How to choose the current frequency when the induction heating furnace heats the billet?

The selection of the current frequency when the induction heating furnace heats the billet is shown in the table

Selection of current frequency when steel billet is diathermy

Diameter of blank /mm	Current frequency/Hz
Diameter of blank /mm	Below the Curie point	Higher than the Curie point
6 -12	3000	450000
12-25	960	10000
25-38	960	3000 -10000
38-50	60	3000
50 -150	60	960
>150	60	60

It can be seen from the table that when the blank is heated at a temperature below the Curie point, the frequency can be one tenth of the Curie point due to the shallow penetration of the current. If dual-frequency heating is used, such as PC steel bars, before and after the Curie point Using different current frequencies can improve heating efficiency. Recently, a 30Hz frequency conversion power supply has been developed to heat large-diameter billets.