A new compression molding process coupled with high-performance carbon-reinforced
thermoplastic composites target lightweight applications, such as assembly
brackets, on aircraft.
Greene, Tweed & Co. of Kulpsville, PA, says Xycomp(R) DLF can be molded into highly complex shapes with three-dimensional features such as ribs, bosses, gussets and flanges. The DLF stands for discontinuous long fibers. Carbon fibers are used to reinforce one of three engineering thermoplastics depending on the application: polyetheretherketone (PEEK), polyetherketoneketone (PEKK), or polyetherimide (PEI).
Components are formed in a compression molding process called ProFusion(TM) that was developed by Greene, Tweed, which installed one ProFusion(TM) press last year, and is installing two more this year.
"This is all about metal replacement," says Tim Greene, global composites product manager at Greene, Tweed.
Design freedom of the ProFusion(TM) process enables varied section thickness or stiffening features that can be added in higher loading areas or removed in lower loading areas to optimize weight savings. Xycomp(R) DLF components also offer molded-in inserts for attachment points, heat sinks and bosses for integration of multiple components and reduction of secondary operations such as drilling or bonding. Greene, Tweed also says performance is enhanced. Greater than 100 percent increases in torque and pull-out performance have been validated versus bonded inserts, according to the company.
Xycomp(R) DLF components are up to 80 percent lighter than metallic materials and are said to offer superior matrix toughness over thermoset composites.
Hundreds of brackets are used throughout airplanes, and have traditionally been made of steel or aluminum. New aircraft designs, such as the Boeing Dreamliner 787 and Airbus A350, use more composite materials and place a major premium on weight reduction. Traditional composites, made with thermoset plastic as matrix materials, could not be designed with enough specific geometry to be used in smaller, more complex components such as aircraft brackets. The thermoplastics in Xycomp(R) DLF allow better flow than thermosets, but are still constrained by high fiber loadings.
Greene, Tweed's DLF material allows for
specified fiber lengths for optimal material flow and performance
characteristics, and uses specialized temperature cycles to control heating and
cooling of the compound in molds. No other details were available.
Greene, Tweed says the material shows exceptional resistance to aerospace solvents, high temperatures and high vibrations for extended component life and reduced maintenance requirements. Xycomp(R) DLF can be recycled and has exceeded all Federal Aviation Administration and airframe interior requirements with excellent FST (flame, smoke and toxicity) performance, in addition to passing 15 minute burn-through tests.
Another composite material, Xycomp(R) 4125, is used to make an aircraft seat assembly that reduces weight 30 percent compared to an aluminum version. In static testing, components made from Xycomp(R) 4125 tested more than 40 percent better than aluminum components.
Greene, Tweed was founded in 1863 as an industrial distribution business. It introduced the G-T Ring, for use in the landing gear of the F-4 Phantom in 1964. The company specializes in the development and production of several high-performance materials, such as Chemraz, a chemical-resistant elastomer, effective in the most extreme temperatures. WR is a high-performance, wear-resistant, carbon-fiber-reinforced thermoplastic composite used in oilfield applications.