Induction hardening is the most widely used method of surface hardening, due to its high productivity and good quality of the hardened layer.

Inducing heath by a high frequency current is based on the so-called "skin effect". The surface layers of the steel objects are heated rapidly to a high temperature, while the inner layers remain cold or, due to the thermal conductivity of steel, slightly heated.

The maximum hardness reached by induction hardening is increased by 2-3 HRC units compared to the hardness obtained by the conventional heating (in a furnace), and cooling performed in the same medium. The other mechanical properties (tensile strength, yield strength, elongation, contraction and impact strength) also show higher values after induction hardening, compared to a conventional one.

Other advantages of induction hardening compared to conventional hardening are:

  • Lower energy consumption;
  • High productivity;
  • The possibility to use mechanization in the process;
  • High quality hardened steel (possibility of replacing alloyed by carbon steels);
  • Absence of oxidation and decarburization;
  • Small deformation.

Induction hardening is applied in cases of a large number of objects, such as gears, crank shafts, turbine blades, rollers for rolling mills, gauges, tools that work under the influence of shock loads and the like.

PPT-TMO S.A. has two induction-type FDF appliances, max power 150KW, for hardening objects with the maximum diameter 250mm and max length 1250mm.