Machinery's Handbook, 31st Edition
2550 Metric Keys and Keyways Material Requirements.— Same as for ANSI/ASME B18.25.2M-1996 (Withdrawn). See page 2539. Advantages of Woodruff Keys.— In the Woodruff key system, half-circular disks of steel are used as keys, the half-circular side of the key being inserted into the keyseat. Part of the key projects and enters into a keyway in the part to be keyed to the shaft in the ordinary way. The advantage of this type of key is that the keyway is easily milled by simply sinking a milling cutter, of the same diameter as the diameter of the stock from which the keys are made, into the shaft. The keys are also very cheaply made, as they are simply cut off from round bar stock and milled apart in the center. Examples of Woodruff keyseat cutters are shown on page 895. Table 6. Keyway Dimensions for Metric Woodruff Keys ANSI/ASME B18.25.2M-1996 (Withdrawn) A
b t 2
Hub
t 1
h 1
z
d + t 2
d – t 1
Key Shaft
d
s
Detail z
Section A-A
A
r
Width
Depth
Tolerance b
Shaft, t 1
Hub, t 2
Radius, R
Normal Fit
Close Fit
Free Fit
Key Size a b × h l × D
Basic Size
Shaft N9
Hub S9
Shaft & Hub P9
Shaft H9
Hub D10
Basic Size
Basic Size
Max. Min.
1
1.0 2.0 1.8 2.9 2.7 3.8 5.3 5.0 6.0 4.5 5.5 7.0 6.5 7.5 8.0
0.6 0.8 1.0 1.0 1.2 1.4 1.4 1.8 1.8 2.3 2.3 2.3 2.8 2.8 3.3 3.3
l × l.4 × 4
1.5 × 2.6 × 7 1.5
+0.1 0
2 2
2 × 2.6 × 7 2 × 3.7 × 10
+0.0125 − 0.0125
+0.025 0
+0.60 +0.20
− 0.004 − 0.029
− 0.006 − 0.031
0.16 0.08
2.5 × 3.7 × 10 2.5
3 3 4 4 5 5 5 6
3 × 5 × 13 3 × 6.5 × 16 4 × 6.5 × 16 4 × 7.5 × 19 5 × 6.5 × 16 5 × 7.5 × 19 5 × 9 × 22 6 × 9 × 22 6 × 10 × 25 8 × 11 × 28
+0.1 0
+0.2 0
+0.078 +0.030
+0.015 − 0.015
+0.030 0
− 0.030 0
− 0.012 − 0.042
0.25 0.16
+0.3 0
+0.2 0
8 0
+0.018 − 0.018
+0.036 0
+0.098 +0.040
− 0.015 − 0.051
0.4 0.25
− 0.036
10.0
10 × 13 × 32 10
a The nominal key diameter is the minimum keyway diameter. b Some of the tolerances are expressed as plus-plus or minus-minus. See Tolerances on page 2549 for more informations.
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