Performance characteristics and applications of Bonded Neodymium magnets

Compared with sintered permanent magnet materials and cast permanent magnet materials, the outstanding advantages of bonded neodymium magnet materials are:

1. Shape freedom. According to application requirements, it can be made into products of various shapes, such as magnetic strips, magnetic sheets, magnetic gears, magnetic tiles, magnetic rings, magnetic tubes and other complex shapes;
2. Dimensional accuracy of product is high, no deformation, and no need for secondary processing;

3. It can be integrally formed with other components to make composite products

4. High mechanical strength, no delamination, no cracking

5. It can be radially anisotropic to produce strong inner and outer multi-pole magnets

6. The production process is relatively simple, and it can be mass-produced automatically with high yield; waste materials are easy to      recycle and reuse. The cost is relatively low;

7. Depending on the choice of binder, products with different physical and chemical properties can be made.

However, bonded NdFeB magnets also have their inherent disadvantages.

• First, the magnetic properties are lower than those of the corresponding sintered permanent magnets and cast permanent magnets;
• Second, their density is small, generally equivalent to 50%~80% of the density of the magnetic powder dense material;
• Third, the hardness and compressive strength are low;
• The fourth, the use temperature is not high, which is restricted by the organic binder.

  

  

Bonded magnets appeared around the 1970s, when SmCo magnets had already reached commercialization. The market situation of sintered NdFeB magnets is very good, but it is difficult to precisely process them into special shapes, and they are prone to cracking, breakage, edge loss, corner loss, etc. during the processing process. In addition, it is not easy to assemble, which limits its application. To solve this problem, the permanent magnet is crushed, mixed with plastic, and pressed into shape in a magnetic field. This is probably the most primitive manufacturing method of bonded magnets. Bonded NdFeB magnets are widely used due to their low cost, high dimensional accuracy, large shape freedom, good mechanical strength, and light specific gravity. Since the emergence of NdFeB permanent magnet powder, flexible bonded magnets have achieved rapid development due to their high magnetic properties.