Estimation of the effect of rotational speed on flow and mixing quality of particles with different shapes in a rotary drum

The application of metal powders in additive manufacturing (AM) is highly attractive because it enables the on-demand production of complex-shaped products with high quality. Powders utilized in AM often consist of a mixture of particles with varying shapes and sizes. While many research studies are devoted to the analysis of flow properties of particles of various shapes, there is still limited research on the mixing and flow behavior of mixtures of differently shaped particles. In this study, we investigated the effect of drum rotational speed on the flow and mixing quality of AlSi10Mg powder using the discrete element method. The powder comprises a binary mixture of spherical and elongated-shaped particles. Our results show a linear increase in the mixing rate with drum rotational speed up to 50 rpm. The rate then exhibits a minor rise up to 60 rpm before a significant drop at 70 rpm, which coincides with a transition from cascading to cataracting regime observed in the simulated flow patterns. The upper dynamic angle of repose, as measured on snapshots of the powder bed, increases, while the lower dynamic angle of repose decreases with an increase in drum rotational speed. Additionally, both translational and rotational particle energies rise at higher drum speeds. The obtained results suggest using a drum rotational speed of around 50 rpm to achieve a high mixing rate of AlSi10Mg powder mixture.