MFDC resistance welding machines can be manufactured for spot,projection,seam or butt welding according to customers,request.The 3-phase mains voltage in the special inverter cintrol is rectified and converted into a 1000Hz alternating voltage.This voltage is sent to a compact,tightly coupled transformer and rectified again on the secondary side.The result is a direct welding current that can be rapidly and exactly regulated.Short time welding(i.e.ring projection)partly as replacement for discharge welding machines,welding galvanized sheet,different materials as well as nonferrous metals and coated materials. http://www.autoweldingmachine.com/