While vehicle engineers admit that there is still a place for steel in their future product’s structures, it will not stop them from seeking alternatives to the tried-and-tested material.
Jaguar has been one of the pioneers of such experimentation, working more and more aluminum into its product range over a number of years. Mark White, Chief Technical Specialist for Body Structures at the Tata-owned manufacturer, admits the trend will only increase.
“Ratan Tata has said Jaguar will be the aluminum car company,” said White. “We have a well-defined plan [for using aluminum] and are looking at other opportunities when they come along, providing the price is right.”
Jaguar’s policy on aluminum has seen a 45% weight savings in the major masses on the body and closures on its cars—on average saving around 150 kg (330 lb) per vehicle. White says that while there is a limit to the percentage gains, he and his team are working to push the envelope.
“When we first started on the first-generation aluminum XJ, we had two types to choose from: 5754 aluminum, which is the equivalent to mild steel, or 6111, more akin to hardened steel,” he recalled. “Now we are working with [aluminum rolling and recycling expert] Novelis on even higher-strength aluminum alloys to apply to some of our products.”
One weight-loss example he highlights on the new XJ is a one-piece door, which has allowed savings of 2.2 kg (4.9 lb) per car from the previous-generation model XJ and reduced the number of parts from 16 to 10.
Another manufacturer to have some success with aluminum is Audi, who recently announced the latest A8 will have a version of its Audi Space Frame (ASF) that is 24% more rigid. The company is saying little about the new product, but Heinrich Timm, head of the organization’s aluminum and lightweight design center in Neckarsulm, revealed that the structure was subjected to “revolutionary alloy developments on the castings and sections” and that “new aluminum sheet plate technologies had been applied.”
Timm continued, “For the optimized application of the materials on the A8 chassis, we use 13 different types of aluminum alloy. We have also developed improved technological processes for joining the parts together.”
Magnesium may be lightweight, but with issues still remaining over its cost, as well as integration problems, aluminum will continue to be the second-choice metal in automotive applications, according to White.
“Used in the right places, it is possible to get 60 to 65% weight savings with magnesium, compared with a 45% cut by changing from steel to aluminum,” White said. “But the problems are joining it to [other materials] in the structure, specifically corrosion issues in this situation.”