Movement of Nugget on the Multiple Projection Welding

Abstract

Projection welding has many effective applications because of the special features. In multiple projection welding, however, we have experienced that the welds have often low strength and are unstable. We observed, the lack of stability of weld strength happens in case of the narrow distance between projections and projection nuggets move to gather at the faying surface. We found, this phenomenon depends upon the "Pinch effect" that is, the electromagnetic contraction between the same directional current through the molten metal, so the movement of nuggets on the multiple projection welding closely relates to the distance between projections, mass of moving parts and electrode force, and consequently, the quick follow-up of electrode results the high strength and good stability.