1、 The American Society of Mechanical Engineers AN AMERICAN NATIONAL STANDARD CLEARANEE HOLES FOR BOLTS, SCREWS, AND STUDS ASME 61 8.2.8-1 MUM Date of Issuance: October 7, 1999 This Standard will be revised when the Society approves the issuance of a new edition. There will be no addenda or written in
2、terpretations of the requirements of this Standard issued to this edition. 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 Standards. The Standards Committe
3、e 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, which provides an opportunity for additional public input from i
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7、ions issued in accordance with governing ASME procedures and policies which preclude the issuance of interpretations by individual volunteers. No part of this document may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher
8、. The American Society of Mechanical Engineers Three Park Avenue, New York, NY 10016-5990 Copyright 0 1999 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A. During its December 3, 1998 meeting, the ASME B18 Fastener Committee authorized preparation of a standard t
9、o establish clearance holes for inch- and metric-threaded fasteners. Some of the metric screw and bolt standards already had, as an appendix, the IS0 273 approved normal-, close-, and loose-clearance hole diameters. It was recognized that for inch standard fasteners there was no B18 standard size re
10、commendation. A draft standard was prepared using common industry inch clearance values selected to follow the general metric design of three degrees of clearance. The recommendations are all tabulated as minimum holes and tolerance is recommended using IS0 273 tolerance classes. The Standard also i
11、ncludes values for fasteners in each system using the standard drill sizes from the other system of measurement. This Standard should provide consistent application design information for the fasteners and can be a step toward rationalization of the tooling for fastener assembly operations. Metric s
12、tandards need not include the appended information in each threaded fastener standard and inch-threaded fastener standards will have standardized clearance hole recommendations. ASME B 18.2.8-1999 was approved by the American National Standards Institute (ANSI) on August 19, 1999. . 111 ASME B18 STA
13、NDARDS COMMllTEE Standardization 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.) OFFICERS D. A. Clever, Chair R. D. Strong, Vice Chair S. W. Vass. Vice Chair R. L. Crane, Secretary COMMITTEE PERSO
14、NNEL J. C. Akins, Safety Socket Screw Corp. J. Altman, Rotor Clip Co. J. B. Belford, Lawson Products, Inc. D. Broomfield, Illinois Tool Works, Inc. J. A. Buda, SPS Technologies D. A. Clever, Deere and Co. T. Collier, Cam-Tech Industries, Inc. R. L. Crane, The American Society of Mechanical Engineers
15、 A. C. DiCola, Wrought Washer Co. A. Dinh, Defense Industrial Supply Center W. D. Downing, Consultant B. A. Dusina, Federal Screw Works D. S. George, Ford Motor Co. J. Greenslade, Greenslade and Co. 6. Hasiuk, Defense Industrial Supply Center A. Herskovitz, U.S. Army ARDEC A. C. Hood, ACH Technologi
16、es J. Hubbard, Rockford Fastener, Inc. F. W. Kern, The Society of Automotive Engineers J. F. Koehl, Spirol International Corp. W. H. Kopke, ITW Shakeproof Assembly Co. J. G. Langenstein, Consultant M. Levinson, ITW Shakeproof Assembly Co. L. L. Lord, Caterpillar, Inc. A. D. McCrindle, Genfast Manufa
17、cturing Co. K. E. McCullough, Consultant R. F. Novotny, Textron M. D. Prasad, General Motors Corp. S. Savoji, ITW Medalist W. Schevey, BGM Fastener Co., Inc. R. D. Strong, General Motors Corp. J. F. Sullivan, National Fasteners Distribution Association R. L. Tennis, Caterpillar, Inc. S. W. Vass, Ind
