Influence of distance between laser and MIG arc on drop transfer process of CO₂ laser-MIG hybrid welding

Influence of different distance between laser and MIG arc on drop transfer process of CO₂ laser-MIG hybrid welding at two kinds of welding currents is studied by using high-speed photography equipment. The experimental results show that drop transfer form produced by single MIG welding at high welding speed is an unstable transfer process. In contrast, during the laser-MIG hybrid welding process, thermal radiation effects of plasma caused by laser on metal drop and attraction force of laser plasma on arc plasma, which results in the variation of arc shape and corresponding forces on metal drop, can have an important influence on drop transfer process. There are different optimal distances between the laser and the arc for different welding currents at which both plasmas can couple well. Under this condition, frequency of drop transfer increases, drop transfer form changes into a single stable spray transfer, welding current and arc voltage remain constant, weld formation is very good, and spatter rate significantly reduces.