Relationship between powder properties and powder layer quality in powder-bed-based additive manufacturing processes
Résumé
The powder spreadability drives the robustness of powder-bed-based additive manufacturing processes (laser powder bed fusion and binder jetting) as well as the performance of the printed parts. A data analysis relying on the characterizations of 59 powders is introduced to better understand and predict powder spreadability. The study is also supported by data coming from a powder spreading bench able to assess the powder layer roughness and apparent density. It is found that the untapped powder apparent density is a relevant indicator of the powder layer
density. The untapped density is itself widely dependent on the particle sphericity measured by morphogranulometry. A statistical model based on multiple linear regressions and standard least square method has been established to predict powder apparent density based on the particle shape and size. The model explains 85% of the variability of the relative powder apparent density and allows an efficient screening of powders spreadability without experiments. A comparison between roller-spreading and blade-spreading is also presented in the study. The compacting forces applied by the roller on the powder bed allow the spreading of fine cohesive powder below 15 microns, which is impossible with a blade. Spreading of such fine powder presents
the advantage to minimize the powder layer roughness