Abstract: Susceptors for induction heating for use in thermoplastic welding are tailored to provide precise control of the heat applied to the weld and especially to control overheating at the edges of susceptor. The preferred susceptor has a central portion having a uniform pattern of substantially similar openings and selvage edge strips devoid of openings to provide a low impedance current path for eddy currents at the edges. We can create aerospace structure, particularly a wingskin-spar assembly, without fasteners.

Abstract: An asymmetric coil which has an "A" winding on one pole of the "C" core and a "B" winding of opposite helical twist, on the other pole, we can achieve relatively uniform, intense heating between the poles with relatively insignificant heating outside the poles. Only one core winding is active at one time. This coil allows us to heat uniformly to the ends of the susceptors on the ribs without remelting or overheating the welded area under the abutting spar, as FIG. 6 illustrates. The asymmetry provided by the two windings of opposite helical sense and the core design allows us to travel in either direction by activating the appropriate coil.