DALLAS - Europe's tiny Smart Car sports plastic body panels with molded-in color. But another innovation remains out of sight: a passenger foot-support pan made by a new process called ``direct forming.''
Frank Henning, an engineer at Fraunhofer ICT, presented a technical paper on the composite forming technology during Antec 2001 in Dallas. In March, the part won the transportation award at the JEC Composites Show in Paris.
Fraunhofer, a contract research and development company in Pfinztal, Germany, coordinated the project for Smart Car maker DaimlerChrysler AG. According to Henning, direct forming allows the use of as much as 50 percent recycled composite materials in a middle core, with no impact on structural properties.
Although it's hidden by carpet, the part is very important. It separates the feet of passengers from the battery compartment and ultimately, the road surface.
The composite part is 40 percent lighter than steel, Henning said.
The process uses Twintex sheet from French composites supplier Vetrotex International. Twintex is a woven sandwich made from polypropylene and glass fibers.
Henning said the cycle time is less than one minute. In his May 8 presentation, he described how direct forming works.
First, two Twintex sheets are clamped into the machine. An extrusion device deposits the core recycled layer. After the mold is closed, it goes into an infrared heater. The mold goes back into the machine for molding, in a process similar to thermoforming.
Trim scrap from the thermoplastic composite goes back into the process.
Henning said one key challenge was keeping the Twintex fabric smooth in the mold, to avoid wrinkles. Project managers used special pneumatic cylinders to track the fabric in the mold.
The next step, he said, is to incorporate features such as ribs, foam, inserts, gas injection and more textile reinforcement into parts made by direct forming.
The Smart Car measures just 5 feet wide and 8 feet long, making the two-seater perfect for tight European city driving. DaimlerChrysler is studying whether to sell the car in the United States.
In Dallas, you can order a steak as large as a Smart Car. But the vehicle gets 57 miles a gallon of precious, $2 a-gallon gas.