Products
Alnico Magnets
The Right Choice for Superior Temperature Stability for Complex Shapes
Alnico Magnets derive their magnetic properties and their name from their main constituents – aluminum, nickel, and cobalt. They have the widest range of temperature stability of any standard magnetic material. Other characteristics include high induction as well as relatively high energy. Manufacture is by sintering or casting.
We stock Alnico magnets in grades 5, 8, and 2. Alnico magnets are your best choice for applications exposed to operating temperatures above 400° Fahrenheit. Up to 1000°F, they maintain about 85 percent of their room-temperature magnetic properties, and changes in magnetization are reversible. See the Stock Magnet Specifications table on the Learn About Magnets page for detailed information.
Sintered Alnico has marginally lower magnetic properties, but better mechanical properties, than cast Alnico. Both are hard and brittle materials. They require skillful machining that is best performed on specialized equipment. The MMPA Standards for Alnico magnets state, in part: “These are materials used primarily for their magnetic capabilities…without regard to their mechanical properties. Therefore, it is generally not recommended that these materials be used for structural or decorative purposes.” Alnico magnets can be pressed directly into nonmagnetic materials. For steel pressings, they should be enclosed in a nonferrous bushing. When specifications call for extremely tight tolerances or complex, non-standard shapes that will require considerable machining, magnetic materials that are easier to work with than Alnico should be considered.
Cast Alnico 2 & 5 have maximum energy products of 5.4 and 5.5, respectively, and are popular choices for applications such as holding assemblies, electronic instrumentation, sensing devices, and communications equipment. For best results with Alnico 5 magnets, the length should be no less than 5 times the crosssection diameter – or 5 times the diameter of a circle equal in area to the cross section.
Cast Alnico 8 HE has the highest temperature stability of any commercially available magnetic material. So it is especially wellsuited to high-temperature applications. Improved crystal structure and alloying techniques achieve a 6.0 energy product and high resistance to demagnetization. Typical uses include computer keyboards, drives, printers, microphones, meters, motors, generators, relays, reed-switch relays, transducers, and Hall-Effect devices.
Sintered Alnico 8H has a 5.25 energy product and high temperature stability, coercivity, and demagnetization resistance similar to Cast Alnico 8. But it can be manufactured to closer tolerances. Its fine grain structure results in highly uniform flux distribution and mechanical strength. So it is ideally suited to applications requiring short magnetic length or involving high-speed motion. Some applications include core meters, traveling wave tube stacks, polarized relays, reed switches, torque transmitting devices, and sandwich-type holding assemblies.
Sintered Alnico 2 has an energy product of 1.5. Magnets of this material are unoriented and can be magnetized in any direction.
Demagnetization Curves of Cast & Sintered Alnico Magnets
