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® 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™
that was developed by Greene, Tweed, which
installed one ProFusion™ 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™ 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® 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.
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
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® 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®
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®
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®
4125 tested more than 40 percent better than
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.