Machinery's Handbook, 31st Edition
2468
Ball and Roller Bearings Table 21. AFBMA and American National Standard Tolerance Limits for Shaft Diameters—Needle Roller Bearing Inner Rings, Inch Type NIR (Used with Bearing Type NIA) ANSI/ABMA 18.2-1982 (R1999)
Shaft Diameter a
Shaft Rotating Relative to Load, Outer Ring Stationary Relative to Load Allowable Deviation from d
Shaft Stationary Relative to Load, Outer Ring Rotating Relative to LoadAllowable Deviation from d
Basic Bore, d
Inch
ANSI m5, Inch
ANSI g6, Inch
Over
Incl.
High
Low
High
Low
0.2362 0.3937 0.3937 0.7087 0.7087 1.1811 1.1811 1.9685 1.9685 3.1496 3.1496 4.7244 4.7244 7.0866 7.0866 9.8425
+0.0005 +0.0006 +0.0007 +0.0008 +0.0009 +0.0011 +0.0013 +0.0015
+0.0002 +0.0003 +0.0003 +0.0004 +0.0004 +0.0005 +0.0006 +0.0007
− 0.0002 − 0.0002 − 0.0003 − 0.0004 − 0.0004 − 0.0005 − 0.0006 − 0.0006
− 0.0006 − 0.0007 − 0.0008 − 0.0010 − 0.0011 − 0.0013 − 0.0015 − 0.0017
a See text for additional requirements. For inner ring tolerance limits, see Table 13.
Most needle roller bearings do not use inner rings, but operate directly on the surfaces of shafts. When shafts are used as inner raceways, they should be made of bearing quality steel hardened to 58 RC (Rockwell C scale) minimum. Table 15 and Table 19 show the shaft raceway tolerance limits and Table 21 shows the shaft seat tolerance limits when inner rings are used. However, whether the shaft surfaces are used as inner raceways or as seats for inner rings, the mean outside diameter of the shaft surface in each of several radial planes should be determined. The difference between these mean diameters should not exceed 0.0003 inch (0.008 mm) or one-half the diameter tolerance limit, if smaller. The radial deviation from circular form should not exceed 0.0001 inch (0.0025 mm), for diameters up to and including 1 in. (25.4 mm). Above one inch the allowable deviation is 0.0001 times the shaft diameter. The surface finish should not exceed 16 micro-inches (0.4 micrometer) arithmetical average. The housing bore and shaft diameter tolerance limits depend upon whether the load rotates relative to the shaft or the housing. Needle Roller Bearing With Cage, Machined Ring, Without Inner Ring: The following cov- ers needle roller bearings Type NIA and inner rings Type NIR. The shape of the housing bores should be such that when the mean bore diameter of a housing is measured in each of several radial planes, the maximum difference between these mean diameters does not exceed 0.0005 inch (0.013 mm) or one-half the housing bore tolerance limit, if smaller. Also, the radial deviation from circular form should not exceed 0.00025 inch (0.006 mm). The housing bore surface finish should not exceed 125 micro-inches (3.2 micrometers) arithmetical average. Table 21 shows the housing bore tolerance limits. When shafts are used as inner raceways their requirements are the same as those given above for Needle Roller Bearings, Drawn Cup. Table 20 shows the shaft raceway toler- ance limits and Table 21 shows the shaft seat tolerance limits when inner rings are used. Needle Roller and Cage Assemblies, Types NIM and NM: For information concern- ing boundary dimensions, tolerance limits, and fitting and mounting practice, refer - ence should be made to ANSI/ABMA 18.1-1982 (R1999) and ANSI/ABMA 18.2-1982 (R1999).
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