What is induction heating?

The induction heating is a process in which an electrically conductive workpiece (= secondary circuit of a short-circuited air transformer) is placed into an electromagnetic alternating field, and the eddy currents resulting therefrom are converted into heat . In the case of ferromagnetic workpieces, losses of magnetization loss contribute significantly to the heating up to the Curie temperature (cobalt: 1121 °C, iron: 768 °C, nickel: 360 °C).

A distinction is made between low frequency (some 50-300Hz), medium frequency (up to 50kHz) and high frequency (from approx. 50kHz), and the respective frequency used determines the penetration depth of the current into the material. The lower the working frequency, the higher the penetration depth of the eddy current into the material to be heated. The depth of penetration is described by the skin effect and is an effect in electrical conductors through which the current density inside a conductor is lower than in external areas. The reason for the skin effect is that the alternating fields penetrating the conductor are largely dampened by the high conductivity of the material even before the inner conductor is reached.

The efficiency of the inductive heating is defined by the electrical conductivity of the material to be heated: steel or stainless steel, both materials with poor electrical conductivity, can be heated very efficiently compared to aluminum or copper. The most common applications of inductive heating are brazing and soldering, hardening, shrinking, tempering, annealing, welding and melting, as well as science and material testing.

The induction field may be formed through nonconductive materials, e.g. Glass, ceramics, etc., and since there is no contamination by an external heat source, this method is also very well suited for protective gas or vacuum technology.

What are the advantages of induction heating?

Unlike traditional methods (e.g. furnaces), the inductive heating can be controlled very accurately. In addition, the heat is applied faster. Because no direct contact must exist, workpieces that have already been installed can be heated with induction heat as well.

The induction heating units themselves offer a number of advantages: they require much less space than, say, furnaces. Because no open flames are utilized and the method itself produces no smoke, ultimately resulting in better working conditions than in conventional methods.

The advantages at a glance:

  • contact-free heating method
  • low space requirements
  • high efficiency
  • exact temperature control