Effects of transverse and axial die pressing on the alignment of Nd-Fe-B compacts: A discrete element method study

Abstract

The effects of transverse die pressing (TDP) and axial die pressing (ADP) processes on the alignment and orientation distribution of the Nd-Fe-B compacts were analyzed by discrete element method (DEM). It was found that ADP-compact had lower alignment than TDP-compact, mainly due to the different degrees of the orientation disruption by particle rotation during pressing. That is, when pressed along the Z-axis, particles rotated mainly along the X-axis and Y-axis. For TDP, only the Y-axis was perpendicular to the particle orientation (X-axis), so the rotation along the Y-axis disrupted the orientation, while the rotation along the X-axis had no effect. However, for ADP, the rotation axes (X-axis and Y-axis) of particles were both perpendicular to their orientation (Z-axis), so rotation along any of these axes decreased the alignment. Therefore, ADP-compact was more impaired by particle rotation than TDP-compact during pressing, in the surface and central regions of the compact.