Cast AlNiCo Magnet
Alnico is produced by either a sintering method or, more commonly, a casting method. The as cast or as sintered shape is acceptable for many applications but surfaces may need to be ground for a smoother surface finish. The as cast look has darkened edges with a slightly rough texture (due to the sand mold edges); a machined face of an Alnico Magnet has a bright silvery metallic surface and is usually extremely smooth as it is often precision ground.
Until about 1975, Alnico Magnets were the most widely used magnets in the world. The last 35 years have seen a sharp decline in the demand for them mainly because of the soaring prices of Cobalt and the availability of high coercivity materials like Ferrites and Rare Earths, the former being also the cheapest. And yet, Alnicos still play an important role in many applications because of their vastly superior ability to withstand high temperatures (up to 550°C) and a very low temperature co-efficient (less than 0.02% per degree C) as compared to Ferrite and Rare Earth Magnets.
Worldwide, Alnicos are produced in several grades, some isotropic (unoriented) and the others anisotropic (oriented). Of these, we produce Alnico-5 and Alnico-6 which are the most popular anisotropic grades and Alnico-3 which is isotropic and primarily used for Speedometer Magnets. We also produce Alnico-8 (isotropic), which is primarily used in powder form for making bonded magnets.