Analysis of the effect of current pulse in the short-circuit phase on metal transfer in the GMAW process with dynamic feeding

The development of variations of the GMAW process, where metal transfer is assisted by the electromechanical movement of the wire (Dynamic Feed—DF), has contributed to the increasing interest in wire and arc additive manufacturing (WAAM) technology. This technology holds the potential to change traditional manufacturing processes. Studies on GMAW variants suitable for WAAM are essential, as it provides opportunities to enhance control over welding outcomes and broaden the application range for different materials. This paper presents an analysis of how current waveform parameters in the GMAW-DF process influence metal transfer and the overall process. The study, conducted with proprietary equipment developed by the Welding and Mechatronics Institute (LABSOLDA) for researching and developing new processes aimed at root pass applications, coating, and parts recovery through additive manufacturing (AM), varied the time and amplitude of the current pulse during the short-circuit phase. The objective was to analyze its effect on the process and the weld bead. The findings indicate that the pulse helps constrict the metal bridge and reduces arc height at the moment of metal bridge rupture, allowing for a reduction in motor movement amplitude and increasing detachment frequency. The methodology also identified errors caused by extrapolating pulse parameters, which are considered crucial for process mapping.