Effect of Current Waveform on Droplet Oscillation in GMAW

Abstract

The active droplet oscillation is a method previously proposed to detach the droplet at currents below the transition current. In this method, a droplet oscillation is actively excited when the current is switched from the exciting peak level to base level. The downward momentum of the droplet is utilized to enhance the droplet detachment. In this work, the current waveform is modified to achieve stronger droplet oscillation with lower average current. The critical change is to separate the droplet growing and exciting processes such that the two processes can be controlled independently. The heat input can thus be reduced, and stronger droplet oscillation is obtained. A further optimized current waveform is proposed to maximize the droplet oscillation energy despite the growing current level.

Optimization of CMT Characteristic Parameters for Swing Arc Additive Manufacturing of AZ91 Magnesium Alloy Based on Process Stability Analysis

“…Zhang et al [18] achieved the desired one-droplet-per-pulse (ODPP) transfer by selecting the appropriate combination of the duration and amplitude of the peak current in the pulsed GMAW (GMAW-P) process of titanium alloy, and the stability of the GMAW-P process was greatly improved due to the precise control of the heat input in different stages of the droplet transition process. Subsequently, a much stronger droplet oscillation with a significantly lower heat input was realized with the active control of the current waveform during the GMAW-P process [19], which further increased the process stability.…”