High-throughput screening of surface roughness during additive manufacturing

Smooth surfaces in the printed parts are essential for long fatigue life and high dimensional accuracy. They are currently achieved by post-process machining and grinding of external surfaces that add extra costs. Mitigating the surface roughness of internal channels remains a challenge. Here we use a high-throughput screening approach that analyzes the value of a dimensionless index for many experiments and provides a pathway for reducing the surface roughness without the need for post-processing. The index is derived by dimensional analysis of causative variables that affect the roughness of the surface such as heat input, powder diameter, layer thickness, pool aspect ratio, Marangoni force, contact angle, and enthalpy of melting of alloys. Using the results of high-throughput screening, we develop easy-to-use process maps that are consistent with the experimental observations. Among the causative variables, heat input and the contact angle of the molten material with the substrate have the highest and lowest influence on the smoothness of printed surfaces. An aluminum alloy, AlSi10Mg is found to be the best choice for printing smooth surfaces among the four alloys considered here. These findings can improve the surface quality of additively manufactured parts that now significantly hinder their wider industrial adaptation.