Tolerances for Shafts
Important Condition: Shaft and ball bearing must be made of the same material; otherwise the different coefficients of thermal expansion1 must be taken into account.
Shaft Tolerance Selection Guide
| Shaft | Load / speeds | Fit | Tolerance d of the ball bearings | Accuracy of the assembly | Typical applications | the inner ring | ||
|---|---|---|---|---|---|---|---|---|
| 0 / –5 μm | Sorting | |||||||
| 0 / –2.5 | –2.5 / –5 | |||||||
| Tolerance shaft (μm) | ||||||||
| Rotating or fixed (alternating) | Low loads, low to medium speeds, no vibrations | Sliding fit | –5 | –5 | –8 | Normal accuracy without special requirements | Guides | fixed |
| –11 | –8 | –11 | Normal accuracy; the inner ring must be laterally displaceable (expansion) | Brakes, clutches | fixed | |||
| fixed | Medium load, medium speed, high frequency vibrations | Press fit | 0 | 0 | –3 | Precise radial. Radial rigidity | Gyroscopes | fixed |
| rotating | Low loads, medium speed, low frequency vibrations | –6 | –3 | –6 | Normal accuracy | Small motors, potentiometers, servomotors | free | |
| fixed | High loads, high speeds, high frequency vibrations | Press fit | +4 | +4 | +1 | The tight fit must be guaranteed at high speeds. High radial rigidity | Rotors, fans, electric motors | free |
| rotating | Medium to high loads, high speeds, high frequency vibrations | –2 | +1 | –2 | ||||
Note: 0 / –5 μm is the myonic bearing bore d tolerance grade; 0 / –2.5 and –2.5 / –5 are the two sortings within this grade. The three "Tolerance shaft" values in the table are the shaft tolerances (μm) required when mating with the corresponding grade / sorting.
Tolerances for Housing Fits
Important Condition: Housing and ball bearing must be made of the same material; otherwise the different coefficients of thermal expansion1 must be taken into account.
Housing Fit Tolerance Selection Guide
| Outer ring | Load / speeds | Fit | Tolerance D of the ball bearings | Accuracy of the assembly | Typical applications | ||
|---|---|---|---|---|---|---|---|
| 0 / –5 μm | Sorting | ||||||
| 0 / –2.5 | –2.5 / –5 | ||||||
| Tolerance housing (μm) | |||||||
| Rotating or fixed (alternating) | Low loads, low to medium speeds, no vibrations | Sliding fit | +5 | +5 | +2 | Normal accuracy without special requirements. Fans; the outer ring must be laterally displaceable (expansion) | Electric motors, servomotors, potentiometers |
| –1 | +2 | –1 | |||||
| fixed | Medium load, medium speed, high frequency vibrations | Press fit | 0 | 0 | –3 | Precise radial guidance, radial rigidity. The outer ring must be laterally fixed | Synchronous motors, gyro suspensions |
| rotating | Low loads, low to medium speed, low frequency vibrations | –6 | –3 | –6 | Normal accuracy | Guides, tension rollers, pantographs | |
| fixed | High loads, high speeds, high frequency vibrations | Tight fit | –3 | –3 | –6 | A tight fit must be guaranteed at high speeds | Rollers, deflection rollers, planetary gears |
| rotating | Medium to high loads, high speeds, high frequency vibrations | –9 | –6 | –9 | It is not necessary for the outer ring to be held laterally. High rigidity | ||
Note: 0 / –5 μm is the myonic bearing outer diameter D tolerance grade; 0 / –2.5 and –2.5 / –5 are the two sortings within this grade. The three "Tolerance housing" values in the table are the housing tolerances (μm) required when mating with the corresponding grade / sorting.
Technical Notes
1 Coefficient of thermal expansion of ball bearing steel: 11×10–6 ºC–1
For more detailed information on fit tolerances or technical support, please contact our application engineers.