Compression bonded magnets are available using many isotropic
neodymium iron boron material grades as well as crushed & powdered
samarium cobalt materials. Combinations of different material grades may
also be used to create specific magnetic characteristics. Compression
bonded magnets offers higher magnetic strength than injection molded
magnets due to their higher magnetic particle density, but are limited
to simpler geometries. The epoxy binder used is resistant to normal
industrial solvent and automotive fluids. To reduce corrosion of the
rare earth magnetic materials, they are further coated with epoxy after
shaping. The normal application temperatures range from below -40°C to
above 165°C.
Compression bonding is most appropriate for relatively simple
geometries due to limitations of the compaction process. The tooling
costs for compression bonding is comparatively low, making it a better
choice than injection molding where volumes are small. However, with
modest automation, compression bonding can also be adopted for high
volume manufacturing, with volumes upto millions of pieces per year.
Production Flow Chart for Compression Bonded NdFeB
Raw material (Mainly NdFeB powder and binder) preparation—Blending NdFeB
powder and binder—Compaction
molding—Machining—Surfacetreatment—Magnetizing—Final
inspection—Packing—Warehousing
Production Flow Chart for Injection Bonded NdFeB
Raw material (Mainly NdFeB powder and binder) preparation—Blending NdFeB
powder and binder—Injection molding—Machining—Surface
treatment—Magnetizing—Final inspection—Packing—Warehousing
The performance of the compression bonded neodymium magnets.
BNP-3 | BNP-6 | BNP-8 | BNP-8SR | BNP-9H | BNP-10 | BNP-11 | BNP-12L | |
Br (mT) | 450-510 | 590-650 | 620-670 | 620-66 | 650-700 | 680-720 | 700-740 | 730-770 |
Br (Gs) | 4500-5100 | 5900-6500 | 6200-6700 | 6200-6600 | 6500-4000 | 6800-7200 | 7000-7400 | 7300-7700 |
Hcb(kA/m) | 199-263 | 302-374 | 390-454 | 405-470 | 421-484 | 413-477 | 430-493 | 366-430 |
Hcb(kOe) | 2.5-3.3 | 3.8-4.7 | 4.9-5.7 | 5.1-5.9 | 5.3-6.1 | 5.2-6.0 | 5.4-6.2 | 4.6-5.4 |
Hcj (kA/m) | 477-597 | 597-796 | 636-796 | 955-1114 | 915-1034 | 636-796 | 636-796 | 517-637 |
Hcj(kOe) | 6.0-7.5 | 7.5-10.0 | 8.0-10.0 | 12.0-14.0 | 11.5-13.0 | 8.0-10.0 | 8.0-10.0 | 6.5-8.0 |
(BH)max (kJ/m 3) | 24-32 | 44-53.6 | 60-68 | 65.6-72 | 72-80 | 76-84 | 80-88 | 84-92 |
(BH)max (MGOe) | 3.0-4.0 | 5.5-7.0 | 8.0-9.5 | 8.2-9.0 | 9.0-10.0 | 9.5-10.5 | 10.0-11.0 | 10.5-11.5 |
Tw/ ℃ | 120 | 120 | 120 | 160 | 160 | 120 | 120 | 110 |
The factory has over 15 years experience on manufacturing and technology on the plastic bonded magnets. With its own molding workshop, the factory can accomplish entire production process in-house from molding design, manufacturing and maintenance. The plant has obtained automatic production with rigorous Japanese-type management and precise equipments imported.
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