What is the difference between the maximum operating temperature and the Curie temperature?

The maximum operating temperature is themaximum temperature the magnet may be continuously subjected to with no significant loss of magnetic strength. This is 176ºF (80ºC) for standard gradesof neodymium magnets. 

The Curie Temperature is the temperature at which themagnet will become completely demagnetized. This is 590ºF (310ºC) for standardgrades of neodymium magnets. 

Higher temperature grades have higher maximumoperating temperatures and higher Curie Temperatures. 

At temperatures betweenthese two points, a magnet will permanently lose a portion of its magnetic strength. The loss will be greater the closer to the Curie Temperature it is heated.