BLOG
04
2026
-
08
Principle of the medium-frequency induction furnace
Principle of the medium-frequency induction furnace
1.1 Operating Principle of Medium-Frequency Electric Furnace
Induction heating is the induction of electrical currents in a conductive object placed within a varying magnetic field. The workpiece to be heated does not need to be a ferromagnetic material; the only requirement is that it possess good electrical conductivity. The vast majority of ferrous and nonferrous metals can be heated and melted using induction. Induction heating and melting can be applied directly only to electrically conductive materials. The induced eddy currents within the workpiece or charge are primarily responsible for generating the heat.
( 1 ) Eddy current
Eddy currents are electric currents induced in a material when it is subjected to a changing magnetic field. The term “eddy current” originates from the swirling or helical motion of these currents within a solid conductive material. In any conductive material exposed to a time-varying magnetic field, eddy currents give rise to energy losses. Even in materials that do not exhibit ferromagnetic properties, such currents can still cause heating.
( 2 ) Hysteresis
Hysteresis is the discontinuity in the magnetization of a magnetic material caused by changes in the applied magnetic field. Reversing the magnetic field requires energy, which is converted into heat. The heat generated by hysteresis contributes to an increase in the temperature of magnetic materials such as iron, steel, and nickel. The rate at which energy is dissipated—i.e., the power—increases with the frequency of field reversals. Once the metal’s temperature exceeds its “Curie temperature” (for steel, approximately…), 1400 ° F ) , Magnetic field loss disappears.
( 3 ) Hysteresis and eddy current losses
In eddy-current induction, eddy-current losses are more significant. The induced currents, driven by changes in the coil’s magnetic field, cause heating of the load.
( 4 ) Power consumption
When an electric current flows through a conductor, power is dissipated in the resistor. This power represents the rate at which electrical energy is converted into thermal energy. The power is proportional to the square of the current and is independent of the direction of the current flow. P=I2R , where, P It is power measured in watts, I It is the current measured in amperes, R This is the resistance measured in ohms. As described in the following sections of this chapter, power is generated by the circulation of induced currents within the workpiece, the molten material, or the charge.
1.2 Medium-frequency coreless induction furnace
The induction furnace consists of a refractory vessel—either a crucible or a furnace lining—capable of containing the molten pool, which is surrounded by a water‑cooled helical coil connected to an AC power supply. The alternating current applied to the coil generates a time‑varying magnetic field concentrated within the coil. This magnetic field induces eddy currents in the charge, and the Joule heating losses associated with these circulating currents serve to heat the charge.
Previous article
Previous article
Latest developments
Xi'an Aobang Technology Co.,Ltd
Mobile: 008613891865812 (Mr. Luo)
Phone: 008602986196449
Email: 1620573240@qq.com
Address: Boai Industrial Park, No. 268 Caotan Sixth Road, Xi'an Economic and Technological Development Zone
Aobang WeChat