SEP 2018


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SEPTEMBER 2018 62 CompositesWorld FEATURE / Welding Thermoplastic Composites calibrate the process. But we prefer to measure the temperature in the weld and feed that back to manage the power to the coil." "Our welding processes are digitally controlled and all process data is stored," says Offringa at GKN Fokker, "but we are moving toward inline process control, based on real-time tempera- ture measurement." He believes this is possible for induction and resistance welding within a few years, while ultrasonic welding is already fairly close. Villegas at TU Delft states that in-situ process monitoring of sequential ultrasonic welding is possible based on the power and displacement curves provided by the welding machine, which make it possible to quickly define optimum processing parameters. In addition to process control, KVE is also working on inline inspection. "If the weld shows a problem, we just go back and reweld it," says van Engelen. "is is why thermoplastic composites are so good," notes Raynal at Composite Integrity. "Rewelding does not hurt them. We have specific technology to weld and de-weld with resistance welding to disassemble by injecting current." FIG. 7 Process time independent of weld length Conduction welding is a new technology being used by GKN Fokker (Hoogeveen, The Netherlands) that uses a kind of hot iron to supply heat along the weldline in seconds. Like resistance welding, process time is independent of weld length, making it attractive for joining 6-10m-long TPC stringers to fuselage skins. Source | GKN Fokker INTERNATIONAL INC. EUROPE Sarl ASIA LTD ADVANCED MATERIALS LTD PRODUCT SPOTLIGHT Thermalimide RCBS Ultra high temperature release film Video available online Benefits: • High temperature resistance for processing thermoplastic parts. • Flexibility for applying pressure over simple contoured shapes. • Superior toughness in comparison to metallic foils, helps avoid tearing.

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