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Alnico Magnets - Aluminium-Nickel-Cobalt Magnets
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Alnico magnet material is an alloy of aluminium-nickel-cobalt which possesses an excellent temperature stability
over a wide temperature range and high residual induction. Their maximum working temperature is about 500°C.
It has strong corrosion resistance capability without any coating for surface protection.
However, its low coercive force limits its applications in many cases. Casting and sintering are two major processes used to
manufacture the Alnico magnets. Alnico magnets with complex shapes may be manufactured by casting. Once the Alnico magnets
are formed, it is difficult to machine or drill them due to the hard and brittle mechanical properties of Alnico.
Magnets are casted or sintered as closely as possible to required sized so that abrasive grinding to finish dimensions and
tolerances is minimized.
Sintered Alnico materials offer slightly lower magnetic properties but better mechanical characteristics than the cast
Alnico materials. Sintered Alnico magnets are most suitable for small sizes. The desired mix of metal powders is pressed
to shape and size in a die,then sintered at about 1700°C in a hydrogen atmosphere.The sintering process is well suited
to large volume production,and results in parts which are structurally stronger than cast magnets. Relatively close
tolerances can be achieved without grinding.
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