Samarium Cobalt (SmCo) Magnets
Extremely strong rare earth magnets, Samarium Cobalt magnets (SmCo) are composed of samarium, cobalt and iron. Not sure if samarium cobalt 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, aged, ground to dimension, magnetized and tested. They are called “rare earth” magnets because the elements of samarium cobalt 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 +/- .010”, whichever is greater.
According to standards, visual imperfections such as hair-line 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.
Magnetizing and Handling - samarium cobalt 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, the magnets be magnetized after assembly. These magnets are NOT for children.
Machining - Since samarium cobalt 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.
Typical Magnetic and Physical Properties of Samarium Cobalt
|Samarium Cobalt Material||Density||Max. Energy Product |
|Typical Residual Induction Br (max)||Coercive Force Hc (min)||Intrinsic Coercive Force (Hci)||Maximum Operating Temperature||Curie Temperature|
|SmCo 18||0.296||8.2||16 - 18||8700||≥8100||≥16000||482||250||1382||750|
|SmCo 20||0.296||8.2||19 - 21||9200||≥8500||≥16000||482||250||1382||750|
|SmCo 22||0.299||8.3||20 - 22||9500||≥8900||≥16000||482||250||1382||750|
|SmCo 24||0.304||8.4||22 - 24||9900||≥9100||≥18000||662||350||1508||820|
|SmCo 26||0.304||8.4||24 - 26||10400||≥9400||≥18000||662||350||1508||820|
|SmCo 28||0.303||8.4||26 - 28||10700||≥9500||≥18000||662||350||1508||820|
|SmCo 30||0.303||8.4||28 - 30||11000||≥9900||≥18000||662||350||1508||820|
Applications of Samarium Cobalt Magnets
- Computer disc drives and sensors
- Traveling wave tubes
- Linear actuators and satellite systems
- Motors where temporary stability is vital
Attributes of Samarium Cobalt Material
- High resistance to demagnetization
- High energy (magnetic strength is strong for its size)
- Good to moderately high temperature stability
- Pricing for samarium cobalt is market sensitive