... different output frequency, which can be broadly classified into: ultra-high frequency, high-frequency, super audio, frequency, etc. Different requirements of ... Such as: hardening layer0.2-0.8mm applicable UHF 100-250 KHz, high-frequency 1.0-1.5mm applicable 40-50 Khz ... furnace and the production efficiency of the specific, small-capacity high-frequency options, most used to super audio, super audio ...