Rare Earth

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 neodymium magnets are extremely strong for their small size, metallic in appearance and found in simple shapes such as rings, blocks and discs.

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Typical Magnetic and Physical Properties of Neodymium Magnet Material

neodymium-diagram

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.

Neodymium Tolerances

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

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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.

Neodymium Magnetizing and Handling

Neodymium Magnetizing and Handling Neodymium 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 neodymium magnetic assemblies, they be magnetized after assembly.

Neodymium Machining

Neodymium Machining Since neodymium 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.

 

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

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