Carbon fiber manufacturer Zoltek (St. Louis, Mo., USA) reported on Nov. 11 that its new carbon fiber automotive body panel system, called Surface RTM, was launched at the 2013 K-Show in Düsseldorf, Germany, for the manufacture of Class A carbon fiber exterior panels.
During the event, KraussMaffei (Munich, Germany) demonstrated, in real-time, the Surface RTM manufacturing process, by producing carbon fiber roof panels for the new Roding sports car.
The Surface RTM process uses Zoltek's Panex 35 carbon fiber and a polyurethane (PU) resin system. This is then overmolded with a polyurethane paint coating, resulting in a premium and paintable surface quality composite part, directly out of the mold.
This Surface RTM process is the result of a year-long, industry partnership using latest Krauss Maffei RTM technology, Henkel PU chemistry, Chomarat C-Ply fabrics, Ruhl PU coatings and Zoltek’s specially sized Panex 35 50k carbon fiber.
The process begins with a carbon fiber fabric produced by Chomarat, which is injected with a PU resin (Henkel's Loctite Max 2). Once cured, the mold is opened slightly to allow the PU overmolding material to be injected (Ruhl). The part is then cured again. The total time from tool closure to tool open is less than 6 minutes. The part is then removed from the tool, power washed and supplied to the painter – who applies a top and clear coat.
The development of Chomarat’s C-Ply fabrics using Zoltek’s low-cost, large-tow carbon fiber is also a significant step forward in cost reduction and, says the company, will set a new standard for price points and quality carbon fiber panels.
Surface RTM eliminates the primer and sand process to hide print-through, which has the potential to significantly reduce final part costs.
“The results were quite spectacular,” says Martin O’Connor, president of Zoltek Automotive. “This high level of surface finish has never been seen before; the combination of PU viscosities, low-cost Panex 35, high-tech fabrics and overmolding has moved the industry forward, offering a wealth of opportunities for automotive applications.”
Additional process development is underway by Zoltek Automotive and industry partners to continue reducing process times and cost.