Bearing Damage: When a Dent Is More Than Just a Dent

When machinery fails, pinpointing the exact failure mechanism is essential for reliable repairs and future prevention.

The photo shows blunt‑force impacts on the bearing ring and raceways. Hammer marks on the ring’s face—classified as ISO 15243:2004 “Plastic Deformation / Indentation by Handling”—are usually easy to remove by simply extracting the hammer. However, the triangular impressions on the raceway indicate a different failure mode, though the underlying cause remains impact.

At 3× to 5× magnification, the manufacturer’s grinding and honing marks are clearly visible both inside and outside the dented area. Permanent, plastic deformation leaves a triangular mark, but the core impact damage—often referred to as “true brinelling”—is evident (ISO 15243:2004, “Plastic Deformation / Overload”).

If you notice wear, rust, and an absence of honing marks at the bottom of the “dents,” the damage is likely false brinelling (ISO 15243:2004, “Corrosion / Frictional Corrosion / False Brinelling”).

In stationary machines subjected to vibration, rollers can break through the oil film and create wear indentations at the roller spacing. These “dents” are not the result of impact; instead, they stem from external vibration and must be traced and eliminated.

Understanding the origins of bearing damage enables the design of effective corrective actions to prevent recurrence. For deeper insight, join our instructor‑led WE204 course, offered worldwide multiple times a year by the SKF Reliability Maintenance Institute.