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Home >> News >>Company News >> Three kinds of permanent magnet materials such as sintered NdFeb, bonded NdFEB and hot pressed NdFEB are introduced
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Three kinds of permanent magnet materials such as sintered NdFeb, bonded NdFEB and hot pressed NdFEB are introduced

The ndFeb permanent magnet is called "Magnetic King". It was discovered in 1983 and industrialized in Japan, China, Europe and the United States in 1985. It has been 35 years since then. Over the past 35 years, the global ndFeb permanent magnet industry has been developing vigorously. The magnetic properties have been constantly setting new records. The varieties and grades of materials have been increasing.


The ndFeb permanent magnet is a foursquare crystal formed by neodymium, iron and boron. According to different production processes, it can be divided into sintered NdFeb, bonded NdFEB and hot-pressed NdFEB.


Sintered Ndfeb


Sintered Ndfeb is the most productive and widely used product in the Ndfeb family. It is produced by powder metallurgy. According to the different coercive force of the products, it is divided into 7 series: N, M, H, SH, UH, EH and TH. At present, the commercial production of sintered Ndfeb, remanence up to 1.45t, the intrinsic coerce up to 2786kA/m, working temperature according to the different coerce between 80°~200°. Sintered NdFeb is easy to be oxidized and corroded, so it needs surface treatment. Phosphating, electroplating, electroless plating, electrophoresis, vapor deposition and other surface treatment methods can be used according to the requirements of the use environment. Common coatings such as zinc, nickel, nickel, copper and nickel, epoxy resin and so on.


Bonded Ndfeb


Sintered NdFeb is difficult to be precisely processed into a special shape, and is prone to cracking, breakage, assembly and other problems in the processing process. To solve these problems, people tried to smash the permanent magnet mixed with adhesive, pressed into shape in the magnetic field, bonded NdFEB came into being. It has the advantages of low cost, high dimensional accuracy, large degree of freedom in shape, good mechanical strength and light specific gravity, and has been widely used in the market.


Bonded NdFeb molding currently has four processes: calendering molding, injection molding, extrusion molding and molding, among which calendering and injection are more mainstream. Bonded NdFeb magnets due to a large number of added adhesives, its density is generally only 80% of the theoretical, so in magnetic weak than sintered NdFeb. Bonded NdFeb is an isotropic magnet with the same magnetism in all directions, so it is convenient to make multi-pole or even multi-pole whole magnet. (Bonded NdFeb can also be made into an anisotropic magnet)


Hot pressed NdFeb


Hot-pressing ndfeb without added to the rare earth elements can be realized under the condition of close to sintered ndfeb magnetic energy, high density, orientation degree is high, the advantages of good corrosion resistance and high coercive force, but the poor mechanical properties, and because the patent monopoly, the manufacturing cost is higher, only a handful of companies on the market at present has realized the hot-pressing ndfeb production of the products.


Due to the limitation of forming technology, at present, ndfeb can only be made into ring by hot pressing, and its application scope is limited to a certain extent. At present, it is mainly used in automobile EPS motor and other fields. Hot pressed NdFeb magnet has high magnetic properties. The maximum radial magnetic energy product of magnetic ring can reach 240 ~ 360kJ/m3. Magnetic ring along the radial orientation, and the radial magnetic uniform, can make the motor running quiet, torque output smooth. At the same time, it has high heat resistance, the service temperature can reach 180℃-200℃.


Three classes of NdFeb permanent magnets each have their own merits


Due to the huge difference in magnetic properties and forming, bonded NdFeb and sintered NdFeb use of the intersection is not big, bonded NdFeb is mainly used in hard disk drive spindle motor and small micro special motor and other fields, while sintered NdFEB is more used in large power drive motor and other fields. Due to the limitation of shape, hot pressed Neodymium iron boron is only used in automobile EPS.


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