Influence of pulsed arc on the metal droplet deposited by projected transfer mode in wire-arc additive manufacturing

The wire-arc additive manufacturing (WAAM) process directly and locally adds materials to fabricate metal components in a layer-by-layer manner. In this study, pulsed arc and non-pulsed arc were used in WAAM process of aluminum alloys. Arc information in manufacturing was used to identify the droplet transfer in projected transfer mode. A calculation method was proposed to analyze the arc pulse effect on the droplet transfer. As a result, it was found that the pulsed arc can achieve higher droplet transfer frequency and the size of the droplet in the pulsed arc is smaller than that in the non-pulsed arc. In addition, the manufacturing efficiency in pulsed arc is higher than that in non-pulsed arc at the similar arc power because of high deposition rate. Although the pulsed arc is more suitable for the WAAM of aluminum alloy than non-pulsed arc, the arc force acting on the droplet in pulsed arc is greater than that in non-pulsed arc. The arc force increases with the increase of the arc power, which is likely to cause the collapse of the materials accumulation layer. Therefore, it is necessary to use a smaller pulsed arc power in WAAM process of aluminum alloys as long as the arc power meets the requirement of manufacturing efficiency.