If well-cared-for and left unexposed to external influences, a permanent magnet will stay strong for a very long time. When in use, it’s a slightly different story. Regardless of how you’re using your magnets, but certainly, in business and industrial applications, it’s important to know what can weaken a magnet so you can replace it as necessary. Replacing your magnets at the most appropriate interval is an important way to protect the value of your investment.  Physical signs that it's time to replace your magnets: 
  1. Chipping
  2. Peeling
  3. Cracking
  4. Shattering
  5. Corrosion
  6. Rust
  7. Loss of volume
Sometimes, however, you can’t see the damage with your eyes. Instead, you may notice the magnets have weakened. Other times, you may not be able to notice this, at least not right away. Instead, their limited capability will affect your bottom line.  For this reason, it’s important to understand the variables that might ultimately lead to a need to replace your magnets. Variables that can degrade your magnet and cause it to weaken include heat, reluctance changes, and external fields. 

Exposure to Heat

When exposed to heat, the atoms in magnets move faster and more erratic. This leads to a misalignment of atoms and thus, a weakened magnet. When exposed to temperatures above 176° Fahrenheit (80° Celsius), magnets will quickly lose their magnetic properties. They will become permanently demagnetized if exposed to these temperatures for an extended period of time or heated at a significantly higher temperature (Curie temperature). Heat demagnetization is also dependent on what types of materials make up a magnet. Some types of magnets such as Samarium-cobalt (SmCo) have higher heat resistance. There are also other types of Neodymium-iron-boron (NdFeB) magnets that are not as susceptible to heat-induced flux degradation.

Reluctance Changes 

When the permeance coefficient is altered, this can cause a change in magnetic charge. The permeance coefficient, also called the operating slope, depends on the magnet shape and how it’s used in a circuit. Put simply, it tells you how difficult it is for field lines to move from the magnet’s north pole to south pole. Displacement from a circuit (taking out, putting in, or changing properties while in use) can cause this kind of shift in magnetic charge. The effect on the magnetic charge depends on how extreme the change is as well as the magnet’s properties. 

External Fields

External magnetic fields can cause magnets to lose their strength. Alnico and ceramic magnets in particular are vulnerable to this. This is often due to an environmental factor, including nearby electromagnets. Storing magnets too close together with opposing forces near each other can also lead to a lost magnetic charge, and bigger, stronger magnets can demagnetize smaller ones.  When not in use, you can avoid this by keeping the magnets in their packaging and storing them in attracting rows.

Apex Magnets and Proper Storage

Even when your magnets are not being actively used, be sure to store them properly. Improper storage can lead to damage on the shelf. At Apex, our stock magnets are stored carefully to expand shelf life. For more information, check out our guide to packing and storing magnets. If you want to have a conversation about what might require you to replace a magnet, call us at 1-304-257-1193.