Discrete element simulation of powder layer spreading by blade sliding: packing factor, mechanism, and optimization

We utilized the discrete element method to simulate the packing of a powder layer by blade spread. Our study revealed the following findings: (1) We uncovered a hereditary relationship that exists between the pouring heap and the packing layer, which plays a significant role in the non-uniform distribution of powder in the packing layer in terms of sizes and shapes. (2) We systematically analysed the influence of sliding speed on powder packing and recommended a threshold sliding rate of 0.15 m/s for achieving a high packing quality. (3) Contrary to the conventional belief that non-spherical powders tend to reduce packing density, our study discovered that the inclusion of a small portion of non-spherical powders can create pathways for efficient gap-filling, resulting in denser packings. (4) By adjusting inter-powder interactions, we observed a transition from discrete powder packing to cluster deposition. (5) We proposed and demonstrated the efficacy of a two-step spreading technique followed by multiple shaking cycles in achieving maximum random packing density. Overall, our work provides a comprehensive understanding of mechanisms involved in the powder spreading process through blade sliding, which may lead to enhanced powder packing density and uniformity and ultimately improved outcomes in additive manufacturing.