Cage damage

The part that gets looked at last. Urgency

Not separate ISO modes, but the overheating, seizure, cage and alignment problems that surround them.

What cage damage looks like

• Worn pockets or bars, cracks, or a broken cage
• Rolling elements loose or bunched together; brass or steel dust in the grease
• A flattened or bent cage from an impact during mounting

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

How cage damage develops

The cage keeps elements apart and guides them. Vibration, misalignment, speed above the bearing's limit, sudden accelerations, skidding or poor lubrication make the elements push on the pockets until the cage wears or fractures. A failed cage quickly destroys everything else.

How fast it progresses: Escalates fast once a bar breaks: pieces jam the rolling elements.

Causes of cage damage

Operating conditions

• Vibration, shock, over-speed, rapid acceleration and deceleration

Lubrication

• Starved pockets

Design & seats

• Misalignment

Mounting, handling & storage

• The cage was struck during mounting

How to confirm it is cage damage

• Check pocket wear and bar thickness
• Check running speed against the bearing's limiting speed
• Look for what loaded the cage: misalignment, vibration or skid

How to fix and prevent cage damage

• Keep speed comfortably under the limiting speed
• Correct misalignment, or use a self-aligning type if it is unavoidable
• Right lubrication for the pockets
• For heavy vibration consider a machined brass or reinforced cage

Easily confused with

• Seizure (end-stage failure): Seizure destroys the cage too; check whether the cage failed first or last.

Catching cage damage early

Cage problems show up at FTF (fundamental train frequency, always below 1× shaft speed, typically 0.35–0.45×), often as erratic, non-periodic vibration rather than a clean tone, which makes it one of the harder faults to pin down. A sub-1× peak is a strong hint the cage, not a race, is the issue.

Other related modes

Questions about cage damage