... , parts surface hardening, tempering, annealing, etc.B: metal brazing, high-frequency brazing, pan bottom brazing, tool ... heat enveloping, heat sealing, metal desiccating, nut inserting, rotor inserting,etc.D: precious metals melting.E. dry resin ... Extraction ect.The heating of metal by induction has been in industrial use since the beginning of the ... recognition in the field of precious metal casting.