Alnico permanent magnets were developed in the 1930's and were the first "Real" performance permanent magnets. They are made primarily from aluminum, nickel, cobalt, copper, iron and sometimes titanium. They can be either cast or sintered.
Characteristics of Alnico magnets
1. Very temperature stable, great for high heat applications
2. Wide range of working temperatures, up to 550ºC
3. May be ground to size
4. Does not lend itself to conventional machining (hard and brittle)
5. High residual induction and energy product compared to ceramic material
6. Low coercive force compared to ceramic and rare earth materials (more subject to demagnetization)
Alnico rotor magnets Alnico rotor magnets are made with Alnico 5 material and have a maximum temperature of approximately 1000°F. They are designed with multiple poles; each pole alternates in polarity. The hole in the rotor is designed for mounting onto shafts. They are excellent for use in synchronous motors, dynamos and air turbine generators. Usually they are supplied un-magnetized unless otherwise requested.