... welding Jewelley clock, annealing glass shelf . Ultrahigh frequency induction hardening device contain four types (Medium frequency,High frequency, ... frequency,Double frequency) it is appliying for classes of machine parts to heat treating(quenching,anneal, temper,normalizing..., ... Siemens IGBT,MOSFET and any other new type induction heating machine. 2.Fast speed,low power consumption,small volume ...