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The Most Concerned Question of Rubber Coated Magnets

The Most Concerned Question of Rubber Coated Magnets

Rubber-coated magnets, due to their unique feature of protecting holding surfaces while producing great holding force, are so widely selected by customers for their holding application. Some of these applications are designed for quite a long time use --- 10 years, 20 or more, so it is fair enough for users to frequently ask: will the magnet force stay unchanged for that long time? To be honest, I would ask the same question. 


Our rubber coated magnets for sale use NdFeB to generate holding force so it makes perfect sense to study how the NdFeB magnet changes over time with its magnetic energy.


A well-designed 12-year long experiment by Zhong Ke San Huan Research Institute has given us the answer. 8pcs un-coated NdFeB magnet samples (Hcj=1240kA/m, 10.2mm length) are put in the environment of 22°C~28°C with full exposure to air for continuous 12 years. These samples were tested with their magnetic flux value and carefully observed once a year at the same time each year. 


Rare-earth Permanent Magnet Materials by Hu Boping, Rao Xiaolei, Wang Yizhong 2017

Rare-earth Permanent Magnet Materials by Hu Boping, Rao Xiaolei, Wang Yizhong 2017


All the measured data show that in the first 6 years, barely any magnetic loss can be found but after that, an obvious right-lower tilted line indicates an ongoing trend of magnetic loss. If we extend the line based on its slope we will come to a conclusion that less than 1% magnetic loss can be seen in 30 years and a magnetic loss of 2% can be seen in 150 years. But remember these are un-coated NdFeB magnets and magnetic loss happens mainly from surface oxidation. NdFeB with surface treatment will have a much better anti-oxidation feature with which we can easily draw a conclusion that even based on a really conservative estimate, a lifetime of 30~50 years can be expected on NdFeB magnets with magnetic loss of less than 1%.


So, use these rubber coated magnets at the temperature that corresponding to their Hcj and the magnetic force will not have a big change (more than 1%) in, at least, 30 years.


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