ASME B18.2.5M-2009 pdf download

ASME B18.2.5M-2009 pdf download.Metric 12-Point Flange Screws.
8 WRENCHING HEIGHT
Corners of the 12 points shall be fully formed and reasonably uniform over the wrenching height, Ku.. Head drive root radius, R4, applies to the entire length of the wrenching height, K1. (see Table 1).
9 GAGING OF 12-POINT FLANGE HEAD
The head shall be gaged using two ring gages, A and B, to demonstrate the coincidental acceptability of wrenching height, corner fill, and width across corners. Gage A shall be placed over the head and shall seat on the flange. Gage 13 shall be placed on the top of the head normal to the screw axis. The two gages shall not be in contact (see Table 2).
10 POSITION OF HEAD
At maximum material condition, the axis of the 12 points of the head shall be within a positional tolerance zone of the diameter specified in Table 3 with respect to the axis of the shank over a distance under the head equal to the nominal screw diameter, D. The datum shall be as close to the head as practicable, but within O.5D from the head, and shall be either wholly plain body or wholly the thread major diameter, not including the thread runout or the underhead fillet.
11 FLANGE
The top surface of the flange shall be conical or slightly rounded (convex), Radius, R2, applies both at the corners and at the flats of the 12 points. The contour of edge at flange peripher) between the maximum flange diameter, D maximum, and the minimum bearing circle diameter, D, minimum, shall be optional provided that the minimum flange edge thickness, C minimum, is maintained at the minimum bearing circle diameter, D, minimum.
12 BEARING SURFACE
The plane formed by the bearing circle shall be perpendicular to the axis of the shank, over a length under the head equal to the nominal screw diameter, D, within the circular runout as specified in Table 3. The measurement of bearing face runout shall be made at the actual bearing circle (i.e., at the line of highest points on any radial line, e.g., by use of straight edge anvil). The datum shall be as close to the head as practical, but within O.5D from the head, and shall be either wholly plain body or wholly thread major diameter, not including the thread runout or the underhead fillet,
13 FILLET
The fillet configuration at the junction of the head and shank shall conform to either Type F, as shown in Table 4,
16 POINTS
The end of the screw shall be chamfered or rounded at the manufacturer’s option from approximately 0.44) mm below the minor diameter of the thread. The length of the point to the first lull-formed thread at major diameter, as determined by the distance the point enters into a cylindrical NOT GO major diameter ring gage, shall not exceed U maximum, specified in Table 8. 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 8.
21.1 Property Class SymboLs
Each screw shall be marked in accordance with the requirements of the applicable specification for its material and mechanical properties.
21.2 Source Symbols
Each screw shall be marked to identify its source (manufacturer or private label distributor).
22 FINISH
Unless otherwise specified, screws shall be furnished with one of the following “standard surfaces as manufactured,” at the option of the manufacturer:
(a) bright uncoated
(1’) thermal black oxide
(c) chemical black oxide
Hydrogen embrittlement tests shall not be required for screws furnished in these conditions.
For other protective finishes specified with an applicable finish specification. precautions to minimize embrittlement shall be exercised.
23 WORKMANSHIP
Screws shall be free from surface imperfections such as burrs, seams, laps, 1oose scale, and other surface irregularities that could affect serviceability and shall conform to ASTM F 788/F 788M unless otherwise stated.
24 INSPECTION AND QUALITY ASSURANCE
Unless otherwise specified, acceptability of screws shall be determined in accordance with ASME Bl8.18.4M except as required in section 25.