The strength of a magnet can be found in the magnet specification known as BHmax, which is the maximum energy density of a magnet. This is defined in Mega Gauss Oersteds, or MGOe. On a Magnetic Demagnetization Curve this is the highest point of the magnet’s strength, or the magnet’s maximum energy product.
For Neodymium (NdFeB) Magnets the BHmax will range, in general, from 30 MGOe to 55 MGOe. So, when choosing or defining your magnet, keep in mind that the higher the number, the stronger the magnet. Neodymium magnets produce the highest MGOe of any permanent magnet material. The most common grades of Neodymium magnets are N35, N38, N40, N42, N45, N48, N50, N52, and N55.
Working temperature (Coercivity, HcJ)
When you look at the magnet table of available materials there are different letters after some of the grades. These letters represent the magnet’s ability to withstand demagnetization forces, which can be temperature or other magnetic forces working against the magnet. We define the coercive force using the most common system, the lettering system. This letter system uses the following letters after the grade to define the magnets specification to fight demagnetization forces: M, H, SH, UH, EH, and AH.
When a letter is used after a magnet grade, it indicates that that specific material has a greater ability to fight demagnetizing forces. For our purpose, we are going to use heat as the demagnetizing force as it is most common force effecting the magnet. And, the following examples are “general rules” and not “hard and fast rules”.
A Neodymium Magnet with no letter after the grade, i.e. N38, or N45, or N52, would indicate that it has the ability to work in an environment that has a maximum operating temperature no greater than 80C°. A magnet with an “M” (i.e. N35M, N42M, etc.) generally means that a magnet can be used in an operating environment up to 100C. An “H” material is good up to 120C, “SH” up to 150C, “UH” up to 180C, “EH” up to 200C, and a “TH” up to 220C. Again, these are general specifications and other factors do play a role in coercivity decisions.
Below you can see a table with all the Neodymium grades Hyab can offer. This list updates frequently since higher specified grades develops yearly. For example, grades with greater BHmax expands to have a better coercivity - can withstand higher demagnetization forces, like heat. Contact us if you would like to know more about the different grades. We help clients daily with customized solutions for their project.