Excessive bearing temperature is a common yet critical issue, often signaling impending bearing failure or underlying problems. Causes can be categorized as follows:
1. Lubrication Issues (Most Frequent Cause)
Insufficient Lubrication:
Grease desiccation or leakage due to prolonged operation without replenishment or seal failure
Underfilling during initial filling/maintenance
Incorrect grease selection:
Viscosity mismatch (too thin → centrifugal loss; too thick → poor flow)
Wrong base oil type or inadequate additives (EP, antioxidant)
Grease degradation from heat, oxidation, or shear
Over-Lubrication:
Overfilled cavity (>30%) → churning losses and friction heat
Grease types prone to thermal buildup under high shear
2. Installation & Misalignment
Improper Installation:
Impact damage during fitting (raceway/roller deformation)
Excessive interference fit → negative clearance → preload friction
Loose fit → fretting corrosion and particulate generation
Misalignment:
Shaft/motor end cover misalignment (angular/parallel deviation)
Baseplate distortion or bent shaft
Consequence: Unplanned radial/axial loads → stress concentration → friction
3. Overload & Abnormal Loads
Mechanical overload beyond design (pumps/fans/conveyors)
Excessive belt/chain tension → radial overloading
Abnormal axial thrust (e.g., unbalanced impellers) exceeding bearing capacity
Mechanical binding (rotor-stator rub, seized load)