Temperature control heats up
Faster infusion is one way to reduce cycle time, but another is faster cure, which typically requires an elevated temperature. The wind industry has infused layups in heated molds for years, most commonly using electrical elements or fluid conduits. Tooling with built-in ducts that heat and cool molds with forced air has been used in the aerospace industry for decades. Using heated and cooled liquids for molding composites first started gaining traction with VEC Technology’s (Greenville, Pa.) Floating Mold technology patent application in 1999, and more recently with QuickStep Technologies’ (North Coogee, Western Australia), “balanced pressure fluid molding” (patent application in 2002). At the JEC Composites Show in 2011, Techni Modul Engineering (Coudes, France) exhibited its self-heated tooling that features a fluid circulation system for oil, water or metal-based fluids. Although VEC describes its Floating Mold processing as resin transfer molding (RTM), and QuickStep markets its process as being adaptable to liquid resin infusion, resin film infusion or light RTM, all three companies can use a variety of fluids to impart temperature control and each describes its composite tooling shells as thin, lightweight and less costly than the traditional metal tools used in RTM.
Composite parts are formed in molds, also known as tools. Tools can be made from virtually any material. The material type, shape and complexity depend upon the part and length of production run. Here's a short summary of the issues involved in electing and making tools.
CFRP composites enable unitized structure with low-drag aerodynamics that transform aircraft performance and reduce cost.
Subscale 5.5m-diameter cryogenic tank demonstrator with innovative fluted-core skirt is formed via robotic AFP and cured out of the autoclave.