usually with rolling bearings or sliding bearings assembled into one

Machine shaft parts, especially the spindle , usually with rolling bearings or sliding bearings assembled into one , and a high speed of rotation , and sometimes it will produce a very high NNCF series bearing heat. This phenomenon if not removed , will cause angular contact ball bearings overheating , and to the corresponding parts of the machine to produce thermal deformation temperature , causes severe spindle and  is not high , which not only affects the accuracy and precision machine itself and bearing will burn .
In general, if used correctly  bearings can be used to reach far fatigue life. Accidental injury prematurely slim section ball bearing but there can not be resistant in case of use . This early damage and fatigue life relative , a failure or an accident is called the quality of use limits. Multiple causes the installation , pay attention to the lubrication on the use , invading foreign body from the outside , for the study of the shaft , the thermal effects of inadequate housing and so on.
Bearing on the state of damage , such as: angular contact ball bearing rings , ribs cards injury, may be considered as a reason for lack of lubricant , not suitable for the oil discharge structure defects, the intrusion of foreign bodies , bearing misalignment , shaft deflection is too large , there will be overlap of these reasons .
Thus , the survey only bearing damage , it is difficult to know the real cause of injury. However , if you know the use of machinery, conditions of use, the bearing structure around the bearing , to understand the situation before and after the accident , combined with state of the bearing damage , and several reasons, we can prevent similar incidents from recurring.