Description of AlNiCo Magnets

·        Alnico magnets are permanent magnets that are primarily made up of a combination of aluminum, nickel, and cobalt but can also include copper, iron, and titanium. Alnico magnets are available in either isotropic or anisotropic versions.

·        The AlNiCo magnets feature excellent temperature stability, high residual induction, and relatively high energies. They are manufactured through either a casting or sintering process.

·        Cast Alnico – Cast alnico is melted and poured into a mold. Once solidified, the material is rough ground, then heat-treated and cooled, sometimes within a magnetic field. When treated in the presence of a magnetic field, the magnet is called anisotropic (oriented). This orients the material to take on maximum magnetization and allows a higher gauss level.

·        Cast AlNiCo magnet that is not heat-treated in a magnetic field is called isotropic (non-oriented). After heat treatment and cooling, alnico can be ground to specific tolerances, then magnetized.

·        Sintered Alnico – Sintered alnico is made from a powdered mixture of ingredients pressed into a die under tons of pressure, sintered in a hydrogen atmosphere, and then cooled either within or without a magnetic field (anisotropic vs.  isotropic).

Characters Of Cast Alnico Magnets

·        Size parameters range from one ounce to about 70 pounds

·        Will cast to a variety of shapes and sizes

Characters Of Sintered Alnico

·        Size parameters range from about one ounce of material up to one cubic inch

·        Pressed to close tolerance/minimal grinding to finish

·        Mechanically strongest of AlNiCo magnets

Characters Of Both Cast And Sintered Alnico Magnets

·        Very temperature stable, great for high heat applications

·        Maximum working temperature 520°C – 548°C

·        May be ground to size

·        Does not lend itself to conventional machining (hard and brittle)

·        High residual induction and energy product compared to ceramic material

·        Low coercive force compared to ceramic and rare earth materials (more subject to demagnetization)

·        Most common grades are 5 and 8

Surface Treatments

• No special surface treatments are required for Alnico magnets since      they are resistant to oxidation. They can, however, be easily plated using      a variety of metals, such as nickel or chrome.