Alnico Magnets

As one of the members of the permanent magnets family, Alnico remains a key choice for many uses. It offers strong magnetic power at a fair cost. Alnico is also known as one of the best heat resistant magnets. It works well in high and low temperatures. It also has the lowest change rate with heat among all common magnet types—just 0.02% per degree Celsius. This gives it great balance in many uses, including permanent magnets for sensors.

To get the best use from Alnico, it should be magnetized after it is placed in the final setup with its pole pieces. To fully magnetize it at the point of use, a strong magnetic force is needed. This force must be 4 to 5 times higher than the magnet’s own resistance to change. For Alnico 5, a magnetizing force of 3000 oersteds (240 KA/m) is best. For Alnico 8, it should be at least 7000 oersteds (560 KA/m). This force only needs to be applied for a short time. So, many setups use impulse magnetizers powered by capacitor discharge. Direct current magnetizers also work well for this.

Alnico is also a good choice when people need magnets for sensors, especially where steady performance is key. In some cases, it may not match the power of the strongest type of permanent magnet, but it offers better heat balance and long-term use.

Stability & Temperature Effects

Alnico magnets hold up well under heat. The change that comes from heat is just 0.02% per degree Celsius and can go back to normal. But if it gets too hot, it can lose some power for good. How much power it loses depends on the size and type of the magnet. This loss is often less than 5%, and it can be fixed by re-magnetizing. But if the heat goes over 1000°F (538°C), a change happens inside the metal. This change cuts the magnetic power fast, and re-magnetizing won’t bring it back.

This is where Alnico shows why it’s one of the top heat resistant magnets. It works better in heat than some other types, like hard ferrite magnets, which may lose power more easily in extreme heat.

Outside magnetic fields can also lower its power. In very exact uses, people may lower the magnet’s output by 5% to 10% on purpose. This step helps stop stray fields from affecting the magnet. This is often done in permanent magnets for sensors where steady output matters most.

Do you have any questions?

AMSC is a leading supplier of high-performance magnets and magnetic assemblies to the automotive, motor, medical technology industries, and so forth.
Our large inventory and warehousing capabilities allow us to serve a wide range of customers with various applications.

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