... 3.Have 8 customers in Thailand 4.IGBT series resonance circuit .Medium frequency induction heating machine:frequency:1.5-20KHZ ... hardening, standard parts forged piece heating before forging. hardware tool heating before forging, steel tube through heating, drill bit welding, metallic ... 250,XZ-300,XZ-400,XZ-500 Example : 1.standard parts,fastener through heating before forging,oxic horizon little. ...