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What is a ceramic magnet?

Ceramic magnets (also known as ferrite magnets) were developed in the 1960’s as a low-cost alternative to metallic magnets. While their hard, brittle quality and low energy exclude them from some applications, ceramic magnets have won wide acceptance due to their corrosion and demagnetization resistance, and low price per pound. Ferrite represents more than 75 percent of world magnet consumption by weight.  Read more…

Ceramic Grades

Adams stocks a variety of ring magnets, disc magnets, rectangular magnets and block magnets in ceramic grades 1,5 & 8. Other configurations can be produced but are not stocked except for specific customer requirements. The standard sizes can be cut and ground to meet your specific requirements. For a comparison of Ceramic Grades 5 & 8, please see our Chart of Properties.

Who uses ceramic magnets?

Ceramic magnets are the first choice for most types of DC motors, magnetic separators, magnetic resonance imaging and automotive sensors.  They are also widely used in craft and hobby projects, and hold a large percentage of the world’s refrigerator magnets!  Additionally, they appear in many educational science kits and are great for a demonstration of magnetic attraction and repulsion.

Ceramic Magnets Stock Selection
Adams offers a wide selection of Ceramic magnet products. Click on your desired product type for stock product specifications.
Our stock ceramic ring magnets are Grade 5, magnetized through the thickness.
View a small sampling of our stock ceramic disc magnets in Grades 1, 5 or 8.
We stock ceramic bar magnets in Grade 5, magnetized through the thickness.
We stock ceramic block magnets in Grade 8, magnetized through the thickness.

Machining and tolerances

Machining must be performed with a diamond wheel, preferably before magnetization. Standard tolerances are +/-.005” for ground dimensions and +/- 2% of feature size for sintered dimensions. Due to their brittle nature, these magnets will not withstand impact or flexing. They are also not recommended to be used as structural components in assemblies. Ceramic magnets are chemically inert non-conductors, which is a benefit in many applications but eliminates the use of the EDM process to produce samples or special shapes.

Temperature constraints and methods of magnetization

Due to Ceramic’s positive temperature coefficient of Hci high temperatures are not generally a major concern with respect to irreversible magnetic loss. Low temperatures, however, pose a much greater risk for permanent demagnetization. For example, a ceramic 5 grade with a permeance coefficient of 1 will start to experience permanent losses below -20°C.

Magnetization

Isotropic ceramic grades can be magnetized in any direction, while anisotropic grades have a preferred direction of magnetization and will only meet their full magnetic potential when magnetized along the “easy axis.”

Gauss Calculations of Ceramic Magnets

Adams will help you calculate magnetic field strength measured in Gauss, on the centerline of a disc magnet or ring magnet magnetized through its thickness, at a distance of X from the surface of the magnet. To get started, please click here.

Certifications

Adams’ Elmhurst facility is ISO9001:2008 certified, and DFARS and ITAR compliant.

Resources

  • Chart of Material Properties
    Displays each permanent magnet material along with its Maximum Energy Product: Bhmax, Residual Flux Density: Br Gauss, Coercive Force: Hc Oersteds, Intrinsic Coercive Force: Hci Oersteds and Maximum Operating Temperature: C / F.
  • Breakaway Force of a Magnet
    Explains the test methods used to determine how much force it takes to pull a magnet directly away from the surface it is attached to.
  • Standard Specifications for Permanent Magnet Materials
    Defines thermal and mechanical characteristics and properties of commercially available permanent magnet materials including Alnico, Ceramic, Rare Earth (Samarium cobalt and neodymium) and Iron-Chromium-Cobalt. Includes a Glossary of Terms and Magnetic Quantities (Symbols, Units and Conversion Factors).
  • Ceramic Product Specifications