Current-independent metal transfer by using pulsed laser irradiation Part 1: System and Verification: A novel process involving the use of a pulsed fiber laser to control the metal transfer in GMAW is investigated

Current-independent metal transfer that allows the droplet to be detached at any reasonable small diameter and low current will provide the gas metal arc welding (GMAW) process with entirely new abilities to better meet possible needs from different applications. To this end, a novel GMAW process involving the use of a pulsed fiber laser to irradiate droplets is proposed as a significant evolution from the previous laser-enhanced GMAW. The laser is focused to a tiny spot to maximize the laser power density and aimed at the liquid droplet. It is expected the irradiation of a pulsed laser with a relatively large peak power would generate an adequate recoil force to dominate the droplet detachment. Laser-induced vaporization is first observed and analyzed. The metal transfer under continuous wave (CW) and pulsed laser irradiation are then experimentally observed/analyzed. The results demonstrate that the current-independent metal transfer is successfully realized by using the pulsed laser, since the selected laser allows much higher peak power in pulsed mode. The desirable one drop per pulse (ODPP) transfer is obtained. Therefore, a pulsed fiber laser not only avoids waste of laser energy but also achieves the desired controllability on the metal transfer. The verified current-independent metal transfer ensures free design or optimization of current waveform without constraint from the metal transfer.