Longo
Page 1
SYMPTOM
CAUSE
SOLUTION
Flaking A. On rolling elements
1. Excessive loading 2. Excessive preloading
B. Localized on raceway
3. Overloading due to expansion • Presence of dirt , rust , or scratches
C. Circumferential on raceway • Presence of dirt , rust , or scratches D. Areas facing each other on 1. Misalignment of shaft or the raceway bearing housings 2. Improper installation
1 . Inspect machine design and bearing selection. 2 . Careful installation 3 . Analyze machine design and bearing application • Replacement, and consider use of a better protected bearing • Replacement, and consider use of a better protected bearing • Correct misalignment and install replacement with care
3. Wear E. Off-center, i.e. , • Excessive thrust load circumferential on one side F. Diagonal on the raceway
G. Areas spaced at pitch intervals of the rolling elements
Correct misalignment or improper installation; select more suitable bearing 1. Deflection of shaft • Correct misalignment or improper installation; select 2. Misalignment of inner and more suitable bearing outer races 1. Vibration without rotation 2. Rust
• Suppress vibration; better protection of bearings
1. Overloading
• Misapplication ; Preload
Seizing A. Cracking
properly; check method of lubrication and selection of lubricant
2. Improper lubrication, e.g ., 3. Improper lubricant
B. Visible damage
• Overloading
• Select more suitable bearing
1. Flaking due impact while in operation or during installation 2. Excessive clearance
1 . Careful handling and installation
1. 2 3. 4. 1. 2. 1. 2.
• Consideration of storage, maintenance and corrosion inhibition
Cracking A. Cracking
B. Splitting
2 . Inspect mounting and preloading 3. Excessive interference or 3 ..Check for proper fit and out of roundness concentricity • large shaft radius at • Inspect accuracy of shaft bearing mounting shoulder and bearing housing construction
Rust A. Throughout bearing
B. Localized C. Corrosion on mounting surfaces, i. e., inner ring bore or outer ring outside diameter
Improper storage Left unprotected Poor cleaning Inadequate rust inhibition Improper packaging Sweating hands Loose mounting Inadequate protection
• Improved storage and maintenance practices • Reconsider construction of shafts and bearing housings ; reconsider moisture protection
Wear A. Rapid wear of rolling elements or races B. Retainer wear
1. Presence of dirt in lubricant • 2. Rusting • Improper lubrication, e.g ., • lack of
Inspect lubricants and lubrication Inspect lubricants and lubrication
Electrical erosion file://localhost/C:/Documents%20and%20Settings/Welcome/Desktop/New%20Folder%20(2)/Bearing%20symptoms.mht
7/5/2011 10:45:13 AM
Longo
Page 2 • Crater-like pitting (fluting)
• Electrical sparking
• Ground stray currents; insulate bearing
Roughening A. Roughness
Dirt pressed between rolling elements and raceways
B. Sparkling surfaces C. Striking during handling
• Careless handling
D. Damage during installation • Careless installation
• Improve maintenance practices • Improve maintenance practices • Improve maintenance practices • Improve maintenance practices
Smearing • Scratched surfaces of raceways or rolling elements
1. Improper lubrication 2. Skewing of rolling elements 3. Improper lubricant
• Inspect lubricant and method of lubrication
A. Wear of race mounting surfaces
1. Excessive clearance in mounting 2. Looseness of bearing retainer
• Inspect seating and accuracy of construction of shaft and bearing housings ; reevaluate design
B. Slippage, discoloration
• Abrasion
• Inspect seating and accuracy of construction of shaft and bearing housings ; reevaluate design
Creep
file://localhost/C:/Documents%20and%20Settings/Welcome/Desktop/New%20Folder%20(2)/Bearing%20symptoms.mht
7/5/2011 10:45:13 AM
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