Dimensional and rotational accuracy
The accuracy of NTN miniature and extra small ball bearings complies with JIS standards. Accuracy standards are listed in the Bearings Tolerances. Flange accuracies are listed as follows.
| Accuracy class | Outer diameter dimensional tolerance |
Outer ring surface runout for rear surface SD1 Max. |
Back face axial runout Sea1 Max. |
Width dimension tolerance ΔC1S or ΔC2S Upper Lower |
Width unevenness VC1S or VC2S Max. |
|
|---|---|---|---|---|---|---|
| ISO standard | Class 0 | see table below | - | - | Identical to same bearing's inner ring VBS | Identical to same bearing's inner ring VBS |
| Class 6 | - | - | ||||
| Class 5 | 8 | 11 | 5 | |||
| Class 4 | 4 | 7 | 2.5 | |||
| Class 2 | 1.5 |
3(1) 4 |
1.5 | |||
(1) Nominal outer diameter, 18 mm or less.
|
Flange nominal outer diameter D1 or D2 mm |
Outer diameter dimensional tolerance ΔD1S or ΔD2S um |
||
|---|---|---|---|
| over | incl. | Upper | Lower |
| - | 10 | +220 | -36 |
| 10 | 18 | +270 | -43 |
| 18 | 30 | +330 | -52 |
| 30 | 50 | +390 | -62 |
Radial internal clearance
Radial internal clearance values should be applied as listed in the table regarding the Bearing Internal Clearance and Preload.
However, for NTN miniature and extra small bearings, the radial clearance values for high precision bearings given as below are applied in many cases.
| MIL Standard | Tight | Standard | Loose | Extra Loose | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Code | C2S | CNS | CNM | CNL | C3S | C3M | C3L | |||||||
|
Internal clearance |
Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. |
| 0 | 5 | 3 | 8 | 5 | 10 | 8 | 13 | 10 | 15 | 13 | 20 | 20 | 28 | |
