In October 2020, Victrex and French aircraft manufacturer and equipment supplier Daher announced that they had produced a 176-ply, 1.2-inch-thick thermoplastic structural aircraft panel using AFP and LMPAEK UDT. This thickness has not been obtainable previously, according to Victrex. The company says the 47 x 23-inch panel meets aerospace industry standards for porosity, crystallinity, consolidation and ply bonding.
“What we see here is our unique UDT properties contributing to the fast AFP process, developed and demonstrated by partners Coriolis Composites and Electroimpact. These manufacturing rates enable all the exciting possibilities of metal replacement with thermoplastic composites on a far-reaching scale in aircraft design,” commented Tim Herr, director of Aerospace at Victrex, in a company press release.
Larroque says the parts made with AFP and LMPAEK could be used for large primary structures. The material would also be appropriate for secondary structural parts like brackets and system attachments, which carry high loads.
Both the LMPAEK resin and the parts made from them must go through the aircraft industry certification process before they can be used for large-scale production.
Reduced Manufacturing Time
Thermoplastic composite companies are using new equipment to reduce the time and steps in production. Continuous compression molding (CCM), for example, enables manufacturers to make a large quantity of laminates very cost effectively. Traditional presses have limitations on the size of the parts produced. “The required pressure, temperature, size and cost of equipment go up exponentially as you go to larger and larger laminates,” says Leach.
One alternative for large-scale parts is vacuum-only processing. “AFP processes are getting to a pretty high level of consolidation, where you may just need a final, vacuum-only process to fully consolidate the part,” says Leach. “You may not even need that; you may be able to fully in-situ consolidate the part.”
To achieve the necessary cost reductions and speed for production of larger parts and variable thickness parts, manufacturers will need to move to automated layup; it’s just not practical to lay up and pack the plies by hand, says Leach. Some companies are using pick-and-place robotic systems, which can lay the fabric forms (dry or prepreg) and increase or decrease the number of plies in certain areas. This enables manufacturers to more easily tailor parts for weight, stiffness and strength.
Injection overmolding is being used to consolidate aircraft components, adding stiffener or attachments to a part. “If you’re going to use continuous fibers, you’re limited in geometry, whereas injection molding can give you much more complex geometry,” says Leach. At high volumes, this can be a very cost-effective way of creating complex shapes.