The effect of contactless support parameters on the mechanical properties of laser powder bed fusion produced overhang parts

Support structures are used in especially overhang areas in laser metal additive manufacturing to prevent parts from distortion due to high thermal gradients. Since the support structures are not a part of the final component, extra time and material are needed for manufacturing. Moreover, they need to be removed after the build is completed. In addition to waste of time and material, distortion and/or surface roughness issues at supported surfaces may be observed during support removal. As a solution, contactless supports with no direct contact between the support and the part are studied in the present work. Contactless support gap, thickness of each contactless support pieces, and the spacing between two contactless support pieces were used as design variables, and dimensional variations, microhardness through thickness, microstructural changes of bottom surfaces, and surface roughness of overhang features were selected as performance outputs. A full set of design of experiments were manufactured by laser powder bed fusion process using Inconel 718 material. It was observed that all three geometrical parameters had influence on the performance outputs.