New developments help automotive composites compete

The use of fibre reinforced plastics continues to grow in automotive applications. Reducing mass is growing in importance due to increased demand for more fuel-efficient and cleaner cars and trucks. Manufacturers have introduced niche vehicles with innovative styling that would not be economically feasible without the design flexibility and reduced tooling costs possible with composites. New materials and technologies have been developed to improve the surface quality and performance of moulded automotive components while lowering production costs.

The European Alliance for SMC reports that overall European glass fibre reinforced plastic (GRP) production suffered in 2002, falling slightly (-1.5%) from year-ago levels due to the weakened economy. A decline in truck production caused a larger drop in consumption of sheet and bulk moulding compounds (SMC/BMC) by the auto-mobile market — down nearly 8% for the year, the group estimates. Glass mat reinforced thermoplastics and long fibre reinforced thermoplastics (GMT/LFT) production overall was up about 9% from a year ago, demonstrating bright future prospects for this class of material. Although new fibre reinforced plastic (FRP) components for automotive applications were put into mass production, about 20% fewer SMC parts were delivered to the European automobile industry, the Alliance says, noting that improvement can be expected in 2003.

One FRP showpiece is Renault's Avantime. About 90% of the sporty vehicle's body surfaces are SMC, providing a weight saving of 36% compared to steel, according to French moulder Matra Venture, which supplies FRP composite components to Renault. They include an SMC body panel assembly, rear hatch assembly and rear load floor module.

The European Composites Industry Association (GPRMC) is hoping to implement European-wide statistical headings for composites by 2007, reports Gustaaf Bos, GPRMC secretary general. Close cooperation with Eurostat and the European Commission is expected to produce reliable statistical data on production in tons and turnover in Euros, he adds.

Demand in the US market for automotive composites and other lightweight materials is strong and will continue growing at a robust pace through 2006 due to increased pressure to improve fuel economy and emissions, according to a study by The Freedonia Group. Composites in 2002 models grew by 9% over the previous model year, from 156 million kg to 174 million kg, according to the Automotive Composites Alliance (ACA). The group predicts continued strong growth of reinforced thermoset composites, especially in exterior body panel applications, niche vehicle components, and pick-up beds, fenders and tailgates. The ACA expects US consumption to increase to 227 million kg by 2005.

Growing use of long fibres

Long-fibre thermoplastic (LFT) technology, first used successfully in European automobile production, is attracting the attention of more North American original equipment manufacturers (OEMs). In Europe, LFT moulding has replaced metal and glass mat thermoplastic (GMT) components in many automotive applications. It is one of the fastest-growing segments of the plastics market in North America and Europe, experiencing 30% growth per year over the last decade, according to business researcher BRG Townsend Inc.

Faurecia, the European leader in front-end modules, uses LFT injection moulding with direct in-line compounding to produce front-end carriers, cockpit modules and other parts. In the process, continuous glass fibres are fed into twin-screw extruders, which chop and mix them with molten polypropylene to produce a 60% polypropylene (PP) and 40% glass compound. Accumulators hold the melt until it is injected. Faurecia reported front end module sales of €440.6 million in the first nine months of 2002, a 2.2% increase over 2001, with the majority of sales going to Audi and the PSA Peugeot Citroen Group.

Door modules for the Ford Fiesta are injection moulded by Faurecia, using StaMax P30M240, a 30% long-glass-fibre reinforced PP supplied by StaMax, the joint venture of Owens Corning (OC) and DSM Automotive Polymers. The material is also used in the front-end module of the 2003 Mini Cooper, which is injection moulded by StaMax. Compared to a steel front end carrier, about 40 fewer parts need to be assembled, according to OC. StaMax compounds are made with patented technology that coats the long glass fibers with a low-molecular weight PP, ensuring full wet-out and excellent dispersion, OC relates.

Mazda Motor Corp recently unveiled front-end and door modules for the Mazda 6 that are injection moulded with Verton® MFX polypropylene reinforced with long glass fibres. Unlike earlier modules made from stamped steel parts or glass mat reinforced thermoplastics, Mazda's new composite modules are stronger, lighter and allow integration of multiple functions, resulting in reduced production costs, relates LNP Engineering Plastics, the material supplier.

