thermoplastic welding is an emerging technology targeted at significantly reducing the manufacture of aerospace structure by eliminating fasteners and the touch labor associated with fasteners to prepare , install , and inspect the assemblies . thermoplastic welds , however , suffer from low pulloff strength because the metal foil susceptor used to heat the bondline is essentially a foreign substance in the weld that is unreinforced . the susceptor of the present invention provides z - direction barbs on the susceptor to increase the pulloff strength .