Unique Long Fiber Injection process makes molding large-sized lightweight parts possible

Facing a challenge to supply a lightweight personal watercraft (PWC) hull without forgoing its strength, Canada's Camoplast, Inc. put into place a unique innovation -Camoplast Long Fiber (CLF™) technology - to produce large parts using the long fiber injection (LFI) process. The Canadian company collaborated with material supplier Bayer MaterialScience and plastics processing equipment manufacturer KraussMaffei to devise a technology. In LFI, long glass fibers are injected along with polyurethane resin in a one-step process: A fiberglass chopper is attached to the polyurethane dispensing mixhead, which is attached to a robot. The robot is programmed to move over the open mold cavity while simultaneously dispensing both the long glass fibers and the polyurethane resin in an open-pour method. At the end of the pour, the mold is closed to form the part. Earlier, PWC hulls have traditionally been manufactured from glass fiber reinforced polyester resin using the robotic shell molding (RSM™) process or sheet molding compound (SMC) process. Bayer MaterialScience developed a proprietary grade of its Baydur® STR 814 polyurethane system which features a 60-second open time (compared with a traditional open time of roughly 10 seconds), enabling the flow of the material and reinforcing glass into tight spaces, previously impossible, thereby making it possible to design-in strengthening ribs, etc. At the same time, KraussMaffei enhanced its proven LFI processing technology by nearly doubling the glass output capability from 180 grams/second to 300 grams/second, enabling the production of the highly reinforced structural parts. Compared to polyester, polyurethane has less density making it inherently lighter weight and thereby contributing to improved PWC acceleration. Polyurethane resin is also a more environmentally friendly alternative to other types of resins like polyester, which contains VOC-emitting styrene that is a hazard to both the environment and machine operators. In addition, using polyurethane and CLF™ allows for faster, more automated production and a smaller manufacturing footprint, which are advantages in both cost-effectiveness and safety. In addition, the tooling design guidance from KraussMaffei, enabled Camoplast to use a nickel shell mold, which is less costly than the steel mold needed in the SMC process. Furthermore, by using in-mold coating technology, Camoplast was able to produce a painted, Class A surface right out of the mold, eliminating costly and time-consuming secondary painting operations.