Process parameters and their effect on metal transfer in gas metal arc welding: a driving force perspective

In gas metal arc welding (GMAW), the optimization of process parameters and the control of metal transfer is pivotal for achieving superior welding outcomes. This study meticulously examines the roles of core process parameters in metal transfer: wire extension and arc geometry, which includes arc length and inter-cathode distance. Using a unique MIG-based non-transferred arc system with symmetrically arranged tungsten cathodes we have achieved distinct control over wire feed rate and arc geometry, independent of the arc current. We investigate the interplay of these parameters and their consequential influence on the driving forces governing metal transfer. While increasing the wire extension enhanced inertial forces, it did not lead to consistent transitions in the metal transfer modes. In contrast, adjusting arc length and inter-cathode distance effectively controlled the electromagnetic force acting on molten droplets, as quantified by the arc spread angle theta. Notably, an increase in the arc spread angle resulted in the elongation of molten droplets. This study clarifies the fundamental relationships between driving forces and process parameters in GMAW. Additionally, it introduces a more advanced evaluation model for electromagnetic force and offers a comprehensive strategy for refining welding control techniques.