Induction melting furnaces

How it works

The coreless induction furnace is the melting unit of the secondary steel, foundry and non-ferrous industries — it turns scrap into liquid metal with electricity and no fuel, and in India it is the backbone of the scrap-to-steel economy.

A coreless induction furnace is a refractory crucible surrounded by a water-cooled copper coil. Alternating current in the coil induces currents in the scrap charge, which heats and melts by its own resistance; the magnetic field also stirs the melt. Furnaces range from a few hundred kilograms for foundries and jewellers to 30 or 40 tonnes for steel mills, with medium-frequency power supplies now standard.

Induction furnaces melt what they are given — they cannot refine like a converter or an electric arc furnace — so the charge must be sorted and clean. That is why induction-furnace mills are such demanding scrap buyers and why pre-sorted, low-residual grades command a premium from them.

Where they are used

India has the largest induction-furnace steel sector in the world: several hundred mills producing ingots and billets from scrap and sponge iron for re-rolling into bars. Foundries everywhere use induction furnaces for iron, steel, copper alloys and aluminium. Non-ferrous ingot makers and brass and copper rod plants use them for melting and holding. Electric arc furnaces, the larger alternative, are listed on our steel pages.

Who makes them

American, German and Indian makers dominate the induction-furnace market; India’s Ahmedabad and Kolkata makers supply the domestic induction-steel industry and export to Asia, Africa and the Middle East. Chinese makers supply lower-cost units widely.

Makers

Long-established makers of this class of machine. Names first; the buttons go deeper.

At a glance

• Coil induces current in the charge — no fuel, no electrodes
• Melts but does not refine; charge must be clean
• Few hundred kg to 40 t
• Backbone of India’s induction-steel sector

Other machinery and related grades