Induction heating

What is induction heating?

Inductive heating itself is based on the following physical principle:

If the metal body to be heated is exposed to the influence of an electromagnetic alternating field, an electric current is induced in it. The flow of current causes the metal to heat up.

Inductive heating is therefore a direct heating process: the heat is generated in the workpiece itself and is not transferred from the outside by conduction, convection or thermal radiation.

The thickness of the surface layer, in which a significant current flow occurs, is characterized by the current penetration depth. Apart from the specified electrical and magnetic material properties of the metal, the current penetration depth only depends on the frequency. At a high frequency the penetration depth is small, at a low frequency the penetration depth is great.

The selection of the correct frequency is an important criterion for implementing a specific heating task. With the frequency, the penetration depth and thus the thickness of the directly heated surface layer can be selected. Depending on the current penetration depth required, a certain operating frequency of the induction system is selected.

Warming target

Ultimately, the desired inductive heating determines the required power and frequency range. The focus is on the material, dimensions, target temperature and desired throughput.

Induction heating

The term “inductive heating” includes all areas of application that fall in the temperature range below the respective good melting point.

This includes the heat treatments

• Hardening
• Tempering
• glow

as well as that

• soldering
• welding
• sintering

and heating for subsequent hot forming and numerous special applications.

Inductive heat treatment

Heat treatment is used to improve material properties. Due to the structural transformation that occurs, hardness, brittleness, toughness, internal stresses and the like can be determined.

Inductive hardening

Induction hardening is a tried and tested process for increasing the quality of structural and structural parts made of steel, cast steel or cast iron. Inductive heating is primarily used to harden surfaces or through hardening of workpiece sections.

Tempering

Tempering is a process that generally follows the hardening process. The material is reheated, e.g. inductively, but to a much lower temperature. In this way, extreme hardness stresses can be reduced without having to accept a significant loss of hardness. At the same time, the brittleness of the hardness structure is reduced and the toughness is improved.

glow

Annealing is the heating to a certain temperature and holding at this temperature with subsequent slow cooling. The method is used to remove a coarse or uneven structure, internal stresses or to produce a soft state for easier processing or shaping.

soldering

Induction soldering systems are particularly suitable for series production because of their ease of automation. Due to the short heating times, the surface of the solder joint remains largely free of scale during the soldering process. The inductively manufactured soldered connections have a high, constant quality.

welding

The local inductive heating can be increased so that the melting temperature is reached and inductive welding is possible. Inductive heating for hot forming / forging

Inductive forging billet heating systems are available for series production for rationalization and automation. The short heating times of inductive heating result in significant advantages for production.

Inductor / heating coil

The core of every induction system is the inductor. This is the part of the system that causes the workpiece to heat up through electromagnetic action. It generally consists of a hollow copper profile through which cooling water flows. The shape of the inductor depends on the part to be heated.

Advantages of inductive heating are for example

• fast and even heating
• high throughput
• Tinder poverty
• no coarse grain formation
• no heat nuisance
• no environmental pollution
• partial hardening
• easy automation
• Scrap reduction
• good, constant quality
• immediate operational readiness
• easy handling
• very little space required
• clean, emission-free heating