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Samarium Cobalt Magnets (SmCo)

Samarium Cobalt MagnetsCollectively known as Rare Earth magnets, Samarium Cobalt (SmCo) and Neodymium Iron Boron (NdFeB) magnets are alloys of the Lanthanide group of elements. Rare Earth magnets are the most advanced commercialized permanent magnet materials today. SmCo magnets are available in a number of different grades that span a wide range of properties and application requirements.

SmCo magnets are brittle and machining operations should be performed prior to magnetization, using diamond tools. We are equipped to fabricate these materials to blueprint specifications.

SmCo magnets are anisotropic, and can only be magnetized in the orientation direction. In general, magnetizing fields of about 35 to 45 kOe are required to saturate SmCo materials.

Common Applications for Samarium Cobalt (SmCo) Magnets

  • Charged particle beam guidance
  • DC, servo, linear, and voice coil motors
  • Halbach arrays
  • Headphones
  • High field yoke magnets
  • High performance stepper
  • Holding systems requiring very high holding forces
  • Instrumentation
  • Loudspeakers
  • Magnetic bearings
  • Magnetic couplings
  • Magnetic resonance
  • Magnetic separation
  • Microphones
  • Particle accelerators
  • Relays
  • Sputtering
  • Switches
  • Undulators
  • Vacuum deposition
  • Wigglers and others

Manufacturing Methods

Pressing and Sintering

Fine SmCo powder is compacted in a die and then sintered, fusing the powder into a solid material. There are two forms of pressing - die pressing (which involves a hard die into which the powder is placed and then pressed), and isostatic pressing (involving a special "rubber" die into which powder is placed and then pressed with equal force in all directions on the powder). Die pressed parts are smaller than isostatically pressed parts. Although the magnetic properties of isostatically pressed parts are higher, the uniformity of magnetic characteristics is usually lower than that of die pressed parts. Sintered parts usually need some finish machining in order to meet final tolerances.

Assemblies

Assemblies can be fabricated by adhering magnets with adhesives to suit a range of environments, by mechanically fastening magnets, or by a combination of these methods. Due to the relatively brittle nature of these magnet materials, press fits are not recommended.

When multiple magnets are assembled in repelling positions, it is advisable to use mechanical fastening in addition to adhesives, since if adhesives were to give way, repelling magnets may dislodge and endanger personnel using them. Our design engineering team will be happy to assist you in designing housings for your magnet assemblies.

Surface Treatments

The corrosion resistance of SmCo is considered good while that of NdFeB is considered poor. Coatings for corrosion resistance are therefore not generally required for SmCo magnets.

Machining

SmCo is extremely brittle, and highly prone to chipping and cracking. Special machining techniques, involving diamond-grinding techniques, must be used to machine this material.

We are fully equipped to machine these materials to your blueprint specifications.

Magnetizing and Handling

All Rare Earth magnets require extremely high magnetizing fields and special consideration must be given to this when designing complex assemblies, if it is intended to magnetize after assembly. Consult us if you foresee any problems.

SmCo materials are mechanically very weak, and magnetically very strong. They must therefore be handled very carefully to avoid damage and injury to personnel handling the magnets. Receiving and assembly personnel should be warned about the dangers of handling magnetized Rare Earth magnets.

Temperature Effects

SmCo magnets can operate at temperatures up to 350°C , depending upon the grade and permeance coefficient. Sm2Co17 materials exhibit superior temperature characteristics as compared to the Sm1Co5 types.

Properties of Samarium Cobalt Magnets (SmCo)

GradeBr
mT (kGs)
Hcb
kA/m (kOe)
Hcj
kA/m (kOe)
(BH)max
kJ/m3 (MGOe)
Max Working
Temp
Tw
YXG18
(SmCo5)
800 (8.0)557 (7.0)1194 (15.0)127-143 (16-18)250 ℃ (482 °F)
YXG20
(SmCo5)
850 (8.5)621 (7.8)1194 (15.0)143-159 (18-20)250 ℃ (482 °F)
YXG22
(SmCo5)
900 (9.0)637 (8.0)1194 (15.0)159-175 (20-22)250 ℃ (482 °F)
YXG22H
(SmCo5)
900 (9.0)637 (8.0)1432 (18.0)159-175 (20-22)250 ℃ (482 °F)
YXG24
(SmCo5)
950 (9.5)677 (8.5)1194 (15.0)175-191 (22-24)250 ℃ (482 °F)
YXG24
(Sm2Co17)
950 (9.5)677 (8.5)1432 (18.0)175-191 (22-24)350 ℃ (662 °F)
YXG24H
(Sm2Co17)
950 (9.5)677 (8.5)1672 (21.0)175-191 (22-24)350 ℃ (662 °F)
YXG26
(Sm2Co17)
950 (9.5)716 (9.0)1432 (18.0)191-207 (24-26)350 ℃ (662 °F)
YXG26H
(Sm2Co17)
1000 (10.0)716 (9.0)1672 (21.0)191-207 (24-26)350 ℃ (662 °F)
YXG28
(Sm2Co17)
1000 (10.0)756 (9.5)1432 (18.0)207-223 (26-28)350 ℃ (662 °F)
YXG28H
(Sm2Co17)
1050 (10.5)756 (9.5)1672 (21.0)207-223 (26-28)350 ℃ (662 °F)
YXG30
(Sm2Co17)
1080 (10.8)796 (10.0)1432 (18.0)223-239 (28-30)350 ℃ (662 °F)