The selection and application of bearings for three-phase induction motors are crucial to ensure efficient operation and extend the lifespan of the motor. Below is a detailed guide on bearing selection and application:
Deep Groove Ball Bearings (6000 Series)
Features : Simple structure, low friction, suitable for high-speed rotation.
Examples : Models 6310, 6205.
Features : High load-carrying capacity, can handle significant radial loads but sensitive to axial loads.
Examples : Models NU310, NJ206.
Angular Contact Ball Bearings (7000 Series)
Examples : Models 7310B, 7206C.
Spherical Roller Bearings (20000 Series)
Features : Self-aligning, adaptable to misalignment between shaft and bearing housing, with extremely high load-carrying capacity.
Examples : Models 22210, 22312.
High Speed (>3000 rpm) : Deep groove ball bearings (higher speed limits).
Temperature : For high temperatures, select heat-resistant materials (e.g., ceramic bearings or special steels).
Pollution : In dusty environments, choose sealed bearings (e.g., those with 2RS suffix for dust covers).
Corrosion : In chemical environments, choose stainless steel bearings (e.g., 440C material).
Grease Lubrication : General purpose, longer maintenance intervals (e.g., SKF LGHP2 grease).
Oil Lubrication : For high-speed or high-temperature applications (requires regular oil replenishment).
Tolerance Fit : Inner ring and shaft should have an interference fit (commonly k6/m6), outer ring and housing should have a clearance fit (H7).
Alignment Check : Measure the coaxiality of the shaft and bearing housing after installation (error Less than or equal to 0.05mm).
Initial Lubrication : Fill 1/3 to 1/2 of the bearing space with lubricant (excess can cause overheating).
Relubrication Cycle : Adjust based on operating time or vibration monitoring (generally every 3 to 6 months).
Overheating (>80 degree ) : Check for insufficient lubrication, overload, or misalignment.
Selection : Deep groove ball bearings (e.g., 6312), suitable for high-speed and light loads.
Selection : Combination of cylindrical roller bearings (NU310) and angular contact ball bearings (7310B) to balance radial and axial forces.
Selection : Spherical roller bearings (22216), resistant to impact and vibration.
Lubrication : Use extreme pressure lithium-based grease (e.g., Mobilith SHC 460).
Safety Redundancy : For heavy loads or frequent start-stop conditions, consider increasing the bearing load rating (e.g., C3 clearance).