Induction heating

Bath dome in a cold-wall induction crucible furnace

Inductive heating and melting requires an interdisciplinary understanding of various scientific fields, including the physical principles of electromagnetic fields, power electronics, thermodynamics, materials science, etc. The complex physical relationships can be illustrated using the example of inductive melting and the description of the individual influencing factors. To illustrate this, imagine a molten metal in a coreless induction furnace. The electrical energy supplied to the system is converted into heat via the electromagnetic field in the metal and spreads through the material by conjugated heat transport, consisting of diffusion and convection. The generally highly turbulent bath movement ensures very good mixing and homogenization of the temperature within the melt. The output cannot be increased at will because the magnetic pressure that occurs dominates over the hydrostatic pressure from a certain value. This causes the melt to collapse and a bath dome forms, which in turn affects the electromagnetic coupling and the efficiency. This limits the maximum power that can be induced in the metal.

Basics

The previous example is intended to illustrate how strongly the individual effects are interlinked. For this reason, we would like to explain to you the mathematical and physical principles of

• of induction heating,
• of induction hardening and
• of inductive melting

a little closer.

As the topics mentioned are very wide-ranging, we ask for your understanding that they cannot be dealt with in detail here. For a deeper insight into the topic, we recommend the following specialist literature:

1. Benkowsky, Induction heating: Hardening, annealing, melting, soldering, welding; basics and practical instructions..., 1990, ISBN 3-341-00813-6
2. Turewicz, Multiphysical process analysis to extend the application limits of the cold-wall coreless induction furnace, TEWISS Verlag, ISBN: 3944586387
3. Mühlbauer, Industrial electric heating technology, ISBN: 380272903X
4. Fasholz, Orth, Inductive heating - physical principles and technical applications, RWE Energie AG

If you have any technical questions on the subject of induction heating, please call us on 06202/8598456. You are also welcome to send us your questions in writing to info@eltatech.de.