Flow of Magnetic Powder in Stepped Cavity Shape under Applied Magnetic Field

Nd-Fe-B magnet, which possesses the highest magnetic performance, is fabricated by powder metallurgy process. The magnetic powder is compacted under an applied magnetic field for the particles' easy directions of magnetization to be oriented along the magnetic flux. It is widely known that the magnetic powder flows and moves during this process both by the applied magnetic field and by the applied pressure. Since this process determines the final properties of the magnet, it is of great importance to clarify the behavior of the powder during the process.In the present study, we focus on the flow behavior of Nd-Fe-B powder due to an applied magnetic field. An attempt is made to make clear the powder flow by in-situ observation with a transparent die set. An FEM-DEM simulation is also performed to investigate the flow of magnetic flux that affects the movement of the powder. It is thereby shown that simulated results of the flow of magnetic powder and change of the structure built-up by particles are in good agreement with experimentally derived ones.