What type of resistance welding do you have?

Resistance welding is broadly divided into lap resistance welding and resistance butt welding.
Lap resistance welding is classified into spot welding, projection welding and seam welding. Resistance butt welding is classified into butt welding and flash welding.
Spot welding uses a pair of electrodes to pressurize multiple plates, and a large current is applied to melt the stacked portions of the plates to create a nugget for welding.
It is often used for vehicle body assembly.
With the projection welding method, one of the objects to be welded has projections, and they are welded to mating parts.
It is often used for welding nuts to vehicle body parts.
Seam welding basically works the same as spot welding, but this method continuously welds using rotating electrode discs.
It is often used for the welding that requires airtightness, such as gasoline tanks for automobiles, drums, and fuel tanks for kerosene.