An electric arc furnace is mainly used for making steel and consist of devices like refractory-lined vessel and electrodes. Electrodes are normally round in section and comes in segments with threaded couplings, so that as the electrodes wear, new segments can be added. The arc forms between the charged material and the electrode. The charge so formed is heated both by current passing through the charge and by the radiant energy evolved by the arc.

Did You Know? Induction heating process is a method in which the electrical conducting material is heated through by eddy currents induced by a varying electromagnetic field. The principle of the induction heating furnace is similar to that of a transformer.

This type of furnace is widely used in latest foundries especially iron where now couplas are replaced by induction furnaces to melt cast iron. The use of couplas result in the emission of lots of dust and other pollutants but the use of induction furnace has minimized this problem to a larger extent. Induction heating furnace comes in various sizes and configuration. However induction furnace has it's own limitation. The induction process used in foundries lacks refining capacity. Charge materials must be clean of oxidation products and of a known composition, and some alloying elements may be lost due to oxidation (and must be re-added to the melt).

Induction furnace capacities range from less than one kilogram to one hundred tonnes capacity, and are used to melt iron and steel, copper, aluminum, and precious metals. The one major drawback to induction furnace usage in a foundry is the lack of refining capacity; charge materials must be clean of oxidation products and of a known composition, and some alloying elements may be lost due to oxidation (and must be re-added to the melt).

The frequency of operation of induction furnace also vary. Usually it depend on the material being melted, the capacity of the furnace and the melting speed required. A high frequency furnace is usually faster to melt a charge whereas lower frequencies generate more turbulence in the metal, reducing the power that can be applied to the melt.

When the induction furnace operates it emits a hum or whine (due to magnetostriction), the pitch of which can be used by operators to identify whether the furnace is operating correctly, or at what power level.

Features
Following are the features of induction furnace:

• Highest chemical durability.
• Lowest alloy losses.
• Leading to highest metal quality with respect to impurities.
• High refractoriness.
• Available in various sizes.
• Comes in different capacities.

Applications
These furnace are designed from various applications. For applications such as adhesive curing and paint drying, the parts are simply inserted into the heating chamber and the furnace is activated. Following are the application of induction furnace:

• Curing
• Drying
• Brazing
• Soldering
• Melting
• Stainless Steel
• Iron Castings
• Foundries

External Sources
http://www.ichmt.org/abstracts/Plasma99/session-3.html

Articles
Induction Furnace : In Steel Manufacturing

Types
Popular type of induction furnace that are widely used are:

• Induction Melting Furnace
• Induction Metal Furnace