Indentations from particles

Over-rolled debris leaves a scatter of dents. Urgency

Permanent dents from overload, impact, rough mounting or trapped debris.

What indentations from particles looks like

• Dents of varying sizes and shapes at irregular positions, often with raised rims
• Scratches and gouges from swarf or chips; fine dents all over from fine grit
• Flaking that starts just behind a dent after some running time

Rotec AI schematic illustration. It shows the typical pattern and is not a photograph of a real bearing.

How indentations from particles develops

Hard particles (swarf left after machining, grit from poor sealing, chips from an earlier failure) get squeezed into the contact. Each leaves a dent with a raised edge that overloads the surface locally; spalls often start there.

How fast it progresses: The sooner the debris is stopped, the better: each dent is a stress raiser for life.

Causes of indentations from particles

Mounting, handling & storage

• Dirty working conditions during mounting; chips left in the housing; debris from an earlier failure not cleaned out

Environment & sealing

• Inadequate sealing; contaminated lubricant

How to confirm it is indentations from particles

• Dents random in size and spacing, unlike the even pattern of overload
• Look for particles in the lubricant and housing
• Ask how the bearing was cleaned, stored and mounted

How to fix and prevent indentations from particles

• Work clean; flush and clean housings thoroughly after any failure
• Fit adequate sealing for the environment
• Keep lubricant clean
• Handle bearings gently and never drop them

Easily confused with

• Overload deformation (true brinelling): Overload dents are evenly spaced and uniform; particle dents are scattered.
• Abrasive wear: Abrasive wear is general and scratched; particle damage is discrete dents.

Other dent modes

Questions about indentations from particles