Seam welding is a Continuous spot welding process.
seam welding is a variant of the basic resistance spot welding process.
In seam welding a series of overlapping nuggets is produced, usually by replacing the conventional spot welding electrodes by wheels that turn as the parts to be welded are fed between them.
Projection welding is a modification of spot welding.
In this process, the weld is localized by means of raised sections, or projections, on one or both of the workpieces to be joined.
Upset butt welding is a welding technique that produces coalescence simultaneously over the entire area of abutting surfaces or progressively along a joint, by the heat obtained from resistance to electric current through the area where those surfaces are in contact.
The welding process used in joining mild steel shanks to high speed drills is Flash butt welding.
In arc welding, the electric arc is produced between the work and the electrode by Contact resistance.