How to Identify Tapered Roller Bearing Damage
Skill Level: Easy | Special Tools: None
Recognizing causes and types of bearing damage can help you prevent further bearing damage resulting in improved bearing life and performance.
Geometric stress concentration (GSC):
Misalignment, system deflections and heavy loading.
Point surface origin (PSO):
Debris and raised metal exceeding the lubricant film thickness.
Oxides or other hard inclusions in bearing steel.
Bearing cone (inner race) large rib face deformation:
Metal flow from excessive heat generation.
Total bearing lock-up:
Rollers skew and slide sideways.
Roller spaced nicking:
Raised metal on races from contact with roller edges.
Roller nicking and denting:
Rough handling or installation damage.
Bearing cup (outer race)-face denting:
Indentations from hardened driver.
Improperly installed or dropped bearing.
Rollers binding and skewing:
Cage ring compressed or interfered with during installation or service.
Excessive End-Play Damage
Cage pocket wear:
Heavy contact between rollers and cage pocket surfaces caused by bearing operating
Uneven localized wear resulting from excessive end-play.
Excessive Preload or Overload Damage
Bearing cone (inner race) bore polishing:
Contact wear and creeping on shaft caused by lack of lubrication and cone bore
contraction from excessively tight setting (preload).
* Damage caused by excessive preload can appear similar to damage caused by
Full race width fatigue spalling:
Caused by heavy loads creating a thin lubricant film and elevated temperatures.
Roller end scoring:
Metal-to-metal contact from breakdown of lubricant film.
Bearing cone (inner race) large rib face scoring:
‘Welding’ and heat damage from metal-to-metal contact.
Improper Fit Damage
Bearing cone (inner race) bore damage:
Fractured cone due to out-of-round or oversized shaft.
Bearing cup (outer race) spinning:
Loose cup fit in a rotating wheel hub.
Foreign Material Damage
Fine abrasive particle contamination.
Debris from other fatigued parts, inadequate sealing or poor maintenance.
Large particle contamination embedding into soft cage material.
Due to thin lubricant film from high loads and low RPM or elevated temperatures.
Wear caused by vibration or relative axial movement between rollers and races.
Electric Current Damage
Electric arc pitting:
Burns created by improper electric grounding while bearing is stationary.
Series of axial burns caused by electric current passing through the bearing while rotating.
Corrosion/ Etching Damage
Surface stain with no significant corrosion from moisture.
Rusting with pitting and corrosion from moisture.
Roller spaced spalling from bearings operating after etching damage.
Bearing damage from shock or impact.
Irregular roller path from deflection, inaccurate machining or wear of bearing seats.
High Spots In Cup Seats
Localized spalling on the bearing cup (outer race) from stress riser created by split
housing pinch point.
TechTips is not intended to substitute for the specific recommendations of your equipment suppliers. Every reasonable effort has been made to ensure the accuracy of the information contained in this writing, but no liability is accepted for errors, omissions or for any other reason.