Precison Ball Bearing - Some bearing damages and protection

If the equipment assembled with ball bearings did not work right, or if the ball bearings themselves were damaged, root causes of the failure can be determined by looking at the condition of the bearings. Higher performance and longer life can be achieved by preventing the damage. Some common failure modes and preventive methods against them are described below.

Abnormal Conditions

Failure modes		Major causes	Solutions
Rotation issue	Unable to rotate or hard to rotate	Grease (amount, type)	reviewing grease, improving (increasing drive force) drive system (motor)
		Contact of parts	reviewing process and design
		Grease degradation (wear particles)	reviewing lubricants, increasing grease fill amount, reviewing grease type
		Flaking (flaking caused by metal fatigue)	reviewing load and rotation conditions, selecting larger size bearing
Noise	Continuous sounds	Resonance of components	reviewing dimensions (thickness) and materials of components
		Brinells on the raceways	reviewing handling and assembly of the bearings, Reviewing transportation process of the equipment (excessive load and shock loads)
		Contamination dents on the raceways	changing designs to sealed type, reviewing working environment
	Intermittent sounds	Insufficient preload	reviewing preload amount from load and rotation conditions
		Contamination dents	changing designs to sealed type, reviewing working environment
		Dents on balls	reviewing process and working environment (contamination, excessive load)
Large vibration		Large internal clearance	decreasing internal clearance
		Improper preload	reviewing preload amount from load and rotation conditions
		Misalignment	reviewing process, dimensional tolerance, cleanliness of the components
		Deformation of the raceways	reviewing precision (roundness) of shafts or housings, reviewing glue and glue process
Temperature increase		Improper grease type and amount	reviewing grease
Temperature increase		Excessive load	reviewing load resistance capability and fits
Grease leak		Improper grease type and amount	reviewing grease
Grease leak		Improper selection of shield and seal	reviewing seal and shield
Damage of plastics (Cracking)		Chemical attack	reviewing lubricants, reducing stress, changing the plastic material
		Excessive interference	reviewing fits
		Weld line	reviewing molding conditions and gate positions

Damages

Damage conditions	Causes	Solutions
Flaking (flaking by metal fatigue)
	Excessive load	reviewing bearing size and load conditions
	Improper assembly	reviewing assembling precision, dimensions of shafts and housings
	Dysfunctional lubricants	reviewing lubricant type and amount
Dents (brinelling)
	Excessive load applied during assembly	Careful handling
	Shock loads applied during handling	Careful handling
Rough surface
	Contamination	reviewing process and working environment
	Dysfunctional lubricants	reviewing lubricant type and amount
Creeping
Creeping	Insufficient interference	reviewing the fit and interference
Electric corrosion
Electric corrosion	Melting caused by electricity conducted inside the ball bearings	setting up insulation and grounding wire