Induction furnace

An induction furnace is a furnace in which the heat is applied by induction heating of metal. Induction furnace capacities range from less than one kilogram to one hundred tones and are used to melt iron, steel, copper, aluminum, and precious metals. The energy transfer to the metal to be heated occurs by means of electromagnetic induction. Any electrically conductive metal placed in a variable magnetic field is cause of induced electric currents, called eddy currents, which will eventually lead to joule heating.


An induction furnace consists of a nonconductive crucible holding the charge of metal to be melted, surrounded by a coil of copper wire. A powerful alternating current flows through the wire. The coil creates a rapidly reversing magnetic field that penetrates the metal. The magnetic field induces eddy currents, circular electric currents, inside the metal, by electromagnetic induction. The eddy currents, flowing through the electrical resistance of the bulk metal, heat it by Joule heating. In ferromagnetic materials like iron, the material may also be heated by magnetic hysteresis, the reversal of the molecular magnetic dipoles in the metal. Once melted, the eddy currents cause vigorous stirring of the melt, assuring good mixing.

Resistance furnaces 

Resistance furnaces are heating installations that use the heat generated by Joule effect in appropriate heating elements (resistors) located on the walls of the furnace chamber, and transmitted to the work piece to be heated mainly by radiation and convection. The electrical energy transformed into heat in the resistors is used in part to raise the temperature of the charge and in part to heat the walls of the chamber and to compensate for the furnace heat losses.



 Electrical Melting Method Vs Induction Melting  Method


Electrical Melting Furnace

Induction Melting Furnace

As there is resistance coil chances of defusing of coil are frequent. Due to this oxidization the coil corrodes.

Coil is the heavy gauge hollow copper pipe having high temperature and double insulation. Due to circulation of cold water the coil lasts for very long time.

First melting usually takes as long as 30 to 45 minutes, hence the chance of oxidization is more and also there is chance of metal loss.

First melting takes only 10 to 15 minutes resulting in null oxidization and zero loss of metal.

In this method, the coil gets heated first & then the heating of crucible takes place followed by the metal heating, which result in loss of heat and metal.

In this method the metal heats with the help of frequency and so there is no loss of heat and metal.

Due to the heat loss powder consumption is always more.

Due to no loss of heat the power consumption reduces significantly.

Because of no stirring effect the metal does not properly melt. At the time of pouring of the ready metal it is found that the metal oxides also come out with the finished metal creating an improper metal stick or rod.

Because of the stirring effect the metal oxides rise to the top of the melting unit creating a separate layer without blocking the flow of pure metal for making the metal stick or rod.

As there is no water circulation the temperature of the workshop unit remains hot for a very long time.

Due to chiller, the machine gets cooled within 2-3 minutes and the temperatures of the workshop unit remains normal.

There is no auto stirring and the metal is stirred with the help of a carbon rod. The metal stick to carbon rod leading to loss of metal and also mixture of carbon with metal.

In this method there is auto stirring without the need of a carbon rod resulting in no loss of metal which remains pure during the entire process.

As there is no stirring effect, there is addition of copper and silver in gold (99.99%) it is not in uniform micro structure. On rolling of stick from, form the wire (metal coil) received after melting it is found not to be in good condition. Because of this there are chances of breaking of chain which is prepared from the wire and also loss of carat value.

Due to the automatic stirring effect there is perfect distribution of copper and silver to be mixed with gold (99.99%). This perfect mixture helps the wire (metal coil) to remain strong for a longer period time and also giving it a high carat value. The wire and strip received after melting is in very good and perfect condition and there are no chances of breaking

During the second melting process the heat is excessively spread out so it is very difficult to put metal in the form of dust or scrap in the crucible. This requires putting the dust form a safe distance to avoid the heat which may result sometimes in dropping of dust and also loss of metal.

Here there is no heat spread; hence it is very easy to add the metal dust. Therefore there is no metal loss.