Audi: Pioneer in Aluminium

Press Release

The Audi A2 and the second ASF generation This development work has clearly been crowned with success: in 1997 Audi exhibited its Al2 design study, a vision of an aluminium car suitable for high-volume production. It took only two years more for this vision to become reality: in 1999 production of the Audi A2 began in Neckarsulm and with it the second generation of ASF technology – the first car to be produced in volume with an all-aluminium body. Its success was due in no small way to the invaluable experience already gained by Audi from series production of the all-aluminium A8 model. The new second-generation ASF vehicle consists of 60 percent sheet aluminium, 22 percent aluminium castings and 18 percent extruded aluminium sections. Audi’s development partner for the A2 in the aluminium area was Algroup Alusuisse (now Alcan). The A8’s Audi Space Frame, weighing only 249 kilograms (some 200 fewer than a steel bodyshell of the same type), set new standards in its market segment, but is surpassed in this respect by the A2’s aluminium body, which weighs only 156 kilograms including add-on parts – 43 percent less than a comparable conventional steel body. Furthermore, the number of elements making up the A2’s body is only 238, compared with 334 in the case of the A8. This has been achieved by combining various components into larger items – in most cases sections or multifunctional castings. For example, the A2 has a single-piece side wall frame, the first time such an item has been produced from aluminium. At the same time, the degree of automation has gone up from 25 percent on the A8 to 85 percent on the A2, a value comparable with conventional pressed-steel body construction. The methods adopted allow up to 300 cars a day to be built. This must be compared with a maximum daily capacity of 80 in the case of the Audi A8. An innovation not matched anywhere in the world is the laser-beam welding process used for the aluminium body elements. About 30 metres of laser weld seams are to be found in the A2. Joining techniques that had already been proved successful on the A8 are the use of self-piercing rivets and MIG welding. These methods succeed in keeping the dimensional tolerances of structural elements down to only ± 0.15 millimetre on the A2 – a benchmark value within the Volkswagen Group. Weight-saving construction methods for the ‘three-litre’ car Like the A8 in 1994, the Audi A2 received the European Aluminium Award in 2000 for its innovative concept. In the same year, this model was awarded the German Industry Innovation Prize for its developed version of the ASF technological principle. Furthermore, Audi went a step further and added the first four-door hatchback in the world with a fuel consumption of only three litres per 100 kilometres to its A2 program. The A2 1.2 TDI actually weighs 135 kilograms less than the already low figure recorded by the A2 1.4 TDI: just 855 kilograms. Its fuel consumption (total according to 93/116/EG) is precisely 2.99 litres of diesel oil per 100 kilometres. One of the methods adopted to achieve this weight reduction is the use of innovative lightweight materials for even more of the car’s components. In this way the running gear, for instance, has been reduced in weight by more than 80 kilograms. The frame to which the axle is attached, the lateral suspension control arms and the suspension struts are made of aluminium, as are the front disc brake calipers and the rear brake drums. The A2 1.2 TDI also has lightweight forged alloy wheels and special tyres which weigh only 4.9 kilograms each thanks to the use of aramid fibres to provide the necessary strength in the tyre carcass. Lightweight forged alloy wheels, incidentally, are now standard equipment on most Audi models. Further weight-saving measures applied to the A2 1.2 TDI included aluminium shock absorbers, front seats in lightweight foam and a rigid rear seat back of sandwich construction, which alone cuts the weight by 19 kilograms. 150,000 aluminium cars In July 2001, Audi reached a new milestone in its successful history of weight-saving car construction by producing its 150,000th aluminium car. The total is made up of more than 93,000 Audi A8s and almost 57,000 A2s. Nor will we have to wait much longer to see Audi’s next aluminium car: in 2002 the successor to the current Audi A8 will be launched, and will once again be of aluminium construction, using a developed version of the ASF concept. Innovative materials in Audi’s car production But that is not all: in all Audi models the proportion of aluminium and other weight-saving materials continues to increase, particularly in the engine, gearbox and running-gear areas. Here are a few examples: the A8 (like the A4 and A6) has aluminium suspension components. On Audi’s flagship model, weight-saving aluminium is also used for the wheel hubs, the front and rear wheel suspension control arms, all brake calipers, the shock absorber pivot mounts and the wheels. In Audi’s new top-of-the-range engine, the W12, which is used to power the A8 L 6.0, aluminium is used extensively. The intake pipe, incidentally, is made from magnesium and secured with aluminium screws – another absolute innovation in the car industry.