Influence of process parameters and head orientation on bead geometry for coaxial wire laser additive manufacturing

Among Directed Energy Deposition (DED) processes for metallic materials, Wire Laser Additive Manufacturing (WLAM), distinguishes itself by the use of a laser beam to melt a metallic wire and produce beads. Successive depositions of overlapping beads generate volumes to obtain parts. Thus, controlling bead geometries is essential for the additive manufacturing process. Several research works have studied these geometries and the influence of the main manufacturing parameters on their dimensions, but few investigated the effect of feeding direction or wire angle. Moreover, all studies on wire angle were carried out with lateral feeding and a constant laser orientation. This paper focuses on the influence of the deposition head orientation for a coaxial wire feed with 3 laser beams on bead geometries. An experimental campaign is conducted with different orientations relatively to a horizontal substrate and the external profiles are measured using optical instruments in order to extract the average profiles and characteristic dimensions. Results indicate an influence of the head rotation around its axis and lateral tilt on the height, width, and asymmetry of the beads.