Product

Bonded NdFeB magnet is composed with compression NdFeB magnet, injection NdFeB magnet and flexible NdFeB magnet. Since its birth in the middle of 1980’s, the demand of bonded NdFeB magnet has been dramatically increasing for the industries of automatic control, automobile, 3C products (computer, communication & consumer electronics) and household electric appliance with virtues as follows:

One of our bonded NdFeB magnet sources was invested by a successful manufacturer of sintered NdFeB magnet in 1998. Supported with transfer of management and technology from the sister department of sintered NdFeB magnet, the source has rapidly grown up as an excellent producer of bonded NdFeB magnet with annual output 300 metric ton. In the past decade, our engineers have been concentrating their efforts on minimizing dimensional tolerance, reducing property deviation of each lot, each piece and even each pole of one magnet, developing new process to make magnet with better performance and improving surface treatment. At our source, quality assurance and environment protection are strictly conducted in compliance with ISO9001, ISO/TS16949 and ISO14001. The self-owned workshop of tooling enables submitting sample and starting mass production in a very short time. In addition to magnet, the source also provides one-stop-solution service of supplying assembled stator and rotor with shaft or steel housing by injection or gluing. The most important attraction of this source is that the whole company team is with innovative and cooperative conception. Thus the source is classified as a reliable partner by some prestigious companies such as HITACHI, NIDEC, PANASONIC and SANYO and frequently awarded with commodity appreciation from them.

Compression NdFeB Magnet

Compression NdFeB magnet, compound of NdFeB alloy powder and epoxy resin as binder, is molded by compact die. Subsequently the molded part is cured at certain temperature. With combination of plastic character, compression NdFeB magnet could be molded with geometries what are not practicable to sintered NdFeB magnet for example big ring with thin wall thickness. At present compression NdFeB magnet is with isotropic character and could be multi-polarily magnetized with preferred orientation and pattern. The high filling ratio of NdFeB alloy powder maximum up to 97% makes compression bonded NdFeB magnet possessing the strongest (BH)max in bonded magnets family. Generally the same size compression NdFeB magnet is cheaper than injection one by using lower grade NdFeB alloy powder due to high filling ratio of powder in case they are with same flux output. Moreover the tooling cost of compression NdFeB magnet is much cheaper.

Compression NdFeB magnet is extensively used in generator, motor, meter, miniaturized sensor and other applications where requiring advantages over sintered one and ferrite magnet. With limitation of binder and high filling ratio of NdFeB alloy powder, adhesive bonding or additional molding are the proper ways to assemble compression NdFeB magnet together with other component. The compression process is usually recommended to mold magnet with simple geometry such as disc, ring, block and cylinder. Segment and other irregular shapes with bores, slot or chamfer are also available by direct compaction process. The dimensional tolerance of compression bonded NdFeB magnet in X-Y plane is economically controlled within +/-0.05mm. Closer tolerance on critical dimension is also achievable and should be negotiated.

Injection NdFeB Magnet

Injection NdFeB magnet is made of composite of NdFeB alloy powder and PPS (polyphenylene sulphide) or PA (polyamide, also called nylon). The compound is injected inside an in-house tool. No magnetic field is generated in this process for orientating purpose, thus injection NdFeB magnet is with isotropic character and can be magnetized with multi-poles and preferred pattern. Injection molding process offers greater freedom on designing shape and smaller deviation of dimension, therefore further machining process could be eliminated on it. The proportion of NdFeB alloy powder and thermal plastic is respectively up to 50%--70% and 50%--30%, that make its magnetic property lower but mechanical strength stronger than compression NdFeB magnet.

Injection NdFeB magnets are with the same application as compression one, but what requires magnets with complex geometry. The character of excellent chip resistance makes handling easier on production assembly line. Injection NdFeB magnet offers more choices including adhesive bonding, additional molding, interference fit and incorporating injection for assembling. Incorporating injection can mold magnetic material into, onto or against other existing components for example shaft, bushes, gears, toothed wheels etc in one process, what brings benefit of saving subsequent assembling cost and enhancing precision of assembly. Tooling cost of making injection bonded NdFeB is also a little more expensive than compaction die.

Flexible NdFeB Magnet

Flexible NdFeB magnet, composite of NdFeB alloy powder and elastomer as binder, is made by either extruding the composite into required profile or calendering the composite into thin, long and big sheet. The big sheet could be further slit into long strip or be punched into any 2D shape. It is the strongest flexible magnet with energy density up to 10.0MGOe. After systematic testing, flexible NdFeB magnet is convinced with excellent environmental and magnetic stability. The current flexible NdFeB magnet is with isotropic character and could be magnetized with varieties of magnetic poles and pattern. It is with advantages of high flexibility, free tooling cost and availability of thin thickness even 0.4mm. Due to its high flexibility, flexible NdFeB magnet strip could be bended and used as a ring with extremely thin wall thickness and high height, particularly what is very difficult to be molded by process of compression or injection. The birth of flexible NdFeB magnet offers more choice for designing mini motor, generator, sensor, flat speaker and other applications. For certain application, flexible NdFeB magnet could be UV treated, laminated with colorful or printed vinyl (PVC) and covered with adhesive.

■Producible Dimension Range of Flexible NdFeB Magnet

Surface Treatment.

In blending process, NdFeB alloy powder is embedded in epoxy resin or other thermal plastics what are solvent resistant against normal industrial and automotive fluids. Therefore bonded NdFeB magnet is more stable than sintered NdFeB magnet. However if the magnet is working in hot, moist and other corrosive environment, then coating is very necessary. Normally compression NdFeB magnet should have surface treated for protection purpose, meanwhile injection and calender bonded NdFeB magnet are no need to be coated due to high volume fraction of binder. The regular surface treatment on compression NdFeB and their performance are shown on the attached table.

Temperature Character

Both magnet remanence and coercive force will be decreased when the temperature on bonded NdFeB magnet is increased. Irreversible and reversible flux loss will take place at the same time. Temperature change will also obviously take effect on swelling, shrinkage, hardness, strength etc physical characters of bonded NdFeB magnet. As a composite, the maximum working temperature of bonded NdFeB magnet is not merely determined by the type of NdFeB alloy powder but also influenced by the used binder. The recommended working temperature of nylon 12 (PA12), nylon 6 (PA6), epoxy resin and PPS are respectively up to 100℃, 120℃, 180℃, 200℃ for continuously working. Regarding the detailed temperature character of bonded NdFeB magnet, please refer to the relative table.

Complementary Knowledge On Choosing Bonded NdFeB Magnet

From the birth in 1982, the inventor has promoted so many types NdFeB alloy powder for being manufactured bonded NdFeB magnet. Various type quenched powder exhibits difference not only on magnetic property and cost, but also on performance at high working temperature and corrosive environment. In making bonded NdFeB magnet, we choose certain type MQ powder to meet customer’s special demand. Sometimes, we would mix different types powder together in blending process to get hybrid advantage. The attached table can help you to get a brief conception on choosing proper power for your application.