The principles to be followed when welding of sheet metal parts.

1. Shorten the length of the secondary circuit as possible and reduce the space area included in the circuit to save energy consumption.

2. Reduce the volume of ferromagnet extending into the secondary circuit as possible, in particular, avoid the lager change of the volume extending into the secondary circuit when welding different solder joints, to reduce the fluctuation of welding current, and ensure the stable quality of each point (When using frequency AC).

1) Single side double spot welding: welding two points at the same time as possible when feed from one side to increase productivity. Single-side feed usually appear invalid shunt phenomenon, waste of energy, and when the distance is too small it will can not be welded.

2) Single side singe spot welding: When the accessibility of one side electrode of the parts is very poor or the part is very large or the secondary circuit is too long, can use this program. From the singe-side feeding of the weldment, need to consider to add the copper pad on the other side to reduce the shunt and act as the fulcrum of the reaction force.

3) Double sided single spot welding: All general purpose welding machines adopt this scheme. Feed from both sides of the weldment, Apply to welding the around solder joints of small parts and large parts.