One Ring to Magnetize Them All…

Radially oriented NdFeB rings reduce production costs

To achieve a radially oriented magnetic field, eight to 12 arc-magnet segments are commonly used to form a ring. These magnet arcs are oriented through their centerline and magnetized prior to assembly. While this enables the production of high-performance magnet assemblies—such as voice coil motors (VCM), linear motors and actuators—the cost of the magnets and assembly labor can be prohibitive for large productions. Such a magnet assembly generally requires in-process grinding, after magnetization, to ensure correct tolerances after assembly.

However, radially oriented, sintered Neodymium Iron Boron rings from Magnetic Component Engineering, Inc., Torrance, CA, offer a more cost-effective solution. Since the ring is manufactured as a single piece, all grinding processes can be done prior to magnetizing and assembly. Even if a surface treatment is required, coating can also be performed prior to magnetizing. Assembly can be easily automated for mass production, thereby reducing assembly costs. Polarization can be either a single pole (inside-outside) or alternating configurations with multiple poles on the OD/ID. Parts can be magnetized either after assembly or externally.

Radially oriented NdFeB rings can be made in a variety of materials with energy products ranging from 28 to 40 MGOe. This allows customization of performance for demanding applications.

Surface treatment is not necessary, but it is recommended for NdFeB magnets, as the material is prone to rapid oxidation, especially in harsh environments. Sintered rings can be coated with IVD aluminum chromate or PR1010 modified black phenolic resin (and even nickel for large production runs). IVD coating is recommended for large production runs owing to the multiple setup costs, but it is popular as an extremely strong oxidation inhibiter that passes salt-spray tests. PR1010 has high resistance to chemicals, is durable and retards oxidation. This coating is also offered by the company for coating other metal components, and especially as a primer on metal prior to bonding.

—SG

For more information:

Circle 155—Magnetic Component Engineering Inc, or connect directly to their website via the Online Reader Service Program at www.rsleads.com/202df-155