Effects of Gravity and Non-Perpendicularity during Powder-Fed Directed Energy Deposition of Ni-Based Alloy 718 through Two Types of Coaxial Nozzle

The consequences of gravity and the nozzle inclination angle in the powder-fed Directed Energy Deposition (DED) process were examined in this study. We also sought to define guidelines and manufacturing strategies, depending on the DED system configuration and the nozzle type. To do so, two nozzle types were used: a continuous coaxial nozzle with a slit of 0.5 mm and a four-stream discrete coaxial nozzle. Although the main effects of the configurations and the nozzles are well-known, their effects on the clad characteristics and the deposition strategy are as yet unclear. In this paper, measurements of a single clad and the effects of different deposition strategies on cladding applications and inclined walls are presented, and the consequences for manufacturing processes are discussed. Based on a complete study of a single clad, working vertically, five different tilted deposition strategies were applied: three to a single clad and two to an inclined wall. The results for both the single clad and the inclined wall reflect a pattern of changes to height, width, area, and efficiency, at both small and large nozzle angles and deposition strategies. The inclined wall presents a maximum horizontal displacement that can be reached per layer, without geometrical distortions. The amount of material per layer has to be adapted to this limitation.