# Induction Heating

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## induction heating

[in′dək·shən ¦hēd·iŋ]
(engineering)
Increasing the temperature in a material by induced electric current. Also known as eddy-current heating.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## Induction Heating

the heating of current carriers through the generation of electric currents in them by an alternating electromagnetic field. The power released in a conductor by induction heating depends on the dimensions and physical properties of the conductor (specific electric resistivity and relative magnetic permeability), as well as on the frequency and intensity of the magnetic field. In induction heating the electromagnetic field is supplied by induction heaters.

Induction heating is characterized by the nonuniform release of power in the object being heated. Eighty-six percent of the power is released in the surface layer (the so-called penetration). The penetration of the current Δ (in meters) is Δ = where ρ is the specific electrical resistivity in ohms • m, μ, is the relative magnetic permeability, and f is the frequency in hertz (Hz).

Low-frequency (50 Hz), medium-frequency (up to 10 kHz) and high-frequency (over 10 kHz) currents are used in induction heating to generate an alternating electromagnetic field. Mechanical and static converters, as well as tube oscillators, are used to supply medium- or high-frequency current to induction heaters.

Induction heating is most widely used in the melting of metals, zone melting, and heating for pressure shaping. Induction heating is the most advanced contactless method of transmitting electrical energy to the object being heated, converting electrical energy directly into thermal energy. A schematic diagram of a device using induction heating is shown in Figure 1.

Figure 1. Schematic diagram of an induction heating device: (1) power supply, (2) capacitor, (3) induction heater, (4) lined crucible, (5) object being heated

### REFERENCES

Babat, G. I. Induktsionnyi nagrev melallov i egopromyshlennoe primenenie. 2nd ed. Moscow-Leningrad, 1965.
Elektrotermicheskoe oborudovanie: Spravochnik. Moscow, 1967.

A. B. KUVAIDIN

## Induction heating

The heating of a nominally electrical conducting material by eddy currents induced by a varying electromagnetic field. The principle of the induction heating process is similar to that of a transformer. In the illustration, the inductor coil can be considered the primary winding of a transformer, with the workpiece as a single-turn secondary. When an alternating current flows in the primary coil, secondary currents will be induced in the workpiece. These induced currents are called eddy currents. The current flowing in the workpiece can be considered as the summation of all of the eddy currents.

In the design of conventional electrical apparatus, the losses due to induced eddy currents are minimized because they reduce the overall efficiency. However, in induction heating, their maximum effect is desired. Therefore close spacing is used between the inductor coil and the workpiece, and highcoil currents are used to obtain the maximum induced eddy currents and therefore high heating rates. See Core loss

Induction heating is widely employed in the metalworking industry for a variety of industrial processes. While carbon steel is by far the most common material heated, induction heating is also used with many other conducting materials such as various grades of stainless steel, aluminum, brass, copper, nickel, and titanium products. See Brazing, Heat treatment (metallurgy), Soldering

The advantages of induction heating over the conventional processes (like fossil furnace or salt-bath heating) are the following: (1) Heating is induced directly into the material. It is therefore an extremely rapid method of heating. It is not limited by the relative slow rate of heat diffusion in conventional processes using surface-contact or radiant heating methods. (2) Because of skin effect, the heating is localized and the heated area is easily controlled by the shape and size of the inductor coil. (3) Induction heating is easily controllable, resulting in uniform high quality of the product. (4) It lends itself to automation, in-line processing, and automatic-process cycle control. (5) Startup time is short, and standby losses are low or nonexistent. (6) Working conditions are better because of the absence of noise, fumes, and radiated heat. See Electric heating

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.

## induction heating

In piping, the heat treatment of completed welds by the heat generated by the use of induction coils around the piping.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
For the practice of induction heating, it means a quadratic dependence of the heat emitting in this region of sheet metal.
GH IA is part of GH Group -one of the largest, most experienced induction heating companies in the world.
Induction heating can be performed as part of the MetalJacket treatment and coating process, eliminating all wet chemistry except for the coating itself.
"His extensive sales experience and wealth of induction heating expertise will prove invaluable as we expand our product range with power supplies and systems from GH Group.
Ferromatik offers nXheat in two forms--an all-zone arrangement in which induction heating completely replaces conventional heater bands, and a Hybrid version in which induction technology is applied only to the feed zone of the barrel while conventional band heaters handle the downstream zones.
Rochester, NY, August 27, 2010 --(PR.com)-- GH Induction Atmospheres, part of the worldwide GH Group, has introduced a new series of 13 induction heating power supplies with a wide frequency range for increased flexibility.
Xaloy Inc., New Castle, Pa, has come up with a more economical "hybrid" version of its nXheat induction heating system for injection machine barrels (previously named Indx).
Inductoheat, the world's largest manufacturer of induction heating equipment, offers product lines ranging from general purpose machines to custom engineered, fully automated heat treating systems, With more than twenty companies around the world, including North and South America, Europe, Australia and Asia, engineering excellence has no boundaries.

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