Metal transfer of aluminum alloy double-wire pulsed GMAW with a median waveform

Abstract

Abstract This paper proposes a double-wire pulsed gas metal arc welding (GMAW) process with a median current waveform based on traditional double-wire pulsed GMAW. A high-speed digital camera and digital oscilloscope were used to simultaneously record the metal transfer process as well as the voltage and current waveforms under different median currents. The median pulse was modeled as an exponential function and a mathematical model of the droplet diameter was established. Further, variation of the output current during the welding process and the influence of pulse parameters on the metal transfer process were accurately described. The results show that the median current has a significant impact on the metal transfer process. When the median current increases, the metal transfer period gradually decreases and the desired one drop per pulse (ODPP) mode, with a moderate droplet size and no droplet collision, is almost achieved within an appropriate median current range. As the median current gradually increases, the droplet diameter also increases but then begins to decrease as the median current further increases and gets closer to the peak current. The droplet offset distance first decreases considerably, then begins to increase, and droplet collision occurs as the median current continues to increase, resulting in an unstable transfer process. Initially, the transfer time decreases and then increases, followed by a subsequent decrease as the median current continues to increase.