Every type of rare earth magnet, whether neodymium, AlNiCo, or something else, has its own alphanumerical system for classifying strength. Each one is unique, and there’s no simple formula for translating a system from one magnet type into the system for another.  Because the classification systems are so different, it’s important to understand each magnet’s rating system so you can prevent magnet failures and potentially costly or dangerous situations. 

Cracking Neodymium’s N-Ratings

Neodymium magnets are categorized by N-ratings, typically formed by an N, then a number, and then sometimes a couple more letters. The N stands for neo, an industry simplification of neodymium. The numbers, however, are more complicated. In general, the number indicates the strength of the magnet, measured in Megagauss Oersted (MGOe). If a magnet has a grade of N-42, it has a maximum energy product of 42 MGOe. For every increase of 1, the magnet’s strength increases by about 1%. For example, an N-42 magnet is about 2% stronger than an N-40 magnet. Once you’ve read the N and the following integers, you need to consider whether there are any letters after the numbers. These letters signal the maximum working temperature (the temperature at which the magnet will begin to lose strength) and the Curie temperature (the temperature at which the magnet will lose all magnetism). Here’s what you can expect for each letter combination:
Letter Max Working Temperature Curie Temperature
No other letters ≤80°C 320°C-330°C
H ≤120°C 330°C-340°C
SH ≤150°C 340°C-350°C
UH ≤180°C 350°C-360°C
EH ≤200°C 360°C-370°C
When using a magnet with an N-rating that includes letters, proceed with caution. Neodymium magnets that can withstand higher temperatures aren’t pure neodymium. In order to withstand high temperatures, the neodymium needs to mix with other, weaker metals. In general, the more heat resistance a neodymium magnet has, the weaker it will be. If you need a magnet with high heat resistance and high strength, you’ll want a magnet with a high numerical rating as well. You’ll also need to keep an eye on your budget as these magnets are generally more expensive than those that aren’t designed to withstand high temperatures.  

Putting Your Knowledge to Use

Now that you understand N-Ratings, let’s practice. Say you have a magnet with the following spec: N-30SH. What do you know about it? The N tells us the magnet is primarily made of neodymium. The 30 tells us its max energy production is 30 MGOe. Finally, the SH means the magnet’s max working temperature is about 150°C, and its Curie temperature is between 340°C and 350°C.

Get Your Hands on Neodymium Magnets

Since you know how neodymium magnets are rated, you should have a pretty good idea of what you need for your facility. Of course, our customer service team is standing by if you need help. When you are ready to buy, Apex Magnets offers a huge selection of neodymium magnets perfectly suited for a variety of applications. If you can’t find what you’re looking for, Apex Magnets offers custom magnets as well.