When there is a problem with the bearing system, the precursor symptoms are noise or heat. Mechanical failures generally manifest as noise first, then begin to heat up, and later develop into bearing wear. The specific symptoms are increased noise, and even more serious problems such as bearing disassembly, motor shaft holding, and winding burnout may occur.

What are the causes of bearing heating and damage?

(1) Assembly and usage factors. Anyone who has been to a bearing manufacturing factory knows that the control of the bearing manufacturing process is particularly strict, especially for some better bearing manufacturers. The key processes of bearings are carried out in a very clean environment; However, in the assembly and later use and maintenance of the motor, sometimes it is not satisfactory: for example, during the assembly process, poor environmental conditions can contaminate the bearings themselves, impurities (particles, other oils, water, etc.) can be mixed into the lubricating oil (or grease), collisions with the bearings during the assembly process, abnormal stress during the bearing assembly process, etc., all of which can cause problems with the bearings in a short period of time. In the process of use, if the motor is placed in a damp or more harsh environment, the bearings may rust, which is also a problem for the bearing system.

Regarding the bearing system, another issue is the sealing between the bearing inner cover and the bearing outer cover, which is what we call the standardization of the sealing oil groove processing. If the processing is not standardized or the diameter of the bearing inner and outer covers exceeds the tolerance, it is also easy for foreign objects to enter the bearing and cause malfunctions.

(2) Problems caused by unreasonable radial fit of bearings. For any bearing product, there are initial clearance and working clearance. Once the bearing is installed, especially when the motor is running, the clearance of the bearing is the working clearance. Only within the normal range of the working clearance can the bearing work normally. In practice, the fit between the inner ring of the bearing and the shaft, the fit between the outer ring of the bearing and the end cover (or bearing sleeve) and the bearing chamber, all directly affect the working clearance or relative operation of the bearing: when the bearing is in a tight clamping state, the working clearance will decrease and the bearing will heat up; Similarly, when the fit is too loose, the problem of bearing runout may occur. When the size of the bearing chamber exceeds the positive tolerance, there may be a problem of running out of the outer ring, that is, the outer ring of the bearing and the bearing chamber undergo relative motion in the circumferential direction. When the diameter of the bearing position exceeds the negative tolerance, there may be a problem of running out of the inner ring of the bearing, that is, the inner ring of the bearing and the bearing position undergo relative motion in the circumferential direction.

(3) The problem of misalignment caused by the lack of concentricity between the stator and rotor. In theory, when the stator and rotor of a motor are coaxial, the radial clearance of the bearings should be relatively uniform during motor operation. If the stator and rotor are not concentric, it is equivalent to the center lines of the two not coinciding, but intersecting. Taking a horizontal motor as an example, the rotor will not be parallel to the foot surface, causing the bearings at both ends to be subjected to a radial and axial external force, which will naturally cause the bearings to work abnormally during motor operation.

HZ-3510 Grounding Continuity Tester