How to Understand the Grade of Sintered NdFeB Magnet?

The grade of sintered neodymium iron boron (NdFeB) magnet is a string composed of three parts: "N" + "number" + "letter". The "N" on the left is the initials of neodymium, which means sintered neodymium iron boron magnet. The "number" in the middle represents the value of the maximum energy product (BH) max. The value varies from 28 to 52. The "letters" on the right reflect the level of intrinsic coercivity Hcj. Classes include "M" (Hcj ≥ 14 kOe), "H" (Hcj ≥ 17 kOe), "SH" (Hcj ≥ 20 kOe), "UH" (Hcj ≥ 25 kOe), "EH" ( Hcj ≥ 30 kOe) and "AH" (Hcj ≥ 35 kOe), which are abbreviations for "Medium", "High", "Extra High", "Extra High", "Extremely High" and "Extraordinary High", respectively.

It should also be mentioned that there are levels where letters are unavailable or default. In this case, Hcj is not less than 12 kOe.

Here are two examples to help understand. The "N45SH" grade refers to sintered NdFeB magnets (BH) up to 45 MGOe with Hcj above the level of 20 kOe or 1592 kA/m. "N52" grade default right letter part indicates relative sintered NdFeB magnets (BH) up to 52 MGOe with Hcj above the level of 12 kOe or 955 kA/m. A permanent magnet with higher coercivity means it is more resistant to demagnetization, including magnetic field demagnetization and thermal demagnetization. In addition, the maximum working temperature Tw of N45 magnets is 80℃, while the maximum working temperature Tw of N45SH magnets can reach 150℃.