Machinery's Handbook, 31st Edition
2548 Metric Keys and Keyways Tolerances.— Many of the tolerances shown in Table 3 and Table 4 are from ANSI/ASME B4.2 (ISO 286-1 and ISO 286-2). As a result, in addition to plus-minus tolerances which are common in the United States, some are expressed as plus-plus deviations from the basic size. Designation.— Keys conforming to this standard shall be designed by the following data, preferably in the sequence shown: a) ASME document number; b) product name; c) nominal size, width ( b ) × height ( h ) × length; d) style; and e) hardness (if other than non-hardened). Optionally, a part identification number (PIN) per ANSI/ASME B18.24 may be used. Material Requirements.— Same as for ANSI/ASME B18.25.1M-1996 (Withdrawn). See page 2539. Metric Keyway Sizes According to Shaft Diameter Based on BS 4235:Part 1:1972 (1986) Nomimal Shaft Diameter, d Key Size, b × h Nominal Keyway Width, b Nomimal Shaft Diameter, d Key Size, b × h Nominal Keyway Width, b Over Up to and Incl. Over Up to and Incl.
Keyways for Square Parallel Keys
(Cont’d) Keyways for Rectangular Parallel Keys
6 8
8
2 3 4 5 6
85 95
95 110
25 28 32 36 40 45 50 56 63 70 80 90
2 × 2 3 × 3 4 × 4 5 × 5 6 × 6
25 × 14 28 × 16 32 × 18 36 × 20 40 × 22 45 × 25 50 × 28 56 × 32 63 × 32 70 × 36 80 × 40 90 × 45 100 × 50
10 12 17 22 30 38 44 50 58 65 75 85
10 12 17 22 30 38 44 50 58 65 75
110 130 130 150 150 170 170 200 200 230 230 260 260 290 290 330 330 380 380 440 440 500
Keyways for Rectangular Parallel Keys
8
8 × 7 10 × 8 12 × 8 14 × 9 16 × 10 18 × 11 20 × 12 22 × 14
10 12 14 16 18 20 22
100
… … … … Note: This table is NOT part of ANSI/ASME B18.25.1M-1996 (Withdrawn) or ANSI/ASME B18.25.3M-2003, and is included for reference only. The selection of the proper size and type of key must rest with the design authority. Metric Woodruff Keys and Keyways This ANSI/ASME B18.25.2M standard covers requirements for metric Woodruff keys and keyways intended for both alignment of shafts and hubs, and transmitting torque between shafts and hubs. All dimensions in this standard are in millimeters (mm). Di- mensions and tolerances for Woodruff keys are shown in Table 5. Recommended dimen- sions and tolerances for keyways are shown in Table 6. For inch series Woodruff keys and keyseats, see ANSI/ASME Standard Woodruff Keys and Keyseats starting on page 2556. Comparison with ISO 3912-1977.— This standard is based on ISO 3912-1977, Woodruff Keys and Keyways . However, to improve manufacturability, tolerances are decreased for the keyway width. The resulting fit is approximately the same. Keys manufactured to this standard are functionally interchangeable with keys manufactured to the ISO standard. Because of tighter width tolerances in this standard, products manufactured to the ISO standard may not meet the requirements of this standard.
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