Overload deformation (true brinelling)

Rolling elements pressed permanent dents into the raceway. Urgency

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

What overload deformation (true brinelling) looks like

• Evenly spaced round (balls) or elongated (rollers) dents at the rolling-element spacing
• Sharp edges, smooth bottoms and no wear inside the dent
• Scored or nicked ring faces and bent cages from rough handling or poor tools

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

How overload deformation (true brinelling) develops

If the load on a stationary or slow bearing exceeds the yield limit of the steel locally, the elements press dents that stay forever. Typical causes: driving a ring on through the rolling elements, dropping the bearing, or an impact during transport. Every later pass over a dent kicks the bearing and can start a spall.

How fast it progresses: Permanent from the first moment, but the bearing may run for a while. Expect noise, vibration and eventual spalling.

Causes of overload deformation (true brinelling)

Mounting, handling & storage

• Force applied through the rolling elements (pressing the wrong ring)
• Hammer blows, tilted or crooked mounting, dropped bearings
• Rough transport or handling

Operating conditions

• Shock loads, overloads while stationary, crashes or jams

How to confirm it is overload deformation (true brinelling)

• Dents spaced exactly at element pitch with sharp edges and no wear
• Look for matching marks on the opposite ring
• Review the mounting method and tooling, and any shock events

How to fix and prevent overload deformation (true brinelling)

• Press or heat only the ring being fitted; never push through the rolling elements
• Use proper sleeves and tools, and follow the mounting procedure
• Protect bearings from shock in transport and while idle
• If real shock loads exist (crusher, press), include them in the Load Calculator

Easily confused with

• False brinelling: False brinelling marks are worn flat and reddish; true brinelling dents are crisp with raised edges.
• Indentations from particles: Particle dents are random in size and position; overload dents are regular and evenly spaced.

Worth knowing

Mounting force through the wrong ring

Pushing a bearing on by its loose ring sends the force through the rolling elements and brinells the raceways. Always apply the mounting force to the ring with the tight fit. Brinelling from impact during shipping, dropping, or hammering shows as evenly spaced dents at the rolling element pitch.

Other dent modes

Questions about overload deformation (true brinelling)