Filling Density and Geometrical Precision of Ring-Shaped Parts: Effects of the Filling Strategy

The influence of sintering on dimensional and geometrical precision has been widely investigated in previous works, both on ring-shaped parts and on industrial products. Results clearly correlated the dimensional precision to the anisotropic dimensional change during sintering, and geometrical precision is also affected by the sintering process. However, both dimensions and geometrical characteristics markedly depend on the result of the compaction process. The origin of geometric errors has been generally attributed to inhomogeneous filling density distribution, but it has never been analyzed systematically. In this study, a commercial Fe-Mo powder mix was used for compacting ring-shaped samples at different height to thickness ratios (H/T). Focusing on the filling strategy, different values for filling shoe speed, suction speed, and number of shakes of the filling shoe were considered. The influence of both geometry and filling strategy on filling density has been derived, and the results have been related to the geometric characteristics.