Alnico

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Alnico Magnets

Developed in the 1930s, Alnico magnets have several attributes that continue to make them the workhorse of the modern permanent magnet industry. Their name is derived from the primary chemical composition of the alloy; AlNiCo – Aluminum, Nickel, and Cobalt, [balance is Fe (Iron)].

Alnico - Cast

Alnico - Sintered

Alnico - Bonded

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The History of Alnico

In 2005, an R&D program was begun to develop improved structural strength, high energy grades of Cast Alnico 9.

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The History of Alnico

In 2005, an R&D program was begun to develop improved structural strength, high energy grades of Cast Alnico 9. Generally, optimum properties of Cast Alnico magnets are achieved with columnar or single crystal structure with the direction of magnetization parallel to the columnar grain axis.

However, this has not been the case for Alnico 5-7 and Alnico 9 which are particularly crack-prone due to their columnar structure. This research led to the development of our superior grades of Cast Alnico 9 with improved physical strength, extended temperature, and time stability, and the highest energy product and coercive force of any alnico materials in the world [BHmax up to 11.5 MGOe]!

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Compression Molded Alnico

A fairly recent addition to the traditional cast and sintered Alnico line is the Isotropic “Bonded” Alnico magnet.

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Compression Molded Alnico

A fairly recent addition to the traditional cast and sintered Alnico line is the Isotropic “Bonded” Alnico magnet. Using thermo-elastomeric [polyethylene, polyurethane], thermoplastic [nylon, PPS], or epoxy based binders, the Alnico powder is carefully blended with the binder and other chemicals, and pressed in a mold.

In addition to pressing complex shapes, like gear teeth, extremely tight dimensional tolerances may be held without secondary finishing. Insert molding can reduce overall system cost. Density is 79% of that for sintered alnico because of dilution by the binder; the maximum operating temperature is limited by binder and reactivity of the powder to between 80° and 200°C.

These magnets resist chipping and permit complex magnetizing patterns. As noted above, Cast Alnico offers excellent magnetic uniformity and temperature stability up to its maximum operating temperature. The temperature coefficient of Br is -0.02%/°C resulting in exceptional uniformity of magnetic properties up to the maximum operating temperature [approximately 96% of room temperature magnetization is retained at temperatures up to 220°C].

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Common Applications for Alnico

Alnico, with its versatile magnetic properties, finds common applications in various fields

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Common Applications for Alnico

  • Magnetic suspension bearings for kWh meters
  • High stability magnetic sensors for use with both reed switches and Hall Effect devices
  • Brush-less DC motor magnets and linear actuators
  • Waveguide components
  • D’Arsonval meter movements and other devices that require magnetic calibration
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Attributes of Alnico Magnets

Alnico magnets’ compact crystalline structure yield relatively high density resulting in good mechanical strength and maximum energy products. Having the lowest temperature coefficient of Br [TcBr] of any commercial magnet material (-0.02%/°C), results in exceptional uniformity of magnetic properties over a wide temperature range.

Approximately 90% of room temperature magnetization is retained at temperatures up to 538°C. Cast Alnico magnets offer the highest operating temperature of any magnet material; up to 450 – 550°C. Because of their optimal chemical structure, they exhibit excellent corrosion resistance and can be cast into various shapes.

Sintered Alnico magnets are mechanically the strongest of the Alnico series, and with the benefit of close tolerance pressing they’re ideally suited for small complex shapes, typically with minimal finish grinding.

Custom Order Alnico Magnets

Don’t allow the difficulties of locating a dependable source for versatile and reliable Alnico magnets hinder your progress. BJA Magnetics is here to address all your magnet-related requirements with our extensive services and diverse range of magnetic materials. Whether you’re seeking Alnico magnets for specific applications, we offer a comprehensive selection to meet your needs. Contact us for inquiries about Alnico magnets, and we’ll ensure you find the right solution for your magnetic needs.

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