How Long Do Rare Earth Magnets Keep Their Magnetism?

Rare earth magnets, such as neodymium magnets, are renowned for their powerful magnetic strength and durability. However, their longevity is not only dependent on their inherent magnetic properties but also on how well they are protected from various environmental factors. This article explores the factors that can affect the longevity of these magnets and offers insights into their preservation.

Factors Affecting Magnetism in Rare Earth Magnets

When it comes to the long-term preservation of rare earth magnets, there are several critical factors to consider. One of the primary concerns is the tendency of these magnets to lose their magnetic strength over time. However, the rate at which this loss occurs can vary significantly based on the type of magnet and the conditions under which it is used.

Corrosion and Wear

One of the most significant challenges to the longevity of rare earth magnets is corrosion. Unlike the commonly perceived stereotype, magnetism is not a storage device that collects and holds energy. Instead, magnets channell magnetic energy in a live state. When exposed to the elements, these magnets can corrode, especially if they are not properly coated or protected.

For example, I have observed a decline in the performance of some nicely crafted wooden boxes that were held together with low-cost neodymium magnets. After a few years in a benign indoor environment, the magnets' surfaces would flake and crumble into a powder. Contrarily, a metal tape measure hulled with a robust neodymium magnet, which was extensively used in construction, remained intact. This magnet had a thick protective coating resembling sintered bronze, shielding it from both mechanical damage and corrosion.

Customers may not be aware of the potential for corrosion until they experience it firsthand. Therefore, designers and manufacturers aiming for long-term durability must choose magnets that have undergone treatment to resist such deterioration.

Brittle Nature of Rare Earth Magnets

In addition to corrosion, another essential factor to consider is the brittleness of these magnets. While extremely resistant to losing magnetization indoors, rare earth magnets can be prone to damage when subjected to high impact or sharp blows.

As I mentioned, the potential for losing magnetism is minimal under normal conditions but it is important to note that rare earth magnets can lose a fraction of a percent of their magnetic power annually, even in environments devoid of extreme vibration or opposing magnetic forces.

Other Factors Affecting Magnetism

There are three primary factors that can diminish a magnet's strength: high heat, extreme vibration, and opposing magnetic forces. If your proposed application does not involve these factors, you can be confident that the magnet will maintain its strength for the lifetime of the furniture or device it is used in.

Conclusion

The longevity of rare earth magnets is a complex issue influenced by various factors, including corrosion protection, brittleness, and the impact of operational conditions. By addressing these factors, designers and manufacturers can ensure the reliable performance of these powerful magnets in a wide range of applications, from decorative items to industrial machinery.