Key Advantages Sintered Alnico Magnets: •Excellent temperature stability •Strong corrosion resistance •The maximum working temperature is up to 500°c •Fine grain •Compact crystal. •Excellent magnetic consistence and evenness. •Suitable for small volume and complex shape magnets. Cast Alnico Magnets: •Excellent temperature stability •Strong corrosion resistance •The maximum working temperature is up to 500°c •Excellent capacity •High density and magnetic properties •Shorter production lead time •Temperature factor of Br is the smallest among all the permanent magnets •Cast Alnico magnets can be produced in relatively complex shapes •Tooling for cast Alnico magnets is relatively low, since sand molds are generally used for the casting process.
Manufacturing Methods Alnico magnets are manufactured through either casting or sintering processes. Cast magnets are manufactured by pouring a molten metal alloy into a mold and then further processing it through various heat-treat cycles. The resulting magnet has a dark gray exterior appearance, and may have a rough surface. Machined surfaces have a shiny appearance similar to steel. Sintered magnets are manufactured by compacting fine Alnico powder in a press, and then sintering the compacted powder into a solid magnet.
Assemblies We are able to manufacture metal and other components of finished sub assemblies using our CNC machining facilities. Assemblies can be fabricated by adhering magnets with adhesives to suit a range of environments, by mechanically fastening magnets, or by a combination of these methods. Due to the relatively brittle nature of these magnet materials, press fits are not recommended.
Surface Treatments The corrosion resistance of Alnico is considered excellent , and no surface treatments are required. However, Alnico magnets are easily plated for cosmetic reasons if required.
Machining Alnico is hard and brittle, and prone to chipping and cracking. Machining or drilling can not therefore be accomplished by ordinary methods. Holes are usually cored in at the foundry, and magnets are cast close to final size and then finish machined to closer tolerances.
Magnetizing and Handling Alnico has a low coercive force, and is easily demagnetized if not handled with care. Because of their relatively low coercivities, special care should be taken to assure that these magnets are not subjected to adverse repelling fields, since these could partially demagnetize the magnets. Magnetized magnets should be stored with papers to reduce the possibility of partial demagnetization. If Alnicos are partially demagnetized, they may be easily remagnetized.
Temperature Effects Up to about 1,000 F, changes in magnetization are largely reversible and re-magnetizable, while changes above this are largely structural and not fully reversible or re-magnetizable. Approximately 90% of room temperature magnetization is retained at temperatures of up to 1,000 F.
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