OC recently announced it will enhance its automotive business with an increased focus on interior acoustics using its VersaMat® thermal and acoustic insulating material, which can be moulded into complex shapes. The company plans to provide composite solutions in headliners, door panels, underhood applications, trunk storage systems and under carpet heat shields with VersaMat technology.

Ticona, the technical polymers business of Celanese AG, recently introduced Celestran® long fibre reinforced poly- butylene terephthalate (PBT) grades with 30%, 40% and 50% fibres. The new grades contain a Ticona PBT polymer specifically formulated to improve the mechanical properties of long fibre composites. They perform much like those made of PP but exhibit greater tensile and flexural strengths, greater impact strength, and they are easier to colour and offer a better substrate for painting and adhesive bonding, Ticona says.

Bayer Automotive Plastics has developed hybrid plastic-metal hybrid technology for front-end modules using its Durethan® glass-fibre reinforced polyamide. Bayer reports increasing interest in the hybrid modules as well as interior applications such as instrument panels, cross-car beams and steering column supports. Bayer and Owens Corning formed an alliance last year to jointly develop LFT polyurethane systems.

Dow Automotive has developed a technique to bond moulded FRP components to metal with continuous, robotically applied adhesive joints. Successfully used to produce hybrid front-end carriers with LFT PP compounds, the process has shown to increase stiffness and structural performance. Dow recently announced an alliance with Cyclics Corp to develop cyclic butylene terephthalate (CBT™) resins for auto-motive applications. Activities will focus on recyclable structural composites, including vertical and horizontal body panels and truck boxes.

Developments in SMC

BASF Corp has introduced DynaSeal primer/sealer for SMC to minimize porosity and paint defects such as ‘popping,’ which occur when air and gases in the SMC substrate pass through a curing clear coat during the paint-baking process. DynaSeal is applied to the surface of the SMC, replacing the OEM's prime coat. Next it is cured using a ultraviolet (UV) light system prior to entering the paint ovens. The result is both a UV and thermal cure, which has eliminated defects related to porosity, reports Meridian Automotive Systems. The company uses the new primer/sealer on fenders for the Ford F-150 Supercrew pick-up and the Lincoln Aviator as well as other compression moulded SMC automotive components.

The ThyssenKrupp Budd Company has developed a new proprietary formulation called Tuff Class A SMC. The resin matrix is Atryl® TCA resin, a new product from AOC that reduces paint pops on SMC components occurring during the thermal-cured painting process. These cosmetic defects require added labour to rework and repair. Atryl provides a more robust resin matrix that enables Budd's Tuff Class A SMC to withstand stresses and resist micro-cracking on the edges of parts better than standard SMC, according to Mike Dorney, VP sales and marketing of Budd's Plastics Division.

David White, ACA chairman and director of sales/composites for Meridian Automotive, notes that in the past, paint popping has been a major obstacle to full-scale use of composites by automakers. “Now with two new solutions to address this issue, there will be few limitations for composite use in the automotive industry,” he adds.

Ford was the first to use the new Tuff Class A SMC on the Ford Explorer Sport Trac box outer panels. It is now used to mould hoods for the Ford Ranger, Mustang Mach I and the Thunderbird as well as fenders and decklid for the T-Bird and the Lincoln Navigator fenders, all moulded by Budd. Laboratory test results with Atryl resin show a minimum of 90% reduction in the formation of paint pops, reports Mike Dettre, AOC's business manager of closed-mould resins. The new formulation also provides a 50% reduction in surface waviness compared to traditional SMC surfaces and a 69% increase in toughness, he adds.

“We believe that this is a quantum leap for the SMC industry,” says Dettre. “It provides a solution to the edge-pop problem, which for the past several years has been the biggest obstacle for SMC in Class A applications.” The higher cost of the Tuff Class A SMC is more than offset by the reduced labour for rework and lower scrap rates, he notes. Budd sells the new material in its raw state to other moulders. AOC will also work with others to develop their own SMC formulations.

