Low-CTE carbon foam tooling system

Advanced Composites Group and GrafTech International Ltd. have developed the ACG GRAFOAM FPA-20 carbon foam tooling system.

A partnership between Advanced Composites Group (ACG, Heanor, U.K.) and GrafTech International Ltd. (Parma, Ohio), a manufacturer of graphite and carbon-based products, has developed ACG GRAFOAM FPA-20 carbon foam tooling system, a low-CTE (coefficient of thermal expansion), low-mass composite tooling material. Reported CTE is 2.3 x 10-6/°C with a thermal resistance that is said to exceed composite processing requirements. Also, it can be machined to near-finished size and then fully encapsulated in ACG’s proprietary, patented, compliant interface technology and a tooling laminate skin, typically ACG’s Low Temperature Moulding (LTM). ACG also reports, however, that the inherent thermal qualities of the carbon foam also allow the application of higher temperature resin systems from the company’s medium- (MTM) and high-temperature (HTM) tooling laminate ranges. Once cured, the final tool profile is created with a second machining operation; any further tooling modifications can be achieved with additional local lamination and subsequent re-machining. Suitable manufacturing processes include tape placement and filament winding, where low weight is a benefit when managing extremely large tools. Development tools, manufactured at ACG for a major aircraft manufacturer in North America, reportedly have achieved dimensional accuracy of ±0.2 mm/0.008 inch on complex surface profiles, and ±0.1mm/0.004 inch on less complex surface profiles.