RARE EARTH MAGNETS

Offshore Solutions can ensure excellent rare earth magnets from China and is very price competitive. Offshore Solutions has audited, qualified and worked with QS-9000 and ISO certified magnet factories in China for over 12 years. OSI is dedicated to managing your project on-site in China and delivering parts to you at lower prices but the same quality, service and terms as a domestic supplier.

There are two types of rare earth magnets available: Neodymium and Samarium Cobalt. They are called rare earth because their composition elements found in the "Rare Earth" or Lanthanides portion of the Periodic Table of Elements.

Neodymium magnets (Nd-Fe-B) are composed of neodymium, iron, boron and a few transition metals. Samarium cobalt magnets (SmCo) are composed of samarium, cobalt and iron. These rare earth magnets are extremely strong for their small size, metallic in appearance and found in simple shapes such as rings, blocks and discs.

Typical Magnetic and Physical Properties of Rare Earth Magnet Material

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Attributes of Neodymium

Very high resistance to demagnetization
High energy for size
Good in ambient temperature
Moderately priced
Material is corrosive and should be coated for long term maximum energy output
Low working temperature for heat applications, but higher levels of heat resistance materials are being introduced periodically.

Applications of Neodymium
Magnetic separators, linear actuators, microphone assemblies, servo motors, DC motors (automotive starters), computer rigid disc drives, printers, speakers

Attributes of Samarium Cobalt

High resistance to demagnetization
High energy (magnetic strength is strong for its size)
Good temperature stability
Expensive material (cobalt is market price sensitive)

Applications of Samarium Cobalt
Computer disc drives, sensors, traveling wave tubes, linear actuators, satellite systems, motors where temporary stability is vital

Rare Earth Tolerances

For as pressed material, tolerance on the thickness (direction of magnetization) is ± .005. Other dimensions are ± 2.5% or ± .010, whichever is greater.

According to IMA standards, visual imperfections such as hairline cracks, porosity and minor chips are commonly found in sintered metallic magnets. A chipped edge is considered acceptable if no more than 10% of the surface is missing. Cracks are acceptable as long as they do not extend across more than 50% of pole surface.

Rare Earth Magnetizing and Handling
Rare earth magnets are very brittle and very strong magnetically. Therefore, it is crucial to handle these magnets with extreme care to avoid personal injury and damage to the magnets. Fingers can be severely pinched between attracting magnets. Magnets can chip if allowed to "jump at" an attracting object. It is highly recommended that when constructing rare earth magnetic assemblies, they be magnetized after assembly.

Rare Earth Machining
Since rare earth magnet material is prone to chipping and cracking, it does not lend itself to conventional machining methods. It can, however, be abrasively ground, but only with the use of liberal amounts of coolant. The coolant minimizes heat fracturing and the risk of fires caused by oxidized grinding dust.