Alnico Disc Magnets

Product Information

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. They are also somethimes shown as Alcomax, Columax, Hycomax and Ticonal brands.

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 (DoM) 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. Alnico5, 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. 

Weaker Isotropic alnico takes complex magnetic fields. Stronger anisotropic alnico has a fixed DoM axis.

Alnico Magnetic Synonyms

AlNiCo, al-ni-co, aluminum-nickel-cobalt, Alloy 11, Alloy 5, Alloy 1

Alnico Disc Magnets Specification

Tolerances

Generally the tolerance on Alnico Magnets is +/-0.005" on diameter and +/-0.15" on length.

Per your request or drawing

We can customized as required

Properties（Theoretical）

Magnetizing and Handling

Magnetizing is done after the magnet has been machined to the correct tolerances. Care should be taken when handling alnico material since it is brittle and can chip or break if dropped on a hard surface. Also, because it has a low resistance to demagnetization, it will lose power if it is stored improperly (poles repelling each other). For best results, store magnetized alnico so that pieces are attracting each other, or with a steel keeper.

Alnico Magnet Manufacturing

Alnico magnets are manufactured through either a casting or sintering process, so they can be made into complex shapes such as horseshoes, which is not possible to do with other magnet materials.

Cast Alnico - Cast alnico is melted and poured into a mold. Once solidified, the material is rough ground, then heat-treated and cooled, sometimes within a magnetic field. When treated in the presence of a magnetic field, the magnet is called anisotropic (oriented). This orients the material to take on maximum magnetization and allows a higher gauss level.

A cast magnet that is not heat-treated in a magnetic field is called isotropic (non-oriented). After heat treatment and cooling, alnico can be ground to specific tolerances, then magnetized.

Sintered Alnico - Sintered alnico is made from a powdered mixture of ingredients that are pressed into a die under tons of pressure, sintered in a hydrogen atmosphere and then cooled either within or without a magnetic field (anisotropic vs. isotropic).

Attributes of Both Cast and Sintered Alnico

- Very temperature stable, great for high heat applications

- Maximum working temperature 975° - 1020° F

- May be ground to size

- Does not lend itself to conventional machining (hard and brittle)

- High residual induction and energy product compared to ceramic material

- Low coercive force compared to ceramic and rare earth materials (more subject to demagnetization)

- Most common grades are 5 and 8

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 (Hci) making them easy to demagnetise.

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

Applications of Alnico Disc Magnets

· Very high temperature applications

· Use in hot oils

· Magnetic Clamping

· Motors and Generators

· Mass spectrometers

· Precision sensors and meters

· Alnico magnets for Aerospace

· Pot Magnets

Packing of Alnico Disc Magnets

Standard Packing:

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 440 gallon liquid totes Special package is available on request.

ATTs’ Alnico Disc Magnets are carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition.

Chemical Identifiers