DEM simulation of the magnetic pressing process of a Nd-Fe-B compact

The behaviors of Nd-Fe-B particles during the magnetic pressing process, in particular the reason for the decrease in alignment degree of green compact during pressing, were investigated systematically via the discrete element method (DEM) and experiments. The simulation results showed that the average alignment degree of the compact increased sharply under an applied magnetic field and then decreased slightly under mechanical pressure. The main reason for the decrease in alignment degree of compact was that particles in different parts of compact traveled different distances during pressing, leading to the decrease in alignment degree of particles close to the surface perpendicular to the applied magnetic field. Furthermore, these two parts of compact had different orientations after pressing since they were subjected to opposite torques. The orientations of different parts of the sintered magnet were also measured by X-ray diffraction (XRD) and pole figures (PFs). The experimental data were in good agreement with the simulation results.