AOC recently announced two other new products that promise improved quality and performance: Chroma Tek® conductive additive for electrostatically painted parts and a developmental UV-resistant SMC material for pick-up boxes. AOC believes Chroma Tek technology, which disperses conductive carbon black throughout SMC, will save OEMs time and money in the production of parts that go through electrostatic painting operations. It avoids the need to apply a conductive UV-cure sealer, commonly used to reduce paint pops, enabling the OEM to use a less costly, non-conductive UV-cure sealer, according to AOC.

AOC's new UV-resistant SMC technology eliminates the need to coat exterior parts such as pick-up boxes to provide protection from UV degradation. In accelerated weathering and road tests, untreated UV-resistant SMC demonstrates the same resistance to surface degradation and fibre blooming as SMC that is treated with a protective coating in a post-mould step, reports Dettre. AOC's goal is to make SMC UV-stable, so that it does not require paint. The product, which should be ready for market by 2004, is expected to reduce the installed cost of exterior SMC components.

Carbon fibre use expanding

Carbon fibre reinforced plastics are showing up on more vehicles as the cost of fibres continues dropping. The Association of Plastics Manufacturers in Europe (APME) reports that alternative precursor materials and new, continuous, high-volume fibre production processes are being studied. Carbon fibre composites will play a key role in the UK government-sponsored Foresight Vehicle LINK programme, which focuses on technologies for mass-market vehicles. Design and manufacturing technology developed in the programme is expected to be viable for annual production volumes of up to 20 000.

A new study on advanced structural carbon products from market research firm Business Communications Company Inc observes that the ability of carbon fibre manufacturers to reduce production costs and diversify into high-volume non-traditional markets will be the principal driver of this sector's growth. The study forecasts an 8.9% average annual growth rate over the next five years for carbon fibres in the North American market, climbing from US$592 million in 2002 to $905 million in 2007.

Carbon fibre reinforced composites, including compression moulded SMC and reinforced injection moulded components, are used extensively on the 2003 Dodge Viper, reducing overall weight by 91 kg, reports Daimler-Chrysler. Carbon fibre SMC, supplied by Quantum Composites Inc, is used in the windshield surround, inner door panels and fender support system, a structural part that replaces a metal structure and consolidates 20 different parts.

The components are moulded by Meridian Automotive Systems, which also supplies a moulded door hinge for the new Viper, using a hybrid SMC blend developed by Quantum that is reinforced with both carbon and glass fibres.

Latest in mouldable panels

Venture Industries is promoting automotive applications of its patented Sandwiform™ glass-reinforced polypropylene structural sandwich material. Panels, which can be covered with decorative skins or carpeting and formed in a one-step, thermo-compression process are especially useful in the trunk area, relates Darius Preisler, VP R&D. The company is demonstrating to OEMs how the material can be used to improve the appearance of the trunk area to give it a “clean look like European cars, without adding a lot of cost,” he says.

Bayer recently introduced BAYPREG F sandwich composite, a new technology that provides a very high stiffness to weight ratio. It promises to become an ideal weight-saving candidate in automotive load-bearing applications such as load floors and pick-up truck tonneau covers, the company says. It combines the lightweight properties of a honeycomb core with the high-strength properties of a fibre reinforced polyurethane skin. Through different combinations of core and facing materials, parts can be produced with just the right weight and stiffness for specific applications, adds Bayer.

Azdel® SuperLite, a glass mat reinforced PP sheet, is being promoted as a means to reduce weight of components such as instrument panels, pillar trim, parcel shelves, roof modules and underbody shields by as much as 50%. The product is distributed by Azdel Inc, a joint venture of GE Plastics and PPG. It is available globally in finished sheets, ready for heating and moulding. The technology uses a manufacturing process similar to papermaking that produces glass content of up to 55%. The sheets can be compression moulded in less than a minute at low pressures of 0.5-5 bar.

Thermoplastic for paint baking

Ford and Venture Industries selected DuPont Rynite® PET polyester resin to produce Ford's first thermoplastic grill opening reinforcement (GOR) capable of withstanding the heat of the thermal-curing process.

