DETROIT—Injection molded automotive parts containing a new electrically conductive additive could shake up a car industry that for years relied on steel-based parts and other materials for electrostatic applications.
The additive, known as Graphite Fibril, might represent a major breakthrough for automakers searching for ways to lower expenses and enhance quality. Instead of spray painting cars, car assembly plants could switch to electrostatic painting, which may increase paint coverage and provide a smoother coating.
The process also would eliminate the need for conductive primer as a bottom coat for nonconductive surfaces, thus lowering emissions and reducing costs.
In addition, carmakers are considering replacing metallic fuel-line systems with lower-cost nylon tubing made with the fibril additive. The conductive material, used to prevent static buildup, could protect tubing from corrosion better than components using stainless-steel fibers.
Still, with all the potential benefits of conductive plastic, the product comes without guarantee of success.
``There's no certainty that conductive plastics will ever become the standard for the auto industry,'' said Ed Gray, technical manager with materials supplier Huls America, which is manufacturing the fuel-system tubing filled with the fibril additive.
``It all depends on how well it actually works in actual applications over a large production run, and how expensive it is. Right now, we're not sure if it's really the wave of the future.''
Developed by Hyperion Catalysis International Inc., a Cambridge, Mass., additive supplier, Graphite Fibril represents the only conductive material used with thermoplastics in commercial use, said Stephen Friend, Hyperion vice president and general manager. Hyperion began developing the material in 1987 but did not launch it in North America until last year.
The additive consists of microscopic hollow tubing no larger than a fleck of dust. Each tube is about 0.01 micron in diameter. The carbon-based fibrils are made from ethylene gas that undergoes a catalyzing process that allows it to be compounded into a variety of thermoplastics.
Already, many carmakers are considering the addition of fibril-filled components to existing car lines. Mitsubishi Motor Sales of America Inc. will decide later this year whether to install side mirror housings made with Graphite Fibril to its Eclipse/Talon line. Toyota Motor Sales U.S.A. Inc. is reviewing test data before deciding whether to use fibril-based grilles for its Camry, said Ron Hendricks, technical manager with United Technologies Automotive, which is injection molding the Mitsubishi and Toyota parts at its Berne, Ind., plant.
In addition, Ford Motor Co. plans to use mirror shells made with fibril technology beginning in March on its current Taurus and Sable lines, he said.
None of the carmakers would comment on the use of the fibril-based components.
The Ford mirror housing shell uses conductive Noryl GTX from GE Plastics, while the Mitsubishi and Toyota parts are molded from a conductive version of Ultramid nylon 6 made by BASF.
At the same time, Ford and Chrysler Corp. have approved the use of fuel-line tubing made of fibril materials, but have not decided if they will add the tubing to their product lines, said Gray at Huls America's Farmington Hills, Mich., facility. Huls recently started manufacturing fibril-filled Vestamid nylon 12 for use with both fuel-line tubing and fuel filters.
Materials supplier GE Plastics has launched a conductive version of its Noryl GTX polyethylene oxide and ether thermoplastics. The Pittsfield, Mass.-based company maintains that the conductive material is less expensive, over short runs, than steel-based materials and nonconductive plastics.
``Pound for pound, conductive plastics competes very well with steel materials used for conductivity,'' said Jeroen Verhoeven, industry manager for exterior body and components at GE Plastics.
According to a GE Plastics study, fenders made with conductive GTX cost $16.84 each to paint, compared with $16.90 for a steel-surface fender and $21.59 for a fender built with a nonconductive GTX surface for production runs of 150,000 units. The difference: No tooling or bracketry is needed with the thermoplastic fender, and nonconductive plastics require a primer.
Verhoeven cautioned that steel surfaces still are the most cost-effective alternative for production runs of more than 150,000 units.
UT Automotive's Hendricks said cost savings are not the primary reason automakers might switch to conductive plastics.
``When you consider the cost right now of Graphite Fibril, the cost benefits are negligible,'' he said.
But Hyperion's tests show that transfer efficiency, which is the amount of paint coverage on a part, is as high as 80 percent for electrostatic painting, compared with 20 percent efficiency for spray painting. Low transfer efficiency leads to wasted paint, which can run as high as $50 per gallon at production plants.
In addition, the conductive material cuts paint emissions as much as 30 percent due to the elimination of primer, Hendricks said. The result is increased capacity in states where stringent emissions standards limit paint production.
``Environmental stability is another key concern,'' Hendricks said. ``Other types of conductive surfaces can damage the physical properties of the substrates underneath the material. The testing we've done has shown that this material leaves a smooth surface and doesn't damage structural integrity.''
Still, not all processors have had good fortune with the material. Key Plastics Inc. in Plymouth, Mich., has been attempting to manufacture exterior door handles using fibril for Ford's CDW-27 world car.
However, the material has not been integrated successfully with glass in the door handles, said Carmen Tripon-Ismail, corporate research and development director for the company.
``We're still hoping for better test results,'' Tripon-Ismail said. ``But right now, we're not ready to use the material with Ford products.''