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Alnico Magnets |
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| Alnico magnets are made from aluminum, nickel, cobalt, iron and a few other elements, such as copper, titanium, and sulfur. |
Alnico magnets are relatively easily demagnetized, but resisting
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oxidation well. Energy product ranges from 1.0MGOe to about 9.0MGOe. Alnico magnets have been popular since the 1930s.
Alnico magnets are manufactured through either casting or sintering processes. Most alnico magnets are manufactured using typical foundry casting techniques, where the molten alloy is poured into sand molds. Very small magnets, usually one ounce or less, are also produced using the press and sinter techniques. Cast Alnico magnets can be made into complex shapes, such as horseshoes, which may not be possible with other materials. Sintered Alnico magnets offer slightly lower magnetic properties but better mechanical characteristics than cast Alnico magnets.
Magnetic Property:
Typical Magnetic Properties of Cast Alnico Magnets
Typical Magnetic Properties of Sintered Alnico Magnets
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Characteristics:
·Excellent temperature stability, small changes in magnetic properties to temperature change.
·Maximum working temperature can be as high as 550°C.
·High residual induction, low coercive force and moderate energy products.
·Strong corrosion resistance capability, no coating needed for surface protection. |
Machining and Tolerances:
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Alnico magnets are hard and brittle (45-55 Rockwell C), and are not suitable for drilling, tapping or conventional machining operations. Standard tolerances for ground dimensions are +/-.005". Close tolerances are also available by abrasive grinding and cutting. Tolerances for cast dimensions vary with the actual part size. Un-ground surfaces are gray to dark brown in color but are bright metallic after grinding. |
Temperature Effects:
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| Alnico magnets have the lowest temperature coefficient of any commercial magnet materials, providing for excellent stability over a wide temperature range. A properly designed circuit using alnico magnets will have a stable flux output during temperature fluctuations. Maximum operating temperature for alnico magnets is 550°C. Up to about 550°C, 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 550°C. |
Surface Treatments:
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Strong corrosion resistance capability, no surface treatments are required. However, Alnico magnets are painted with color for cosmetic reasons if requested. |
Magnetization:
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| Alnico magnets require magnetizing fields of about 3kOe. 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. Alnico magnets can be partially demagnetized if like poles of magnets are brought together. Placing individual magnets in contact with ferrous materials can also partially demagnetize them. Typical open circuit Alnico 5 applications require a long magnetic length to pole surface ratio (usually 4:1 or greater) to avoid self-demagnetization. Because of its higher coercivity, Alnico 8 may be used in shorter lengths and in disc shapes. If Alnicos are partially demagnetized, they may be easily re-magnetized. |
Applications:
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Widely used in instruments, meters, speakers, separators, magnetos, sensor, microwave device, automatic control appliance, aviation, spaceflight, military technology, etc. |
Shapes and Sizes Available:
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Various shapes and sizes are available. Non-standard shapes and sizes also can be made according to blueprint specifications. Please contact us for your needs. |
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