Bearing Damage Analysis

To learn more about each damage mode contact your local Kaman branch or sales representative.

Foreign Material

Typical causes include improper cleaning methods, poor oil and filtration wear.

Hard particle contamination

Contamination bruising

Fine particle contamination

Internal cage wear from fine particle contamination

Corrosion/Etching

Typical causes include damaged packaging, improper storage and worn or damaged seals.

Roller spaced spalling

Corrosion on the outer ring race

Etching and corrosion

Advanced corrosion and spalling

Inadequate Lubrication

Typical causes include improper greases or oil viscosity, low flow rate and high operation temperatures.

Race deformation from excessive heat generation	Pealing	Scoring damage in roller end	Complete bearing lockup	Rib scoring
Roller scoring

Fatigue Spalling

Typical causes include high load, misalignment and stress concentration.

Fatigue spalling on a cylindrical roller bearing	Point Surface Origin (PSO) spalling	Fatigue spalling on ball bearing inner ring
Geometric Stress Concentration (GSC) spalling

Excessive Preload, Overload and Rollout

Typical causes include excessive load and/or misalignment and improper mounting procedure.

Roller fracture	Peeling	Rollout in bearing outer ring
Outer ring subcase fracture

Misalignment

Typical causes include high load, shaft or housing deflection, inaccurate housing, or shaft machining.

Geometric Stress Concentration (GSC) spalling on bearing outer ring

Irregular roller path caused by deflection

Irregular roller path (180 degrees opposite of above)

Geometric Stress Concentration (GSC) spalling

Handling Damage

Typical causes include improper tool selection (hardened drivers) and poor handling practices.

Outer ring denting	Fractured inner ring rib	Broken rib on outer race
Roller spaced nicking

Cage Damage

Typical causes include improper handling, tools and procedures.

Cage deformation

Roller binding and skewing

Bent bridge

Deep dent on cage

High Spots and Fitting Practices

Typical causes include improper machining, grinding, or repair methods.

Localized spalling

Marks from high spot on the housing

Metal tearing and wear

Pinch point

Improper Fit in Housing or Shafts

Typical causes include wrong size and poor form, shaft or housing stress riser and inaccurate machining.

Loose outer ring fit in a wheel hub

Fracture on inner ring

Metal contaminant

Brinell and Impact Damage

Typical causes include rough handling and shock loads exceeding the material's limits.

Roller impact damage

True metal deformation

Shock loading

True brinell on needle bearing drawn cup race

False Brinelling

Typical causes include excessive vibration during shipment, or when the shaft is stationary.

Extreme vibration

False brinelling on a shaft where a cylindrical bearing was mounted

Wear caused by vibration

False brinell on outer race

Burns from Electric Current

Typical causes include improper electrical grounding of equipment, welding damage, or static discharge.

Electric arc fluting

Fluting caused by electric current

Electric arc pitting

Roller with electrical arc burns

Adhesive Wear

Typical causes include improper oil film, excess cage friction and gross roller sliding

Roller flats and adhesive wear

Spherical roller bearing with adhesive wear

Skidding, raceway surface

Cylindrical roller end with adhesive wear

Needle Bearing Installation Damage

Typical causes include improper tool design, tool positioning, poor roller alignment and excessive force.

Roller lock-up

Bearing stamping lip fracture

WARNING: Never spin a bearing with compressed air. The rollers may be forcefully expelled creating risk of serious bodily harm. Proper maintenance and handling practices are critical. Failure to follow installation instructions and to maintain proper lubrication can result in equipment failure, creating risk of serious bodily harm.

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