Effect of cohesion on the gravity-driven evacuation of metal powder through Triply-Periodic Minimal Surface structures

Evacuating the powder trapped inside the complex cavities of Triply Periodic Minimal Surface (TPMS) structures remains a major challenge in metal-powder-based additive manufacturing. The Discrete Element Method offers valuable insights into this evacuation process, enabling the design of effective de-powdering strategies. In this study, we simulate gravity-driven evacuation of trapped powders from inside unit cells of various TPMS structures. We systematically investigate the role of cohesive energy density in shaping the retention profile. Overall, we conclude that the Schwarz-P and Gyroid topologies enable the most efficient powder evacuation, remaining resilient to cohesion-induced flow hindrance. As the cohesion energy density is increased from 0 to , the two geometries transition from trapping almost negligible powder to 4.10% and 22.2% respectively. However, our results reveal that powders beyond a cohesive energy density of should be strictly avoided due to catastrophic retention across all TPMS structures. Furthermore, for the two unit cells, we analyse detailed kinematics and interpret the results in relation to particle overlaps and contact force distributions, finding that the Schwarz-P is uniquely hindered by transient arching. This insight is valuable for devising cost-optimized, energy-efficient protocols for de-powdering.