Study on 3D printing a fine quality bone-mimetic porous structure with minimized shape error in pore size: a parametric work on key laser parameters in SLM

One current trend in orthopedics is the production of bone-mimetic porous structures using selective laser melting (SLM). However, there is still a lack of knowledge on fine-tuning the process to ensure the quality of such complex products. Therefore, this study sought to gain insight into how the laser parameters affect the pore shape and mechanical properties. Specifically, based on Voronoi tessellation, the bone-mimetic porous structure was designed to have an average pore size of 600 mu m and fabricated by an SLM machine using Ti-6Al-4 V powder. The laser power and scan speed varied at 80-160 W and 550-950 mm/s, respectively. Afterward, the pore shape error was manually measured using micro-CT images, and the mechanical properties were obtained through compression tests. As a result, the pore narrowed in response to stronger laser powers and slower scan speeds, more dominantly altered by the former. In addition, greater dimensional inaccuracies led to higher mechanical properties, showing a positive correlation. Consequently, the combination of the weakest laser power (80 W) and the fastest scan speed (950 mm/s) exhibited the closest pore size distribution to the design with minimized shape errors of 135-150 mu m while maintaining clinically acceptable levels of compressive strength and elastic modulus (131.45 MPa and 6.24 GPa, respectively). Our findings can serve as valuable references for successfully manufacturing the latest porous implants.