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What is the Difference Between Sintered NdFeB Magnet and Bonding NdFeB?

NdFeB magnets can be divided into two types: bonded NdFeB and sintered NdFeB. The difference between the two is mainly in the process. Bonding NdFeB is made by adding NdFeB magnetic powder to the binder. Bonding is actually injection molding, while sintering is vacuumed and heated at high temperature! The sintered neodymium iron boron permanent magnet material adopts powder metallurgy technology. The smelted alloy is made into powder and pressed in a magnetic field to form a compact. The compact is sintered in an inert gas or vacuum to achieve densification, in order to improve the coercivity of the magnet , Usually requires aging heat treatment.

Sintered NdFeB is a powder metallurgy process, generally called NdFeB, the material itself is very hard, the hardness is about 560-580Hv, but it is quite brittle. The density is about 7.4-7.6 g/cm3, with high resistance to demagnetization, but the temperature stability is general. According to different performance levels, the maximum working temperature is between 80-250 degrees Celsius. If there is no electroplating or coating, the corrosion resistance of the material is very high. Poor, easily oxidized. The resistivity of the material is about 160 micro ohm centimeters, the recovery permeability is about 1.05 μreo, the temperature coefficient of remanence is between -0.12~-0.1%/degrees Celsius, and the temperature coefficient of intrinsic coercivity is about -0.6%/degrees Celsius.

The price of bonded NdFeB is relatively cheap. On the one hand, there are less materials and fewer processes. The current process technology of sintering NdFeB is too poor, and the process of bonding NdFeB is simple, so the price is very different; bonded NdFeB magnets It is a magnet made of quick-quenched NdFeB magnetic powder and a binder through “compression molding” or “injection molding”. Bonded magnets have high dimensional accuracy, can be made into magnetic components with relatively complex shapes, and have the characteristics of one-time molding and multi-pole orientation. The bonded neodymium iron boron has high mechanical strength and can be formed with other supporting components at one time during forming.

The main difference between the two products lies in the process flow. The bonded NdFeB magnet is actually made of NdFeB magnetic powder and adhesive, which is similar to injection molding. Sintered NdFeB is made with the complicated process described above. It is formed by vacuuming and heating at high temperature.

Bonded NdFeB magnets are not as good as sintered NdFeB magnets in terms of performance. The reason is that they are made with adhesives, and the density is only 80% of the theoretical level. In general, the application range of sintered NdFeB magnets will be wider and higher than bonded ones.