Wire feed pulsation as a means of inducing surface tension metal transfer in Gas Metal Arc Welding

Abstract Gas Metal Arc Welding (GMAW) derivative processes have gained attention due to their capacity to perform specific functions, such as reducing spattering during short-circuiting. However, the short-circuiting transfer nature allows devising other features, such as to work with low current yet with high voltage. Although this arrangement is typical of globular transfer when applied in GMAW, the assistance of wire feed pulsation by itself could make the use of this combination doable. Therefore, this work aimed at exploring the technical feasibility of short-circuiting GMAW with higher voltage level with the aid of a wire feed pulsation technique, rather than relying on current waveform control strategies. In this case, a home-developed device that superimposes a pulsation linear movement to the wire over its continuous movement was employed. To prove the concept, wire pulsation and long arc length during arcing were applied in experiments with the power source operating either in constant voltage or constant current modes. In order to quantify and validate the approach, a range of pulsation frequencies was explored and compared with conditions with continuous feeding. The metal transfer regularity was evaluated following the Laprosolda Metal Transfer Regularity Criterion, and geometric parameters of the weld beads were compared as complement. To assess the metallic transfer behavior, high-speed imaging was also used. A reasoning in terms of arc length was successfully applied to different conditions based on the melting rate equation and misleading voltage usage in short-circuiting for this purpose was demonstrated. The results showed that the wire feed pulsation approach is adequate to improve metal transfer regularity in short-circuiting GMAW, as long as the power source is set to operate in current constant mode. Furthermore, the actual arc length plays a significant role in the wire feed pulsation process performance.