Factors Affecting Magnet Aging
Permeance coefficient (PC) value of magnet
- Magnets with higher PC values have either same diameter with longer length or same length with smaller diameter.
- Magnets with higher PC values have better self demagnetization characteristics and hence lower aging loss.
Density of magnet
- To achieve higher density, magnets are pressed with higher tonnage. This causes additional powder fracturing which creates fresh surfaces.
- Exposed fresh surfaces lead to higher aging loss.
Saturation of magnet
- Insufficient saturation of the magnet results in
- Reduced squareness of hysteresis loop
- Lower Hci
- Reduced squareness and lower Hci leads to higher aging loss.