Machinery's Handbook, 31st Edition
1716
Metric Screws and Bolts Table 3. American National Standard Metric Heavy Hex Screws ANSI/ASME B18.2.3.3M-2007 (R2014)
K K 1
L
L g
B (REF)
L s
S
C X (REF)
E
D w
D s
Incomplete Thread Optional Point Construction
Fillet
15°–30°
Property Class and Manu- facturer’s Identification to Appear on Top of Head
Nominal Screw Dia., D , and Thread Pitch
Washer Face Dia., D w
Width Across Flats, S
Width Across Corners, E
Washer Face Thickness, C
Body Diameter, D s
Head Height, K
Wrenching Height, K 1
Max.
Min.
Max.
Min.
Max.
Min.
Max.
Min.
Min.
Max. Min. Min.
5.2 0.6 0.3 19.6 6.2 0.6 0.3 22.5 7.0 0.8 0.4 25.3 8.8 0.8 0.4 31.4 10.5 0.8 0.4 38.0 13.1 0.8 0.4 46.6 15.8 0.8 0.4 55.9
M12 × 1.75 12.00 11.73 21.00 20.67 24.25 23.35 7.76 7.24
14.00 13.73 24.00 23.67 27.71 26.75 9.09 8.51 16.00 15.73 27.00 26.67 31.18 30.14 10.32 9.68 20.00 19.67 34.00 33.00 39.26 37.29 12.88 12.12 24.00 23.67 41.00 40.00 47.34 45.20 15.44 14.56 30.00 29.67 50.00 49.00 57.74 55.37 19.48 17.92 36.00 35.61 60.00 58.80 69.28 66.44 23.38 21.72
M14 × 2 M16 × 2 M20 × 2.5 M24 × 3 M30 × 3.5 M36 × 4
All dimensions are in millimeters. Basic thread lengths, B , are the same as given in Table 13. Transition thread length, X , includes the length of incomplete threads and tolerances on grip gaging length and body length. It is intended for calculation purposes. For additional manufacturing and acceptance specifications, reference should be made to the Standard. ANSI letter symbols designating dimensional characteristics are in accord with those used in ISO Standards except capitals have been used for data processing convenience instead of the lower case letters used in the ISO Standards. Metric Screw and Bolt Diameters.— Metric screws and bolts are furnished with full di- ameter body within the limits shown in the respective dimensional tables, or are threaded to the head (see Metric Screw and Bolt Thread Lengths on page 1725 ) unless the pur - chaser specifies “reduced body diameter.” Metric formed hex screws ( Table 4 ), hex flange screws (Table 4 ), hex bolts ( Table 4 ), heavy hex bolts ( Table 4 ), hex lag screws ( Table 5 ), heavy hex flange screws ( Table 7 ), and round head square neck bolts ( Table 9 ) may be obtained with reduced diameter body, if so specified; however, formed hex screws, hex flange screws, heavy hex flange screws, hex bolts, or heavy hex bolts with nominal lengths shorter than 4 D , where D is the nominal diameter, are not recommended. Metric formed hex screws, hex flange screws, heavy hex flange screws, and hex lag screws with reduced body diameter will be furnished with a shoulder under the head. For metric hex bolts and heavy hex bolts this is optional with the manufacturer. For bolts and lag screws there may be a reasonable swell, fin, or die seam on the body adjacent to the head not exceeding the nominal bolt diameter by: 0.50 mm for M5, 0.65 mm for M6, 0.75 mm for M8 through M14, 1.25 mm for M16, 1.50 mm for M20 through M30, 2.30 mm for M36 through M48, 3.00 mm for M56 through M72, and 4.80 mm for M80 through M100.
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