| Sound |
Features |
Causes |
| Hiss |
Small bearings |
Raceway, ball or roller surfaces are rough. |
| Buzz to Roar |
Loudness and pitch change with speed. |
Resonation
Poor fit (Poor shaft shape)
Bearing rings deformed.
Vibration of raceways, balls, or rollers
(For large bearings, if this sound is minor, then this is considered
normal).
Brinelling |
| Crunch |
Felt when the bearing is rotated by hand. |
Scoring of raceway surface (regular).
Scoring of balls or rollers (irregular).
Dust/Contamination
Deformed bearing ring (partial interference clearance). |
| Hum |
Disappears when power supply is switched off. |
Electromagnetic sound of motor. |
| Chatter |
Noticeable at low speeds.
Continuous at high speeds. |
Bumping in cage pockets (insufficient lubricant) --eliminated
by clearance reduction or pre-loading.
Rollers bumping into each other on full-roller bearing. |
| Clang/Clatter |
Metallic, loud bumping sound.
Thin section large bearing (TTB) at low speeds. |
Bearing ring deformed.
Grating of key. |
| Screech/Howl |
Occurs mainly on cylindrical roller bearings.
Sound changes with speed.
Loud metallic sound that disappears temporarily
when grease is added. |
Large radial clearance.
Poor lubrication/grease consistancy. |
| Squeak |
Metal-to-metal spalling sound.
High pitch |
Spalling of roller and rib of roller bearing.
Small clearance
Poor lubrication |
| Squeal |
Generated irregularly due to grating. |
Slip on fitting surfaces.
Grating on mounting seat, of key, etc. |
| Faint tinkle |
Irregular (not changing with speed).
Primarily on small bearings. |
Dust in bearing. |
| Rustle |
Sound quality remains the same even if speed changes (Dirt).
Sound quality changes with speed (Scoring). |
Dirt
Raceway, ball, or roller surfaces are rough. |
| Rustle |
Generated intermittently at regular intervals. |
Chafing at the labyrinth.
Contact of cage and seal. |
| Rustle patter |
Regular and continuous at high speed. |
Generated by retainer.
Normal if sound is clear.
Grease is inadequate if sound is generated at low temperatures
(Use soft grease).
Wear of cage pockets.
Insufficient lubricant.
Low bearing load. |
| Growl |
Continuous at high speeds. |
Scoring on raceway, balls, or rollers. |
| Quiet Fizzing/Popping |
Generated irregularly on small bearings. |
Bursting sound of bubbles in grease. |
| Large Sound Pressure |
Large Sound Pressure |
Rough raceway, roller, or ball surfaces.
Raceway, rollers, or balls are deformed by wear.
Large clearance due to wear. |
