thermoplastic welding is an emerging technology targeted at significantly reducing the manufacturing cost of aerospace structure by eliminating fasteners and the touch labor associated with fasteners to prepare , install , and inspect the assemblies . quality welds are highly dependent upon achieving appropriate temperatures everywhere along the bond line . the present invention is a system that uses a secondary coil to detect misalignment between the induction coil and the susceptor which would result in an excessive bond line temperature and to provide control signals for the coil or parasitic compensation to avoid the overheating .