CompositesWorld
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99 CompositesWorld.com NEWS N E W S N S N E W S E N W S W from glass/PPS, are robotically machined and drilled near the Pinette press by a Pana- sonic VR-016 robotic system. All of the wing leading edge parts — skin, spar, ribs, reinforcements — eventually come together in the Tool Jig Room for assembly and welding. Fokker has experi- mented over the years with a variety of welding technologies, but for A380 wing leading edge assembly, it settled on resistance welding. For that method, a metal mesh strip coated with PPS is attached to the contact edge of each rib (Fig. 6, p. 96). Te rib is then inserted into the jig, secured by a rib holder rail. Te welder then moves from rib to rib, and a current is applied to each for 1 minute at one end of the metal mesh. Tis is followed by a 1-minute hold and a 1-minute cool-down. Te current melts Fokker Aerostructures thermoplastic composites was one of the composites industry's biggest news stories in the frst decade of the 21 st Century. Tat program also consumes the biggest space at the Hoogeveen plant. Te work is done in the plant's Tool Jig Room, so named because it is dominated by eight two-sided jigs — one side for the left wing, the other side for the right wing — in which Fokker welds the thermoplastic leading edge skin and spar with a series of reinforcing ribs. Each jig accommodates a 3.5m length of leading-edge skin. Each wing leading edge comprises eight 3.5m sections, for a total leading-edge length of 26m, spanning from each wing's inboard engine to its wingtip. Te welding of the thermoplastic skins and thermoplastic ribs is important because this assembly technology creates what is, in efect, a unifed thermoplastic composite structure. Te beneft is signif- cant because it relieves the manufacturer of what would otherwise be a costly addi- tional step necessary for aircraft certi- fcation: Adhesively bonded skins and ribs would require the redundant use of mechanical fasteners. But welded skins and ribs do not. However, this makes the consistency and repeatability of the welding process critical. Te leading edge skin (Fig. 4, p. 96) and spar are fabricated via hand layup, using a glass fber/PPS semipreg provided by TenCate Advanced Composites under the Cetex brand. Te skin and spar are layed up using single plies of the semipreg, which are cut on Gerber Technology (Tolland, CT, US) fatbed cutting tables. Ply positioning guidance is provided by Virtek Vision International's (Waterloo, ON, Canada) laser projection systems. Te parts are bagged and then consolidated in an auto- clave at 320°C, with a total cycle time of 3 hours — 6-9 hours is typical for thermoset composites. Ribs and stifeners (Fig. 5, p. 96) are compression molded on a Pinette Emidecau (Chalon Sur Saone, France) press using the same Cetex material, but supplied by TenCate as preconsolidated sheets. Te Cetex sheets are frst softened in an infrared heater and then quickly transferred to the press, which ofers a 0.5-second closed cycle, says Ofringa. Stif- eners for the wing leading edge, fabricated