Industrial applications of induction heating continue to emerge due to advancements in the design of solid-state induction power sources, the reduction in equipment size, the advantages of integrating computer technology with the induction process and the capability of more accurate and consistent results over other techniques. Some less well-known processes that use induction heating include semisolid forming, shrink fitting, crystal growing, degassing and gettering. From adhesive curing to zone refining, induction heating extends into almost every manufacturing field.
Induction heating of a metallic component is achieved by passing high-frequency electric current through a coil surrounding a workpiece, which in turn induces a high-frequency electromagnetic field in the piece. The magnetic field induces eddy currents in the workpiece, and the electrical resistance of the piece to the flow of current causes the piece to heat up. The depth at which the current flows is dependant on the frequency of the magnetic field; that is, shallow depth at higher frequencies and deeper at lower frequencies. This frequency/case depth relationship is known as the penetration, or reference, depth. The depth of heating is a function of the electrical frequency applied, the heating time and the power density applied to the component being heated.