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*

CharacteristicConfigurationSize RangeABEC 1ABEC 3PABEC 5PABEC 7PABEC 9P
Mean O.D. tolerance limitsAll0-.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 Open0-.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
Shielded0-.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 roundnessOpen0-.7086 in..0001.0001.00005
.7086-1.1811 in..0001.0001 .00008
Shielded0-1.1811 in..0002.0002
O.D. taperAll0-.7086 in. .0001 .0001 .0005
.7086-1.1811 in. .0001 .0001.0008
Shielded0-1.1811 in..0002 .0002 
Radial runoutAll0-.7086 in. .0006 .0004 .0002 .00015 .00005
.7086-1.1811 in. .0006 .0004 .0002 .00015 .0001
Width variationAll0-1.1811 in. .0002 .0001.00005
O.D. runout with faceAll0-1.1811 in. .0003 .00015.00005
Race runout with facePlain0-.7086 in..0003.0002.00005
.7086-1.1811 in. .0003.0002.0001
Flanged0-1.1811 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*

CharacteristicConfigurationABEC 1ABEC 3PABEC 5PABEC 7PABEC 9P
WidthSingle 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 diameterRadial RunoutMean Diameter Tolerance
OverIncl.
Inner Ring0.354331.181100.0002+.0000
-.0002
1.181101.771650.0003+.0000
-.0003
1.771652.559060.0004+.0000
-.0004
Outside Diameter
Outer Ring0.551181.102360.0002+.0000
-.0002
1.102363.149610.0003+.0000
-.0004

*Measurement in inches.


ABEC 7T Tolerances*


Bore diameterRadial RunoutMean Diameter Tolerance
OverIncl.
Inner Ring0.354330.70866 0.0001 +.0000
-.0002
0.708661.771650.00015 +.0000
-.0002
1.771652.55906 0.0002+.0000
-.0003
     Outside Diameter
Outer Ring0.55118 1.102360.00015+.0000
-.0002
1.102361.968500.0002+.0000
-.0004
1.968502.559060.0002+.0000
-.0003

*Measurement in inches.