It’s a great question, and one we often hear. Our rubber-coated magnets use NdFeB (neodymium) to generate their holding force, so it’s important to understand how the magnetic energy of NdFeB changes over time.
A well-designed 12-year experiment conducted by the Zhong Ke San Huan Research Institute provides valuable insight. In the study, 8 uncoated NdFeB magnet samples (Hcj=1240kA/m, 10.2mm length) were exposed to air at temperatures between 22°C and 28°C for 12 continuous years. The magnetic flux of each sample was measured annually to track any changes.
The data showed that during the first 6 years, there was almost no detectable magnetic loss. After that, a gradual decline in magnetic strength was observed. Projecting this trend, the study concluded that uncoated NdFeB magnets would experience less than 1% magnetic loss over 30 years, and around 2% loss over 150 years. However, it’s important to note that this loss was primarily due to surface oxidation.
Our rubber-coated magnets, with their protective surface treatment, have significantly better resistance to oxidation. Based on conservative estimates, NdFeB magnets with surface treatment are expected to retain more than 99% of their magnetic force for 30 to 50 years.
Therefore, as long as these rubber-coated magnets are used within their specified temperature range, you can expect minimal magnetic force changes—less than 1%—over at least 30 years.
