It may seem like a small inroad in vehicle weight reduction, but the debut of a brake pedal and its housing unit made from fiber-reinforced thermoplastics on a MY2014 German sports car serves as a vivid example of weight-conscious products reaching production application.
ZF’s in-development pipeline for lightweight driveline and chassis technologies spotlights aluminum, high-strength steels, composite-reinforced plastics, and fiber-reinforced plastics.
“We are doing a lot of prototype projects with different customers,” Dr. Stefan Sommer, CEO of ZF Friedrichshafen AG, said during a sit-down interview with Automotive Engineering at the 2014 North American International Auto Show in Detroit on Jan. 14.
One in-development project is a fiber-reinforced-plastic suspension strut and knuckle module. Compared to a steel counterpart, the plastic version provides an approximate 16% weight savings.
“Our European customers and the Big Three OEMs in North America are very interested in this. They want to have this lightweight suspension and knuckle module on the fast track. But it’s revolutionary technology, and we need to keep that in mind,” said Sommer.
Before the module is deemed production-ready, very specific issues need to be rectified. “We need to lower the cycle times. So a more mature mass volume production [system] needs to be developed,” said Sommer.
The structural quality of a plastic-fiber strut also differs from a conventional steel strut. “The material is very robust in the direction of the fibers. But if an impact comes from a direction that is different than the direction of the fibers, it’s more fragile than metal. We need to make a fiber-reinforced-plastic component that is at least as strong as steel in a crash situation,” Sommer said.
ZF technical specialists also are working on a chassis application that weighs 40% less than the traditional steel counterpart. The study concept’s core component is a rear axle with a wheel-guiding transverse leaf spring made of glass-fiber-reinforced plastics. With this design, the spring takes over the steering function and also absorbs the load-bearing demands. Fuel consumption and CO2 emissions reductions top the list of benefits associated with this lightweight chassis application concept.
ZF’s Schweinfurt, Germany, composite technology center, which opened in mid-2013, is key to the weight reduction effort. “This center is where we are developing the production processes and the designs for future applications using fiber-plastics and other lightweight materials,” Sommer said.