Designing inductors for heating internal surfaces
July 22nd, 2010
Induction heating of the internal surfaces of a workpiece for applications such as hardening, tempering, annealing, shrink fitting, and brazing has several unique features related to the physics of the process and the selection of process parameters, compared with heating of external surfaces. There are four main coil styles for heating internal surfaces: solenoid-type cylindrical coils (single-turn and multiturn), rod-type coils, hairpin inductors (single or double), and “C”-core coils. This article reviews design features of solenoid-type internal coils (also called inside diameter or ID coils), which are the most popular inductors for heating internal surfaces.