What is quality grade?
You will often see that magnets are labeled with a combination of letters and numbers such as N42, N42SH, N35UH. The following explains what this means.
The numbers?
The numbers tell you how much energy the magnet produces regardless of the size of the magnet. The higher the number, the more energy (Maximum Energy Product, MGOe) the magnet can produce. You will therefore find that a higher number results in a more powerful magnet. A magnet with a quality grade of 40 is therefore less powerful than a magnet of similar size but with a quality grade of 52.
Currently, the weakest magnets have a quality grade of 35, while the strongest have a quality grade of 52. You'll find that most magnets have a quality grade of 40 or 42, as this is where you'll find the best strength-to-price ratio.
The letters?
The numbers are often preceded and followed by a letter. The letter on the left side indicates the type of magnet. This will typically be N for Neodymium. The letters on the right side indicate the Max Operating Temperature and the Curie temperature. Examples are N42, N42SH, N35UH and others. Often the letter on the right-hand side is omitted so it just says N42. In this case, the maximum operating temperature is 80 degrees and a Curie temperature of 310 degrees.
What should I know about quality grade before buying a magnet?
Whether you need magnets for an electric motor or to lift an object, it's important to know the strength of the magnet. If the magnet is too strong (the quality grade is too high) it can damage its surroundings. If the magnet is too weak (quality grade is too low), you may not get the desired result. Besides the quality grade, there are also other things that influence the strength of a magnet. These include, for example:
- The shape and proportions of the magnet
- The volume of the magnet
- The magnet's surroundings. For example, if the magnet is covered in metal or if the metal to which the magnet will adhere is not 100% magnetic.
As you can see, quality grade is a theoretical value that can be difficult to relate to or translate into practical use. That's why we also measure the strength of magnets by testing how many kg they can hold. You can find this information on the individual product pages.