“One area that’s evolving is cylinder head covers. There’s a fair amount of market penetration there, but you still see metal in those applications.”
The thing that can lead to a change, he suggests, is the fact that as new engines appear, there is a greater integration of electronics and controls. Plastic materials facilitate integration, he says, molding those components right into the head covers rather than having to perform secondary operations to accomplish that, as is the case with metal.
One of the challenges that needs to be addressed in the metal-to-plastic transition is not performance-related, but economic. “The bigger the part, the more problematic it is to shift from metal to plastic because the raw material costs are higher,” Berkowski says. However, they are looking at the ways and means to facilitate this transition. And one of those ways is through the introduction of a new engineering polyamide, Ultramid Endure.
Berkowski explains that Endure, a glass fiber-reinforced material, is developed to handle high temperatures—such as those experienced in areas like components of the charge-air duct such as intercooler end caps, resonators, charge-air lines, and throttle valves, as well as components on the somewhat cooler side of the turbocharger—over long periods of time. (Even the aforementioned intake manifolds have applicability: such as those with integrated water-cooled intercoolers.) Berkowski says that the melting temperature of Endure is not higher than a nylon 66, but that it has superior performance during long exposure: it is capable of handling 220°C for over 3,000 hours. (The peak temperature it handles is 240°C.)
“This transcends all standard nylons and puts us in the realm of some exotic, high-end plastics that are more expensive,” he says. “There are some applications today where plastics provide so much value—like charge air coolers and parts around the exhaust system—where the industry has adopted high-end plastic materials. But Ultramid Endure has better economics, easier processability, and is more readily available on a global basis.”
One area of a car that seems as though metal is simply the appropriate material is in the area of wheels. Sure, you can have plastic wheel covers, but plastic wheels?
BASF worked with smart on the development of the smart forvision concept car, which was unveiled at the 2011 Frankfurt Motor Show. During the introduction, Dr. Annette Winkler, head of smart, said of the electric concept vehicle, “With the forvision smart is doing justice to its role as Daimler’s think tank for urban mobility . . . With the clear objective of greatly increasing the zero-emission range, we concerned ourselves with all factors that influence this on the vehicle. This resulted in completely new concepts and materials in the areas of insulation, reflection, lightweight design and energy management. In addition to transparent organic solar cells, transparent and energy-saving lightemitting diodes and infrared-reflective films and coatings, high-performance foams are used for insulation against cold and heat. smart is also setting new standards of lightweight design with the use of the first all plastic wheels.”
Berkowski says that the wheel is made with an Ultramid polyamide with long-glass material (Ultramid Structure) rather than a choppedglass. He says that for the smart forvision application, there is a weight savings of approximately 3 kg per wheel compared with a traditional metal wheel. Performance testing of the wheel has shown that it has thermal and chemical stability, dynamic strength, and toughness. And while the wheel was developed for a concept car, Berkowski says that they have developed the wheel to the extent that it could eventually be put into production with some additional product testing. He points out, however, that at this point, the polyamide wheels are best suited for A- and B-class vehicles. (There are, incidentally, metal inserts in the plastic structure so the wheels can be bolted to the axles.)
“Seat frames have been metal forever, basically,” Berkowski says. Not surprisingly, they’re developing the means to replace the metal with thermoplastics. BASF has been working with Faurecia (faurecia.com
) on the development of a seating component that integrates the seat frame and the back panel into one. Not only does this result in a construction that is approximately 20% lighter, but is also 1-in. (15%) thinner than conventional seats, which is becoming increasingly important to interior designers as vehicles are being downsized.
To engineer the seat they used continuous fiber reinforced thermoplastic (CFRT) inserts in strategic locations to impart the required strength. Rather than using the CFRT for the entire structure, this approach, which involves locating the inserts in the molding tool and then molding around them, they are able to reduce the cost of the component, as the CFRT material is more costly.
To determine where the inserts need to be located, they developed ULTRASIM, a computer-aided engineering tool that allows the engineers to input the physical properties of the materials, accounting for the glass-fiber orientation, then perform structural analysis.
“Anybody can compound glass and nylon, but when you get to nextgeneration applications like the seatback and the wheel, it’s not just compounding capability, but knowing how it is going to work,” Berkowski says.