The Art of Aerospace Composites

This article reviews the advanced resin transfer molding (RTM) process of GKN Westland Aerospace. This process is refined enough, with customized equipment and a proprietary resin binding material, so that hundreds of different aircraft parts that would otherwise be heavier (made of titanium) are being produced for customers that include GE, Pratt & Whitney, Lockheed Martin, and Boeing. GKN is making five-axis, hollow vein, and integrated attachment nodes. It has produced carbon-fiber and resin components as thick as 3½ inches, and designs can combine what were many parts. Depending on the part and desired strength (in the desired directions), the fiber tow is woven in a variety of ways. For strength in mainly one direction, the engineers specify that 75 percent of the tow runs in one direction and just 25 percent of it is used to weave across it, for example. The next step in GKN’s advanced RTM evolution is a unihybrid composite that takes great loads in just one direction and can be made very thick, up to 3½ inches. A slightly less rigorous process has already been licensed, to a company in Mexico that produces a component for the Dodge Viper sports car.