Analysis of metal transfer and correlated influences in dual-bypass GMAW of aluminum

Dual-bypass gas metal arc welding (DB-GMAW) is a modified GMAW process. In this novel process, the base metal current is decreased from the melting current by adding two tungsten electrodes to a conventional GMAW system. The resultant bypass arcs change the forces affecting on the droplet, and the resultant metal transfer becomes more desirable. To understand the desirable changes in the metal transfer, this paper applies established theories to analyze the changes in the forces acting on the droplet and the effects of these changes on the metal transfer behaviors. Analysis shows that the bypass arcs and currents lower the critical current needed to achieve the desired spray transfer. Experimental results obtained by a high-speed camera show that the analysis agrees with experimental data.