magnet life
We have had many inquiries regarding the shelf life of permanent magnets as well as the lifespan of neodymium magnets. The answer is simple, there is no shelf life; however, since everything has to do with magnets, it's not that simple.We have had many inquiries regarding the shelf life of permanent magnets as well as the lifespan of neodymium magnets. The answer is simple, there is no shelf life; however, since everything has to do with magnets, it's not that simple.
Shelf life is when a product can no longer perform its intended function, or become unhealthy or dangerous. In order for a permanent magnet to no longer perform its intended function, it would need to lose some or all of its ability to create a net external magnetic field. The degree of this loss will determine the ability of the magnet to work.
So if the magnet is left alone on a shelf, there are no external influences, only "magnetic creep" that could cause the magnet's magnetic field to decrease. "Magnetic creep" occurs when a magnet begins to succumb to self-demagnetizing forces. Generally, this takes a long time to implement even a small change without any other stress on a well-designed magnet. What is a long time? Years to decades, depending on the magnetic alloy.
However, in the real world where we have to store, handle, pack, count, etc. magnets, they can experience other negative factors. What factor is the storage experience of the magnet experience that can negatively affect the ability to generate a net field?
Volume loss is the most prominent factor, which can come from corrosion or impact, where the actual chip or part of the magnet is removed. If the magnet is smaller, the magnetic field it can generate is lower. Since protecting magnets is so important in their intended application, they must also be protected during storage.
To prevent corrosion, always keep magnets in a clean, dry environment. Preferably keep them packaged by the magnet supplier. Usually, magnets are provided to attract in rows, sometimes with spacers. Magnets should also be kept in the configuration provided by this supplier to eliminate the possibility of volume loss due to handling.
Permanent magnets are magnetized with very strong magnetic fields. Sometimes, magnets can encounter magnetic fields from other magnets that can be damaged. This is especially true when magnets with multiple different part numbers are stored in the same area. Larger, stronger magnets can create fields that partially eliminate smaller magnets. Some magnetic alloys are more susceptible to this. Some grades Alnico (aluminum nickel cobalt) and ceramic (strontium ferrite) are the most susceptible alloys.
Steps to mitigate the effects of external magnetic fields:
Place the magnet in the packaging provided by the supplier
Keep the attraction of the magnets in a row, and where the rows attract
Keep the wrap and remove the bump separate from the magnet
Heat will always have an effect on permanent magnets, but most storage and shipping methods will never reach a temperature high enough to cause irreversible losses in the magnet. However, high temperatures will have negative effects from corrosion and demagnetization. It is good practice to store magnets in an environment that humans will find comfortable.
If you have older magnets, or magnets with a questionable storage history, there are steps you can take to evaluate your inventory.
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