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Rare Earth Magnet (Ring Countersunk)

  • NSN0586 & NSN0590
  • NSN0586 & NSN0590
  • NSN0587 & NSN0589
  • NSN0587 & NSN0589
Calculated at checkout

Product Description

Shape: Ring, Countersunk
Grade: N40

Rare earth magnets are the strongest type of permanent magnet currently made. They are amazingly powerful for their size and have innumerable uses. The permanent magnets system are composed of licensed grade 40 neodymium iron boron magnetic material and are plated in nickel-copper-nickel for a shiny corrosion resistant finish.

Part Number NSN0586 NSN0587 NSN0589 NSN0590
South South North North
Outer Dia 0.50" 0.75" 0.75" 0.50"
Inner Dia 0.15" 0.20" 0.20" 0.15"
Thickness 0.125" 0.125" 0.125" 0.125"
Pull Force 3.2 lbs 5.8 lbs 5.8 lbs 3.2 lbs
Surface Field 3531 gauss 3112 gauss 3112 gauss 3531 gauss
Quantity 12 6 6 12


Rare Earth Magnet Composition
Rare earth magnets are magnets composed of alloys of the Lanthanide group of elements. The two Lanthanide elements most prevalent in the production of permanent magnets are Neodymium and Samarium. There are numerous alloy formulations of rare earth magnets covered under many different patents but the most common commercial varieties are Neodymium-Iron-Boron (NdFeB) and Samarium Cobalt (SmCo). Neodymium-Iron-Boron magnets are the most advanced commercialized permanent magnet material available today.

Rare earth magnets are available in sintered and bonded forms. Sintered magnets are a type of ceramic composed of the compressed powder of the alloy material being used. Sintering involves the compaction of fine alloy powder in a die and then fusing the powder into a solid material with heat. While the sintered magnets are solid, their physical properties are more similar to a ceramic and are easily broken and chipped - so handle them carefully, especially near metal or other magnets where they want to snap closed quickly. (Bonded magnets use a polymer base to hold the alloy powder together. The energy product of bonded magnets is much lower than that of the sintered magnets.) Sintered NdFeB magnets are generally plated or coated with a material to prevent corrosion. There are various coatings available. Nickel-Copper-Nickel plating has excellent corrosion resistance and durability as well as providing an clean and shiny appearance. All of our stock rare earth magnets are sintered Neodymium-Iron-Boron magnets plated in Nickel-Copper-Nickel.

Magnet Grades
The grade of a magnet directly refers to the Maximum Energy Product of the material that composes the magnet. It in no way refers to the physical properties of the magnet. Simplistically, grade is generally used to describe how "strong" a permanent magnet material is. The energy product is specified in the units Gauss Oersted. One MGOe is 1,000,000 Gauss Oersted. A grade forty (N40) would have a Maximum Energy Product of 40 MGOe. The higher the grade the “stronger” the magnet.


Material Sintered Neodymium-Iron-Boron (NdFeB)
Shape Ring
Plating Ni-Cu-Ni (Nickel)
Magnetization Direction Thickness
Grade N40
Maximum Operating Temperature 80 Deg C (176 Deg F)
Dimensional Tolerance +/-0.005"
Brand Magcraft
Packaging Magpak Tube
Remanent Flux Density Br (kG [T]) 12.5-12.8 [1.25-1.28]
Coercivity HcB (kOe [kA/m]) >=10.9 [>=867]
Intrinsic Coercivity HcJ (kOe [kA/m]) >=12.0 [>=995]
Maximum Energy Product Bhmax (MGOe [kJ/m3]) 38-41 [302-326]
Density p(g/cm3) >=7.45
Compression Strength (Mpa) 600-1200
Bending Strength (Mpa) 150-380
Vickers Hardness (HV) 460-660
Recoil Permeability (urec) 1.05
Electrical Resistance (Ohm*mm2/m) 1.25-1.55
Curie Temperature Tc (°C) 310
Thermal Expansion Coefficient 100°C//(x10^-6/K) 6
Thermal Expansion Coefficient 100°C?(x10^-6/K) -1

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