“This application demonstrates there is still a great deal of unrealized potential for high-performance thermoplastics in the automotive industry,” comments Ken Hines of DuPont Automotive.

The one-piece GOR, which replaces a heavier SMC GOR, debuts on the 2003 Lincoln Navigator and Ford Expedition. Using Rynite lowers complexity and reduces assembly time by eliminating the need for labour-intensive drilling and trimming steps, says Hines, who expects the success of this programme to open more opportunities for high-heat resistant thermoplastics in body and chassis applications.

LDM Technologies is promoting the elimination of underhood clutter to North American OEMs with its Engine Compartment Optimization (ECO™). The system streamlines the look of the engine compartment using injection-moulded and blow-moulded covers of reinforced high-temperature nylons and ABS, adding to the perception of quality. Wires, hoses, belts, fluid containers and other components are hidden from view, improving the appearance of the underhood area along the lines of European cars, relates Chris Fusco, design director. Calling the engine compartment the ‘forgotten zone,’ he observes that it is the last area in which North American OEMs have not been competitive.

General Motors, working with Basell Polyolefins, continues development of automotive applications for nano- composites. First used on vehicles by GM for a low-volume minivan step option, the material is being targeted for high-volume applications of external trim parts such as body side mouldings, cladding, rocker panels and other components, according to Robert Ottaviani, manager of the Advanced Polymers Group at the General Motors R&D Center in Warren, Michigan.

Three grades of TPO-based nano- composites have been commercialized by Basell Polyolefins, which has an exclusive license on GM's process to manufacture the material. The nanocomposite materials are reinforced with molecule-size particles of purified smectite clay in concentrations as low as 2.5%. The material is durable and scratch resistant, plus it has the potential for cost reduction, says Ottaviani.

While weight reduction is the primary advantage of replacing steel with fibre reinforced plastics, other benefits are equally important to automotive OEMs. They include cost reduction through the consolidation of multiple parts and lower tooling costs, corrosion and impact resistance, and design freedom not possible with steel.

Demand for niche vehicles boosts composites growth

Niche vehicles, including the Ford Thunderbird, captured top ratings in the J.D. Power and Associates 2002 Automotive Performance, Execution and Layout (APEAL) Study. The T-Bird, with thermoset FRP making up 60% of the exterior body panels (totaling about 80 kg) ranks highest in the competitive entry luxury car segment. The car also ranked highest in its segment in an earlier J.D. Power Initial Quality Study.

Composites provided Ford with specific design advantages that it needed to achieve the styling reminiscent of the original T-Bird roadster without incurring the high expense of steel stamping tools, according to Peter Kantz, manager of Closures and Exterior Systems for Ford Lifestyle Vehicles. “With composites, we were able to carry over a lot of styling themes in a low-volume car that would have been too expensive to do in steel or aluminium,” he observes. “Flowing the rear decklid around the tail lamps is easy with composites, but we would have had trouble doing it with metal.” The FRP panels also reduce the base curb weight of the 3863-lb (1752 kg) two-door convertible while providing corrosion, dent and mar resistance, he notes.

The Thunderbird's hood with integral scoop, deck lid, fenders and grille opening panel are supplied by The Budd Company's Plastics Division (Troy, Michigan) using a proprietary SMC formulation (27% glass) for automotive components with Class A surfaces. The 40 lb (18 kg) hood, and 31 lb (14 kg) deck lid are assembled from compression moulded inner and outer panels bonded together using a two-part epoxy adhesive.

Mike Dorney, VP Sales and Marketing of Budd's Plastics Division and past chairman of the US-based Automotive Composites Alliance (ACA), observes that Ford was able to use aggressive styling on the Thunderbird primarily because of the lower overall tooling investment advantage offered by FRP moulding — about 50% less than tooling for steel panels. He feels that the growing desire of consumers for uniquely-styled niche cars and trucks and the demand for cost-effective production by automakers will be the main drivers to the growth of composites in the automotive industry.