FOR AUTO RTM

“Snap-Cure” Epoxies
NEWS
molding compound (SMC) molding or metal stamping processes.
The company has worked for the past seven years with BMW on its
i3 production car program, which uses Huntsman’s trademarked
Araldite LY 3585 resin, coupled with Aradur 3475 hardener in a
high-pressure RTM process (see “Learn More”).
“The Aradur resin chemistry allows us to adjust the chemistry
and the cure time for an optimized reaction, for a specific part,”
adds Harms. “As the robustness of the resin system and processes
continue to evolve, OEMs can now begin targeting more parts
to convert into composites.” Currently, several European OEMs
are “aggressively” evaluating the Huntsman product, he adds, on
programs potentially starting in 2017.
Adapting prepregs to automotive demands
Hexcel (Stamford, CT, US) offers a snap-cure prepreg, trademarked
HexPly M77, that has a two-minute cycle at 150°C (80 bar pressure)
for a 5-mm-thick part. The low tack of HexPly M77 enables the
prepreg to be cut into precise shapes by laser cutter, then robotically
oriented, assembled and consolidated into flat preforms. Its
T g
of 125°C enables demolding of cured parts while hot for a faster
production cycle, says the company. M77’s long shelf life at room
temperature reportedly helps fabricators meet their lean manufacturing
goals.
HexMC, the company’s trademarked carbon/epoxy molding
compound material — made with HexPly M77 — also has been
adopted by the automotive industry. At 150°C, a complete cycle
takes 120 seconds from mold close to mold open, for a 4-mmthick
part, but low viscosity and gel time enable the resin to flow
and conform to mold contours while air is evacuated, for complex
part geometries. M77 prepregs and HexMC (based on M77) are
targeted for structural body-in-white parts and for aesthetic parts
that require a carbon fiber look. HexPly M77 can be used for body
panels that are subsequently painted. Although Lamborghini is a
well known Hexcel customer, using 90-minute cure products for
its Aventador LP700-4 roof part, Hexcel says that its faster-curing
products are certainly contenders for series production applications
(see “Learn More”).
Toray Composites (America) Inc.’s (Tacoma, WA, US) Dr. Felix
Nguyen, a principal research scientist at Toray’s composite materials
research laboratory, says its G83C prepreg is “very robust and
versatile” for both autoclave and advanced fast-cycle processing
methods: “The material is ideal for high-volume automotive Class
A parts, due to its fast-cure characteristics that balance resin flow
and cure kinetics.” Indeed, the material has been used for several
years by Plasan Carbon Composites for the Chevrolet Corvette and
Dodge Viper sports car programs. Although data sheets for the
product show conservative cure times of 20 minutes, depending
on cure temperature, Lownsdale asserts that the G83C material
can cure very quickly, in less than six minutes, in the Plasan Rapid-
Clave machine process, and he says that faster cures are possible.
Nguyen notes that Toray’s research laboratory in Tacoma is
charged with the development and expansion of composites usage
in aerospace, as well as automotive, sport and industrial applications,
and anticipates involvement with the recently formed
Institute for Advanced Composites Manufacturing Innovation
Mass-production
suspension
component
Hexion “snap-cure” Epikote
Resin TRAC 06170 has been
used to create a composite
coil spring for the Audi A6
Avant 2.0 TDI Ultra model.
The spring is manufactured by
S.ARA Composites SAS, part
of the SOGEFI Group. Hexion’s
companion Epikote TRAC
06720 curable preform binder,
cured at 160°C, helps make part
preforms possible.
Source | Hexion
Autoclave-quality without the wait
Plasan Carbon Composites’ RapidClave process molds G83C rapid-cure epoxy
prepreg from Toray Composites America (Tacoma, WA, US), a well-characterized
material used on the Boeing 787 Dreamliner. Source | Globe Machine Mfg. Co.
CompositesWorld.com
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