Arc plasma, droplet, and forming behaviors in bypass wire arc-directed energy deposition

This study presents a new variant of arc-directed energy deposition (Arc-DED) called bypass wire Arc-DED, in which a bypass wire is fed into the arc and separates part of currents from the arc to form a bypass arc. The novelty is that optimal process conditions, including the bypass wire feed mode, the angle between the main and the bypass wires, and the intersection of both wires to substrate distance, were revealed by evaluating the process stability and the bypass current. Furthermore, how the bypass current affects the heat input to deposited layers was explored for the first time by comparing this technique with external wire Arc-DED in which no current passes through the external wire. A comparison with conventional Arc-DED in terms of forming quality was performed. Since the bypass wire is difficult to contact the molten pool, the front feed mode achieves a larger bypass current than the back feed mode. A smaller angle between both wires produces a larger bypass current. More stable main and bypass arcs and a larger bypass current can be obtained when the intersection of both wires is on the substrate surface. The bypass current can decrease the heat input to deposited layers. Nevertheless, it has a less significant effect on decreasing the heat input than the auxiliary wire. This study demonstrates the potential for bypass wire Arc-DED to achieve a higher deposition rate and a lower heat input to deposited layers without compromising the forming quality.

Automated summary

This study presents a new variant of arc-directed energy deposition (Arc-DED) called bypass wire Arc-DED, which utilizes a bypass wire to form a separate bypass arc. Optimal process conditions were determined by evaluating process stability and bypass current, including bypass wire feed mode, angle between wires, and wire intersection distance to the substrate. The study also explores how the bypass current affects heat input to deposited layers and compares it with external wire Arc-DED. The findings demonstrate that bypass wire Arc-DED has the potential to achieve higher deposition rates and lower heat input without compromising forming quality.