INDUCTION HEATING is a method of heating electrically conductive materials by the application of a varying magnetic field whose lines of force enter the workpiece. In this process, the varying magnetic field induces an electric potential (voltage), which can then create an electric current depending on the shape and the electrical characteristics of the workpiece. These so-called eddy currents dissipate energy and produce heat by flowing against the resistance of an imperfect conductor.
Because all metals are fair electrical conductors, induction heating is applicable to several types of metal processing operations such as melting, welding, brazing, heat treating, stress inducement, zone refining, and heating prior to hot working. The technique also lends itself to a variety of nonmetal applications including adhesive bonding, graphitizing carbon, drying, curing, and superheating glass. Of these applications, heat treating predominates in terms of the number of units used, with surface hardening of steel and cast iron being the most prevalent use. Compared to furnace techniques, induction heating can often provide energy savings and much higher heating rates than convection, radiation, conduction, or even flame-impingement processes. Other advantages of induction heat treating, which stem from this noncontact method and its generation of heat within the workpiece, are:
Ease of automation and control
Reduced floor space requirements
Quiet and clean working conditions Suitability for integration in a production line or general work area due to the elimination of secondary or radiated heating