AlNiCo Ring Magnet

Product Details

AlNiCo magnets have the best temperature coefficients of any magnet material. Alnico magnets are a best choice in extremely high temperature applications.

AlNiCo magnets are Cast or Sintered. They are an alloy of Aluminium, Nickel and Cobalt hence the term Al-Ni-Co. AlNiCo magnets have the best temperature coefficients of any magnet material. AlNiCo magnets should be regarded as the best choice in extremely high temperature applications. They can be produced by Casting or Sintering. Cast AlNiCo is the most common form of AlNiCo magnet. Casting is often used to get “near net shape” AlNiCo magnets. Casting AlNiCo is cost effective for both low and high volume, for small and very large magnets. Sintered AlNiCo magnets are not so commonly used due to lower magnetic performance and limitation to simpler shapes. Anisotropic magnets have the direction of magnetisation permanently within the structure and give the maximum performance.

Isotropic magnets can be magnetised in many ways as they have no preferred direction of magnetisation but give reduced performance. Cast AlNiCo 5 is the most common grade of AlNiCo , with the LNG44 variant of AlNiCo 5 (Alcomax 3) being the most popular. AlNiCo 5, AlNiCo 8 and AlNiCo 9 all exist with several sub-grades with differing performance characteristics. It is common for the magnet pole faces to be machined to finish. AlNiCo produced to specific Br, Hc, Hci and BHmax may be possible but at extra cost. Keeping within normal grades is advised but bespoke AlNiCo magnets are available.

Advantages & Disadvantages of AlNiCo Magnets

Advantages

• Cast Alnico offers a near net shape. Cast alnico can be produced to complex shapes with complex magnetic patterns.

• Alnico Br as high as NdFeB at room temperature.

• Can be used up to 450-550 degrees C (842-932F).

• Least variation in magnetic output with temperature change of any magnetic material.

• Can be cast in very large sizes.

Disadvantages

• Sintered alnico is usually limited to small to medium sizes and simpler shapes.

• Low coercivity (Hcj) making them easy to demagnetise.

• Complex cast alnico sometimes needs sand mold tooling which can be expensive if existing tooling is not available.