ANN ARBOR, MICH. -- Plastics have a strong potential to help the auto industry reduce weight and improve efficiency, but for the next five to seven years, auto industry veterans and researchers say metal will still be the predominant material of choice.
During two days of testimony before the National Research Council's Committee on Fuel Economy of Light-Duty Vehicles in Ann Arbor, Feb. 12-13, industry experts pointed to financial and logistical reasons why advanced high-strength steel and aluminum will lead the way in vehicle construction until 2020.
Carbon-fiber composites are very intriguing, light and strong, said Matthew Zaluzec, global materials and manufacturing researcher for Ford Motor Co. and a member of the U.S. Automotive Materials Partnership — part of the U.S. Council for Automotive Research LLC cooperative. But carbon-fiber prices are close to $10 a pound, compared to 40 cents a pound for competitive metals, he said.
"And even if someone presented to me a $2 per-pound carbon fiber, the infrastructure to manufacture it at high volumes does not exist," Zaluzec said.
The NRC committee is part of continuing research into the auto industry's need to reduce vehicle weight to meet higher fuel economy requirements by 2025.
The U.S. government, through the National Highway Traffic Safety Administration, has also looked at cost and safety issues involved in reducing vehicle weight. In a new study for NHTSA conducted by EDAG Inc. of Auburn Hills, Mich., and its partners, researchers used a 2011 Honda Accord sedan as a baseline and studied various replacement materials to produce the major components, along with the weight savings from those options and the cost involved in alternatives.
It was important, said EDAG program manager Harry Singh, to control costs. Consumers have not been willing to pay much more for a more efficient car, so EDAG targeted improvements that would add no more than 10 percent to the overall production costs to build the car. The study wanted to increase production costs by no more than $1,500.
Making a car with extensive use of carbon-fiber composites would cut weight by 50 percent, Singh said, but it would add $2,700 to its costs.
In comparison, a car using a combination of advanced steel, aluminum and plastics in targeted locations would cut weight by 24.5 percent but only add $319 to production costs. An aluminum-intensive vehicle would cut weight by 35 percent and cost an additional $927.
The U.S. auto industry has developed around using metals, Zaluzec noted. Automakers buy steel, stamp it, shape it into frames and body parts, weld it, paint it and send out finished cars.
"To disrupt that flow is a real leap of faith," he said. "For 2016, you're going to be driving cars that are made mostly of steel and aluminum. It's all about the infrastructure. I can buy it now, and I know I'll be able to buy it five years from now."
Most automakers lack in-house plastics production. The best potential to use plastics at this time and in the near future is in parts and complete assemblies that are produced by suppliers outside the assembly plant, which can be bolted into place ready-to-use — rather than forcing automakers to develop alternative assembly patterns. That could include more structural plastics for complete bumper systems — including the bumper beam — along with oil pans and other parts.
"We're going to have to walk before we can run," Zaluzec said.
Carbon fiber already is about to be produced for 20,000 vehicles for General Motors Co.'s upcoming Corvette Stingray, noted Keith Christman, managing director of plastics markets for the Washington-based American Chemistry Council. Auto supplier Plasan Carbon Composites of Bennington, Vt., is building a new plant in Walker, Mich., to produce body panels for the 2014 Corvette, and expects to be able to produce parts for 50,000-100,000 vehicles a year within a few years.
Plasan will mold the parts in a proprietary process that brings carbon-fiber cycle time down to 17 minutes, said Jackie Rehkopf, Plasan senior researcher. The company believes it will get that cycle time down to five minutes before the 2025 fuel economy deadline.
ACC also recently completed a study on the potential for plastics and other composites to be used extensively as a replacement material on a pickup truck, using a 2007 Chevrolet Silverado as its test vehicle.
That study pointed to a potential for overall weight savings of more than 400 kilograms on the truck, by using both new composites such as carbon fiber and established plastics such as a polycarbonate/ABS blend in pillars and roof systems said Tom Hollowell, president of WTH Consulting LLC, which conducted the study for ACC. WTH is in Apex, N.C., a Raleigh suburb.
Hollowell noted, however, that the study did not include costs associated in the replacement parts.
He also said further development of predictive engineering software for composites is needed. ACC recently released a new database to help improve software development.