Anisotropic dimensional change on sintering may strongly affect the precision of parts produced by press and sinter. In previous work a design procedure accounting for anisotropic dimensional change of axi-symmetric parts (disks and rings) has been developed on the basis of experimental data. In this work the procedure has been applied to predict the anisotropic dimensional change of real parts produced in industrial conditions, providing that coaxial rings were identified in the geometry of the actual parts. Parts were highly different for material, complexity of geometry, green density and process conditions. Parts were measured in the green and sintered state and the measured dimensional changes were compared to the predicted ones, finding a good agreement. The procedure was also adapted to predict dimensional change of an oval feature, and highly satisfactory results were obtained.

The anisotropic dimensional changes during sintering was investigated for rings made of eight different materials with different green densities and H/(Dext-Dint) ratio. Dimensional changes are affected by green density, as shown in previous works, while the geometrical parameter does not display a clear influence. The anisotropy parameter K defined in a previous work does not describe anisotropy of dimensional change unambiguously, due to the anisotropy of shrinkage/swelling in the compaction plane. A new anisotropy parameter (K3D) was therefore defined considering the dimensional changes of internal diameter, external diameter, and height. This parameter display an unambiguous dependence on the equivalent isotropic dimensional change and will be used in further work to develop a predictive model for the prediction of the anisotropic dimensional change during sintering of parts with different green density and geometry.

The anisotropy of dimensional change in compaction plane of rings made of three low alloyed steels was investigated as a function of green density and geometry. Increasing green density and (D ext -D int )/H ratio, the anisotropy of both shrinkage and swelling increases. A correlation with springback during ejection of the rings from die cavity after cold compaction was found. The ratio between the dimensional changes of diameters, as a function of the ratio between springback of diameters, describes a linear correlation intersecting point (1,1), representative of isotropic behaviour. This correlation confirms the hypothesis of an effect of micropores, generated in the green parts during ejection from die cavity, on dimensional change anisotropy. An analytical correlation was determined for the anisotropy of dimensional change in the compaction plane as a function of green density and geometrical parameter, which can be implemented in the design methodology accounting for the anisotropic dimensional change previously proposed.