Induction Furnaces

The principle used in induction furnace is comparable to that of the functioning of transformer. A method in which electrical conductors gets heated through eddy currents induced by a fluctuating electromagnetic field. This innovation is of recent origin that finds wide application in industrial and domestic application saving substantial quantities of energy. Induction furnace has minimized several disadvantages that were difficult to control in arc furnace.

Adhesive curing, paint drying, brazing, soldering, melting, iron casting, foundries are some of the areas of application. These furnaces are designed to suit variety of application. Available in different sizes and capacities, these furnaces have unique features, like very high chemical durability, high refractory properties, low alloy losses and evolve premium metal quality free of impurities.

However, the induction process usage in foundry lack refining capacity and materials charged must be free of oxidation products. This will result in loss of alloy elements due to oxidation and must be added again to the molten material. The frequency of induction furnace is dependent on the melted material and the speed as high frequency furnace is faster in melting the charge as against the lower frequency furnace generates more turbulence in molten stage. Strangely, there will be humming, the pitch of which is an indication to identify the operating power level of the induction furnace alerting the operator.

The application of induction furnace in steel industry is phenomenal. Both high and medium frequencies are popular in steel making. Mild steel, Stainless steel, Alloy steel of many grades are some of the types that are usually manufactured by Induction Melting Furnace in steel industry. Other applications are melting scrap, direct reduction of iron, alloy making etc.

Direct reduced iron posed a problem in carbon adjustments till the chemistry of the melt turned out to be under control by virtue of these induction furnaces. Using this technology, continuous castings of billets or rolling mills to make bars are successfully done.

As compared to electric arc furnaces, induction furnaces consume less power. The refractory quantity employed also is low. The cost of electrodes is quite economical. Initial investment on plant and machinery also is much less. These economical advantages in the manufacture of steel by employing induction-melting furnace make this very popular.

All input metals are chemically analyzed before charging to keep control of the composition of the end product. Percentage of sponge iron in the charge is adjusted depending on the high carbon, sulphur and phosphorous content that will be known in chemical analysis. When 80% of the process is through, a sample is tested to ensure the carbon percentage. If it is found to be high more sponge iron is added. If carbon is found to be less then cast iron scrap and turnings are added. This is how the composition is controlled. Since there is no vigorous arcing, the iron is subjected to lesser oxidation keeping the losses to the minimum. Spectrometer usage help control the chemical composition in the production of low alloy steel by Induction Melting Furnace.

Stainless steel is produced before making mild steel and the raw material is purged with molten metal to which liquid elements and alloy are added as it progresses. Ferro-alloy is added while the mild steel scrap is melted and this molten metal is then refined. Special cast iron, stainless steel used for utensils are also made in these furnaces. The economy and versatility of these furnaces have created an everlasting demand for these induction furnaces.

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