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Internal clearance is determined so that appropriate clearance will remain after the bearing is mounted to the shaft with an interference fit. Typical clearance groups for the deep groove ball bearings are C2, CN, C3, C4, and C5. CN(Normal)
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●Data of standard radial clearances for bearings under no load
Tolerance in μm.
| Bore | C2 | Normal | C3 | C4 | C5 | ||||||||
| Over | Including | ||||||||||||
| mm | Inch | mm | Inch | min. | max. | min. | max. | min. | max. | min. | max. | min. | max. |
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2.5
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0.0984
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10
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0.3937
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0
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7
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2
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13
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8
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23
|
14
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29
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20
|
37
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● The radial clearances of bearings with electric motor quality
Tolerance in μm.
| Bore | CM | ||||
| Over | Including | Min. | Max. | ||
| mm | Inch | mm | Inch | μm | μm |
| 10 | 0.3937 | 18 | 0.7087 | 4 | 11 |
| 18 | 0.7087 | 24 | 0.9449 | 5 | 12 |
| 24 | 0.9449 | 30 | 1.1811 | 5 | 12 |
| 30 | 1.1811 | 40 | 1.5748 | 9 | 17 |
| 40 | 1.5748 | 50 | 1.9685 | 9 | 17 |
| 50 | 1.9685 | 65 | 2.5591 | 12 | 22 |
● Data of the mini-deep groove ball bearing under no load
Tolerance in μm.
| Clearance Code | MC1 | MC2 | MC3 | MC4 | MC5 | MC6 | ||||||
| Clearance | min | max | min | max | min | max | min | max | min | max | min | max |
| 0 | 5 | 3 | 8 | 5 | 10 | 8 | 13 | 14 | 21 | 21 | 29 | |
● Clearance correction under loads
When the internal clearance of a bearing is measured, a slight measurement load is applied to the raceway so the internal clearance may be measured accurately. However, at this time, a slight amount of elastic deformation of the bearing occurs under the measurement load, and the clearance measurement value (measured clearance) is slightly larger than the true clearance. This discrepancy due to the elastic deformation must be compensated for.
● Clearance correction for standard radial clearance
Units: μm.
| Nominal Bore Dia d (mm) | Measuring Load | Radial Clearance Correction Amount | ||||||
| over | incl | (N) | {kgf} | C2 | CN | C3 | C4 | C5 |
| 10(incl) | 18 | 24.5 | {2.5} | 3 to 4 | 4 | 4 | 4 | 4 |
| 18 | 50 | 49 | {5} | 4 to 5 | 5 | 6 | 6 | 6 |
| 50 | 280 | 147 | {15} | 6 to 8 | 8 | 9 | 9 | 9 |
● Clearance correction for miniature radial clearance
Units: μm.
| Clearance Symbol | MC1 | MC2 | MC3 | MC4 | MC5 | MC6 |
| Clearance Correction Value | 1 | 1 | 1 | 1 | 2 | 2 |
● The measuring loads are as follows:
Units: mm
| Design | Miniature Ball Bearigs | Extra Miniature Ball Bearigs | Measuring loads | ||
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Metric size bearings |
Outside diameter Bore diameter |
D ≥ 9 d< 10 |
Outside diameter | D < 9 | 2.5N { 0.25kgf } |
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Inch size |
Outside diameter Bore diameter |
D ≥ 9.525 d < 10 |
Outside diameter | D < 9.525 | 4.4N { 0.45kgf } |
