Bearing Symptoms.pdf

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

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7/5/2011 10:45:13 AM

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