Induction hardening involves a high-frequency alternating current passing through a suitably shaped coil in order to induce a fast heating on the surface of a metal piece appropriately located within its electro-magnetic field.

Depth of hardening is controlled by resistivity of material, current frequency, heating time, hardenability features of the material.

Induction hardening can be performed via “single-shot operation” in which the entire area to be treated is heated up in one operation, then quenched, and via “progressive operation” which involves relative movement of the heating inductor, the quenching shower and the piece.

Localized hardening in a specific area of the piece can be of course achieved by the combination of a suitable coil design and manipulation.

Induction hardening generates a hard, wear-resistant surface of the piece together with an improving tensile strength and fatigue resistance. Because only the surface of the piece is heated and quenched, heat-treatment deformations are reduced to an absolute minimum.