Laser enhancement of wire arc additive manufacturing

Additive Manufacturing (AM) can be used for the fabrication of large metal parts, e.g. aerospace/space applications. Wire Arc Additive Manufacturing (WAAM) can be a suitable process for this due to its high deposition rates and relatively low equipment and operation costs. In WAAM, an electrical arc is used as a heat source and material is supplied in the form of a metal wire. A known disadvantage of the process is the comparably low dimensional accuracy. This is usually compensated by generating larger structures than desired and machining away excess material. So far, using combinations of arc in atmospheric conditions with high precision laser heat sources for AM have not yet been widely researched. Properties of the comparable cheap arc-based process, such as melt pool stability and dimensional accuracy, can be improved with the addition of a laser source. Within this paper, impacts of adding a laser beam to the WAAM process are presented. Differences between having the beam in a leading or a trailing position, relative to the wire and arc, are also revealed. Structures generated using the arc-laser-hybrid processes are compared to ones made using only an arc as the heat-source. Both geometrical and material aspects are studied to determine the influences of laser hybridization, applied techniques including x-ray, EDX and high precision 3D scanning. A trailing laser beam is found to best improve topological capabilities of WAAM. Having a leading laser beam on the other hand is shown to affect CMT synergy behavior, promoting higher deposition rates but decreasing topological accuracy.