Tampa, Florida - Canadian plastics moulder Camoplast Inc. has solved a problem for a leading manufacturer of personal watercraft (PWC). This was to find a way to manufacture a lightweight PWC hull, without sacrificing strength - and with improved performance for the user. It also had to be less expensive to produce, according to materials supplier Bayer MaterialScience.
Ottowa-based Camoplast produced a hull utilising the next generation of long-fibre injection (LFI) technology, based on a proprietary formulation of a BMS Baydur STR 814 polyurethane system. The 12-ft-by-3-ft PWC hull - the first-ever application of this technology - was on display at the BMS booth at COMPOSITES+POLYCON, 15-17 Jan 2009.
For decades, PWC hulls have been made from glass-fibre-reinforced polyester resin (GRP) using robotic shell moulding or a sheet moulding compound. Camoplast researched many alternatives and materials, ultimately determining that a modified LFI method could meet its customer's goal of a strong, lightweight PWC hull with a superior Class A finish, yet less expensive.
In LFI, long glass fibres 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 mould while simultaneously dispensing both the fibres and the polyurethane resin. The mould is then closed to form the part.
A difficulty which had to be overcome was that the rapid cure of polyurethane resin made it hard to fabricate large part such as PWC hulls.
Camoplast collaborated with Bayer MaterialScience and plastics processing equipment manufacturer KraussMaffei to devise the Camoplast Long Fiber (CLF) technology.
First BMS developed a proprietary grade of its Baydur STR 814 system, with a 60-second open time (compared to a traditional open time of roughly 10 seconds). This enabled the material and reinforcing glass to flow into tight spaces, not previously possible, and thus made it possible to build in strengthening ribs, etc. At the same time, KraussMaffei nearly doubled the glass output capability of its LFI technology from 180 g/s to 300 g/s, allowing production of highly reinforced structural parts.
Using polyurethane over the traditional GRP resins offers benefits to the manufacturer and the consumer. As it is less dense than polyester, polyurethane is inherently lighter and so contributes to improved craft acceleration. The CLF-made hull weighs 25 percent less than the previous version.
Safety was also a consideration. "The hull of a PWC is the largest and most vulnerable part of the vehicle. As it breaks over waves there is the chance that it could crack," said Yves Carbonneau, engineering director, Camoplast, in a BMS press release. "Using a light material -- the Baydur STR 814 system, reinforced with moulded-in ribs -- we achieved the necessary strength to withstand big waves and other safety issues that are inherent with a PWC."
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