Manufacturing Process of Sintered Neodymium Magnets


Courtesy of

Manufacturing of neodymium magnets mainly involves 8 steps. Prepare Materials -> Melting -> Milling -> Molding -> Sintering -> Machining -> Plating -> Magnetization. Inspections will be applied during every process mentioned above.

Prepare Materials

A rare earth magnet mainly consists of 3 elements neodymium, iron and boron. The materials are pure boron, pure iron and rare earth metals. The rare earth metals may include neodymium (pure neodymium, praseodymium-Neodymium alloy, neodymium oxide). Several other rare earth elements may be added to partly replace neodymium: Dysprosium, Terbium, Gadolinium, Holmium, Lanthanum and Cerium. Copper, Cobalt, Aluminium, Gallium and Niobium may be added to improve other properties of the magnets. Please detailed function of these materials, please refer to our function of materials added to neodymium magnets. For detailed recipes, please refer to our raw materials used in manufacturing of neodymium magnets.


Raw materials need to be melted in vacuum induction furnace to form Nd2Fe14B alloy. The finally product of this step is fine strip-casting flakes (SC flakes) consisted with uniform Nd2Fe14B crystal. The melting process need to be finished in very short time to avoid excessive oxidation of the rare earth metals.


A 2 step milling process is adopted in manufacturing practice. The first step is called hydrogen decrepitation which involves reaction between hydrogen and neodymium and the alloy to break the SC flakes into smaller particles. The second step is called jet milling which will turns the Nd2Fe14B particles into even smaller particles with diameters ranging from 2-5μm.


The NdFeB powder is pressed to form a solid with desired shape in strong magnetic field. The pressed solid would obtain and maintain a preferred magnetization direction.


The pressed NdFeB solid need to be sintered to form the NdFeB block. Sintering process involves 3 steps: Dehydrogenation, Sintering and Tempering.


The sintered NdFeB block need to be machine to get the desired shape and size.


Uncoated NdFeB is highly prone to corrosion and will quickly lose magnetic properties in the presence of moisture. So all commercial neodymium magnets need to be coated. The most common type of coating is a three layer coating: nickel, copper and nickel. For detailed coating type, please refer to available coating type for neodymium magnets.


Process NdFeB block need to be placed in strong magnetic field to obtain desired magnetic strength.

Customer comments

No comments were found for Manufacturing Process of Sintered Neodymium Magnets. Be the first to comment!