Modelling of the short-circuiting transfer process in GMA welding. A numerical model for metal transfer phenomena in GMA welding

Abstract During gas metal arc (GMA) welding, such as MAG welding, the welding wire serves as a welding system electrode. The electrode wire is melted by arc heat to form a metal drop on the wire tip. Under the effects of forces such as gravity and electromagnetic force, the metal drop detaches from the wire and transfers to the base metal. Despite welding wire being continuously supplied, molten metal is intermittently transferred to the base metal. For this reason, various factors affecting the progression of GMA welding, such as the arc length and shape alongside the heat source and so-called arc initiation position, fluctuate in time and space. That is to say, metal transfer phenomena control arc stability and are moreover closely related to welding quality itself as well as to operability factors such as generation of spatter and welding defects. To clarify the corresponding mechanisms, it is necessary to undertake theoretical investigations in conjunction with observations by high-speed imaging.