Induction furnace converts three-phase alternating current into direct current after rectification, and then converts direct current into adjustable medium frequency current to supply medium frequency alternating current flowing through capacitor and induction coil, generate high-density magnetic lines of force in induction coil, cut metal materials in induction coil, and generate large eddy current in metal materials. This eddy current also has some properties of intermediate frequency current, that is, the free electrons of the metal itself flow in the metal body with resistance to generate heat. For example, if a metal cylinder is placed in an induction coil with alternating medium frequency current, the metal cylinder does not directly contact the induction coil. The temperature of the energized coil itself is very low, but the surface of the cylinder is heated to redden, or even melted, and this reddening and melting speed can be achieved as long as the electrical power is adjusted. If the cylinder is placed in the center of the coil, the temperature around the cylinder is the same, and the induction furnace will not produce harmful gas to pollute the environment.

Because induction furnace has the above advantages, it has been widely used in various industries. For example, if cupola coke furnace is used to smelt molten iron, the composition of molten iron from the cupola cannot be adjusted, the temperature is difficult to control, the quality of the cast roll is poor, the yield is low, and the benefit is poor. Moreover, the molten iron temperature of this cupola cannot rise to 1600 ℃. The induction melting furnace is used to smelt molten iron, and the benefit is obviously improved.