Selection of induction heating frequency: according to the technical requirements of heat treatment and the requirements of heating depth, the higher the frequency, the shallower the depth of heating.

The depth of high frequency (above 10KHZ) heating is 0.5-2.5mm, which is generally used for heating small and medium-sized parts, such as small modulus gears and small and medium-sized shaft parts.

Medium frequency (1~10KHZ) heating depth of 2-10mm, generally used for large diameter shaft class and large and medium modulus gear heating.

Power frequency (50HZ) heating hardening layer depth of 10-20mm, generally used for large size parts of the heat, large diameter parts (diameter &Oslash: more than 300mm, such as rolls, etc.) surface hardening.

The depth of the hardened layer of the induction hardening surface depends on the frequency of alternating current, and the frequency is generally high and the depth of the hardening layer is shallow. The relationship between frequency f and heating depth δ can be obtained by the following empirical formula: δ=20/√f(20°C); Delta =500/√f(800°C).

Where: f is the frequency, the unit is Hz; δ is the heating depth in millimeters (mm).

Induction heating surface quenching has the advantages of good surface quality, small brittleness, hard oxidation and decarburization of hardened surface, small deformation, etc., so induction heating equipment has been widely used in metal surface heat treatment.

Induction heating equipment is to generate a specific frequency of induction current, induction heating and surface quenching treatment equipment.