Neodymium Magnets are very susceptible to losing their effective magnetic field at elevated temperatures. The Neo magnet grade should be carefully selected to account for the operational temperature of the application and the magnet’s geometry. All magnet alloy will gain or lose effective magnetic field as the temperature flucuates. Neo magnets will lose effective field as the temperature increases and are said to have a Negative Temperature Coefficient. When compared to other magnet alloy options, neo magnets lose magnetic field at a faster rate. Neo magnets effectively have a higher Temperature Coefficient (TC) when compared to other commercial alloys.
This high rate of change relative to temperature exposure results in Neodymium magnets being very susceptible to demagnetizing from elevated operating environments. The magnet may be exposed to a temperature which does not fully demagnetize, but reduces its’ magnetic performance to a state that it no longer is able to provide sufficient magnet field to support the application.
The loss that has been discussed thus far is considered reversible. This means that the magnet will recover the loss as it cools back down. What is typically published by suppliers of magnets is the Reversible Temperature Coefficient (RTC) for each particular grade of Neo for both the Residual Induction (Br) and the Intrinsic coercive Force (Hci). The RTC as well as the recommended Maximum Operating Temperature must be considered when selecting a Neo magnet grade for an application above ambient room temperature.
© 2018 Dura Magnetics, Inc. All rights reserved