Alnico Magnets

These have excellent temperature stability coupled with high residual induction. High energies characterize Alnico materials that are primarily composed of alloys of Aluminum, Nickel and Cobalt. The Alnico magnets are manufactured through two different processes like casting or sintering. The cast magnets can be manufactured in different complex shapes like horseshoes, which is not possible with other magnet materials. On the other hand sintered Alnicos offer comparatively lower magnetic properties but better mechanical characteristics than cast Alnicos. One of the most commonly used of all cast Alnicos is Cast Alnico 5, which is extensively used for various applications like rotating machinery, meters, instruments, sensing devices, and holding applications, to name a few.

Machining or drilling cannot be accomplished by ordinary methods as Alnico is hard and brittle material. The holes are cored in at the foundry and the magnets are cast close to final size before machine finishing to closer tolerances. It also has a low coercive force, and can be easily demagnetized if not handled properly. To obtain maximum performance of Alnico 5, its magnetic length has to be approximately 5 times its pole diameter or equivalent diameter.

Manufacturing Methods

These magnets are manufactured using different processes such as casting or sintering. The cast magnets are manufactured by pouring a molten metal alloy into a mold and then further processing it through various heat-treat cycles. The resulting magnet has a dark gray exterior appearance, and may have a rough surface. The machined surfaces have a shiny appearance similar to steel. Sintered magnets are manufactured by compacting fine Alnico powder in a press, and then sintering the compacted powder into a solid magnet.