It is common for bearing to break down sometimes. But the key is making the judgement and dealing with it. The followings are reasons why bearings broke down.
1. High temperature of bearing:
When the machine is working, the part of bearing has a certain temperature. Don't worry, this is normal. Using your hand touching this part, it means normal if you feel not very hot, otherwise it shows the temperature is too high.
The reason of bearing's high temperature: Lubricant quality doesn't meet the requirement or it was metamorphic; the viscosity of lubricating oil is too high; assembling bearing tightly (insufficient gap); too much load.
2. Bearing noise:
It's normal if the rolling bearings have some running noise. But if the noise is big or abnormal, it means the bearing is out of order.
Reasons why rolling bearings have noise:
1) On the one hand, the surface between outer ring and inner ring wear down. On the other hand, when the bearing is under high-intensity work, metals of its surface peel off and then the bearing radial gap increases.
2) On the on hand, bearing lubrication is insufficient, so there is dry friction. On the other hand, the bearing breaks.
3) When the bearing wore and became loose, the retainer will be out of order. This also can cause the noise. You can judge the reason of bearing's breakdown according to the bearing's damage situation after disassembling the roller bearing and examining it.
3. Metal of raceway surface peeled:
Bearing roller and the inner and outer ring raceway surface are subjected to periodic load, resulting in periodic changing stress. When the number of stress cycles come to a certain value, metal of the roller or inner and outer ring raceway surface peeled. If the bearing load is too large, this situation will be worse. In addition, if the bearing installed in wrong way or the bearing bent, metal of roller will also peel. The peeling of metal can reduce the bearing's running precision and make noise.
4. Bearing burns:
The raceway and roller of burnt bearing has temper color. The reason of burning is lack of lubrication, bad quality of lubricating oil, lubricating oil going bad or assembling bearing tightly and so on.
5. Plastic deformation:
It means the bearing has plastic deformation when the interface between roller and raceway had uneven pits. Usually, bearing of rotating with low speed exists this situation.
6. Bearing race having cracks:
The reason why bearing race has cracks maybe the bearing fitting tight, inner ring or outer ring being loose, bearing container being out of shape, the surface of bearing being machined poorly and so on.
7. Retainer having cracks:
The reason is lack of lubrication, roller breaking, bearing race skewing and so on.
8. Seat rings and raceway wearing out badly:
The reason is lack of lubricating oil, unmatched lubricant grade, something dropping in seat rings and so on.