SUPERIORITY OF INDUCTION MELTING

Over cupola

*To heat the iron upto 1400 C cupola consumes 55 kg. /ton of fuel against 500   kWH of Induction.· Cupola uses extra 60 kg/ton fuel to super heat the melt 100   C   compared to 65 kWH /ton consumption of induction.Elimination of pig-iron.
*Utilization of low cost borings and turnings gives on effective metal coast saving   of 33%.
*The metal loss is only 1% compared to 5-10 % in cupola.The consumption of   refractory is 10 kg./ton in induction.
*Heat efficiency of cupola is 10-15% but the over all heat efficiency in Induction is   40-50%.
*Sampling, adjustment of temperature, holding of temperature is impossible with   cupola.
*The composition in cupola alter three times per day. Changes of carbon, silicon   in   the melt are negligible in Induction for holding for few days.

Over arc furnace

Cooler, quitter, cleaner and safer working condition, due to elimination of noisy arcs & gaseous product.· Elimination of Electrode consumption (5-15kg./ton).

*Shorter melting time, due to no 'carbon pick-up' which eliminates the oxidizing   operation and result in lower power consumption.
*Fast and complete homogenization of alloy due to stirring action.· Lower   oxidation   loss.· Better power utilization of equipment.· Ability to hold metal   temperature   for long period of time.
*Elimination of stock control equipment when melting clean scrap.
*Elimination of sample taking and analysis of each melt, due to more predictable   melting.

Specialty of melting iron

*A continuous supply of molten metal.
*Excellent temperature control.· Elimination of air pollution problems without   costly   collection systems.
*Elimination of sulphur pick-up and silicon loss.
*Easier control of carbon content.
*Improved machinability.
*Higher physical properties in the iron.
*More nearly uniform hardness of iron .
*Complete homogenous metal because of stirring action.
*Increased fluidity that allows lower pouring temperature.
*Excellent, reproducible chemistry control.
*Ability to hold iron over prolonged periods without discernible change in   chemistry.
*Melt losses on the order of only 2% for normal gray iron, and even better on Si   and alloy iron.
*Elimination of effect of humidity variations on iron quality.
*Highly automated controls
*Elimination of need for highly skilled operator.
*Comfortable, clean, cool working conditions.
*Reduction of slag disposal problems.
*Elimination of coke and limestone storage and handling .
*Elimination of pig bed because cold ladle metal can be returned for rehashing .
*Heating of ladles pouring temperature by filling two or three times and returning   chilled metal to the furnace.
*Continuous pouring schedule releasing space required for mold storage.·   Simplified   charging and reduced labour requirements.
*Regulation of rates to suit requirements without incurring chemistry and   temperature problems.
*Ability to melt borings, turnings, and scrap materials with excellent recovery and   no charge formality other than the charge opening of the furnace
*Accurate   and rapid chemistry without intermediate iron.
*Ability to super heat.
*Fire hazards is minimum. The Induction furnace does   excellent job in eliminating   segregation with no labour.
*It is cold top, less oxidation and higher recovery.
*Better utilisation of available space
*Used for melting steel & alloys requiring lower carbon than that obtainable in   crucible & are furnace.
*Induction melting in acids lining of rolling mill scrap yields a steel with all qualities   of acids steel which are so valuable for gun & aeroplane and other steel   requiring   good transverse test.
*Heat resisting steel, die & other complex steel , and refractory chromium alloys   can be melting in acid or basic linings without substantial alteration of   composition.
*Manganese steel scrap can be remelted without substantial loss of manganese.

Aluminium melting : *

*The increased thermal resistance of oxide coated particle of Aluminium is the   chief reason why they are difficult to melt in furnace operated on the principle   of   radiation, convection and conduction. This difficulty is overcomes by   induction .

*As the emissivity factor of Aluminium is very low, heat given to the path through   surface or the surface load is very low, but the induction surface rating is more   than 3 times than others.
*Because of the stirring actions there is uniform temperature throughout the bath   in Induction heating.
*In fuel fired or electric furnaces the bath temperature is uneven and vary from 500    C to 750 C, because of this melting loss and gas absorption is very high but it is   very low in Induction because of stirring action .
*Another advantage of electro magnetic stirring is that in many case the   ingredients of high melting point like Copper or Nickel can be dissolved directly   thus eliminating the use hardeners.
*The hydrogen 'ofcourse' is not present or produced on the gaseous covering of the   bath contained , in Induction furnaces as it is a cold top. The hydrogen absorption   in the path is eliminated.
*The most of the users of the Induction furnace in the foundry report that they are   not using the fluxes and they have found only one half the degassing agent to be   necessary as compared with other furnaces.
*The reverberatory furnace of good condition can rarely prevent the melting loss of   much less than 5% and a crucible furnace of tilting variety is ranged between 2-3%   while the melting loss is of 0.8% in Induction.

Brass

*The precision alloying is possible by directly adding the elements.
*The zinc loss is minimum
*The metal loss is less than 1% compared to 5% in fuel fired furnaces. The high   Frequency furnaces melts hard materials of Tungstan-Cromium-Carbide group and   which can be casted in form moulds as a temperature of 2000 to 2300 C.

Galvanizing induction furnace

The Induction melting unity provides an entirely new approach with refractory container of essentially unlimited life which do not in any way contribute to the formation of dross from job.· The galvanizer will agree however that 10% can be gained by elimination of iron kettle and at least 10% by perfect temperature control.

Vaccum induction furnace

*One of the main characterised of vacuum melt alloys are their consistent   properties e.g. vacuum melted copper is practically free from volatile impurities,   and better than o.f. h.c. copper.
*Low carbon content of less than 0.005% is possible in vacuum Induction melting.   This is better than are melting.· Vacuum melted magnetic materials give better   performances than by any other process.
*It is easier to control boron in vacuum Induction melted alloys. only 15 ppm of   boron in waspaloy doubles the rapture life · The vacuum melted bronze could be   brazed where as the other is not .
*The vacuum melted bronze could be brazed where as the other is not.
*The vacuum melting of 'cleanliness' alloys (52100) gives a marked increase in   bearing life.
*It is used for production of finished castings by lost wax investment process to   increases both titanium and aluminium content in Nickel base alloys and there-by   achieve high temperature strengthening associated with the   precipitation hardening elements.

Zone refining

Induction heating is ideal method of heating. This gives a very short zone than any other process.· Induction Heater is preferred in floating zone technique, zone leveling, crystal pulling and levitation.· The stirring action of Induction melting increase the efficiency of the zone refiner.

Levitation induction melting

*Rapid alloy preparation and also alloying addition can be made while the melt is   in   levitation.
*The charge touches no crucible or container during the heating, melting and   draining stages.
*The heated or molten charge can be protected by a suitable atmosphere and   vacuum.
*The molten charge can be drained gradually or dropped as a whole and it may   even be feasible to solidify the still levitated melt and drop it solid.
*Volatile impurities can be distilled or pumped away .
*Used for melt purification and homogenization .
*Gas -metal reaction kinetic studies, solidification studies, Liquids slag and   refractory reaction studies can be conducted.
*Working in weightless condition permits the creation of special alloys which can   not   be product by other means.