ASME B18.2.3.2M:2005 pdf download

ASME B18.2.3.2M:2005 pdf download.Metric Formed Hex Screws
1 SCOPE
(a) This Standard covers the complete dimensional and general data for metric formed hex screws recog- nized as American National Standard. Formed hex screws are cold formed products with fully upset (non-trimmed) heads. Formed hex screws are stan- dard only in sizes M5 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 Stan- dard 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 sup- pliers concerning lists of stock production formed hex screws.
2 COMPARISON WITH ISO STANDARDS
(a) Because of numerous differences between this Standard and ISO 4015, a detailed summary is included in Appendix C. (b) At its meeting in Varna, May 1977, ISO/TC2 studied several technical reports analyzing design con- siderations 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 com- pressive 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 1 lists the sizes selected by ISO/TC2 to be ISO standard. M10 screws with 15 mm width across flats are cur- rently being produced and used in the U.S. and many other countries. This size, however, is not an ISO stan- dard. Unless M10 screws with 15 mm width across flats are specifically ordered, M10 screws with 16 mm width across flats shall be furnished. (c) Letter symbols designating dimensional charac- teristics 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 com- ponent features thereof used in this Standard, refer to American National Standard ASME B18.12.
5 DIMENSIONS
(a) All dimensions in this Standard are given in mil- limeters (mm), and apply before coating, unless stated otherwise. (b) Symbols specifying geometric characteristics are in accordance with ASME Y14.5M.erance zone of the diameter specified in Table 2 with re- spect to the axis of the shank (derived median line) over a length under the head equal to the nominal screw di- ameter, D. 6.1.6 Bearing Surface. The bearing surface shall be flat and washer-faced. The diameter of the washer face, measured at 0.1 mm above the bearing surface, shall not exceed the actual width across flats, S, nor be less than the specified minimum washer face diameter, D w min. The circular runout of the bearing surface with respect to the axis of the shank (derived median line) shall be within the full indicator movement (FIM) as specified in Table 1. The measurement of bearing surface runout shall be made as close to the periphery of the bearing surface as possible while the screw is held in a collet or other gripping device at the distance of one diameter under the head. 6.1.7 Underhead Fillet. The fillet configuration at the junction of the head and shank shall be as shown in Figs. 2 and 3, and shall have limits as specified in Table 3. The fillet shall be a smooth and continuous curve fairing smoothly into the bearing surface and the shank within the limits specified. No radius in the fillet contour shall be less than R minimum. 6.2 Body Diameter (a) The diameter of the body on screws that are not threaded full length shall be within the limits of D s , spec- ified in Table 1, unless the purchaser specifies screws with reduced diameter body. For screws threaded full length, the diameter of the unthreaded shank under the head shall not exceed the specified maximum body di- ameter, D s , nor be less than the minimum body diame- ter, D si , given in Table 2. (b) Screws may be obtained with reduced diameter body as specified in Table 4. The grip gaging length, L g max. shall be as specified in Table 5. The diameter, D s , and length, L sh , of the shoulder shall be as specified in Table 4. Reduced diameter body screws with nomi- nal lengths shorter than 4 times their nominal diameter are not recommended.