14 years experience expert of stable permanent magnet supplier

How to correctly choose the material grade of NdFeB?

When you’re trying to figure out the right neodymium magnet for your design needs, you’ll always see the terms “grade” or “N-grade” from any supplier or manufacturer. In addition to some other criteria such as coating, tolerances, etc., the desired material grade must be defined for the neodymium magnet.

The material class is the maximum energy product (BH)max, or the maximum strength to which this magnet material can be magnetized. In other words, it is related to the magnetic flux output per unit volume. It is measured in millions of Gauss Oersteds (MGOe), which is the product of the attraction force (Gauss) and the persistence of the force (Oersted), which is also equivalent to 7,958 kJ/m3. Generally, the larger the value, the stronger the magnet. Grades are determined in the initial steps of neodymium magnet manufacturing. Based on a precise formulation of rare earth constituents for each respective material grade, our factories precisely weigh, melt, pulverize, grind and thoroughly mix them.

Material grades start with the nomenclature “N” for neodymium magnets, followed by a 2-digit value between 25 and 58, where 58 is the magnetic strength option for maximum power. (But in theory, the highest level can be up to N64, but it has not been achieved in production.) Generally speaking, N52 is the highest, but now our factory can achieve N58 level, which is very mature. Available grades are divided into: N35-N58 no ending letters (80°C), N33M-N50M (100°C), N35H-N48H (120°C), N30SH-N45SH (150°C), N30UH-N40SH (180°C), N28EH- N38EH (200°C) and N30AH-N33AH (220°C). Celsius is the corresponding maximum operating temperature each grade can withstand before the magnet irreversibly loses a fraction of its magnetic strength. Magnet grade is a good indicator of magnet strength. Generally speaking, the higher the number, the stronger the magnet. The pull force of the magnet varies with the grade or N number. Double the N number and you’ll find roughly double the pull.