AMSTERDAM - Automotive plastics suppliers say applications will increase with the trend toward better material properties, integrated parts assemblies and new production processes.
But plastics suppliers still face fierce competition from steel and aluminum producers.
Roberto Piatti, managing director of Stile Bertone, the Turin design firm, said the choice between plastics and aluminum varies according to fashion.
'Plastic was popular some years ago, especially for specialist cars,' said Piatti. 'Now the trend is toward aluminum. But we have already experienced a revolution in plastics through the application of bumper systems. That really helps to change the face of a car.'
Higher temperature resistance of plastics is one area of opportunity for suppliers. It will allow greater use of plastics under the hood, including intake manifolds and air chambers.
Growth also is expected for conductive engineering plastic body fenders, which allow for on-line painting at temperatures of up to 200 degrees centigrade following electrostatic dipping.
Renault uses plastic front fenders for both the Scenic and Clio, while DaimlerChrysler uses plastic fenders and tailgates with integrated plastic structures for the Mercedes-Benz A-class.
D/C's Smart has solid-colored plastic panels that do not need painting. Volkswagen uses plastic fenders on the New Beetle because their shape does not allow them to be made out of steel.
Jeff Wigham, marketing program manager at GE Plastics in Bergen op Zoom, the Netherlands, said annual production volumes of 800,000 fenders poses no problem. But he said that further development of materials and processes is essential for other and more widespread use.
'The whole automotive industry is working on it, so we expect a major breakthrough in the next five years for such applications,' said Wigham.
Automobiles Matra, which produces the Renault Espace with steel body structure and bonded plastic panels, says plastic bodywork has its production limits. 'Currently, a daily output of between 150 and 300 cars is the maximum for complete plastic-paneled cars for economic reasons,' said Alain Gurliat, director of research and development.
Alan Stone, a composites engineer at Lotus Engineering, said relatively low tooling costs make production of glass-fiber-reinforced plastic composites feasible at annual volumes as low as 800. Lotus currently produces 3,200 composite-bodied Elise sports cars per year. 'It is a matter of economies of scale,' he said. 'Steel-bodied cars are viable from 10,000 units annually.'
GE Plastics expects more applications in the future. Development of vertical body panels made from plastics began about five years ago and is now accepted by the industry. But it will take another three to four years before horizontal panels are applicable, said Farshid Tabankia, business manager of exterior body panels at GE Plastics.
Horizontal panels, like roof, trunk and rear decklids, are more exposed to heat and sun and imperfections such as gaps between panels are easier to see.
'The requirements are tougher,' said Tabankia. 'With horizontal panels, production tolerances have to be smaller, in an effort to decrease gaps and compensate for heat expansion. Horizontal panels also require better material properties because they are more exposed to heat and sun.'
Suppliers say that plastic panels allow more design freedom. The next-generation PSA/Peugeot-Citroen/Fiat minivan, due in 2001, will feature a single steel structure for all Peugeot, Citroen, Fiat and Lancia versions. Unique plastic panels will express the individual brand images, PSA sources say.
The crashworthiness of plastics and composites is still a subject of debate. Lotus has one answer. It has developed 'sacrificing' plastic composite structures for the Elise sports car. Unlike thermoplastics, which bounce back into shape, 'sacrificing' plastic panels shatter and thus absorb more impact energy - like steel when it crumples.
'We achieved that by special alignment of the fibers,' Stone said. 'We are developing a relationship with major plastics manufacturers like Dow and BASF to see if our principles are applicable to large-volume crash systems.'
Lotus will supply this technology in two to three years to other makers of small sports cars.
Plastics suppliers also say they are making advances in recyclability. 'Fenders with easy fittings will help to shorten assembly time as well as disassembly time,' said Wigham of GE Plastics. 'But the problem is that no infrastructure for efficient recycling exists.'
He said that current engineering plastics are 90 percent recyclable.
Gurliat of Matra says the Espace is 86 percent recyclable, enough for the 2005 European recycling legislation.
Automakers still have a clear choice between steel, aluminum and plastics.
'The quality and properties of steel and aluminum have considerably improved recently,' said Gurliat. 'Steel has become lighter and stronger. Production tools for steel have also become cheaper.'
The Renault Avantime body, due to begin production soon at Matra, will have its lower body structure made of steel, the upper part from aluminum, and will be clad with plastic panels, said Gurliat. 'The competition between these materials has increased, to the benefit of a lower price and better quality.'
