Effect of process on the magnetic properties of bonded NdFeB magnet

The effects of magnetic separation, coupling treatment, lubricating treatment, preform and biaxial molding on the density and magnetic properties of bonded NdFeB magnet were investigated. The results demonstrate that magnetic separation separates the powders with low coercive force; coupling treatment improves the interfaces between the powders and the binders; decrease in volume fraction of the binder increases magnetic properties of the magnet; granular arrangement improves both the magnetic and mechanical properties when powders are arranged in certain size; lubricating treatment improves the formability of the magnet and preform and biaxial molding improves both density and magnetic properties greatly. Combining these methods, the density of the bonded NdFeB magnet can reach 6.52 g/cm3 and the maximum energy product can reach 114 kJ/m3.