When you complete identification of the material best suited for your magnet or magnetic assembly,
the next step is to determine the magnet’s specific grade for your application.

For Neodymium Iron Boron, Samarium Cobalt, and ferrite (ceramic) materials, the grade is an indicator of
magnet strength:
The higher the material grade number, the stronger magnet strength.

Below are few factors when you consider selecting the grade for your application:

1, Maximum Operating Temperature

Magnet performance are incredibly sensitive to fluctuations in temperature, for example, a Max 120℃ magnet
works at 110℃ for 8 hours without a break, the magnetic loss will happens. So we should choose magnet Max 150℃。
so it is critical to have your operating temperature range defined prior to choosing the grade.

2, Magnetic Holding Force

When determining the magnetic field density needed, firstly magnet material take into consideration.
A magnetic separator in conveyor separation do not need neodymium magnet, better ceramic is more economical.
But for a servo motor, neodymium or SmCo has strongest field in smallest size, which is perfect in precision instrument.
Next you can select a suitable grade.

3. Demagnetizing Resistance

Magnet’s demagnetizing resistance has a big impact on your design. Your maximum operating temperature
is directly correlated with the intrinsic coercive force(Hci). It is the resistance to demagnetization.
The higher Hci means the higher operating temperature.
While heat is the major contributor to demagnetizing, it is not the only factor. So a good Hci selected
for your design can effectively avoid demagnetization.