Core Principles of Motor Bearing Selection

Preferred Bearing Type

• Conventional asynchronous motors, frequency conversion motors, low-voltage motors: Deep groove ball bearings are preferred, suitable for scenarios mainly with high speed, low noise and radial load, with high cost performance;
• High-voltage motors, high-power motors, motors with axial force: Angular contact ball bearings or paired deep groove ball bearings are selected to bear composite loads and improve operation stability;
• High-speed motors, precision motors: P6 and P5 grade precision deep groove ball bearings are selected to reduce vibration and abnormal noise and ensure operation accuracy.

Preferred Seal and Cage

• Industrial motors prefer double-side sealed bearings (2RS/ZZ) to block the intrusion of dust and oil pollution and reduce operation and maintenance;
• Nylon cages are selected for high-speed motors to reduce noise and raise the speed upper limit; steel cages are selected for heavy-load motors to enhance load-carrying capacity.

Key Point of Clearance Selection

Motor Bearing Installation: Core Details to Avoid Abnormal Noise and Jamming

• Strictly prohibit violent knocking: Adopt hot installation or press fitting, the pressure only acts on the mating ring to avoid damage to raceways and rolling elements;
• Control mating tolerance: Interference fit between inner ring and journal, clearance fit between outer ring and end cover, over-tight fit is easy to cause heating, over-loose fit is easy to cause ring slipping;
• Ensure coaxiality: Correct the concentricity of motor end cover and journal, installation deviation will directly cause vibration and abnormal noise;
• Thorough cleaning: Clean impurities on journal and end cover before installation to avoid foreign matters being brought into the bearing interior.

Motor Bearing Lubrication: Core Link to Eliminate Heating and Premature Aging

• Select special grease: Motor-specific extreme pressure lithium-based grease/polyurea grease, adapted to motor speed and temperature rise, reject inferior general grease;
• Precise quantity control: Double-side sealed motors are pre-filled with grease at the factory without additional filling, open motors are filled with 1/3 of the space, and excessive filling is the main cause of heating;
• Regular grease supplement: Supplement grease for high-speed motors every 3~6 months, and for low-speed motors every 6~12 months to avoid grease aging and drying up.

Daily Operation and Maintenance and Fault Prejudgment

• Regular temperature measurement: The normal temperature of motor bearing ≤70℃, stop the machine immediately to check lubrication, installation and load when it exceeds 80℃;
• Monitor abnormal noise: If periodic abnormal noise and harsh noise occur, check bearing clearance, rolling element damage and impurity intrusion;
• Avoid overloading: Long-term overload operation will accelerate bearing fatigue spalling, control the motor load within the rated range;
• Moisture and rust prevention: Do a good job of motor sealing in humid environment to prevent bearing corrosion, and regularly check the rust prevention status of grease.