Numerical heat transfer modeling in coated powder as raw material of powder-based rapid prototyping subjected to plasma arc

摘要

Heat transfer in coated powder particles used as raw material in selective electrical discharge sintering is investigated numerically through the finite-volume method during the binding stage. In this stage, the thermal energy of the plasma arc is distributed to all of the nodes of coated powder by conduction. Transient heat transfer analysis in spherical coordinates with radiation and convection thermal boundary conditions at the outer surface of the coated powder is carried out in this study. Then grid and time independence are investigated and the temporal temperature distributions in both the radial and angular directions are obtained. The results indicate that the temperature at the outer surface of the top hemisphere of the coated powder is higher than the temperature on the outer surface of the bottom hemisphere. In addition, the temperature gradient in the polymeric layer is higher than that in the metal powder. Therefore, the polymeric neck growing in the lateral direction is greater than that in the depth of the powder bed.