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SAMARIUM COBALT MAGNETS

Samarium cobalt magnets (SmCo) are composed of samarium, cobalt and iron. These rare earth magnets are extremely strong for their small size and found in simple shapes such as rings, blocks and discs. Not sure if Samarium Cobalt is the best material for your application? Click here for an attribute and application comparison for all of the magnetic materials we offer.

Choose from one of the following shapes:
  • Applications
  • Attributes
  • Tolerances
  • Machining
  • Magnetizing & Handling
  • Magnetic & Physical Properties
  • Compare & Contrast

Applications of Samarium Cobalt Magnets

  • Computer disc drives
  • Sensors
  • Traveling wave tubes
  • Linear actuators
  • 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 temperature stability
  • Expensive material (cobalt is market price sensitive)

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 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.

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.

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.

Typical Magnetic and Physical Properties of Samarium Cobalt Magnet Material
Magnetic
Material
Density
Max. Energy Product BH (max)
Residual Induction BR
Coercive Force HC
Intrinsic Coercive Force HC
Normal Maximum Operating Temp.
Curie Temp.
lbs/in
g/cm
MGO
Gauss
Oersteds
Oersteds
Fº
Cº
Fº
Cº
SmCo 18
0.296
8.2
18.0
8700
8000
20000
482
250
1382
750
SmCo 20
0.296
8.2
20.0
9000
8500
15000
482
250
1382
750
SmCo 24
0.304
8.4
24.0
10200
9200
18000
572
300
1517
825
SmCo 26
0.304
8.4
26.0
10500
9000
11000
572
300
1517
825

Compare and Contrast Magnetic Applications and Materials

Applications of Samarium Cobalt Magnets

  • Computer disc drives
  • Sensors
  • Traveling wave tubes
  • Linear actuators
  • 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 temperature stability
  • Expensive material (cobalt is market price sensitive)

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 is corrosive and should be coated for long term maximum energy output
  • Low working temperature for heat applications, but higher levels of heat resistance materials are being introduced periodically

Applications of Ceramic Magnets

  • Speaker magnets
  • DC brushless motors
  • Magnetic Resonance Imaging (MRI)
  • Magnetos used on lawnmowers and outboard motors
  • DC permanent magnet motors (used in cars)
  • Separators (separate ferrous material from non-ferrous)
  • Used in magnetic assemblies designed for lifting, holding, retrieving and separating

Attributes of Ceramic Material

  • Least expensive material compared to alnico and rare earth magnets
  • High intrinsic coercive force
  • Available in simple shapes only due to manufacturing process
  • Lower service temperature than alnico, greater than rare earth
  • Finishing requires diamond cutting or grinding wheel
  • Lower energy product than alnico and rare earth magnets
  • Most common grades of ceramic are 1, 5 and 8 (1-8 possible)
  • Grade 8 is the strongest ceramic material available
  • Tooling can be expensive

Applications of Alnico Magnets

  • Magnetos
  • Separators
  • Sensors
  • Electron tubes
  • Traveling wave tubes
  • Radar
  • Holding magnets
  • Coin acceptors
  • Clutches and bearings
  • Motors
  • Distributors
  • Relays
  • Controls
  • Generators
  • Receivers
  • Telephones
  • Microphones
  • Bell ringers
  • Guitar pickups
  • Loudspeakers
  • Security systems
  • Cow magnets

Attributes of Cast Alnico

  • Size parameters range from 1 ounce to about 70 pounds
  • Will cast to a variety of shapes and sizes

Attributes of Sintered Alnico

  • Size parameters range from about one ounce of material up to one cubic inch
  • Pressed to close tolerance/minimal grinding to finish
  • Mechanically strongest of alnicos

Attributes of Both Cast and Sintered Alnico

  • Very temperature stable, great for high heat applications
  • Maximum working temperature 975° - 1020° F
  • May be ground to size
  • Does not lend itself to conventional machining (hard and brittle)
  • High residual induction and energy product compared to ceramic material
  • Low coercive force compared to ceramic and rare earth materials (more subject to demagnetization)
  • Most common grades are 5 and 8