Which is higher in intrinsic coercivity UH, H, N, and SH?

Many people often see models such as N35H, N42SH, N38UH when purchasing neodymium iron boron magnets, thinking that UH, H, SH are only different in temperature resistance. In fact, these suffixes not only represent the temperature resistance level, but also indicate significant differences in the intrinsic coercivity (Hcj) of magnets. So, which of the intrinsic coercivity UH, H, N, and SH is higher?

According to common industry standards, the intrinsic coercivity of H-grade is ≥ 17 kOe (approximately 1353 kA/m), SH grade is ≥ 20 kOe (approximately 1592 kA/m), and UH grade is ≥ 25 kOe (approximately 1989 kA/m). Therefore, the intrinsic coercivity of the three is ranked as UH>SH>H. The higher the intrinsic coercivity, the stronger the magnet's ability to resist high temperatures and demagnetization from reverse magnetic fields. Therefore, UH grade is more suitable for high temperature and high load conditions such as new energy vehicle drive motors, industrial servo motors, and high-speed motors, while H grade is more suitable for general industrial applications below 120 ℃.

Comparison of intrinsic coercivity between UH, H, N, and SH

How should one choose?

A safety margin should always be built in. If the operating temperature of the equipment is relatively low, the H class will suffice for most requirements. Where equipment needs to operate continuously at around 120°C, the SH class is recommended. For high-temperature conditions of around 150°C or applications involving strong reverse magnetic fields, the UH class offers greater reliability.

The above provides an overview of which intrinsic coercivity grade—UH, H, N or SH—is the highest. Should you have any queries regarding selection, quotations or prototyping, please do not hesitate to contact Carichi.

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