ABIS Miniature and Precision Ball Bearings
Importance of Correct Fitting of Bearings
With bores of 0.6 to 90mm and precision grades to ABEC 7
General Information
Importance of correct fitting of bearings
A bearing can only perform to its full capacity when it is correctly fitted on the shaft and in the housing. Insufficient interference on fitting surfaces could cause bearing rings to creep in a circumferential direction. Once this happens, considerable wear occurs on the fitting surface and both shaft and housing can be damaged. Furthermore, abrasive particles may enter the bearing causing vibration, excessive heat and damage to raceways. It is therefore necessary to provide bearing rings under rotating load with an adequate interference fit to prevent creep. When using thin-type bearings under low load, the bearings should be fastened by a nut. Statically loaded bearings generally do not need to be fitted with an interference fit. Only when subject to a high degree of vibration do both inner and outer rings require fitting with an interference fit.
| Fitting of Bearing and Shaft | ||||
Condition (Steel Shaft) | Shaft Bore Diameter | Shaft Tolerance Class | ||
| Thin-Type | Others | |||
Inner ring rotating | Light load ≤ 0.06C or fluctuating load | 10 ≤ d ≤ 18 | h5 h5 h5 | js5 js5 js5 |
| Standard load = 0.06 – 0.11C | 10 ≤ d ≤ 18 18 ≤ d ≤ 30 30 ≤ d ≤ 50 | js5 js5 js5 | j5 k5 k5 | |
| Outer ring rotating load | Necessary for inner ring turning easily around shaft | All bore diameters | g6 | g6 |
| Unnecessary for inner ring turning easily around shaft | All bore diameters | h6 | h6 | |
| Fitting of Bearing and Housing | ||||
| Condition (One-Piece Housing) | Axial Directional Movement of Outer Ring | Tolerance Class of Housing Seats | ||
| Thin-Type | Others | |||
| Inner ring rotating load | Varying loads | Easy to move | H7 | H7 |
| Light or standard loads | Easy to move | H8 | H8 | |
| High temperature of inner ring and shaft | Easy to move | G7 | G7 | |
| Light or standard load Precision rotation | As a rule, impossible to move | K6 | K6 | |
| Possible to move | JS6 | J6 | ||
| Quiet operations | Easy to move | H6 | H6 | |
Indeterminate load | Light or standard load | In general, possible to move | JS7 | J7 |
| Standard or heavy load | As a rule, impossible to move | K7 | K7 | |
| Large shock load | Impossible to move | M7 | M7 | |
| Light or fluctuating load | Impossible to move | M7 | M7 | |
| Outer ring rotating load | Standard or heavy load | Impossible to move | N7 | N7 |
| Thin-type housing seats heavy or large shock load | Impossible to move | P7 | P7 | |
| Characteristics of Load and Fitting | |||
| Â Rotating Ring | Load | Load Condition | Fitting |
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Inner ring rotating loadOuter ring static load | Interference fit for inner ringClearance fit for outer ring |
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Outer ring rotating loadInner ring static load | Clearance fit for inner ringInterference fit for outer ring |
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| In case of fluctuating load direction or unbalanced load | Rotating or static | Indeterminate load direction | Interference fit for inner and outer ring |
