May_June_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 1 9 2 0 *Member of ASM International O utwardly, 1988 was an unevent- ful year for aluminum auto body sheet (ABS). The only major an- nouncement took place at the Birming- ham Motor Show, where a supercar prototype dubbed XJ220 was the cen- terpiece of the Jaguar stand. The car was intended to gauge interest in the Jaguar supercar and it elicited somuch attention that a production version was planned. When it launched three years later, two major changes had taken place: The V12 had been replaced by a racing-derived turbocharged V6, allowing the car to be shortened accordingly; secondly, Ford Motor Company acquired Jaguar in Feb- ruary 1990. Despite its status as a pricey ultra-low volume supercar, it justifies in- clusion in our story by being the first im- plementation of the Alcan aluminum vehicle technology (AVT) system in a new vehicle. The prototype displayed in Bir- mingham was actually cured in an oven at Alcan’s Banbury laboratories. Back in Japan, Honda was mak- ing progress on its aluminum project. The first public reveal on February 2, 1989, at the Chicago Auto Show was a sensation. Styled from concepts by Pin- infarina, the car showed no hint of the formability limitations previously asso- ciated with aluminum. This was in part due to the new 6xxx alloys developed by Kobe and Sumitomo: They allowed Honda’s talented stamping engineers to make parts look as aggressive as if they had been styled for steel. For en- gineers worldwide, they looked like the product of a graduate class in stamp- ing engineering. Although the stamping was sensational, the underlying body joining technology was conventional resistance spot welding (RSW). However, the transition to produc- tion would prove difficult for Honda. Without computer models to help pre- dict and compensate for springback, tool development was a painful suc- cession of recuts, each aiming to final- ly bring the stubborn aluminum parts into tolerance. When the NSX went on sale in September 1990, Honda had managed to develop a sports car that could compete with Ferrari’s best—at less than half the cost. While the car re- ceived much acclaim, only 16,000 units were sold over its 15-year run. As the NSX was launching, Audi was working on the clay for its own alu- minum vehicle—a range-topping sedan, the A8. Much had happened in the eight years since the start of the de- velopment agreement with Alcoa. Un- like the aluminum prototype displayed at the 1985 Hannover Motor Show, the production vehicle was built around a spaceframe concept, combining ad- vanced structural castings, 6xxx al- loy extrusions, and stampings. In close collaboration with the engineers and researchers of the Alcoa Technical Cen- ter, Audi had concluded early on that a spaceframe would provide the opti- mal balance between structural perfor- mance, investments, and variable cost for the intended production volume of their flagship. By forgoing the tradition- al stamped unibody solution and using castings and extrusions, Audi and Al- coa had mostly eliminated the need to AUTOMOTIVE ALUMINUM—PART VII Aluminum Intensive Vehicles Make Headway Launching an aluminum vehicle into production is a far greater challenge than building a fleet of prototypes. Laurent Chappuis,* Light Metal Consultants LLC, Grosse Ile, Michigan Robert Sanders,* Novelis Inc., Atlanta 1991 Jaguar XJ220. Courtesy of Wikimedia Commons/Kieran White.