Selecting a grade is the next step, once you have decided which permanent magnet material is best for your application.
Generally, a grade indicates the Maximum Energy Product of a magnet. For instance, Grade 32 implies the (BH)max is
about 32 MGOe. A higher grade of permanent magnet has a better performance.
However, higher grade is usually associated with a higher cost. Taking sintered NdFeB magnets as an example,
the price of Grade 45 is twice and even more of that of Grade 33. Other property parameters, such as remanence Br and
coercive forces Hci and Hcb, also need to be considered in selecting a grade. One way to select the
suitable grade for your application is experiment. You can purchase the several magnets with different grades in the same size and shape
(some suppliers have these magnets available on their shelves) and try each grade until you find one right for your applications.