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Selection of Motor Bearings

 

The selection of motor bearings is crucial to the overall performance of the motor. When choosing bearings, it is essential to comprehensively evaluate their suitability. First, the design life of both the motor and the bearing, as well as the bearing’s fatigue life, must be assessed to determine the appropriate bearing size. Attention should also be paid to potential issues such as grease aging, wear, and noise. Additionally, depending on the specific application of the motor, the bearing’s accuracy, fit, clearance, cage, lubrication, sealing, and installation characteristics should all be carefully considered.

 

During bearing installation, the fit between the bearing's inner diameter and the shaft, and the outer diameter and the housing, is a critical step. If the fit is too loose, it may cause creep, damaging the shaft or housing and allowing wear particles to enter the bearing, leading to heat buildup, vibration, and reduced performance. Conversely, excessive interference can cause changes in the bearing's inner and outer diameters, reduce internal clearance, and even affect the precision of the bearing rings.

 

When selecting motor bearings, multiple factors should be considered comprehensively, including size, accuracy, fit, clearance, cage, sealing, lubrication, special requirements, installation, and use. Below are some key points to consider when selecting motor bearings:

 

1. Motor Bearing Size Selection: The bearing size should be determined based on the machinery used and its design life, with an appropriate increase in the fatigue life factor, while also considering factors such as shaft strength, rigidity, and mounting dimensions. The bearing size should match the specific motor model and specification.

 

2. Motor Bearing Accuracy Selection: General industrial motors can use P6 or P0 level precision. Bearing accuracy is divided into five grades: P0, P6, P5, P4, and P2, improving in sequence. The selection of bearing accuracy should be based on the motor’s performance requirements and operating environment.

 

3. Principles for Selecting Rolling Bearing Fit: Choose the appropriate fit according to load conditions, load type and magnitude, bearing size, and other factors.

 

4. Motor Bearing Clearance Selection: Bearing internal clearance includes radial, axial, and angular clearance. During operation, the clearance generally decreases, which can shorten bearing life or cause overheating. Therefore, the initial clearance of the bearing should be slightly greater than zero.

 

5.Selection of Bearing Cage Material and Structure: Choose the appropriate cage material and structure according to bearing usage requirements, such as stamped riveted cages, stamped wave cages, stamped crowned cages, and solid nylon cages. The choice of cage in bearing selection significantly impacts the motor's stable operation and service life.