Bearing Damage Analysis

Bearing Damage Analysis	Possible reasons	Solutions
Burns	• Clearance too small (including clearance for the deforming part) • Insufficient lubrication or inappropriate lubricant • Load too heavy (pre-load too heavy) • Skewing rollers	• Choose proper clearance(increasing clearance) • Check lubricant type and ensuring amount • Check application conditions • Avoid position error • Check surrounding design(including lead to bearing) • Improve the mounting method
Cage Damage	• Torque load too big • High speed rotation or speed changing too frequently • Poor lubrication • Intrusion of foreign matter • Vibration too big • Bad mounting(mounting in leaning conditions) • Abnormal increase in temperature(resin cage)	• Check application conditions • Check lubrication conditions • Re-consider choice of cage • Pay attention to applications • Consider rigidity of shaft and bearing box
Corrosion	• Insufficient amount of interference • Small bearing oscillating angle • Insufficient lubrication (or without lubrication) • Not stable load • Vibration in the transit	• Check the interference and the conditions of the lubricant • Separable packing of inner rings and outer rings when in transit, pre-load shall prevail if the bearings are un-separable • Re-consider choice of lubricant • Re-consider choice of bearings
Cracks	•Shock load too heavy •Interference too big •Big peeling off and frictional cracks •Poor precision of the mounting side(corner circle too big) •Frictional cracks •Mal-applications(using copper hammer, intrusion of big foreign matter)	•Check the application conditions •Set proper interference and check material quality •Improve mounting and application methods •Prevent frictional cracks(check lubricants)
Dent & Bruise - Intrusion of solid foreign matter or pits in the surface caused by shock or scratches from mounting	• Solid foreign matter intrusion • Peels inside the bearing • Shock from mal-mounting peeling off • Mounting in leaning conditions	• Improve mounting and application methods • Prevent foreign matters from intruding • Check other parts if caused by metal pieces
Electric Corrosion - Red corroded particles in the fit surface	• Insufficient amount of interference • Small bearing oscillating angle • Insufficient lubrication(or without lubrication) • Not stable load • Vibration in the transit	• Check the interference and the conditions of the lubricant • Separable packing of inner rings and outer rings when in transit, pre-load shall prevail if the bearings are un-separable • Re-consider choice of lubricant • Re-consider choice of bearings
Peeling off - Peeling off and deformation of the rotational surface	• Load too heavy or improper applications • Mal-mounting • Poor precision of the shaft or bearing box • Clearance too small • Intrusion of foreign matters • Rusting • Hardness decrease caused by abnormal high temperature	• Re-consider the application conditions • Consider other bearing specifications • Check the processing precision of the shaft and bearing box • Consider the surrounding design • Check the mounting method • Check the lubricant and lubrication method
Rust	• Poor maintenance • Improper packaging • Insufficient rust-preventive • Intrusion of moist acid liquid • Taking the bearing by hands	• Maintenance to prevent rusting • Reinforcing the sealing function • Check the lubricant regularly • Pay attention to bearing applications
Scratches - Rough surface with small deposit, scratches between the flanges of rings and the side surfaces of the rollers	• Re-consider lubricant and lubricating method • Check application method • Set proper pre-load • Reinforce the sealing function • Use bearings correctly	• Re-consider lubricant and lubricating method • Check application method • Set proper pre-load • Reinforce the sealing function • Use bearings correctly
Wear - Surface worn, leading to dimension changes with scratches and traces	• Foreign matters in the lubricant • Poor lubrication • Rollers skewing	• Check lubricant and lubrication method • Reinforce sealing function • Prevent positioning error
Fretting surfaces wear producing red rust colored particles that form hollows. On the raceway surface, dents called false brinelling are formed at spacing equal to distances corresponding to the rolling elements.	• If a vibrating load works on contacting elements resulting in small amplitude oscillation, lubricant is driven out from contact, and parts are worn remarkably. • Oscillation angle of the bearing is small. • Poor lubrication (no lubrication) • Fluctuating load • Vibration during transportation • Vibration, shaft deflection, installation error, loose fit.	• Inner ring and outer ring should be packaged separately for transportation. If not separable, bearings should be preloaded. • Use oil or high consistency grease when bearings are used for oscillation motion. • Change lubricant • Fix shaft and housing • Improve fit