Bearing failure is a relatively concentrated type of motor failure, which is closely related to the selection, installation and subsequent maintenance of bearings. Combined some actual analysis cases and data accumulation to make a simple classification of rolling bearing structure failures and causes, and shared it with you.
1 Analysis of the causes of bearing heating
● When single-row ball bearings are used at both ends of the motor, the bearing jacket cannot smoothly creep in the bearing chamber due to the thermal expansion and contraction of the rotor, and the bearing clearance is "eaten up", causing the ball to bear a large additional axial force.
● The bearing is too close to the stator and rotor windings, or is affected by the heat radiation of the towed equipment.
● The ventilation and heat dissipation of the bearing part are not good.
● Excessive or serious loss of grease causes dry grinding of the bearing; or there are impurities in the grease.
● The matching tolerance between the inner sleeve of the bearing and the shaft, or the outer sleeve of the bearing and the bearing chamber, tends to interference.
● Improper bearing selection: such as inappropriate clearance, model and limit speed do not meet the requirements, etc.
● The base is deformed, causing the coaxiality of the stoppers at both ends to exceed the tolerance.
● The dynamic balance of the motor rotor exceeds the tolerance.
● The bearing itself is of poor quality.
● Interference from the equipment towed by the motor.
2 Analysis of the causes of high noise in motor bearings
● Improper bearing clearance selection.
● Motor dynamic balance is out of tolerance.
● Motor bearing distance is too large.
● Grease dries up or leaks.
● Improper matching between the inner and outer sleeves of the bearing and the shaft and bearing chamber.
● Uneven load.
● Installation and commissioning do not meet the requirements, such as the coaxiality of the motor and the equipment being dragged is out of tolerance.
● Poor quality of the bearing itself, such as loose cage, deformation of the raceway, etc.
3 Causes of large vibration in the bearing position
● Excessive bearing clearance.
● Impurities enter the bearing raceway.
● Excessive bearing distance.
● The shaft is not round, causing the raceway of the inner sleeve of the bearing to deform (also the source of noise).
● Uneven load.
● The bearing is damaged during motor assembly, such as hitting the bearing sleeve hard, causing the rolling element and raceway to be damaged.
4 Analysis of the causes of bearing running
● More than 90% of the reasons for unqualified products in the manufacturer are problems in the motor manufacturer.
● Many times of disassembly and assembly make the "knife peak" of the inner and outer sleeves of the bearings smooth. The main reason is still in the motor manufacturer, such as poor processing roughness.
5 Analysis of the causes of friction between the bearing cover and the shaft
● Excessive bearing clearance causes the rotor to sink.
● The designed clearance is too small or the manufacturing is out of tolerance.
● The parts are deformed greatly during use, destroying the coaxiality of related parts.
● The bearings are seriously heated, causing the related parts to deform.
6 Analysis of the causes of rubber oil seal failure
● Inappropriate matching with motor-related parts.
● Overheating of the bearing part.
● The material quality of the oil seal itself is poor.
● Too long use time.
7 Analysis of the causes of impurities in the grease
● Improper operation during motor assembly causes dust and impurities to enter the grease.
● The protection level of the inner and outer covers of the bearing does not meet the requirements.
● The rubber oil seal is aging and failed.
8 Analysis of reasons for grease drying up or outflow
● Bearing temperature is too high.
● Improper grease brand selection.
● The motor has not been running for a long time.
● The bearing structure design is unreasonable.
9 Analysis of reasons for oil filling and oil draining failure
● Improper design structure
● Long-term non-use, grease drying up, grease cannot be injected, or cannot be discharged after injection Analysis of reasons for premature bearing damage
● The bearing itself is of poor quality.
● The model selection is not appropriate.
● Lubrication does not meet the requirements.
● The shaft current causes electrical corrosion to the bearing.
