Powder spreading of irregular particles with thermal properties

Understanding the thermal and mechanical behavior of the powders used in additive manufacturing is important for improving the quality and reliability of the finished part. The heat transfer in the powder bed is influenced by particle shape, the dependence of interaction properties on temperature as well as the blade speed. The heat transfer in the powder bed strongly influences the quality of the finished powder layer, such as the packing density and the surface profile. In this context, the role of particle shape coupled with its thermal properties is hardly ever explored in the literature and thus is a subject of great potential. In this study, we introduce an extension of the Discrete Element Method (DEM), to simulate non-spherical particles with heat transfer enabled by merging a multisphere algorithm with a thermal discrete particle model. The application of this model is demonstrated with simulations of a powder spreading process using Polyamide 12 (PA12) powder particles of irregular shapes. We characterize the packing density and the surface profile of the powder layer subjected to varying blade speed and the dependence of the particle stiffness on temperature. We observe that the packing density decreases and its standard deviation increases with increasing blade speed. Further, the packing density is more sensitive to small values of dependence of the particle stiffness on temperature. The mean surface roughness is observed to increase with increasing blade velocity. These results demonstrate the potential of our model in exploring the spreading process for real powder particles featuring variety of irregular shapes by considering their thermal and mechanical aspects.