ASME B18.2.3.2:2005 pdf free download

ASME B18.2.3.2:2005 pdf free download.Metric Formed Hex Screws.
(a)ASME B18.2.3.2 covers the complete dimensional and general data for metric formed hex screws recognized as American National Standard. Formed hex screws are cold formed products with fully upset (non-trimmed) heads. Formed hex screws are standard only in sizes MS thru M24, with lengths up to 150 mm, or 10 times nominal screw size, whichever is shorter.
(b) 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 suppliers concerning lists of stock production formed hex screws.
2 COMPARISON WITh ISO STANDARDS
(a) Because of numerous differences betwcvn this Standard and ISO 4015, a detailed summary is included in Appendix C.
(h) At its meeting in Vama, May 1977, ISO/TC2 studied several technical reports analyzing design considerations influencing determination of the best series of width across flats for hexagon bolts, screws, and nuts. A primary technical objective was to achieve a logical ratio between underhead (nut) bearing surface area (which determines the magnitude of the compressive stress on the bolted members) and the tensile stress area of the screw thread (which governs the clamping force that can be developed by tightening the fastener). Table I lists the sizes selected by ISO/TC2 to be ISO standard.
M10 screws with 15 mm width across flats are currently being produced and used in the US. and many other countries. This size, however, is not an ISO standard. Unless MI0 screws with 15 mm width across flats are specifically ordered, M10 screws with 16 mm width across flats shall be furnished.
fr) Letter symbols designating dimensional characteristics are in accord with those used in ISO standards, except that capital letters have been used instead of the lower case letters used in ISO standards.
3 TERMINOLOGY
For definitions of terms relating to fasteners or component features thereof used in this Standard, refer to American National Standard ASME B18.12.
6.6.2 Body Length,Ls Body length,L, is the dis-tance,measured parallel to the axis of the screw, fromthe underhead bearing surface to the last scratch ofthread or top of the extrusion angle, whichever is clos-est to the head. For standard diameter-length combina-tions of screws that are not threaded full length, thevalues of Le min. are specified in Table 5. For diameter-length combinations not listed in Table 5, the minimumbody length,as calculated and rounded to one decimalplace, shall be equal to the maximum grip gaging lengthascomputed, minus the transition thread lengthasspec-ified inTable8(Lmin.= Lg max.- X ref.).Ls min.shallbe used as a criterion for inspection. For screws that arethreaded full length, the distance from the underheadbearing surface to the face of a noncounterbored or non-counter-sunk standard GO thread ring gage assembledby hand as far as the thread will permit shall not exceedthe length, La,as specified in Table 8. For screwsthreaded full length, the last scratch of thread must notbe within the maximum fillet length,F1 max., as speci-fied in Table 3: L min.=Fmax.
6.6.3 Thread Length，B. Thread length,B, a refer-ence dimension, as specified in Table 8, is intended forcalculation purposes only, and is the distance, measuredparallel to the axis of the screw, from the extreme endof the screw to the last complete (full form) thread.6.6.4 Transition Thread Length,X.The transitionthread length,X, as specified in Table 8, is a referencedimension intended for calculation purposes only. It in-cludes the length of incomplete threads and tolerances on grip gaging length and body length. The transitionfrom full thread to incomplete thread shall be smoothand uniform. The major diameter of the incompletethreads shall not exceed the actual major diameter of thecomplete (full form) threads. The transition threads shallhave a rounded root contour.
6.6.5 Position of Body-to-Thread. For productswith cut threads,at maximum material condition, theaxis of the screw body,De(derived median line),overa length equal to the nominal screw diameter from thelast scratch of thread, shall be within the positional tol-erance zone diameter specified in Table 2 with respectto the axis of the thread, over a length equal to the nom-inal screw diameter from the last complete thread.Agage and gaging procedure for checking body positionis given in Nonmandatory Appendix B.