Spiral growth selective laser melting of axisymmetric objects from Cu-Ni–Sn alloy powder: a mass rate efficiency and physical properties study

Fabrication of metallic solid objects was achieved using an experimental spiral growth selective laser melting (SG-SLM) 3D printer. This device incorporates a cylindrical coordinate system, thus coined spiral growth manufacturing (SGM), instead of the ubiquitous Cartesian coordinate system found in commercial powder bed fusion selective laser sintering/melting (SLS/SLM) equipment. How the fabrication parameters, laser beam power, and powder layer thickness affect the properties of the resulting 3D printed parts are addressed by assessing the volumetric energy density of each parameter set. This magnitude is then correlated with the mass rate efficiency and physical and mechanical properties of printed ring-shaped objects. A design of the experiment was set up varying the thickness of the powder layer from 400 to 600 μm and the nominal laser beam power between 150 and 250 W; the rpm used was set to 1. The experiments were carried out using a commercial powder copper alloy processed under flowing argon gas. Results show a decreasing trend between the mass rate efficiency and the volumetric energy density; moreover, an increase in the mass density of the specimens with volumetric energy density is observed; however, a decrease in ultimate stress is witnessed instead. Microhardness is almost independent of volumetric energy density while % porosity slightly increases with the latter. Current work is underway to achieve a lower layer thickness below 100 microns.