Study on the Droplet Transition Models in Laser Welding with Filler Wire

This study is intended to examine the droplet transition in the welding process. Tests were performed using a high-speed camera to assess the effect of the vertical distance between the laser–wire intersection and workpiece (H) on droplet transition. Meanwhile, forces on the droplet were analyzed to evaluate the transition model during laser welding with filler wire. The results showed that the droplet transition model, transition frequency, droplet size and forces of the model all changed with Hlevel changing. Droplet transition and the welding process showed stability at an Hlevel of 1 mm. Based on the liquid bridge transition model, the droplet was transferred to the molten pool in the state of balance, while the droplet entered into the molten pool under non-equilibrium state during globular transition.