What are bonded Nd-Fe-B magnets?
What are bonded Nd-Fe-B magnets?
Bonded NdFeB magnet consists of Nd2Fe14B, which is a synthetic magnet. Bonded NdFeB magnet is a kind of magnet which is made by mixing rapidly quenched NdFeB magnetic powder and binder through “pressing molding” or “injection molding”. The size precision of bonded magnet is high, and it can be made into magnetic components with relatively complex shape, and has the characteristics of one-time forming and multi-polar orientation. Bonded NdFeB magnet has high mechanical strength, and can be molded with other matching components at one time.
Bonded magnets appeared in the 1970s, when SmCo was commercialized. The market situation of sintered permanent magnet is very good, but it is difficult to be precisely machined into special shape. Moreover, it is easy to crack, damage, edge drop, corner drop and other problems in the process of processing. In addition, it is not easy to assemble, which limits its application. In order to solve this problem, the permanent magnet is crushed, mixed with plastic, and pressed in magnetic field. This is probably the most original manufacturing method of bonded magnet. Bonded NdFeB magnets are widely used because of their low cost, high dimensional accuracy, large shape freedom, good mechanical strength and light specific gravity, with an annual growth rate of 35%. Since the appearance of NdFeB permanent magnet powder, flexible bonded magnet has developed rapidly because of its high magnetic properties.
Advantages of Bonded NdFeB magnet
High remanence, high coercivity, high magnetic energy product, high performance price ratio, easy to process various sizes and minimum specifications. Compared with sintered magnet, it can be formed in one time without secondary processing, and can be made into magnets with complex shapes, which is also incomparable with sintered magnet. The volume and weight of motor can be greatly reduced by using it.
Application fields of Bonded NdFeB magnet
Bonded NdFeB magnet is made of NdFeB magnetic powder and adhesive. Since the successful development of this material in 1988, it has developed rapidly and the output has increased exponentially. As a kind of high-performance permanent magnet material, it is in line with the trend of short-term, small-sized, light-weight and thin-walled electronic products.
The production and application of bonded Nd-Fe-B permanent magnet is relatively late, and its application range is not wide, and its consumption is small. It is mainly used in office automation equipment, electrical installation machinery, audio-visual equipment, instrumentation, small motor and metering machinery, mobile phone, CD-ROM, DVD-ROM drive motor, hard disk spindle motor HDD, other micro special DC motors and automatic instruments. In recent years, the application proportion of Bonded NdFeB magnet permanent magnet materials in China is as follows: computer accounts for 62%, electronic industry accounts for 7%, office automation equipment accounts for 8%, automobile accounts for 7%, appliances accounts for 7%, and others account for 9%.
What shapes can be made of Bonded NdFeB magnet?
The main ring is more common, in addition, it can be made into circular, cylindrical, tile shaped, etc.
Advantages of extrusion molded Nd-Fe-B bonded magnets are listed as below:
- Magnets are continuously extruded to keep the same dimensions and properties along the length. Taper is negligible.
- Magnets of over 1 meter in length can be achieved. And one set of hard tools can make products of different lengths.
- Extruded magnets have lower porous ratio and better corrosion resistance than compression molded ones. For certain applications coating is unnecessary.
- Higher performance can be expected for less resin composition than injection molded magnets.
Bonded NdFeB magnets have high dimensional accuracy, uniformity and consistency. It can be made into a complex shape which is difficult to realize with sintered Nd-Fe-B magnets, and can be easily integrated with other metal or plastic parts. Bonded NdFeB magnets are characterized by various magnetization modes, low eddy current loss and strong corrosion resistance.
Easy integrated forming
Various magnetizing patterns
Good magnetic uniformity
Strong corrosion resistance
Bonded NdFeB magnets are mainly used in computer hard disk and optical disk drive, printer / copier motor and magnetic roller, energy-saving household appliances, consumer electronics and control components and other information technology industries. Their applications in micromotors and new energy vehicle sensors are gradually becoming the new mainstream market.
Magnetic Properties of Bonded Nd-Fe-B Magnets
Feature of Magnetization
Long Term Irreversible Loss
Physical and Mechanical Properties