The firstapplication of a new long-fiber injection molding technology is the hull of apersonal watercraft that will hit the market this summer.

The newtechnology produces a lighter, more efficient hull, according to YvesCarbonneau, engineering director at Camoplast,a privately owned company based in Sherbrooke, Quebec.  

In the newprocess developed jointly between Camoplast, BayerMaterialScience and Krauss-Maffei,long glass fibers are injected along with polyurethane resin in a one-stepprocess. A fiberglass chopper is attached to the polyurethane-dispensingmixhead, which connects to a robot. Therobot is programmed to move over the open mold cavity while simultaneouslydispensing both the long glass fibers and the polyurethane resin in anopen-pour method. At the end of thepour, the mold is closed to form the part in a low-pressure process.

The goals ofthe project are to achieve a superior Class A finish, reduce part weight withoutsacrificing strength, and keep costs down.

"Becausethis particular customer had used glass-reinforced polyester resin for years,initially there was skepticism that making such a big leap to a new material,polyurethane, and a new technology would result in high performance and greataesthetics," says Carbonneau.

BayerMaterialScience developed a proprietary grade of its Baydur STR 814polyurethane system, which features a 60-second open time compared with atraditional open time of roughly 10 seconds. This facilitates the flow of thematerial and reinforcing glass into tight spaces, making it possible todesign in strengthening ribs, and other features that can boost theeffectiveness of the hull.

KraussMaffeienhanced its long-fiber processing technology by nearly doubling the glassoutput capability from 180 g/sec to 300 g/sec, enabling theproduction of the highly reinforced structural parts.

Camoplastreaped other benefits, as well, by switching to CLF and the Baydur STR 814system. Polyurethane is a more environmentally friendly alternative to othertypes of resins like polyester, which contains VOC-emitting styrene that is ahazard to both the environment and machine operators. In addition, usingpolyurethane and CLF allows for faster, more automated production and a smallermanufacturing footprint, which are advantages in both cost-effectiveness andsafety.

Because polyurethaneis less dense than polyester the hull produced with the new process weighs 25percent less than the previous hull.

"The hullof a personal watercraft is the largest and most vulnerable part of thevehicle. As it breaks over waves there is the chance that it could crack," saysCarbonneau. "The part must have the best structural and mechanicalcharacteristics while remaining lightweight for high performance. By using alight material, the Baydur STR 814 system, reinforced with molded-in ribs, weachieved the necessary strength to withstand big waves and other safety issuesthat are inherent with a personal watercraft."

Camoplast uses a nickel shell mold, which is less costly than the steel mold needed inthe sheet molding compound process. And by using in-mold coating technology,Camoplast is able to produce a painted, Class A surface right out of the mold,eliminating costly and time-consuming secondary painting operations.