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Mag Applications |
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| Alnico |  |
Alnico magnets are widely used in electronic ignition systems, medical instruments, generators, motors, meters, switches, tools and vending machines etc. Composed mainly of aluminum, nickel, and cobalt with trace elements such as titanium and copper, it is manufactured through casting or sintering. The main advantage of alnico is the very low temperature coefficient and the wide temperature range from -459 F to more than +752 F for various application. Alnico has relatively low coercivity and is hard and brittle. Alnico magnets are cast or sintered as closely as possible to the required size so that any grinding and polishing for the final finish can be minimized. Alnico 5 and Alnico 8 exhibit the preferred direction of orientation and are the most popular anisotropic grades that are designed to produce high magnetic output in a specified direction. Orientation is achieved during special heat treatment, by cooling the casting from 2000F at a controlled rate within a magnetic field which conforms to the preferred direction of magnetization. Cast Alnico 5 has a maximum energy of 5 MGOe or more and is used extensively in rotation machinery, communications, meters and instruments, sensing devices and holding applications. Alnico 8 has a higher resistance to demagnetization with a cobalt content up to 35%, which allows it to function well for short lengths(i.e., length to diameter ratios of less that 2 to 1.) Sintered Alnico has slightly lower magnetic properties but better mechanical characteristics than the cast Alnico materials and hence most suitable for small size (less than 1oz.)application. Sintered at 2300F in a hydrogen-rich environment, it is designed for large volume production that can produce parts of better structural strength and relatively better tolerances without grinding. |