An induction furnace works by utilizing a high-voltage electrical source from a primary coil. This coil induces a low-voltage, high current in the secondary coil or metal.
The two types of induction furnaces are coreless induction and channel induction furnaces. The coil in a coreless induction furnace consists of high-conductivity copper tubing wound into a helical coil. The coil is water cooled by water recirculating and being cooled in a cooling tower. Ramming a granular refractory between the coil and hollow internal former forms the crucible. The interaction of the magnetic field and electrical currents produce a stirring action within the molten metal. The coreless induction furnace is generally used for melting high-melting-point alloys.
The molten metal is contained in a refractory-lined steel shell in a channel induction furnace. An induction unit that forms the melting component of the furnace is attached to the steel shell and connected by a throat. The secondary component is comprised by the formation of a transformer in which the molten metal loops. The metal is forced to circulate into the main well of the furnace by the heat generated within the loop. Channel induction furnaces are generally used as a holding and super-heating unit for higher melting point alloys or for melting low-melting point alloys.