Influence of the arc length on metal transfer in the single potential double-wire MIG/MAG process

The search for competitiveness in the modern industries, represented by demands for higher productivity and cost reduction, leads to investment in new technologies. This is the context in which the double-wire MIG/ MAG process was conceived; the idea was to design a process that combines the versatile features of the MIG/MAG process with the high productivity of the submerged arc process. The objective of this work was to evaluate the influence of different arc lengths, at the same current level, on the metal transfer modes and the bead geometry profiles. Using equipment consisting of two linked power sources and a torch with single electrical potential, the series of welds was carried out at three different arc length conditions. A methodology to obtain different arc lengths at the same current and wire-feed speed levels was proposed and validated. The metal transfer was observed using the shadowgraph technique with a high-speed camera, while the geometry was evaluated from macrographies of weld bead transversal sections. A trend in transfer mode changes was observed from short circuit to spray for the highest arc lengths, and to a much higher attraction between the drops. This change in the transfer mode implies better beads finishing and higher thermal and deposition efficiencies.