AlnicoAlnico Advantages (+) Alnico Disadvantages ( - )
Long field depth Easy to demagnetize
High heat stability 975°-1020°F Hard and brittle to machine, must be ground
Corrosion resistant Expensive due to Nickel and Cobalt
Alnico Magnet Basics information:
Made from aluminum, nickel, cobalt, copper, iron and sometimes titanium.
They can be either cast (poured) or sintered (pressed and baked).
They are often used in sensor applications because of their long feild depth.
They are supplied "as cast" or ground on selected surfaces. An as cast surface will look brown / grey / red. A ground surface will look shiny like Nickel.
The Alnico horseshoe shape, used long ago, has become an icon for magnets, even though this shape is increasingly replaced. Alnico horseshoes can often be replaced by ceramic assemblies to save money.
The most common grades of alnico are 5 & 8.
The optimum geometry for alnico is unique among magnets.
Cast alnico is melted and poured into a mold. Once solidified, the material is rough ground and then heat treated and cooled, sometimes in a magnetic field. When treated in the presence of a magnetic field, the magnet is called isotropic. This orients the material to take on maximum magnetic field. After heat treatment and cooling, the material can be ground to specific tolerances and then magnetized.