Neodymium magnet strength grading

Neodymium magnets or more commonly known as NIB, NefeB or super magnets are the strongest as well as most widely used commercial magnets available worldwide. With the chemical composition of Nd2Fe14B, neo magnets have a tetragonal crystalline structure and are chiefly constituted of elements of neodymium, Iron and Boron. Over the years, neodymium magnet has successfully replaced all other types of permanent magnets for widespread application in motors, electronics and various other everyday instruments of life. Due to a difference in the requirement of magnetism and pull force for each task, neodymium magnets are easily available in different grades. NIB magnets are graded according to the material that they are made up of. As a basic rule, higher the grades, stronger will the magnet be.

The neodymium nomenclature always starts with an ‘N’ followed by a two digit number within the series of 24 till 52. The letter ‘N’ in the grades of neo magnets stands for neodymium whereas the following numbers represent the maximum energy product of the specific magnet which is measured in ‘Mega Gauss Oersteds (MGOe). Mgoe is the basic indicator of the strength of any particular neo magnet as well as the range of the magnetic field generated by it within any equipment or application. Although the original range begins with N24 however, the lower grades are no longer being manufactured. Nowadays the top manufacturers such as Stanford Magnets begin production of neodymium magnets from grade N33 and above. Similarly, while the maximum possible product energy of NIB is estimated to reach N64 yet such high energy levels have not yet been explored commercially and N52 is the highest current neo grade readily made available to consumers.

Any additional letters following the grade refer to the temperature ratings of the magnet, or maybe the absence of it. The standard temperature ratings are Nil-M-H-SH-UH-EH. These final letters represent the maximum threshold functioning temperature i.e. Curie temperature that a magnet can withstand before it permanently loses its magnetism. When a magnet is operated beyond the Curie temperature, the result would be a loss of output, reduced productivity and eventually irreversible demagnetization.

However, the physical size and shape of any neodymium magnet also plays an integral role in its ability to effectively operate at comparatively higher temperatures. Moreover, another thing to remember is that the strength of a good quality magnet is proportional to the number, so that N37 is only 9% weaker than N46. The most reliable way to calculate the exact grade of a neo magnet is through the use of a hysteresis graph testing machine.

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