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CERAMIC MAGNETS

Ceramic (ferrite) magnets are composed of strontium carbonate and iron oxide. They are charcoal gray in color and usually appear in the forms of discs, rings, blocks, cylinders, and sometimes arcs for motors. Not sure if ceramic 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 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

Tolerances

Pressed dimensions are either +/– 2% or +/– .025”, whichever is greater. Cut dimensions are either +/– 3% or +/– .025”, whichever is greater. Thickness tolerances are normally ground to +/– .005”, according to International Magnetics Association/Magnet Materials Producers Association (IMA/MMPA).

Visual imperfections such as cracks, porosity, voids, surface finish, etc. (commonly found in sintered ceramic magnets) do not constitute cause for rejection. Chips are acceptable if no more than 5% of the pole surface is removed. Cracks are acceptable, provided they do not extend across more than 50% of the pole surface.

Machining

Since ceramic material is so brittle, it requires special machining techniques and equipment. We are fully equipped to cut and grind ceramic material to your specifications.

Magnetizing and Handling

Ceramic magnet material is extremely brittle and can chip or break if dropped on a hard surface, or if allowed to “jump at” an attracting object. Handle with care. The weakest grade of ceramic material is grade 1, which is typically non-oriented. Grades 5 and 8 are oriented ceramic material. Grade 8 is the strongest ceramic magnet material available (Refer to properties chart below). When making magnetic assemblies with ceramic, it is typically easier for production purposes to magnetize the product after assembly.

Typical Magnetic and Physical Properties of Ceramic 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
Ceramic 1
0.177
4.9
1.05
2300
1860
3250
400
204
842
450
Ceramic 5
0.177
4.9
3.4
3800
2400
2500
400
204
842
450
Ceramic 8
0.177
4.9
3.5
3850
2950
3050
400
204
842
450
Note: Unshielded open circuit ceramic magnets should not be subjected to more than 400°F or they will require remagnetization.

Compare and Contrast Magnetic Applications and Materials

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 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 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 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