Plastic Composites Are Strong Enough to Replace Steel
Posted by Al Elger on Wed, May 09, 2012
Because of more stringent federal fuel-efficiency expectations, the automotive industry has been looking for ways to reduce the weight of cars to reduce fuel consumption. One of the solutions is proving to be plastic composites that are just as strong as the metal they replace—and significantly lighter. Both thermoplastic and thermosetting composites are being engineered to replace steel and aluminum without compromising performance. Making these parts from plastic composites can also increase innovation in the design phase, giving manufacturers more opportunities to reduce overall production costs.
Reinforcing plastics with short glass fibers improves strength, stiffness, and heat deflection temperatures. Glass fiber-reinforced thermoplastics and polypropylenes are being used more in the automotive industry to replace metal parts (as well as plastic parts that don’t last as long as glass-reinforced plastics). Glass-reinforced polyamide and polyphthalamide are becoming popular replacements for metal in cylinder heads and other engine cooling components in vehicles. Glass-fiber content can be 50 percent or more, creating a very high modulus. These short glass-reinforced plastics can be ideal materials for parts and products in other industries where superior strength, heat-resistance, and lighter weight are required.
There are also long fiber-reinforced thermoplastics and polypropylene (LGFPP)—although these are more expensive, they are higher performance, especially in high-temperature applications. Because of its strength, LGFPP is an ideal material for manufacturing parts with thinner walls—which also reduces weight and material costs. LGFPP also has a lower specific gravity than other resins such as PA or PC/ABS, another cost reducer.
Carbon fiber-reinforced plastic (CFRP) is another family of lightweight materials that provide superior strength and has high interest among automobile manufacturers, especially for larger body parts such as side panels, which could reduce the weight of a car by 50 percent or more.
To further this research, Ford Motor Company has partnered with Dow Chemical Company to investigate ways to bring carbon fiber into high-volume auto production—with the goal of reducing the average car’s weight by 750 pounds. Key research considerations include material cost, faster processing of carbon fiber molding, and discovering new ways to join composites to metal. Carbon fiber is already in production in limited volumes for specialty cars, most notably Germany’s BMW, but the process is slow and expensive.
Not to be outdone, General Motors Company just signed a deal with Japanese firm Teijin Ltd. to build a $7.9-million composites development center in the Detroit suburb of Auburn Hills. The center will develop large-volume carbon fiber production for the auto industry using a proprietary process that can mold carbon fiber reinforced thermoplastic within cycle times of one minute.