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