Paving process of nylon powder considering mesoscopic forces in selective laser sintering

Powder paving is an intermediate process of selective laser sintering (SLS). The dimensional accuracy and mechanical properties of sintered components are directly affected by the quality of the powder paving process, which is closely related to the flow characteristics of the powder and the process parameters of powder paving. This study investigated the simulation and optimization of the nylon powder paving in SLS by combining a discrete-element-method numerical simulation with a process test. A dynamic model was established to describe the flow and paving process of nylon powder at a preheating temperature considering mesoscopic van der Waals and electrostatic forces. The effects of the physical parameters and ambient temperature on the flow characteristics of nylon powder were analyzed, and the intrinsic relationship between the physical parameters of nylon powder, the process parameters of powder paving, and the quality of the powder paving were explored. A multi-objective regression model of the quality of powder paving was established using the response surface methodology, and a genetic algorithm was adopted to optimize the quality of the powder paving. A scientific and intelligent database of the nylon powder paving process in SLS was constructed by matching the process parameters of powder paving and physical parameters of the nylon powder, and the level of the SLS process was improved.