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Bonded NdFeb Magnets

 

bonded_neo_rings

 

Features: Isotropic, Multiple Poles, Magnetizing Along Any Axis, High Energy.

A recently introduced material in the NdFeB family is the bonded NdFeB with energy products currently in 3 – 12 MGOe range. Bonded NdFeB magnets could be made to close tolerances right off the tool, minimizing the need for finish machining.

Bonded neodymium-iron-boron magnets are made by patented materials — MQP family. These materials are produced from fast quenching processing. Molten Nd 2Fe14B alloy flows under pressure onto a chilled rotating wheel. The alloy is instantaneously cooled at a rate of about one million º C/second. This process forms flakes of NdFeB. The flakes are then crushed into 200-micron particle-sized powder. These fine grain size isotropic NdFeB particles have high thermal stability in terms of flux density and intrinsic coercivity. The annealed powder can be combined with a variety of plastics or polymers, epoxy resin for injection or compression molding. The blend is fed into mold in a cold compacting process to form the magnets which are subsequently oven-cured. This process permits magnet shapes and dimensions — ± 0.002″ or 0.05 mm in tolerances — that were previously impractical or impossible.

Our bonded magnets are coated by electrophoresis coating processing using different epoxy resins to meet our customers’ requirement. The thickness of the epoxy resin coating can be controlled to 15 to 35 microns. One or two coating layers may be applied depended on different working environments. These coated magnets could survive in the salt fog spray test (5 % NaCl, 35º C) for 200 to 600 hours. The coating could be grey or black in color. The finished coating is smooth, free of voids and pin-holes. Nickel-coating and Zinc-coating are also available for your selection.

The finished magnet parts might be magnetized along any axis and with multiple poles on any surface because of their isotropic nature, though special magnetizing fixtures must be constructed for this.

The Curie temperature, Tc, of Bonded NdFeB magnets varies from 305º C to 470º C depended on powders used.

We can custom-make a variety of bonded NdFeB magnets to meet our customers’ special needs. They could be a magnet ring — a large ring with a outer diameter up to 8″ or 200mm; or a small ring with wall thickness as thin as 0.04″ or 1.0mm. They also could be arcs, blocks, disks, etc.

 

bonded cylinder magnets

 

MAGNETIC CHARACTERISTICS
( In five grades )

Residual Induction
Br
3,500 – 7,500
Gauss
Coercive Force
bHc
3,000 – 6,000
Oersted
Intrinsic Coercivity
iHc
8,000 – 14,000
Oersted
Energy Product
BHmax
3 – 12
MGOe

 

Mechanical clamping or epoxy adhering are the most popular methods of fastening NdFeB magnets to an assembly. Due to their brittle nature, press-fit is not recommended.

We also custom-make plastic injection molding compound NdFeB magnet parts for special order in large quantities.

 

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