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Samarium Cobalt MAGNETS

Release time:2017-04-13 09:57     Author:Nature

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Keywords: MAGNETS

Permanent Samarium Cobalt magnets (SmCo) are composed of samarium, cobalt and iron. These rare
earth magnets are extremely strong for their small size, metallic in appearance and found in simple shapes
such as rings, blocks and discs.
Samarium Cobalt Magnet Features
Samarium Cobalt (SmCo) disc magnets are powerful magnets rare earth magnets composed of samarium
and cobalt. They are commonly used in high performance motors, magnetic couplings and magnetic
separators. These are brittle magnets and are prone to cracking and chipping. Samarium magnets can be
used for high temperature applications where neodymium will not work.
Features include:
Samarium cobalt magnets are hard and brittle and may chip or break if dropped.
They have high magnetic properties
Samarium cobalt magnets offer good thermal stability
Samarium cobalt magnets are resistant to corrosion
Samarium cobalt magnets resistant to demagnetization
Temperature Considerations
A Samarium Cobalt magnet can withstand higher temperatures than a Neodymium magnet. The maximum
operating temperatures for Samarium Cobalt magnets are between 250 and 550 °C; Curie temperatures range
from 700 to 800 °C. Additionally, a Samarium Cobalt magnet is less subject to corrosion than a Neodymium
magnet, and usually does not require coating or plating.
Gluing Magnets
Several factors must be considered to assure the effective performance of the magnet, the adhesive and the
resulting bond. These include the chemical and physical properties of the magnets and the surfaces to which
they are affixed. Detailed coverage of all these factors, along with some adhesives to try, is covered in our
white paper Gluing Magnets.

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.

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 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.

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, they be magnetized after assembly.

Samarium Cobalt 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.