ASME B18.2.3.3M-2007 pdf download

ASME B18.2.3.3M-2007 pdf download.Metric Heavy Hex Screws.
1 INTRODUCTORY NOTES 1.1 Scope 1.1.1 This Standard covers the complete general . and dimensional data for metric heavy hex screws recog- nized as American National Standard. 1.1.2 The inclusion of dimensional data in this Standard is not intended to imply that all of the sizes in conjunction with the various options described herein are stock items. Consumers should consult with suppli- ers concerning lists of stock production sizes. 1.2 Comparison With ISO Standards 1.2.1 ISO has not yet initiated development of an ISO standard for heavy hex screws. However, nominal diameters and thread pitches, body diameters, widths across flats, bearing surface diameters, head heights, thread lengths, thread dimensions, and nominal lengths are in accord with ISO standards for related hex head screws and bolts. 1.2.2 Letter symbols designating dimensional characteristics are in accord with those used in ISO stan- dards, except capital letters have been used instead of the lowercase letters used in ISO standards. 1.3 Terminology For definitions of terms relating to fasteners or compo- nent features thereof used in this Standard, refer to ASME B18.12. 1.4 Dimensions .1.4.1 All dimensions in this Standard are in milli- meters, unless stated otherwise. 1.4.2 Symbols specifying geometric characteristics are in accord with ASME Y14.5M.
2.1.5 True Position of Head. At maximum material condition, the axis of the hex head shall be located at true position with respect to the axis of the screw (determined over a distance under the head equal to one screw diame- ter) within a tolerance zone of diameter specified in Table 1. 2.1.6 Bearing Surface. The bearing surface shall be flat and washer-faced. Diameter of bearing surface shall not exceed the width across flats nor be less than the specified minimum washer face diameter. For referee purposes, measurement of bearing surface diameter shall be taken at 0.1 mm above the bearing surface. The plane of the bearing surface shall be perpendicular to the axis of the body within the circular runout specified in Table 2. The measurement of bearing face runout shall be made as close to the periphery of the washer face as possible, while the screw is held in a collet or other gripping device at a distance equal to one screw diame- ter from the underside of the head. 2.1.7 Underhead Fillet. The fllet configuration at the junction of the head and shank shall be as shown in Figs. 1 and 2, and shall have limits as specified in Table 3. The fllet shall be a smooth and continuous curve fairing smoothly into the underhead bearing surface and the shank within the limits specified. No radius in the fillet contour shall be less than R minimum. 2.2 Body Diameter The diameter of the body on screws that are not threaded full length shall be within the limits specified in Table 2. For screws threaded full length, the diameter of the unthreaded shank under the head shall not exceed the specified maximum body diameter, nor be less than the minimum body diameter specified in Table 1. 2.3 Screw Length The length of the screw shall be measured parallel to the axis of the screw from the underhead bearing surface to the extreme end of the shank. Tolerances for screw lengths are given in Table 4.
2.6 Thread Length 2.6.1 The length of thread on screws shall be con- trolled by the maximum grip gaging length, Lg, and the minimum body length, Ls, as set forth in paras. 2.6.2 through 2.6.5. 2.6.2 Grip gaging length, Lg maximum, is the dis- tance measured parallel to the axis of the screw, from the underhead bearing surface of the face of a noncoun- terbored or noncountersunk standard GO thread ring gage assembled by hand as far as the thread will permit. For standard diameter-length combinations of screws, the values for Lg maximum are specified in Table 6. For diameter-length combinations not listed in Table 6, the maximum grip gaging length, as calculated and rounded to one decimal place, shall be equal to the nominal screv length, L, minus the reference thread length, B, as speci- fied in Table 1 (Lgmax. pL – B). Lg maximum shall be used as a criterion for inspection. 2.6.3 Body length, Ls minimum, is the distance, measured parallel to the axis of the screw, from the underhead bearing surface to the last scratch of thread or top of the extrusion angle, whichever is closest to the head. For standard diameter- length combinations of screws, the values of Ls minimum are specified in Table 6. For diameter- length combinations not listed in Table 6, the minimum body length, as calculated and rounded to one decimal place, shall be equal to the maximum grip gaging length as computed minus the reference transition thread length as specified in Table 7 (Ls min. p Lg max. – Xref.).