DEM Simulation of the Single-Acting Pressed and Double-Acting Pressed Nd–Fe–B Compacts

Abstract

The orientation distribution of Nd-Fe-B compacts under single-acting pressing (SAP) and double-acting pressing (DAP) was simulated by the discrete element method (DEM). The results showed that for both SAP and DAP compacts, the particles in the central section had a higher alignment degree than those near the die wall in the direction parallel to the applied magnetic field, due to the relative motion between different sections within the compacts. Moreover, the sections near the punches had more poorly aligned particles because they underwent a longer movement distance and a larger compressive force. Meanwhile, the DAP compact had a higher alignment degree than the SAP compact, owing to the smaller differences in movement distance among various sections in the DAP compact during the pressing process. Furthermore, the orientation direction varied in the direction parallel to the applied magnetic field, and exhibited a mirror symmetry in the direction parallel to the applied compressive force for the DAP compact. The results provided an insight to optimize the magnetic pressing process and improve the quality of Nd-Fe-B compacts.