent Apec HT grades offer HDTs to 354|degrees~F, nearly 100|degrees~F higher than conventional lens grades.

Miles' Bayfill EA energy-absorbing polyurethane foam systems are being evaluated for air-bag-equipped vehicles to help meet federal motor vehicle safety standards, including side-impact protection. Also, a U.S. automaker will apply the foam for energy absorption behind the fascia.

Several cost-effective modular and hybrid concepts introduced by Miles over the past few years are in developmental stages. A plastic/metal concept for doors and other complex load-bearing structures are under development at one of Detroit's Big Three. Backes projects that within the next two or three model years, the door concept may evolve into a production-level program for a lift gate on a sports utility vehicle. The design involves placing a perforated steel sheet in a mold and then injecting Miles' Durethan BKV 130 polyamide 6 resin to produce a strong, bonded composite. In another concept, metal doors and other body panels are encapsulated with Miles' Bayflex polyurethane and polyurea systems.

For exterior cladding, wheel covers, fascia, spoilers, and grilles, two-component polyurethane coatings hold an estimated 30% market share. Since the 1991 model year, one of Detroit's Big Three has specified the coatings for all its wheel covers. Miles projects that other automakers will convert within the next few model years.

Special-effect polyurethane coatings provide a soft, leather-like look and feel for hard plastic components. Using Desmodur polyisocyanates from Miles Industrial Chemicals Division, a 1993 luxury car has the coatings on nearly 20 interior parts.

INTEGRAL-COLORED TRIM

The trend toward low-gloss, integrally colored interior trim continues. Monsanto Chemical Group's Lustran LGA ABS has several unpainted applications in the Chrysler LH platform, including the center console's trim components. GM selected Lustran LGA for interior trim parts in its Suburban and N platform cars, the Pontiac Grand Am, and Oldsmobile Achieva. The new Subaru Legacy has interior trim parts molded of Lustran HH 1829, a low-gloss, high-heat ABS.

Door-handle bezels on the LH platform are molded of Triax 2000, Monsanto's PC/ABS alloy, as is the top close-out panel for the instrument panel in the 1993 Mazda 626; and the center trim panels and steering column close-out panels of the 1993 Mazda-built Probe and Mitsubishi Gallant.

Bumper guards on the new Cadillac Brougham, combining appearance and impact strength, are made of TAPP 2100-Triax 2953, a plating-grade PC/ABS alloy, co-developed by Monsanto and Siegel-Robert Inc. Ford selected Centrex weatherable polymer for the license-plate pockets of its 1993 Econoline van, yielding cost savings over the previous painted material. Other Centrex exterior uses are mirror housings on the Subaru Legacy and the Geo Tracker; the grille on the Toyota Hi-Lux; and the cowl screens on several Chrysler and Ford vehicles. Painted Vydyne mineral-reinforced nylon is used for the exterior rear tail-lamp close-out panel on the Chrysler LH platform.

TRANSMISSION PARTS

Phillips 66 reports interest in replacing metal transmission parts, such as torque converter and servo components, with dur-able, high-temperature, stress-resistant plastic. Robert Still, automotive market manager, reports successful test results with its Ryton PPS. Replacing steel with Ryton PPS cuts weight by 80%.
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Author:Wigotsky, Victor
Publication:Plastics Engineering
Article Type:Cover Story
Date:Oct 1, 1992
Words:3503
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