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Neodymium Magnets

 

Extremely strong for their size, Neodymium (Nd-Fe-B) rare earth magnets are composed of neodymium, iron, boron and a few transition metals. Not sure if neodymium is the best material for your application?

Manufacturing - In general, the elements are melted together and milled into a powder that is dry-pressed to shape in the presence of a magnetic field. The material is then sintered, ground to dimension, magnetized and tested.

They are called “rare earth” magnets because the elements of neodymium are classified as such in the lanthanides section of the Periodic Table of the Elements.

Tolerances - For as-pressed material, tolerance on the thickness (direction of magnetization) is +/– .005”. Other dimensions are +/– 2.5% or +/– .005”, whichever is greater.

According to standards, visual imperfections such as hair-line cracks, porosity and minor chips are commonly found in sintered 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 the pole’s surface.

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 rare earth magnetic assemblies, they be magnetized after assembly. These magnets are NOT for children. Please see our safety warnings page for more information. 

Machining - Since Neodymium is prone to chipping and cracking, it does not lend itself to conventional machining methods. It can, however, be abrasively ground before being plated, 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.

Typical Magnetic and Physical Properties of Neodymium Magnet Material

Neodymium MaterialDensityMax. Energy Product BH (max)Residual Induction BrCoercive Force HcIntrinsic Coercive Force (Hci)Maximum Operating TemperatureCurie Temperature
lbs/in3g/cm3MGOGaussOerstedsOerstedsFCFC
Neodymium 30H0.2677.430110001050017000248120626330
Neodymium 350.2677.4351230010500≥1200017680593.6312
Neodymium 400.2677.4401290010500≥1200017680593.6312
Neodymium 420.2677.442130009500≥1114017680593.6312
Neodymium 450.2677.4451350011000≥1200017680593.6312
Neodymium 480.2677.4481420011600≥1200017680593.6312
Neodymium 520.2677.4521480010000≥1100017680593.6312

Since many combinations of elements and orientations are possible, additional grades are available.

Applications of Neodymium Magnets

  • Magnetic separators
  • Linear actuators
  • Microphone assemblies
  • Servo motors
  • DC motors (automotive starters)
  • Computer rigid disc drives, printers and speakers

Attributes of Neodymium Material

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