Even when the working point of a magnet is well above the knee, small irreversibel losses may take place when the magnet is first time heated to the operating temperature. This is due to the fact that corners and edges of a magnet are less stable and thus easier to demagnetize than the bulk. In the case of a small magnet this effect can be considerable.
In the case that the working point is only slightly above the knee, time dependent irreverible losses may occur. The amount of losses incease with increasing temperature and decreasing permeance coefficient, and indicated by the pictures below.