Cosma cuts weight & cost & improves the ride: Cosma thinks it has a new, less expensive way to manufacture body, chassis and suspension components, along with new thinking on how to configure truck suspensions

Automotive Design & Production, March, 2007 by Kevin M. Kelly

A New Take on Flex

Cosma International (www.cosma.com), the chassis and body systems division of Magna International, has developed a process that could revolutionize the way body and chassis components are manufactured. Called the "Flexible Body Architecture" program, it combines high-strength steel (HSS) tubes with aluminum to construct chassis and body components that cost less and weigh the equivalent of all-aluminum components. By using HSS tubes that are combined with aluminum castings via the semisolid casting process, Cosma is able to develop body architectures and chassis components that can turn a unibody vehicle architecture into a myriad of vehicle configurations with little additional investment; all it takes is a change to the length and thickness of the tubes to accommodate a different engine, GVW or body structure. The same process can be used to manufacture control arms and other chassis parts of different sizes and configurations. The use of bending and hydroforming technologies to construct the tubes allows for limitless configurations when it comes to section thickness and shape, while the use of expensive aluminum is minimized. On an engine cradle, for example, nearly 40% of the aluminum is replaced with HSS. "With the Flexible Body Architecture we can build fully modular structures thanks to increased commonality. To move from a sedan to a crossover, for example, we just have to change four parts and modify six others. We have full flexibility when it comes to changes in overall wheelbase, overhang and track width," said Swamy Kotagiri, executive director or research and development and engineering at Cosma. He estimates Cosma's program would cut overall investment by upwards of 20% not only from the reduced use of aluminum, but also through the reduction of steps in the manufacturing process. Kotagiri points out that a conventionally made engine cradle typically requires multiple MIG weldings and other attachment processes, while the Flexible Body Architecture example was done in one step. Cosma plans to have the Flexible Body Architecture in production in 2009.

Suspending Common Thinking

Cosma's Frame Integrated Rear Suspension Technology (FIRST) provides "the ride of a car that works like a truck," according to Kotagiri. FIRST amalgamates the benefits of both Independent and solid axle suspensions. FIRST behaves like an Independent suspension in single wheel events and like a solid axle in dual wheel events. Kotagiri adds the configuration is lighter than an independent rear suspension, weight neutral to a solid rear axle configuration, and reduces sprung mass by upwards of 20%. On the packaging side, FIRST can be installed at a lower floor height than a conventional solid axle, improving legroom. Cosma plans to have FIRST installed on a production vehicle by 2011, "or maybe earlier," Kotagiri said.

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Kevin M. Kelly

kkelly@autofieldguide.com

by Kevin M. Kelly

SENIOR EDITOR