Induction Melting

Principle of Induction Melting

There is no essential difference between using a pulsed magnetic field to heat a solid billet and melting metal for casting. The principle of induction heating described in this chapter still applies here. The pulsed magnetic field on the surface of the melt induces an induced electromotive force in the material, which then acts as a secondary short-circuited coil, causing current to flow in the metal and heat the metal. Except when the scrap steel is heated to the relative magnetic permeability of the Curie point, all concepts related to the skin layer depth can be used without restriction for the molten material.

The advantages of induction melting are as follows

1. It can avoid the generation of undesirable metallurgical reactions such as oxidation and reduction reactions, and eliminate harmful gases and combustion products such as sulfur pollution.

2. Fast melting speed. For the same capacity, induction furnaces have a higher daily output than other types of furnaces.

3. The operating cost of the equipment is low, and its energy cost is as low as or slightly higher than that of high-efficiency fuel furnaces.

4. Improved working conditions, no large amount of heat loss and smoke from the furnace, no pollutants and ash, etc.

5. Reduced metal loss. When smelting copper-zinc alloys, the zinc loss due to oxidation can be less than 0.5% by weight.

6. Automatic stirring (this may be harmful under certain conditions).

7. Low maintenance cost of refractory lining. Because the furnace body is not higher than the metal itself like a fuel furnace, the cost of refractory lining of the slot induction furnace is lower than that of the fuel furnace, but the cost of refractory materials of the coreless induction furnace is higher.

8. Can be used for special processes, such as vacuum smelting, and can be used to produce alloys that cannot be produced by other methods. The description in this article is a typical smelting equipment. Since the principles of these equipment are the same, only two commonly used electric furnaces need to be discussed-coreless induction furnaces and slot induction furnaces