French materials company PlastiCell has developed an
interesting new technology, creating more design opportunity. Honeycomb cells
made from high-performance plastic film provide significant strength and
One target application is aircraft OEMs that are trying
to dramatically reduce weight, like the Boeing Dreamliner 787 which remains
about 8 percent above its projected weight.
The cells are made from Victrex APTIVô film, which are thermoformed
into shape in combination with fiber reinforcement. No adhesives are used.
Because they consist only of PEEK polymer, any scrap and end-of-life parts can
be fully recycled, providing further advantages over traditional
phenolic/aramid fiber and aluminum-based honeycombs.
The honeycomb structures are made via two steps ó forming
thin APTIV film sheets to create semi-hexagonal shapes, and sequential stacking
of sheets and welding with a laser along lines at the contact points to achieve
Core blocks made in this way can be machined to shape
before molding by a variety of processes. Finished structures are produced by
press molding pre-formed and pre-heated composite skins onto the honeycomb in a
forming tool. The honeycomb cores conform to the mold geometry due to the
combination of the pressure inside the mold and the temperature of the mating
surfaces. The result is excellent bonding between the core and the skins.
"Unlike traditional honeycombs, which are produced with
adhesive systems, the PlastiCell process uses laser welding to join the APTIV
film layers within the honeycomb matrix. This maintains the performance
properties of the base film and this is what makes this solution so ideal,"
says Marc Le Monnier, founder and manager of PlastiCell.
"The thermoplastic film used for the honeycomb and for
the surface skins must fulfill the aircraft industry standards for flame
performance, smoke and toxicity, as well as offering mechanical performance and
low weight," says Didier Padey, market development manager France for Victrex
Victrex PEEK meets these requirements and also offers chemical
resistance, high temperature performance, hydrolysis resistance, and also has wear
resistance when compared with other high-performance engineering polymers.
PEEK-based honeycomb is also said to provide numerous other
advantages, including impact resistance. Unlike an aluminum or thermosetting
honeycomb, PlastiCell's honeycomb will not remain deformed by accidental
impacts during machining or assembly of the part, or due to the material's high
temperature performance. The honeycombs can operate continuously up to 428F, a
thermoformable honeycomb core allows for the production of parts with short
cycle times using an autoclave-free process.
There is no size
constraint as it is possible to make an endless honeycomb using PlastiCell's
manufacturing process. Part size limitation is dictated by the hydraulic press
platen size. Flat and curved parts can be made using this process and the
flexibility of the thermoplastic honeycomb allows it to be formed into
cylindrical shapes. Additionally, parts can be permanently laser marked for
product identification and traceability.
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