Maximum Energy Product and Grades of Neodymium Magnet
Neodymium magnets are the strongest permanent magnets known. They are less apt to be demagnetized and are often graded using the prefix ‘N,’ representing Neodymium.
The higher the grade, the stronger the Neodymium magnet. The mega-gaussian-oersted (MGOe) of Neodymium magnets ranges from 30 MGOe to 55 MGOe. An N42 neodymium magnet will not be as strong as an N52 neodymium magnet. However, the performance of the N42 neodymium magnet can be elevated by altering its pole size or, in some neodymium magnets with thin poles, the temperature of the neodymium magnet.
Samarium Cobalt magnets have MGOe ranging between 16 MGOe and 32 MGOe. The common Samarium Cobalt magnets are graded 16, 18, 20, 22,…, 32. As with Neodymium magnets, higher-ranked neodymium magnets are stronger than lower-ranked neodymium magnets under controlled environmental circumstances.
What happens if a neodymium magnet has a letter after its grade, N42H? Since temperature can affect a neodymium magnet’s performance, neodymium magnets are often graded to indicate the temperature at which they can perform.
A Neodymium material graded as N42 shows that the neodymium magnet can operate at temperatures below 80oC. An N46M neodymium magnet can be used at a maximum operating temperature of 100oC. Other known temperature grades are:
- “H,” for up to 120C
- “SH” up to 150C
- “UH” up to 180C
- “EH” up to 200C, and
- “TH” up to 220C
Should neodymium magnet grades be a priority when purchasing neodymium magnets? It depends. High-grade neodymium magnets cost more than low-grade ones, which is a determining factor for the kind of purchase made. Besides, the letters behind each grade inflate the price of the neodymium magnet. So, an N36H neodymium magnet will possibly cost more than an N36 neodymium magnet. And in some cases, a low-grade neodymium magnet with a higher letter will cost more than a high-grade neodymium magnet, such that an N32SH neodymium magnet may cost more than an N40 neodymium magnet.
Should you purchase the highest strength material every time? Perhaps not. The strongest neodymium magnet isn’t always the best neodymium magnet for an application. You may need to use a neodymium magnet that can produce a specific magnetic field at a specific distance. The right neodymium magnet for a magnetic project may be a Neodymium 34, so using a Neodymium 42H will likely cause a malfunction in operation.
Another consideration for choosing neodymium magnets is the possibility of combining neodymium magnets. In some situations, a neodymium magnet can be combined with another neodymium magnet to induce a focused magnetic field. The strength of such neodymium magnets is of minor importance. A high-grade neodymium magnet with a thin diameter may underperform compared to a low-grade neodymium magnet with a thick diameter.