Audi’s Incredible ASF
Heinrich Timm—Head of Lightweight Development, AUDI AG, started work on the Audi Space Frame (ASF) program in 1983. Then it was fast all the way. By 1987 there was a prototype. By 1994 there was the first production vehicle, the Audi A8, a premium car with underpinnings unlike any other volume car. Eleven years from program initiation to production.
While that might strike you as being, well, not inordinately fast, consider that Timm and his group in Neckarsulm, Germany, were doing something that even people in the aluminum industry at the time didn’t think could be done.
Timm was nothing if not demanding. When he started, aluminum elongation in production was on the order of 1%. The limit—really stretching things, literally and figuratively—was 3%. “I asked for 15%,” he states in a rather matter-of-fact manner. He knew that in order to create a truly lightweight structure predicated on diecastings and extruded sections—sections that changed in dimension in order to fulfill structural purposes—he would need to get better performance from aluminum.
But he knew that light-weighting with aluminum was an important thing to achieve as it provides, he says, about a 40% weight savings compared with a steel vehicle. So he pushed the industry, and he was able to develop the ASF.
Of course, there were other challenges that the people at the Audi Aluminum and Lightweight Design Center had to address. For example, manufacturing processes had to be developed in order to make the vehicles cost competitive. By and large, the auto industry is predicated on stamping and welding, and here they were with extrusions, diecastings, and sheet. So, for example, rather than relying on spot welding for assembly, they developed punch riveting, adhesive bonding, and laser-MIG hybrid welding processes. Self-tapping screws are employed, as well. One consequence of this (beyond the highly rigid structures) is that they have been able to increase the amount of automation in the manufacturing of the vehicles from about 25% when they started to over 80% today.
This capability has Audi to produce more than 550,000 vehicles with ASF, including the A8, TT, and R8, as well as some 9,000 Lamborghini Gallardos.
The latest manifestation of Timm’s structural engineering prowess is the 463-lb. spaceframe employed for the 2010 R8 5.2 FSI quattro. That’s as in a 5.2-liter V10 with direct injection and Audi’s patented Quattro all-wheel-drive system (in this case with an 85% rear bias for performance). The entire car, with a six-speed manual, weighs 3,715 lb.; it’s 3,726 lb. for the six-speed R tronic sequential manual transmis-sion. The overall weight distribution for the midengined sculptural beauty is 44% front, 56% rear.
Top speed: 196.4 mph (which, if you’re feeling like Top Gear’s Stig, you can experience while listening to the standard Bang & Olufsen 465-W 12-speaker audio system).
As time has gone on, they have gone from all-aluminum structures in Neckarsulm to those that combine other materials, such as high-strength steel and magnesium. However, Timm notes, “Aluminum remains the primary material, but we are intensively investigating the other materials, with our primary focus on fiber-reinforced composites.”—GSV