Improvements in Tooling and Injection for High Volume Fraction LCM

摘要

Liquid composite molding (LCM) processes have been effectively used for the production of low cycle time, low volume fraction, and high cycle time, high volume fraction parts, but the production of high fiber fraction structural composites combined with short cycle times required by even low volume automotive production remains a challenge. With support from the NIST's Advanced Technology Program, Stewart Automotive Research has developed tooling and molding technology that allows a fiber preform to be filled primarily through its thickness, greatly reducing the flow path and infusion times, resulting in volume fractions comparable to autoclave cured composites. By manipulating an articulated upper mold surface under computer control, the preform is held in place while resin is distributed over its surface and then forced through the thickness. Infusion time is largely independent of part size, while tooling costs scale linearly with size. Because of the short infusion path, the process can operate at low pressures, which helps to offset the cost of the more complex tooling. Altair Engineering (Troy, Michigan) has developed a robust process simulation that is used to optimize the program controlling the mold actuation.