... , uneven heating, temperature fail, easily lead to damage to the workpiece and so on.Choosing the correct ... frequency, first of all, It is necessary to know the technical requirements of heating products, ... -500KHz) Φ4-16 mm applies to the high-frequency (50-100 KHz) Φ16-40 mm applies to VHF (10-50 ... copper, lead and other precious metals .According to a furnace and the production efficiency of the ...