The most commonly used grade names are; Alnico 5, Alnico 8, Alnico 9, Alnico 5DG, Alnico5-7, Alnico8HC, Alnico 6, Alnico 2, Alnico3, Alnico 500, Alnico 400, Alnico 600 and Alnico 700, etc.
Alnico magnets are widely used today in applications where strong permanent magnets are needed and/or high temperatures are present, in applications requiring low coercivities (the ability to demagnetize and re-magnetize easily). Also has good resistance to demagnetization from vibration and shock.
The advantages of alnico magnets are high magnetic flux density, low-temperature coefficient of magnetic properties, high mechanical strength, and very stable magnets. Alnico magnets are generally (approx. four times) stronger than regular ferrite (ceramic) magnets, but not as strong as rare-earth magnets, they are also electrically conductive, unlike ceramic/ferrite magnets. Alnico magnets are available in either isotropic or anisotropic versions.
On a cost per pound basis, this material is comparable to the cost of neodymium magnets. However, in most applications, alnico is much less powerful than Neodymium magnets.
However, the coercive force and maximum energy product are not high. They limit their applications in many cases.
There are two production processes used to manufacture Alnico Magnets: casting and sintering, magnetization is possible only in axial direction.
AlNiCo magnets have high remanence, but low coercivity – this fact determines the magnetization direction. Optimal ratio of diameter and length of the magnet is 1:4. Magnetic field of AlNiCo magnets can be weakened by demagnetizing. AlNiCo is a hard material; machining is possible by grinding. Working temparature is between -270°C and +500°C. AlNiCo magnets are resistant against acids and solvents.
The casting process allows the magnet to be manufactured into complex shapes. Sintered Alnico is made from a powdered mixture of ingredients that are pressed into a die under tons of pressure. The Sintering process allows for the magnets to be manufactured to tighter tolerances and higher mechanical strength.
Alnico magnets have high magnetic flux density, high resistance to corrosion and excellent temperature stability. Though the corrosion resistance of alnico is excellent, and, in most cases, no surface treatments are required, alnico magnets can be plated for aesthetic applications.
Alnico magnets are widely used in industrial and consumer applications where strong permanent magnets are needed and/or high temperatures are present.
What makes Alnico a preferred magnet material for many manufacturers is its high induction levels with good resistance to demagnetization and stability. This occurs because industrial sintered alnico magnets have a low-temperature coefficient and are produced at an affordable cost.