Ceramic (ferrite) permanent 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.
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
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
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,
Typical Magnetic and Physical Properties of Ceramic
All magnet materials demonstrate
reversible strength loss as they approach Maximum Operating Temperature.
* NOTE: Unshielded open circuit ceramic magnets should not be subjected
to more than 400°F.
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
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
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.