Audi is the only automobile manufacturer in the world that uses the Aluminium Space Frame principle for volume production. In 1993, when it introduced an all-aluminium car body concept for the first time, the manufacturer with the four-ring emblem set a new standard in the large-car class. This was the Audi A8, which even in its current form remains a unique model with its aluminium body and all-wheel drive.
When the new Audi Space Frame (ASF) concept was first shown to the public in 1993 at the German International Motor Show in Frankfurt, it was a world first, and ushered in a new era in car making. A year later, the series-production version of the Audi A8 had its world premiere at the Geneva Motor Show. Jürgen Lunemann, Manager of the Audi plant in Neckarsulm, recalls: “This new large saloon model started a revolution in automobile engineering, and led to the development of a number of alternative lightweight body concepts, not only using aluminium as a new material but also in pressed-steel bodywork.” Alternative grades of steel, for instance, became available increasingly often. At 222 kilograms, the current A8 body structure is about 43 percent lighter than an equivalent steel body.
Advantages of the aluminium body
Weight-saving body construction yields a significant reduction in fuel consumption and therefore helps to keep CO2 emissions to a minimum. In the words of Albrecht Reimold, Head of Planning in Neckarsulm and, as the former A8 Body Construction Manager, one of the pioneers of aluminium body construction: “Cars being sold today incorporate more equipment than before, which increases their weight. An aluminium body helps to counteract this trend. Systematic weight-saving is a firm feature of modern car making.” Compared with the previous model, the torsional rigidity of the current Audi A8 bodyshell is 61 percent higher, which makes the car distinctly more agile and improves its ride quality, so that it qualifies as the most sporty luxury saloon on the international market.
Aluminium body construction
For the new material, Audi also developed new manufacturing techniques. While becoming familiar with these, Audi used manual construction methods to a large extent on the first A8 model, but the number of robots has now risen from 25 on the first generation to 150 on the current A8. The degree of automation reached in A8 aluminium body construction is 85 percent, matching the level achieved on conventional steel car bodies. When the new-generation model appeared, daily output rose from a maximum of 80 to 120 cars, with two-shift operation. 400 people are employed on A8 body construction.
After the A8 came further models using the ASF aluminium body construction principle, for example the Audi A2, Audi TT, Lamborghini Gallardo and R8 sports car. Volume production of aluminium bodies in Neckarsulm is acknowledged throughout the automobile industry as an impressive achievement.
More than 400,000 cars with an aluminium body have so far been built in Neckarsulm, including 105,136 of the first-generation A8 and more than 120,000 of the second generation. Audi remains the only carmaker to undertake high-volume car production using the Space Frame technique. The Audi A8, as technological leader in the premium segment, is also the only car in the large luxury class to combine the advantages of an aluminium body and all-wheel drive.
Audi Space Frame
The Audi Space Frame is a high-strength aluminium structure that combines sheet metal, extruded sections and pressure-cast elements. For their Space Frames, the specialists in Neckarsulm have developed special light alloys and process techniques; these have been brought even closer to perfection for the second model generation. In addition to welding and adhesive bonding, the punch riveting joining technique was adopted for the first time in automobile manufacturing.
The second-generation Audi A8 was introduced in 2002, and once again had the lightest body in its class. A year later this luxury saloon received the “European Car Body Award”, the top European prize for innovation in vehicle body construction. Manufacturing techniques were optimised still further, to permit the use of large multifunctional pressure cast elements and complex, topologically optimised extruded sections. In this way the number of parts needed was significantly reduced, production was speeded up, and thanks to the large optimised cast aluminium ‘nodes’ and extruded sections, the body became more rigid, with an even higher standard of safety.
Aluminium and Lightweight Construction Centre: the name for a vision
In 1994 Audi opened its Aluminium Centre in Neckarsulm, at which it grouped together under one roof all its experience in weight-saving vehicle construction, and combined the know-how available from its development, production planning and quality assurance areas. Today, Neckarsulm is not only a competence centre in weight-saving design but also a benchmark for the automobile industry all over the world.
In March 2003 the name was changed to ‘Aluminium- und Leichtbau-Zentrum’ (‘Aluminium and Lightweight Construction Centre’). Heinrich Timm, the Centre’s Manager, is one of the pioneers who developed the ‘aluminium-intensive car’ back in 1983. He explains: “The name was chosen to confirm that other materials as well as aluminium are becoming increasingly important in lightweight body construction, and that ‘intelligent mixed construction’ is the path we must pursue in the future.
When the Audi V8 was being designed, the first idea was to substitute aluminium for steel while retaining the traditional type of bodyshell, but we soon realised that this was not the answer.” In 1997 Timm, together with the current Head of Planning in Neckarsulm, Albrecht Reimold, received Vienna University’s Professor Ferdinand Porsche Prize as the principal inventor and developer of the Audi Space Frame. The Space Frame is essential if the characteristics of aluminium as a construction material are to be fully exploited.
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