Engineering Reference
Miniature & Instrument Ball Bearings
Tolerances
For more than thirty years, NHBB has been an active member in the American Bearing Manufacturers Association (ABMA) and its associated ball bearing technical committee, the Annular Bearing Engineers’ Committee (ABEC). The ABEC tolerances listed in the attached document are current as of this posting. These tolerances are reviewed regularly and updated as required. The ABMA Standards may be obtained by contacting: ABMA, 2025 M Street, NW, Suite 800, Washington, DC 20036.
Inner Ring*
Characteristic | ABEC 1 | ABEC 3P | ABEC 5P | ABEC 7P | ABEC 9P |
---|---|---|---|---|---|
Bore tolerance limits | +.0000 –.0003 | +.0000 –.0002 | +.0000 –.0002 | +.0000 –.0002 | +.0000 –.0001 |
Bore 2 pt. out of roundness | — | — | .0001 | .0001 | .00005 |
Bore taper | — | — | .0001 | .0001 | .00005 |
Radial runout | .0004 | .0002 (1) | .00015 | .0001 | .00005 |
Width variation | — | — | .0002 | .0001 | .00005 |
Bore runout with face | — | — | .0003 | .0001 | .00005 |
Race runout with face | — | — | .0003 | .0001 | .00005 |
*Measurement in inches.
(1) Add .0001 to the tolerance if bore size is over 10mm (.3937 inch).
Outer Ring*
Characteristic | Configuration | Size Range | ABEC 1 | ABEC 3P | ABEC 5P | ABEC 7P | ABEC 9P |
---|---|---|---|---|---|---|---|
Mean O.D. tolerance limits | All | 0-.7086 inch (0-18 mm) | +.0000 –.0003 | +.0000 –.0003 | +.0000 –.0002 | +.0000 –.0002 | +.0000 –.0001 |
.7086-1.181 inch (over 18-30 mm) | +.0000 –.0004 | +.0000 –.0003 | +.0000 –.0002 | +.0000 –.0002 | +.0000 –.00015 | ||
Maximum O.D. tolerance limits | Open | 0-.7086 inch (0-18 mm) | +.0001 –.0004 | +.0001 –.0004 | +.0000 –.0002 | +.0000 –.0002 | +.0000 –.0001 |
.7086-1.1811 inch (over 18-30 mm) | +.0001 –.0005 | +.0001 –.0004 | +.0000 –.0002 | +.0000 –.0002 | +.0000 –.00015 | ||
Shielded | 0-.7086 inch (0-18 mm) | +.0002 –.0005 | +.0002 –.0005 | +.00004 –.00024 | +.00004 –.00024 | — — | |
.7086-1.1811 inch (over 18-30 mm) | +.0002 –.0006 | +.0002 –.0005 | +.00004 –.00024 | +.00004 –.00024 | |||
O.D. 2 pt. out of roundness | Open | 0-.7086 in. | — | — | .0001 | .0001 | .00005 |
.7086-1.1811 in. | — | — | .0001 | .0001 | .00008 | ||
Shielded | 0-1.1811 in. | — | — | .0002 | .0002 | — | |
O.D. taper | All | 0-.7086 in. | — | — | .0001 | .0001 | .0005 |
.7086-1.1811 in. | — | — | .0001 | .0001 | .0008 | ||
Shielded | 0-1.1811 in. | — | — | .0002 | .0002 | — | |
Radial runout | All | 0-.7086 in. | .0006 | .0004 | .0002 | .00015 | .00005 |
.7086-1.1811 in. | .0006 | .0004 | .0002 | .00015 | .0001 | ||
Width variation | All | 0-1.1811 in. | — | — | .0002 | .0001 | .00005 |
O.D. runout with face | All | 0-1.1811 in. | — | — | .0003 | .00015 | .00005 |
Race runout with face | Plain | 0-.7086 in. | — | — | .0003 | .0002 | .00005 |
.7086-1.1811 in. | — | — | .0003 | .0002 | .0001 | ||
Flanged | 0-1.1811 in. | — | — | .0003 | .0003 | — | |
Flange width tolerance limits | — — | — — | +.0000 –.0020 | +.0000 –.0020 | +.0000 –.0020 | — — | |
Flange diameter tolerance limits | — — | — — | +.0050 –.0020 | +.0000 –.0010 | +.0000 –.0010 | — — |
*Measurement in inches, unless otherwise indicated.
Ring Width*
Characteristic | Configuration | ABEC 1 | ABEC 3P | ABEC 5P | ABEC 7P | ABEC 9P |
---|---|---|---|---|---|---|
Width | Single bearing | +.000 | +.000 | +.000 | +.000 | +.000 |
–.005 | –.005 | –.001 | –.001 | –.001 | ||
Duplex pair | — | — | +.000 | +.000 | +.000 | |
— | — | –.015 | –.015 | –.015 |
*Measurement in inches.
ABEC 5T Tolerances*
Bore diameter | Radial Runout | Mean Diameter Tolerance | ||
---|---|---|---|---|
Over | Incl. | |||
Inner Ring | 0.35433 | 1.18110 | 0.0002 | +.0000 -.0002 |
1.18110 | 1.77165 | 0.0003 | +.0000 -.0003 | |
1.77165 | 2.55906 | 0.0004 | +.0000 -.0004 | |
Outside Diameter | ||||
Outer Ring | 0.55118 | 1.10236 | 0.0002 | +.0000 -.0002 |
1.10236 | 3.14961 | 0.0003 | +.0000 -.0004 |
*Measurement in inches.
ABEC 7T Tolerances*
Bore diameter | Radial Runout | Mean Diameter Tolerance | ||
---|---|---|---|---|
Over | Incl. | |||
Inner Ring | 0.35433 | 0.70866 | 0.0001 | +.0000 -.0002 |
0.70866 | 1.77165 | 0.00015 | +.0000 -.0002 | |
1.77165 | 2.55906 | 0.0002 | +.0000 -.0003 | |
Outside Diameter | ||||
Outer Ring | 0.55118 | 1.10236 | 0.00015 | +.0000 -.0002 |
1.10236 | 1.96850 | 0.0002 | +.0000 -.0004 | |
1.96850 | 2.55906 | 0.0002 | +.0000 -.0003 |
*Measurement in inches.