Numerical analysis of molten-pool behavior during selective laser sintering for improving the performance of polycaprolactone bone scaffold

Abstract. Polycaprolactone (PCL) bone scaffolds fabricated by selective laser sintering (SLS) have great potential for repairing bone defects. Appropriate porosity and sufficient mechanical strength are important characteristics of ideal bone scaffolds. These characteristics are closely related to the SLS process parameters, including laser power, scanning speed, preheating temperature, powder layer thickness, and scanning spacing. However, there is still a lack of theoretical research from the perspective of molten-pool analysis on how SLS process parameters affect the performance of PCL scaffolds. Because of the short interaction time, extremely small dimensions, and complex process, it is very difficult to evaluate the behavior of the molten pool, especially for PCL, and it is necessary to consider Marangoni flow and its viscoelastic characteristics. In this study, the behavior of a PCL molten pool with three different energy densities (Ed) was simulated considering the Marangoni flow and viscoelastic characteristics. Three PCL scaffolds with different Ed values were prepared, and their porosity, mechanical strength, and microstructure were comprehensively evaluated. The results indicated that an appropriate increase in Ed resulted in an increased depth of the molten pool, a decrease in porosity, and strengthened mechanical properties. This study provides new knowledge for understanding and optimizing the performance of SLS-prepared scaffolds.