Table 4. Keyway Dimensions and Tolerances for Metric Square and Rectangular Parallel Keys ANSI/ASME B18.25.3M-2003 (R2008) Width Tolerances and Deviations Greater than Basic Size Table 4. (Continued) Keyway Dimensions and Tolerances for Metric Square and Rectangular Parallel Keys ANSI/ASME B18.25.3M-2003 (2008)
Keyway Width
Keyway Depth
Tolerance and Resulting Fit a
Shaft, t 1
Hub, t 2
Radius, r
Normal Fit
Close Fit
Free Fit
Shaft
Hub
Shaft and Hub
Shaft
Hub
Key Size, b × h
Nom- inal
Nom- inal
Toler ance
Toler ance Fit
Nomi nal
Toler ance Max.
Toler ance Fit
Toler ance +0.055 − 0.015
Toler ance +0.135 +0.075
Toler ance +0.185 +0.125
Fit
Fit
Fit
4 6 4 7 5
3.3 4.3 3.3 4.4 3.3 4.9 3.8 5.4 3.8 5.4 4.3 6.4 4.4 7.4 4.9
16 × 7 16 16 × 10 16 18 × 7 18 18 × 11 18 20 × 8 20 20 × 12 10 22 × 9 10 22 × 14 22 25 × 9 25 25 × 14 25 28 × 10 28 28 × 16 28 32 × 11 32 32 × 18 32 36 × 12 36 56 × 32 56 63 × 32 63 70 × 36 70 80 × 40 80 100 × 50 100
+0.080 − 0.030
0.080L 0.045T
+0.095 +0.055
0.095L 0.020T
0.055L 0.060T
0.135L 0T
0.185L 0.050L
7.5 5.5 5.5 9 9 6
0.6
+0.085 − 0.035
0.085L 0.050T
+0.110 +0.060
0.110L 0 025T
+0.050 − 0.010
0.050L 0.075T
+0.135 +0.085
0.150L 0T
+0.200 +0.110
0.200L 0.065L
+0.2 0
+0.2 0
10 7 b 11 b
7.5 b
+0.110 − 0.050
0.110L 0.075T
+0.170 +0.090
0.170L 0.035T
+0.090 − 0.020
0.090L 0.105T
+0.200 +0.125
0.225L 0T
+0.300 +0.225
0.300L 0.100L
1.6
20
12.4 14.4 15.4 17.4
22 25
2.5
90 × 45 90 +0.130 0.130L +0.180 0.180L +0.095 0.095L +0.225 0.225L +0.340 0.340L 28 − 0.050 0.085T +0.090 0.045T − 0.015 0.120T +0.135 0T +0.255 0.120L 31
19.5 a In columns labeled “Fit,” L indicates the maximum clearance between the key and keyway; the T indicates the maximum interference between the key and keyway. b This value differs from that given in ANSI/ASME B18.25.3M , which is believed to be inaccurate.
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