Production of Nd-Fe-B-Magnets by Metal Injection Molding

Net-shape production of complex sintered Nd-Fe-B magnets can become a key element for their resource efficient manufacturing. Metal Injection Molding (MIM) is a well-established powder metallurgical process which achieves complex final geometry with little to no finishing and is being developed for NdFeB. Two different Nd-Fe-B alloy powders were mixed with a multi-component binder system and shaped by MIM into cubes of 10 x 10x 10 mm3. Anisotropic samples were produced by applying a magnetic field during molding. Afterwards the samples underwent a two-step debinding process and were sintered under various conditions. The magnetic properties and the alignment factor were investigated by analyzing the demagnetization curves of magnetized samples. The influence of different debinding and sintering conditions on the carbon content was investigated by hot gas extraction. It was found that MIM is suitable to produce isotropic and anisotropic Nd-Fe-B magnets with high densities up to 98%. Compared to pressed magnets the magnetic orientation is only slightly lower.