Hard Ferrite (ceramic) magnets, composed of barium or strontium, were developed in the early 1960's as an alternative to the more expensive metallic magnets. This class of magnet is very hard, brittle and possesses lower energy characteristics compared to other magnetic materials. However, it is very popular and widely used because of its excellent resistance to demagnetizaion, corrosion, and the advantageous pricing.
Ferrite magnets are manufactured by pressing, sintering, or injection molding. These magnets can be both anisotropic and isotropic. Anisotropic grades are oriented in the manufacturing direction and must be magnetized in the direction of orientation. Isotropic grades are not oriented and can be magnetized in any direction.
Applications of Ceramic 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
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.
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.
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