Inductotherm India Pvt. Ltd.-induction, furnace, melting, heating, heat treatment, welding, reheating, foundry, steel, ingot, induction, hardening, forging, brazing

INDUCTION MELTING FURNACE

The coreless induction furnace is composed of a refractory container, capable of holding the molten bath, which is surrounded by a water cooled helical coil connected to a source of alternating current. Figure shown is a simplified cross section of a coreless induction furnace.

The principle of operation of the induction furnace is the phenomena of electro-
magnetic induction.

The induction (generation) of the electrical current in a conductive metal (charge) placed within a coil of conductor carrying electrical current is known as electromagnetic induction of secondary current.

The alternating current applied to the coil produces a varying magnetic field which is concentrated within the helical coil. This magnetic field passing through the charge induces secondary current in the charge piece. The current circulating in the charge produces electrical (I²R) losses which heat the charge and eventually melt it.

INDUCTION HEATING - A BETTER WAY

Why induction heating ?

Induction heating is a subfield of industrially used electric heating. All electrically - conductive materials can be heated quickly and cleanly with pollution free induction heating. Features include :

Selected parts of the workpiece can be heated.

Heating time and temperature can be precisely controlled.

There is no smoke or soot pollution;

Heating operation can be integrated in semi - automatic production sequences;

Induction equipment can usually be operated by unskilled personal

Key advantages of induction heating

Very fast partial hardening;

High production rates;

Significant reduction in pollution, distortion, forging scale, energy and space requirements;

High degree of reproduction and automation;

What is induction heating ?

Placing a metal body in an alternating magnetic field creates eddy currents, causing losses through which the metal is heated.

Skin effects concentrate these currents in the outer layers. The inductor traversed by an alternating current creates a magnetic field, which should be optimally adapted to the workpiece.

The depth of heating can be influenced by varying the AC frequency, but it also depends on the concentration of flux capacity, on the length of treatment and the material of the workpiece, i.e. its heat - conduction properties.

Medium frequency is usually used for melting , forging heat treatment and annealing. For hardening and soldering, medium or high frequency may be used, depending on the treatment required.

Major uses of induction heat treatment

Melting ferrous and non - ferrous metals with temperatures up to 1800⁰c.

Heating for forging up to 1250⁰c.

Stress relieving and normalising steels after cold forming between 750⁰c and 950⁰c.

Surface hardening of steel or cast iron workpieces at 850⁰c to 950⁰c.

Soft soldering and brazing up to 1100⁰c.

Recrystallisation.

Tube and Pipe Welding.

Tube Welding Process In the HFI (High Frequency Induction) tube welding process, high frequency current at approximately 400 kHz is induced in the open seam tube, an induction coil located ahead of (upstream from) the weld point, as shown in the picture.

The coil acts as the primary of a high frequency (HF) transformer, and the open seam tube acts as one-turn secondary. As in general induction heating application, the induced current path in the work piece (formed strip) tends to confirm to the shape of the induction coil. Most of the induced current completes its path around the end (apex) of the Vee-shaped opening in the strip.

Last update on - 7th March, 2007