Processing Process Of Sintered NdFeB Magnets

Manufacturing processes:
Ingredient Weighting→Melting & Strip Casting→Hydrogen Decrepitation→Jet Milling→Aligning & Pressing→Sintering & Annealing→Material Testing→Machining→Surface Treatment→Product Inspection→Magnetizing→Packing & Shipping

 

Post processing：
The outer contour of the magnet is generally finished by a centerless grinder (cylindrical magnet) or a surface grinder (square magnet), so that the rough magnet has a regular outer contour and reaches the specified geometric size;

 

The cutting process is to use a diamond internal circle slicer or a wire cutting machine to cut the finished rough magnet into a shape and size close to the finished product;

 

The fine grinding process is to use a surface grinder, a double-sided grinder or other grinders to process the cut magnets to meet the requirements of the finished product;

 

Chamfering is a pretreatment process before electroplating, in order to alleviate the uneven thickness of the coating caused by the relatively concentrated current density on the edge of the magnet during the electroplating process. Due to the small size and different shapes of the usual sintered Neodymium finished magnets, the free-rolling finishing process is most suitable for mass chamfering of this product. Free tumbling and finishing technologies include: vibration tumbling, eddy current tumbling, centrifugal tumbling, spindle tumbling and other methods. Among them, the vibratory barrel grinding has high production efficiency and fast chamfering speed, and has been widely used by sintered Nd-Fe-B magnet processing manufacturers;

 

Electroplating is to form a protective layer on the surface of the magnet, which is usually achieved by free barrel plating, and for larger magnets, rack plating is used. The coating of sintered Nd-Fe-B magnets is divided into Ni plating, Zn plating, phosphating, electrophoresis, alloy plating, composite plating, etc. depending on the use environment and appearance requirements of the magnet.

In addition to electroplating, the surface protective layer of sintered NdFeB magnets also has physical vapor deposition (PVD) method. Physical vapor deposition is divided into three types: evaporation plating, sputtering plating, and ion plating, which can form Al, Zn, Cr and other coatings; Chemical vapor deposition (CVD) can form nitride and carbide coatings of Ti, Cr, etc. In addition, sintered NdFeB magnets can also obtain various surface protection layers by surface chemical passivation, electroless plating, hot dipping, thermal spraying and other methods.

 

The inspection and testing process is to test the various indicators specified by the product such as the size and shape tolerance, appearance state, coating corrosion resistance, and magnetic properties of the finished magnet.