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

1. High-frequency (10KHZ or more ) heating depth 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 shaft parts. 　　

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

3 , power frequency (50HZ) heating hardened layer depth of 10-20mm , generally used for the heat transfer of larger size parts, large-diameter parts ( 300mm diameter , such as rolls, etc.) surface quenching. 　

     The depth of the hardened layer of the induction hardened surface layer depends on the frequency of the alternating current. Generally, the frequency is high and the heating depth is shallow, and the depth of the hardened layer is shallow. The relationship between the frequency f and the heating depth δ has the following empirical formula:

δ=20/√f (20°C) ; δ=500/√f (800°C)

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

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

The induction heating device is a device that generates a specific frequency induced current, performs induction heating and surface hardening treatment.