1、Metric Heavy Hex ScrewsAN AMERICAN NATIONAL STANDARDRevision of ANSI B18.2.3.3M-1979 (R2001)ASME B18.2.3.3M-2007Intentionally left blank ASME B18.2.3.3M-2007Revision of ANSI B18.2.3.3M-1979 (R2001)Metric HeavyHex ScrewsAN AMERICAN NATIONAL STANDARDThree Park Avenue New York, NY 10016Date of Issuance
2、: October 31, 2007This Standard will be revised when the Society approves the issuance of a new edition. There willbe no addenda issued to this edition.ASME issues written replies to inquiries concerning interpretations of technical aspects of thisStandard. Periodically, certain actions of the ASME
3、B18 Committee may be published as Cases. Casesand interpretations are published on the ASME Web site under the Committee Pages athttp:/cstools.asme.org as they are issued.ASME is the registered trademark of The American Society of Mechanical Engineers.This code or standard was developed under proced
4、ures accredited as meeting the criteria for American NationalStandards. The Standards Committee that approved the code or standard was balanced to assure that individuals fromcompetent and concerned interests have had an opportunity to participate. The proposed code or standard was madeavailable for
5、 public review and comment that provides an opportunity for additional public input from industry, academia,regulatory agencies, and the public-at-large.ASME does not “approve,” “rate,” or “endorse” any item, construction, proprietary device, or activity.ASME does not take any position with respect
6、to the validity of any patent rights asserted in connection with anyitems mentioned in this document, and does not undertake to insure anyone utilizing a standard against liability forinfringement of any applicable letters patent, nor assume any such liability. Users of a code or standard are expres
7、slyadvised that determination of the validity of any such patent rights, and the risk of infringement of such rights, isentirely their own responsibility.Participation by federal agency representative(s) or person(s) affiliated with industry is not to be interpreted asgovernment or industry endorsem
8、ent of this code or standard.ASME accepts responsibility for only those interpretations of this document issued in accordance with the establishedASME procedures and policies, which precludes the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an
9、electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersThree Park Avenue, New York, NY 10016-5990Copyright 2007 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword ivCom
10、mittee Roster . vCorrespondence With the B18 Committee vi1 Introductory Notes . 12 General Data 1Figures1 Fillet Detail for Short Screws 32 Fillet Detail for Long Screws 3Tables1 Tolerance Zone . 22 Dimensions of Heavy Hex Screws . 33 Dimensions of Underhead Fillets 44 Length Tolerances 45 Dimension
11、s of Points . 46 Maximum Grip Gaging Lengths and Minimum Body Lengths . 57 Thread Lengths . 6Nonmandatory AppendicesA Screw Straightness Gage and Gaging Procedure . 9B Body Position Gages and Gaging Procedures 10iiiFOREWORDAmerican National Standards Committee B18 for the standardization of bolts, s
12、crews, nuts,rivets, and similar fasteners was organized in March 1922 as Sectional Committee B18 underthe aegis of the American Engineering Standards Committee (later the American StandardsAssociation, then the United States of America Standards Institute and, as of October 6, 1969,the American Nati
13、onal Standards Institute, Inc.) with the Society of Automotive Engineers andthe American Society of Mechanical Engineers as joint sponsors. Subcommittee 2 was subsequentlyestablished and charged with the responsibility for technical content of standards covering wrenchhead bolts and nuts.At its meet
14、ing on December 4, 1974, Committee B18 authorized preparation of a series ofstandards for metric fasteners. Subcommittee 2 was assigned responsibility for developing stan-dards for metric hex bolts, screws, and nuts.At a meeting on September 22, 1976, Subcommittee 2 organized the contents of a stand
15、ardcovering eight different hex head screw and bolt products. Actual drafting was postponed untilISO/TC2 could reach final decisions relating to basic dimensions and characteristics of hex bolts,screws, and nuts. At ISO/TC2 meetings held in April 1977, final actions were taken. Committee B18affirmed
16、 the TC2 decisions at a meeting on June 29, 1977, and drafting of this Standard wasstarted.In February 1978, Committee B18 established a cooperative program with the Department ofDefense to draft American National Standards for metric fasteners in such a way that they couldbe used directly by the Go
