An innovative process for the production of lightweight thermoplastic honeycomb structures using Victrex APTIV film has been developed by PlastiCell of France. The unique design of the honeycomb provides an ideal solution for aerospace and other industries seeking to reduce weight while maintaining high levels of strength and stiffness. APTIV thermoplastic honeycomb can be thermoformed into shape in combination with fibre reinforced VICTREX PEEK polymer composite skins to create unique structural parts without the use of adhesives. Consisting only of PEEK polymer, any scrap and end of life parts can be fully recycled, providing further advantages over traditional phenolic/aramid fiber and aluminium based honeycombs.
The process to produce PlastiCell’s honeycomb comprises two main steps; 1) forming thin APTIV film sheets to create semi-hexagonal shapes, and 2) sequential stacking of sheets and welding with a laser along lines at the contact points to achieve melt-bonding. Core blocks made in this way can be machined to shape before molding by a variety of processes. Finished thermoplastic honeycomb structures are produced by press molding pre-formed and pre-heated composite skins onto the honeycomb in a forming tool. The combination of the pressure inside the mold and the temperature of the mating surfaces cause the honeycomb core to conform to the mold geometry while ensuring 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,” said 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. VICTREX PEEK polymer not only meets these requirements but also offers excellent chemical resistance, high temperature performance, hydrolysis resistance, and also has excellent wear resistance when compared with other high performance engineering polymers,” said Didier Padey, Market Development Manager France, Victrex Polymer Solutions.
Apart from its unique performance properties and environmental benefits the VICTREX PEEK-based honeycomb provides numerous other advantages including excellent impact resistance; unlike an aluminium or thermosetting honeycomb, PlastiCell’s honeycomb will not remain deformed by accidental impacts during machining or assembly of the part and, due to the material’s high temperature performance, (the honeycombs can operate continuously up to 220°C (428°F), 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 unique flexibility of the thermoplastic honeycomb even allows it to be formed into cylindrical shapes. Additionally, parts can be permanently laser marked for product identification and traceability.