Application Of Induction Heating

Induction heating finds its greatest application in the metals-processing industries Primary use fall into major categories of heating prior to metalworking, heat treating welding and metal melting .while these are the most common uses, a variety of other operations such as paint curing adhesive bonding and zone refining of semiconductors are also amenable to induction heating methods. Each of these application is briefly discussed below.

Preheating prior to Metal working :- Induction heating prior to metal working is well accepted in the forging and extrusion industries its readily adapted to through preheating of steel, aluminum alloys, and specially metals such as titanium and nickel–base alloys. Frequently the work pieces in these type of application consist of round, square, or round –cornered square bar stock .For steel the high heating rate of induction processes minimizes scale and hence material losses the rapid heating boosts production rates Induction heating is also useful for selectively preheating bar stock for forming operations such headings.

Heat Treating :- Induction heating is used in surface and through hardening tempering and annealing of steel .A primary advantage is the ability to control the area that is heat treated. Induction hardening the most common induction heat treating operation improvise the strength ,wear, and fatigue properties of steel .Steel tubular products, for e.g. Lend themselves quite readily to hardening by induction in continuous –line operation. Tempering of the steel by induction, although not as common as induction hardening of steel restore ductility and improves fracture resistance. Also less commonly applied is induction annealing which restore softness and ductility–important properties for forming of steel aluminum alloys and other metals.

Melting :- Induction processes are frequently used to melt high quality steel and nonferrous alloys (e.g. aluminum and copper alloys ) advantage specific to induction melting as compared with other melting processes include a natural stirring action (giving amore uniform melt) and long crucible life ..

Welding Brazing and Soldering :- High-frequency induction welding offer substantial energy saving because heat is localized at the weld joint the most common application of induction welding is welded tube or pipe products that lend themselves to high-speed ,high –production automated processing .induction baring and soldering also rely on local heating and control capabilities inherent in the induction heating process

Curing of Organic Coating : Induction is used to cure organic coating such as paint on metallic substrates by generating heat with in the subtract .By this mean curing occurs from within minimizing the tendency for formation of coating defects . A typical is application is drying of paint on sheet metal.

Adhesive bonding :- Certain automobile parts such as clutch plates and brake shoes make use of thermosetting adhesive as in paint curing induction heating of the metals parts to curing temperature can be excellent mean of achieving rapid bonding metals to nonmetals seals widely used in vacuum device also rely heavily on induction heating.

Semiconductor Fabrication :- The growing of single crystal of germanium and silicon often relies on induction heating . Zone refining zone leveling ,doping ,and epitaxial disposition of semiconductor materials also make use of the induction process.Tin Reflow. Electrolytic ally deposited tin coasting on steel sheet have a dull, matte , Non uniform finish .Heating of the steel to 230 deg (450 f) by induction causes reflow of the tin coating and result in a bright appearance and uniform coverage . Sintering:- Induction heating is widely used in sintering of carbide perform because it can provide the necessary high temperature (2550 deg or 4620 deg ) in a graphite retort or susceptor with atmosphere control other perform of ferrous and nonferrous metals can be sintered in a similar manner with or without atmosphere protection.

Advantage of Induction Heating :-
Induction Heating offer a number of advantage over furnace techniques ,such as:
1] Prior to the development of induction heating gas and oil-fired furnace provided the prime mean of heating metals and nonmetals . 
2] Quick heating development of heat within the work piece by induction provides  much higher heating rates than convection and radiation processes  that occur in furnace
3] Less scale loss. Rapid heating significantly reduces material loss due to scaling
relative to slow gas fired furnace process
4] Fast start-up. Furnace contain large amount of refectory materials that must   be heated during start up resulting in large thermal inertia the internal heating   of the induction process eliminate this problem and allow much quicker start-up.
5] Energy saving when not in use the induction power supply can turned off   because restarting is so quick. With furnace energy must be supplied   continuously to maintain temperature during delays in processing and to avoid    long start-up.
6] High production rates because heating time are short induction heating often   allows increased production and reduced labour cost.
In addition to those listed above other advantage that induction heating system offer include
1] ease of automation and control
2] reduced floor–space requirements
3] quite, safe, and clean working condition
4] low maintenance requirements .