17、vernment for procurement purposes. The Department of Defenserequested that each of the eight products be covered in separate standards, and Subcommittee 2accepted this approach at its meeting on June 27, 1978.The 1979 Edition was approved by ballot of Committee B18 on September 15, 1978, and wassubs
18、equently approved by the secretariat and submitted to the American National StandardsInstitute for designation as an American National Standard. This was granted on March 26, 1979.This revision was approved by the American National Standards Institute (ANSI) onJuly 11, 2007.ivASME B18 COMMITTEEStand
19、ardization of Bolts, Nuts, Rivets, Screws,Washers, and Similar Fasteners(The following is the roster of the Committee at the time of approval of this Standard.)STANDARDS COMMITTEE OFFICERSD. A. Clever, ChairR. D. Strong, Vice ChairS. W. Vass, Vice ChairR. L. Crane, SecretarySTANDARDS COMMITTEE PERSO
20、NNELV. Cartina, Aztech LocknutD. A. Clever, Deere however, theyshould not contain proprietary names or information.Requests that are not in this format may be rewritten in the appropriate format by the Committeeprior to being answered, which may inadvertently change the intent of the original reques
21、t.ASME procedures provide for reconsideration of any interpretation when or if additionalinformation that might affect an interpretation is available. Further, persons aggrieved by aninterpretation may appeal to the cognizant ASME Committee or Subcommittee. ASME does not“approve,” “certify,” “rate,”
22、 or “endorse” any item, construction, proprietary device, or activity.Attending Committee Meetings. The B18 Standards Committee regularly holds meetings, whichare open to the public. Persons wishing to attend any meeting should contact the Secretary ofthe B18 Standards Committee.viASME B18.2.3.3M-20
23、07METRIC HEAVY HEX SCREWS1 INTRODUCTORY NOTES1.1 Scope1.1.1 This Standard covers the complete generaland dimensional data for metric heavy hex screws recog-nized as American National Standard.1.1.2 The inclusion of dimensional data in thisStandard is not intended to imply that all of the sizesin con
24、junction with the various options described hereinare stock items. Consumers should consult with suppli-ers concerning lists of stock production sizes.1.2 Comparison With ISO Standards1.2.1 ISO has not yet initiated development of anISO standard for heavy hex screws. However, nominaldiameters and th
25、read pitches, body diameters, widthsacross flats, bearing surface diameters, head heights,thread lengths, thread dimensions, and nominal lengthsare in accord with ISO standards for related hex headscrews and bolts.1.2.2 Letter symbols designating dimensionalcharacteristics are in accord with those u
26、sed in ISO stan-dards, except capital letters have been used instead ofthe lowercase letters used in ISO standards.1.3 TerminologyFor definitions of terms relating to fasteners or compo-nent features thereof used in this Standard, refer toASME B18.12.1.4 Dimensions1.4.1 All dimensions in this Standa
27、rd are in milli-meters, unless stated otherwise.1.4.2 Symbols specifying geometric characteristicsare in accord with ASME Y14.5M.1.5 Referenced StandardsThe following is a list of publications referenced in thisStandard. Unless otherwise specified, the standard(s)referenced shall be the most recent
28、issue at the time oforder placement.ASME B1.3M, Screw Thread Gaging Systems forDimensional Acceptability Inch and Metric ScrewThreadsASME B1.13M, Metric Screw ThreadsMProfile1ASME B18.2.8, Clearance Holes for Bolts, Screws, andStudsASME B18.12, Glossary of Terms for MechanicalFastenersASME B18.18.1,
29、 Inspection and Quality Assurance forGeneral Purpose FastenersASME B18.18.2, Inspection and Quality Assurance forHigh-Volume Machine Assembly FastenersASME B18.24, Part Identifying Number (PIN) CodeSystem Standard for B18 Fastener ProductsASME Y14.5M, Dimensioning and TolerancingPublisher: The Ameri
30、can Society of MechanicalEngineers (ASME), Three Park Avenue, New York,NY 10016-5990; Order Department, 22 Law Drive,P.O. Box 2300, Fairfield, NJ 07007-2300ASTM F 468M, Specification for Nonferrous Bolts, HexCap Screws, and Studs for General Use (Metric)ASTM F 568M, Specification for Carbon and Allo
31、y SteelExternally Threaded Metric FastenersASTM F 738M, Specification for Stainless Steel MetricBolts, Screws, and StudsASTM F 1941M, Electrodeposited Coatings on ThreadedFasteners (Metric)Publisher: ASTM International (ASTM), 100 Barr HarborDrive, West Conshohocken, PA 194282 GENERAL DATA2.1 Heads2
32、.1.1 Top of Head. The top of head shall be fullform and chamfered or rounded. The diameter of thechamfer circle or the start of rounding shall be equal tothe maximum width across flats within a tolerance of15%.2.1.2 Head Height. The head height is the distance,as measured parallel to the axis of the
