ASME B18.2.3.3M pdf free download

ASME B18.2.3.3M pdf free download Metric Heavy Hex Screws
2.1.5 True Position of Head. At maximum material condition, the axis ofthe hex head shall be located at true positionwithrespectto the axis ofthe screw (determined overa distance underthe head equalto 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 fillet 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 filletshall 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 ofthe 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 ofthe screw from the underhead bearing surface to the extreme end of the shank. Tolerances for screw lengths are given in Table 4.
2.4 Points The end ofthe screw shall be chamfered from a diame- ter equal to or slightly less than the thread root diameter to produce a length of chamfer or incomplete thread within the limits for U specified in Table 5. The end of the screw shall be reasonably square with the axis of the screw, and where pointed blanks are used, the slight rim or cup resulting from roll-threading shall be permis- sible. At the manufacturer’s option, the end of the screw may have a rounded point of radius, R e , as specified in Table 5.
2.5 Straightness At maximum material condition, the axes ofthe screw body and thread major diameter shall be within a straightness tolerance diameter equal to 0.006L for nomi- nal screw lengths, L, 300 mm or shorter and 0.008L for screws having nominal lengths, L, over 300 mm through 600 mm. A gage and gaging procedure to check straightness is given in Nonmandatory Appendix A.
2.6 Thread Length
2.6.1 The length of thread on screws shall be con- trolled by the maximum grip gaging length, L g , and the minimum body length, L s , as set forth in paras.
2.6.2 through 2.6.5.
2.6.2 Grip gaging length, L g 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 L g maximum are specified in Table 6. For diameter-length combinations not listed in Table 6, the maximumgrip gaginglength, as calculated and rounded to one decimal place, shall be equal to the nominal screw length, L, minus the reference thread length, B, as speci- fied in Table 1 (L g max. p L − B). L g maximum shall be used as a criterion for inspection.
2.6.3 Body length, L s 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 L s 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 (L s min. p L g max. − X ref.). L s minimum shall be used as a criterion for inspection. Screws of nominal lengths equal to or less than the length, L u , as specified in Table 7 shall be threaded full length. For screws that are threaded full length, the distance from the underhead