The internal defects of the bearing that gave rise to this phenomenon were as follows:
Bearing inner and outer ring or ball rupture is one of the most serious defects. The reason is that the bearing is not fit with the journal of the shaft, and too much force is used to force it in, which often results in the rupture of the inner and outer ring.
Because of the high heat caused by poor heat dissipation or oil failure, the bearing usually discoloration with the ball and the gripper first, and then the shaft ring also appears blue and purple. The hardness of the bearing will be weakened because of annealing, and the bearing will lose its use value. Excessive lubricating oil, which is stirred violently by a high speed rotating ball or shaft, often produces the maximum heat and causes the bearing to discolor.
3. Bead mark
Due to improper assembly or excessive force, the ball is hard rolled on the raceway, resulting in a permanent deformation of the raceway. This concave deformation of the same shape as the ball is called a bead mark.
The strong vibration caused by the unbalance of the fan rotor or the friction between the motor rotor and the stator will result in the concave shape similar to the bead mark on the bearing shaft respectively.
Peeling is a symptom that the metal in the bearing raceway becomes shedding from the surface of the raceway. The reason for this phenomenon is the fatigue of the material after the load and the gradual aging of the material.
Corrosion is usually caused by the invasion of water vapor into the bearing, and
using lubricating oil unqualified (e.g. contain water, acid or alkaline liquid). The corrosion of the original bearing smooth surface becomes rough, rough surface is more easily oxidized, to accelerate the formation of corrosion.
In addition to the above defects and causes, dust, sand and other impurities intruded into the bearing, will also accelerate the wear of bearing.http://www.jnblower.com/