ASME B18.2.3.3M-2007 pdf free download.Metric Heavy Hex Screws.
2.1.5 True Positeon of Head. At maximum material condition, the .mis ol the hex head shall be located at tnie position with respect to the axis of the screw (determined over a distance under the head equal to one screw diameter) within a tolerance iont of diameter specified in Table I.
2J.6 Bearing Surface. The bearing surface shall be flat and washer-laced Diameter of hearing surface shall not exceed the wklth 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 runnut 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 diameter 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. I and 2, and shall have limits as specified in Table 3. The fillet 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 th unthreaded shank under the head shall not exceed the specified maximum body diameter, nor be less than the minimum body diameter specified in Table I.
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.
2.4 Points
The end of the screw shall he chani lered from a d ian,eter 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 permissible. At the manufacturer’s option. the end of the screw may have a rounded point of radius, Rr, as specified in Table 5.
2.5 Straightness
At maximum material condition, the axes of the screw body and thread major diameter shall be within a straightness tolerance diameter equal to 0.0O6L for nomi-nal screw lengths,L, 300 mm or shorter and 0.008L forscrews having nominal lengths,L, over 300 mm through600 mm.A gage and gaging procedure to checkstraightness 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, Lg, and theminimum body length,Lo. as set forth in paras. 2.6.2through 2.6.5.
2.6.2Grip gaging length, Lg maximum, is the dis-tance measured parallel to the axis of the screw, fromthe underhead bearing surface of the face of a noncoun-terbored or noncountersunk standard GO thread ringgage assembled by hand as far as the thread will permit.For standard diameter-length combinations of screws,the values for L maximum are specified in Table 6. Fordiameter-length combinations not listed in Table 6, themaximum grip gaging length, as calculated and roundedto one decimal place, shall be equal to the nominal screwlength, L, minus the reference thread length,B, as speci-fied in Table 1 (L max.=L-B).Lg maximum shall beused as a criterion for inspection.
2.6.3 Body length,L minimum, is the distance,measured parallel to the axis of the screw.from theunderhead bearing surface to the last scratch of threador top of the extrusion angle,whichever is closest tothe head. For standard diameter-length combinationsof screws,the values of Lx minimum are specified inTable 6.For diameter-length combinations not listed inTable 6, the minimum body length, as calculated androunded to one decimal place, shall be equal to themaximum grip gaging length as computed minus thereference transition thread length as specified in Table 7.