Double-sided pulsed laser driven metal transfer in GMAW

Abstract

Current-independent metal transfer, in free-flight or short-circuiting mode, was previously achieved by utilizing single-side pulsed laser irradiation on the droplet. However, the droplet was always detached with a deflection approximately along the laser incident direction, but not in the wire axial way as generally expected. The droplet deflection also acts as a cushion to the laser impulse. Hence, the double-sided pulsed-laser-driven metal transfer is studied by comparing it with that of non-laser and single laser enhanced metal transfer in this paper. The results demonstrate that double-sided laser irradiation leads to a significant increase in the transfer frequency and process stability. Differing from the way of droplet deflection driven by single laser irradiation, double-sided symmetrical laser irradiation with the same laser pulse parameters results in wire-axial metal transfer of higher frequency, either in drop spray or short-circuiting transfer mode, depending on the arc length. Moreover, the dual laser irradiation contributes considerably to melt the wire when the current is ultra-low. The wire tip was even shaped to a pencil-like profile by the lasers, similar to that of traditional stream spray transfer in high-current GMAW, which facilitates the co-axial metal transfer. The transfer frequency of short-circuiting transfer and drop spray transfer under 80A current is up to100 Hz and 150 Hz (0.8 mm wire diameter, pure argon shielding gas), respectively. Even the current is as low as 40 A, the drop spray transfer frequency can still be up to 100 Hz.