Induction crucible furnaces for melting of ferrous and nonferrous metals

The advent of electric furnaces offers the advantage of much higher thermal energy utilization efficiency than fuel-fired furnaces. This is due almost entirely to the reduction in flue gas losses.

To compare the potential of electrothermal energy with fuel-fired heating of industrial furnaces, it's useful to consider the substitution coefficient, which is on the order of two to three times greater than the efficiency of electricity.

The mature development of power diodes and thyristors has made it possible to build electrical generators based on the use of variable magnetic fields. Indeed, the induced currents, or eddy currents, produced by this equipment enable us to obtain, through the Joule effect, sufficiently high thermal power to ensure the industrial melting of metals.

This type of thermoelectric melting generator for foundries is the electric induction furnace. Based on this equipment model, furnace manufacturers have developed several types with different capacities and electrical power ratings for use in the foundry industry.

Following an introduction to magnetic fields and a review of the principles of electromagnetic field application, this article describes this modern metal melting process and the design of crucible induction furnaces. It also describes the refractory lining of the crucible, the operating conditions for this type of furnace and its use in foundries.