33、 screw, from thetop of the head to the plane of the bearing surface.2.1.3 Wrenching Height. The wrenching height isthe distance, measured at a corner of the hex, from theplane of the bearing surface to the last plane of fullformed hex, i.e., the plane closest to the top of head atwhich the width acr
34、oss corners of the hex is within itsspecified limits.2.1.4 Corner Fill. The rounding due to lack of fill atthe six corners of the head shall be reasonably uniform.ASME B18.2.3.3M-20072.1.5 True Position of Head. At maximum materialcondition, the axis of the hex head shall be located at trueposition
35、with respect to the axis of the screw (determinedover a distance under the head equal to one screw diame-ter) within a tolerance zone of diameter specified inTable 1.2.1.6 Bearing Surface. The bearing surface shall beflat and washer-faced. Diameter of bearing surface shallnot exceed the width across
36、 flats nor be less than thespecified minimum washer face diameter. For refereepurposes, measurement of bearing surface diametershall be taken at 0.1 mm above the bearing surface. Theplane of the bearing surface shall be perpendicular tothe axis of the body within the circular runout specifiedin Tabl
37、e 2. The measurement of bearing face runout shallbe made as close to the periphery of the washer face aspossible, while the screw is held in a collet or othergripping device at a distance equal to one screw diame-ter from the underside of the head.2.1.7 Underhead Fillet. The fillet configuration att
38、he junction of the head and shank shall be as shownin Figs. 1 and 2, and shall have limits as specified inTable 3. The fillet shall be a smooth and continuous curvefairing smoothly into the underhead bearing surface andthe shank within the limits specified. No radius in thefillet contour shall be le
39、ss than R minimum.2.2 Body DiameterThe diameter of the body on screws that are notthreaded full length shall be within the limits specifiedin Table 2. For screws threaded full length, the diameterof the unthreaded shank under the head shall not exceedthe specified maximum body diameter, nor be less
40、thanthe minimum body diameter specified in Table 1.2.3 Screw LengthThe length of the screw shall be measured parallel tothe axis of the screw from the underhead bearing surfaceto the extreme end of the shank. Tolerances for screwlengths are given in Table 4.2.4 PointsThe end of the screw shall be ch
41、amfered from a diame-ter equal to or slightly less than the thread root diameterto produce a length of chamfer or incomplete threadwithin the limits for U specified in Table 5. The end ofthe screw shall be reasonably square with the axis ofthe screw, and where pointed blanks are used, the slightrim
42、or cup resulting from roll-threading shall be permis-sible. At the manufacturers option, the end of the screwmay have a rounded point of radius, Re, as specified inTable 5.2.5 StraightnessAt maximum material condition, the axes of the screwbody and thread major diameter shall be within a2Table 1 Tol
43、erance ZoneNominal Head True Minimum BodyScrew Position Diameter forDiameter Tolerance Product Positionand Thread Zone Threaded of BodyPitch, D Diameter to Head, Dsito ThreadM12 H11547 1.75 0.84 10.68 0.70M14 H11547 2 0.98 12.50 0.70M16 H11547 2 1.12 14.50 0.70M20 H11547 2.5 1.40 18.16 0.84M24 H1154
44、7 3 1.68 21.80 0.84M30 H11547 3.5 2.10 27.46 0.84M36 H11547 4 2.52 33.12 1.00straightness tolerance diameter equal to 0.006L 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
45、 given in Nonmandatory Appendix A.2.6 Thread Length2.6.1 The length of thread on screws shall be con-trolled by the maximum grip gaging length, Lg, and theminimum body length, Ls, as set forth in paras. 2.6.2through 2.6.5.2.6.2 Grip gaging length, Lgmaximum, is the dis-tance measured parallel to the
46、 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 Lgmaximum are specified in Table 6. Fordiameter-
47、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 (Lgmax. pL B). Lgmaximum shall beused as a criterion for inspection.2.
48、6.3 Body length, Lsminimum, 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 diameterlength combinationsof screws, the values of Lsminimum are specif
49、ied inTable 6. For diameterlength 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(Lsmin. pLgmax. X ref.). Lsminimum shall be usedas a criterion for inspection. Screws of nominal lengthsequal to or less than the length, Lu, as specified in Table 7shall be threaded full length. For screws that arethreaded full length, the distance from the underheadASME B18.2.3.3M-2007Table 2 Dimensions of He
