The Principle & Use of Induction Furnace For Steel Melting

Induction furnace for steel melting utilize the principle of electromagnetic induction to heat metal. They are mainly divided into two types: chute type and crucible type.

The chute type operates continuously using the Joule heat of the molten metal, while the crucible type relies on the heat generated by the charge itself to melt the metal.

Crucible type furnaces typically have a smaller capacity and are suitable for scientific research, new product development, and precision casting.

Induction furnaces can also be classified as cored (IF) or coreless (IF) furnaces, depending on whether they have a furnace core. They are also classified as power frequency furnaces and medium frequency induction furnaces, based on their frequency.

The advantages of induction heating are high thermal efficiency, precise temperature control, and rapid melting. The operating frequency and power of the induction furnace determine its heating characteristics, which can be adjusted according to different metals and process requirements.

The Principle & Use of Induction Furnace For Steel Melting

The core principle of an induction electric furnace is electromagnetic induction and the electrothermal effect. It can be understood as a "transformer" that uses a magnetic field to heat and stir the metal.

1. Alternating Current Generates Alternating Magnetic Field:

The power system of the IF furnace inputs alternating current at mains frequency (50/60Hz) or intermediate frequency (100Hz-10,000Hz) into the induction coil outside the furnace body.

According to Biot-Savart's law, the coil passing through the alternating current generates a strong, constantly changing alternating magnetic field inside and around it.

2. Magnetic Field Induces Current in the Charge:

The metal charge (such as scrap steel, alloys, etc.) inside the furnace is itself a conductor. This alternating magnetic field passes through the metal charge.

According to Faraday's law of electromagnetic induction, the changing magnetic field induces an electromotive force inside the conductor, thus forming a strong eddy current.

3. Eddy Currents Generate Joule Heat:

The metal charge itself has resistance. When a strong eddy current flows through this resistance, according to Joule's law (P = I²R), a large amount of heat is generated.

This heat is generated directly within the metal material, therefore it is highly efficient. The generated heat accumulates rapidly, gradually heating and melting the metal from room temperature until the required casting temperature is reached.

4. Stirring effect of electromagnetic force:

The current in the induction coil and the eddy currents in the furnace charge generate an interacting electromagnetic force (Lorentz force).

The direction of this force causes the molten steel to circulate strongly within the furnace, i.e., the "electromagnetic stirring" effect. This helps to:

• Homogeneize composition: Ensures rapid and uniform distribution of alloying elements.
• Homogeneize temperature: Prevents localized overheating or undercooling zones within the furnace.
• Remove impurities: Helps non-metallic inclusions float to the slag.

Applications of Induction Electric Furnaces

Induction furnace for steel melting are widely used in:

• Foundry industry: 

Used for melting cast iron, cast steel, alloy steel, non-ferrous metals, etc., and is a core piece of equipment for precision casting and high-end casting production.

• Special steel plants: 

Used for melting high-alloy steel, stainless steel, tool steel, high-temperature alloys, and other steel grades with strict composition requirements.

• Metallurgical laboratories: 

Used for small-batch alloy development and materials research.

In conclusion, whether cored or coreless furnaces, industrial frequency, medium frequency furnace, or other induction furnaces, they have all become star products in modern advanced smelting equipment due to their high efficiency, cleanliness, strong controllability, and high melt quality.

If you have any questions or needs, please feel free to contact us.

E-mail: alice@srfurnace.com  / Tel: +86 15686041999 (Alice)

E-mail: anna@srfurnace.com  / Whatsapp: +86 159 2955 5868 (Anna)

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Xi'an Sanrui Electric Furnace