Overview of Alnico Magnets
- High saturation values
- Excellent thermal stability
- Good corrosion resistance
Alnico is from the family of magnets that was the first to be developed, becoming commercially available in 1932. The most common production method is by casting, although the powder metallurgy sintering process is particularly suitable for small and more complex parts. The poor resistance to demagnetization, cost of the base alloy and the advent of new materials have led to a reduction in its use. However, there are specific advantages which make it the choice in certain critical applications.
The Curie Point is significantly higher than for all other permanent magnet materials enabling it to be used at elevated temperature. The losses in flux density when heated are both very low and predictable. It is also considered to have excellent corrosion protection, although in some instances a plating may be used for aesthetic reasons.
Discreet components are made to order and there is usually a minimum batch requirement.
Alnico rods are oriented along their length making this the only possible direction of magnetization. Due to their low coercivity, short aspect ratio bars will demagnetize very easily, and in most cases, magnetization is recommended after assembly or at the point of use. The alloy is crystalline, brittle and difficult to machine and commonly contains voids and hairline cracks; unless significant in size, this will not affect the performance.
The problems of demagnetization are not apparent in “closed circuit” application and the high remanence values and other specific advantages open up design possibilities. Being metallic, complex parts can be produced from our wire erosion facilities and supplied in a complete assembly.