Electric Induction Furnaces

Electric induction furnaces are the highly used furnaces for melting iron and non ferrous alloys. As compared to other cupola furnaces, these furnaces are pollution free and have outstanding metallurgical control. They are available in capacity ranging from a few kilograms to 75 tonnes.

Principle :
Firstly the high voltage is passed in the primary coil, which induces low voltage and high current across the metal charge which acts as a secondary coil. Due to electrical resistance, electrical energy is converted into heat which fuses the charge. Once the metal is in its molten state the magnetic field yields a stirring motion. The stirring rate is determined by the applicable power and frequency. This rate is controlled to lower the temperature gradients in the charge and to assure entire melting of charge and adequate mixing of alloy and fluxing materials. On the other side, excess stirring can raise lining damage, oxidation of the alloys, high amount of slag, inclusions and gas pick-up.

 

Types :
The two most common electric induction furnaces are :

Usage :
Electric induction furnaces are available in varied sizes. Efficient as well as durable, these furnaces are capable to melt a vast range of metals, still little refining of the metal is possible. Due to reduced refractory wear, the operating costs of them are very less. The melting time of metal is very small thus metal is delivered at small and regular intervals. Along with ease of simplicity, they need very small quantities of metal composition which can be easily melted in very less time. Around 60% of the energy supplied to the furnace is transferred to the charge. The efficiency of an induction furnace installation is determined by the ratio of the load useful power to the input power drawn from the utility. The overall fuel consumption in the furnace is over 2000 kWh/ tonne.

Disadvantages :