1、&The American Society ol Mechanical Engineers A NA MERIC A NN ATION AL STA ND A RD METRIC THHEADF ORMING AND THREAD-CUTTING TAPPING SCREWS ASME 818.8.5M-2000 Revision of ANSI/ASME B18.8.5M-1988(R1993)Date of Issuance:August 31,2000 The 2000 edition of this Standard is being issued with an automatic
2、addenda subscription service.The use of an addenda allows revisions made in response to public review comments or committee actions to be published as necessary.The next edition of this Standard is scheduled for publication in 2005.ASME issues written replies to inqumes concerning interpretations of
3、 technical aspects of this Standard.The interpretations will be included with the above addenda service.ASME is the registered trademark of The American Society of Mechanical Engineers.This code or standard was developed under procedures accredited as meeting the criteria for American National Stand
4、ards.The Standards Committee that approved the code or standard was balanced to assure that individuals from competent and concerned interests have had an opportunity to participate.The proposed code or standard was made available for public review and comment that provides an opportunity for additi
5、onal 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 to the validity of any patent rights asserted in connection with any items ment
6、ioned in this document,and does not undertake to insure anyone utilizing a standard against liability for infringement of any applicable letters patent,nor assume any such liability.Users of a code or standard are expressly advised that determination of the validity of any such patent rights,and the
7、 risk of infringement of such rights,is entirely their own responsibility.Participation by federal agency representative(s)or person(s)affiliated with industry is not to be interpreted as government or industry endorsement of this code or standard.ASME accepts responsibility for only those interpret
8、ations of this document issued in accordance with the established ASME procedures and policies,which precludes the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of
9、the publisher.The American Society of Mechanical Engineers Three Park Avenue,New York,NY 10016-5990 Copyright 2000 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A.FOREWORD ASME Standards Committee B 18 for the standardization of bolts,screws,nuts,rivets,and simil
10、ar fasteners was organized in March 1922 as Sectional Committee BI 8 under the aegis of the American Engineering Standards Committee(later the American Standards Association,then the United States of American Standards Institute,and,as of October 6,1969,the American National Standards Institute,Inc.
11、).The Society of Automotive Engineers and the American Society of Mechanical Engineers served as joint sponsors.Subcommittee 3 was subsequently established and charged with the responsibility for technical content of standards covering slotted and recessed head screws.In accordance with a general re
12、alignment of the subcommittee structure on April I,l 966,Subcommittee 3 was redesignated Subcommittee 6.At its meeting on December 4,1974,Standards Committee B 18 authorized preparation of a series of standards for metric fasteners.Subcommittee 6 was assigned the responsibility for developing produc
13、t standards covering metric machine screws and tapping screws.In subsequent meetings of Subcommittee 6,held over the ensuing two years,the content of the proposed metric standards was discussed and organized.It was decided the coverage should be limited to flat countersunk,oval countersunk,and pan h
14、ead styles having slotted and Types I and IA cross-recessed drive provisions and the hex and hex washer head designs.The spaced thread tapping screws would cover soft converted sizes 2.2,2.9,3.5,4.2,4.8,5.5,6.3,8,and 9.5 for Types AB and B thread-forming screws and Types BF and BT thread-cutting des
15、igns.Metric coarse series thread sizes 2,2.5,3,3.5,4,5,6,8,and I O would apply for Types D,F,and T thread-cutting tapping screws.Also,it was the consensus that the respective head envelopes for both machine screws and tapping screws of comparable sizes should remain consistent with established inch
16、practices.In 1976,the Industrial Fasteners Institute published IFI-502,documenting dimensions and specifications as then agreed upon and coordinated to the extent possible with International Organization for Standardization(ISO)proposals,which Subcommittee 6 authorized as a first draft proposal for the metric tapping screw document.Because the common head for machine and tapping screw approach differed considerably from existing metric practices and ISO drafts,particularly in regard to countersu
