INGOLSTADT - Mass-produced aluminum chassis and body-panels are still a distant dream, but the industry is slowly moving in that direction.
Audi's A8, for example, has been built in volumes of 15,000 annually. Its replacement will be built at 35,000 a year.
Kenneth Sears, chief engineer for vehicle design at Lotus Engineering, says there are several obstacles to much wider use of aluminum. These include:
Fluctuating aluminum prices, and fears about big rises
The auto industry's traditional iron and steel culture
Established manufacturing processes
The need for new production lines and methods
The need to change suppliers
To switch bodies from steel 'will require an enormous commitment from car manufacturers.'
So far, an aluminum-made chassis and body has made sense only in low-volume production.
The Lotus Elise's bonded and riveted box-section aluminum chassis was engineered with the help of Danish-based Hydro, while the Audi A8's frame/bonded panel structure was developed in conjunction with aluminum supplier Alcoa.
But in general, aluminum will progress component by component.
Audi has volume plans
'We are interested in having a lot of suppliers, otherwise you have no free market and costs will go up,' says Ulrich Hackenberg, Audi director of vehicle concepts and technical project management.
'It is not only big companies involved in development but small suppliers who are developing parts of the car with us,' he says. 'For example the bumpers, the longitudinal members in the cabin roof and the window frames were all developed with different suppliers.'
Audi says it has no specific project plan for a small car based on the AL2 concept cars shown at the Frankfurt and Tokyo auto shows. However, the second-generation aluminum technologies and alloys demonstrated in these concepts will be used in the replacement A8 model due after 2000.
Audi plans to build 35,000 units of the new A8 annually, compared with 15,000 units of the current model.
Audi does intend to produce a lightweight, low-consumption family car starting in the next decade, says Hackenberg.
'We are looking for bigger volumes in aluminum through making aluminum products more practical, reducing manufacturing time and reducing welding,' he said. 'We are trying to reduce the number of castings and welds, especially of curved connections.'
Rectangular junctions are easier to weld. Also, Audi is seeking new alloys that meet the needs of specific components.
Steelmakers are fighting back against the threat from aluminum. Most modern, mass-produced steel bodies contain at least four different types of steel, with panels of varying thickness to perform different tasks.
The ULSAB consortium of steelmakers aims to develop a steel body that is 40 percent lighter than current bodies.
But Hackenberg is convinced that aluminum has economic advantages. He believes a steel body that is 40 percent lighter would be prohibitively expensive and involve expensive plastics and composites.
'We do not think that is the way to produce lightweight bodies,' he says. 'We think aluminium is the right way.'
Common for parts
Although aluminum has a long way to go as the basic material for car bodies, it is well established for components such as engine blocks. Jaguar's and Lotus's new V-8 engines and the new Porsche engine.
Aluminum alloy suspension elements on the latest BMW 5 series have been praised for improving ride quality.
Magnesium also has its supporters, including Fritz Indra, director of advanced engineering at GM Europe's Technical Development Center in Ruesselsheim, Germany. He favors magnesium because it is even lighter, and for the ease with which it can provide thin castings.
Both materials probably have a place in the future.
The P2000 low-consumption prototype vehicle unveiled by Ford in the USA two weeks ago has seat frames, rear brake drums and front fenders of aluminum, brake pedal wheels of magnesium, and other parts of titanium and carbon fiber.
The all-aluminum P2000 body demonstrates weight savings. The chassis weighs 135kg, compared with 284kg for the steel-shell Taurus, which is its benchmark. But it is not realistic as a production car.
'The cost equation is such that we can't justify making all the changes on the P2000 to a production car yet,' says Chuck Risch, technology manager for Ford's input into the US Partnership for a New Generation of Vehicles program. 'But we're working on it.'
'The decision to switch to aluminum is too big for anyone to take,' Sears says. 'While you have the futurists who say we should all drive lighter cars, the industry has a responsibility for decisions on which the employment of thousands depends. There are engineers making aluminum cars in every corner of the industry, but engineering is not the regime. The questions of confidence and business responsibility are bigger than the engineering aspect.'