Ceramic (Ferrite) Permanent Magnets

Ceramic Magnets Are composed of strontium carbonate and iron oxide. They are charcoal gray in color and usually appear in forms of blocks, discs, rings, cylinders and sometimes arcs for motors.

Attributes of Ceramic Magnets:

  • High intrinsic coercive force
  • Tooling is expensive
  • Least expensive material compared to alnico and rare earth magnets
  • Limited to simple shapes due to manufacturing process 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 are possible)
  • Grade 8 is the strongest ceramic material available

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), Magnetic assemblies designed for lifting, holding, retrieving and separating.

Tolerances:

For a 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:

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

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.