After the total number of operating hours or the total number of revolutions of the bearing exceeds the calculated life of the bearing, fatigue spalling occurs as normal fatigue failure. The reason for the normal failure is that the metal on the rolling surface starts to sprout fatigue cracks from the subsurface and cracks to the surface layer to fall off the metal fragments --- flaking because the number of stress cycles in operation exceeds the fatigue limit of the material. Normal fatigue failure performance characteristics: fatigue crack initiation in the subsurface, it can not see, with ordinary instruments can not detect it. Exfoliated pieces of rough and irregular surface, the original rolling surface leaving scars pits, known as pitting。 Pitting once appeared, that the rapid expansion of a short time that is caused by full fatigue spalling, it is advisable to replace the bearing, otherwise it will cause the bearing accidental scrapped, the installation site may even have serious consequences.
Fatigue spalling, which exceeds the calculated lifetime, is in fact the inevitable eventual event that the potential of the material has been fully exploited。 If the user's working life is still not satisfied with the requirements in the bearing lubricant add the appropriate extreme pressure additives, switch to higher performance or larger size bearings, or the choice of vacuum smelting, multiple vacuum refiner Steel bearings。