18、ustrial Fasteners Institute C. B. Wackrow, MNP Corp. R. G. Weber, Fairfield University W. K. Wilcox, Naval Sea Systems Command C. J. Wilson, Industrial Fasteners Institute V SUBCOMMllTEE 2 - EXTERNAL DRIVE FASTENERS S. W. Vass, Chair, Industrial Fasteners Institute R. L. Crane, Secretary, The Americ
19、an Society of Mechanical Engineers D. Broomfield, Illinois Tool Works, Inc. R. M. Byrne, Trade Association Management, Inc. D. A. Clever, Deere and Co. A. P. Cockman, Ford Motor Co. R. J. Corbett, Huck International Industrial Fasteners A. Dinh, Defense Industrial Supply Center D. S. George, Ford Mo
20、tor Co. J. Greenslade, Greenslade and Co. A. Herskovitz, U.S. Army ARDEC M. W. Holubecki, Electric Boat Corp. J. Hubbard, Rockford Fastener, Inc. L. L. Lord, Caterpillar, lnc. A. D. McCrindle, Genfast Manufacturing Co. K. E. McCullough, Consultant J. A. Schlink, Caterpillar, Inc. R. L. Tennis, Cater
21、pillar, Inc. C. 6. Wackrow, MNP Corp. W. K. Wilcox, Naval Sea Systems Command C. J. Wilson, Industrial Fasteners Institute vi CORRESPONDENCE WITH THE B18 COMMITTEE General. ASME Standards are developed and maintained with the intent to represent the consensus of concerned interests. As such, users o
22、f this Standard may interact with the Committee by requesting interpretations, proposing revisions, and attending Committee meetings. Correspondence should be addressed to: Secretary, B 18 Main Committee The American Society of Mechanical Engineers Three Park Avenue New York, NY 10016-5990 Proposing
23、 Revisions. Revisions are made periodically to the Standard to incorporate changes that appear necessary or desirable, as demonstrated by the experience gained from the application of the Standard. Approved revisions will be published periodically. The Committee welcomes proposals for revisions to t
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29、rther, persons aggrieved by an interpretation may appeal to the cognizant ASME Committee or Subcommittee. ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity. Attending Committee Meetings. The B18 Main Committee regularly holds meetings, w
30、hich are open to the public. Persons wishing to attend any meeting should contact the Secretary of the B18 Main Committee. vii CONTENTS . Foreword III Committee Roster v Committee Correspondence vii 1 Scope 1 2 Comparison With IS0 Standards 1 2.1 Metric Fasteners . 1 2.2 Inch Fasteners . 1 3 Dimensi
31、ons 1 3.1 Inch Fasteners . 1 3.2 Metric Fasteners . 1 3.3 Tolerances 1 3.4 Clearances 1 Tables 1 Inch Clearance Hole Allowances 2 2 Clearance Holes for Inch Fasteners . 2 3 Clearance Holes for Metric Fasteners . 3 4 Metric Clearance Hole Allowances 4 Mandatory Appendix I Nonsystem Drills 5 ix ASME B
32、18.2.8-1999 CLEARANCE HOLES FOR BOLTS, SCREWS, AND STUDS 1 SCOPE This Standard covers the recommended clearance hole sizes for #O through 1.5 in. and MI .6 through MI00 metric fasteners in three classes of clearance using a close-, normal-, and loose-fit category. 2 COMPARISON WITH IS0 STANDARDS 2.1
33、 Metric Fasteners The hole sizes for metric fasteners are in agreement with IS0 273, Fasteners-Clearance Holes for Bolts and Screws, except the IS0 273 covers fastener sizes MI through M 150. 2.2 Inch Fasteners The hole sizes for inch fasteners are patterned after USA common usage and the general cl
34、earances trans- lated from the metric standard. The hole tolerances are based on the IS0 System of Limits and Fits, as required by IS0 273. 3 DIMENSIONS 3.1 Inch Fasteners The recommended drill sizes for inch fasteners are tabulated by nominal drill designation as letter, numbers, or fractional size
35、s. The drill sizes were selected to provide as nearly as practical a step-patterned clearance size for the minimum recommended hole (see Table I). The maximum recommended hole size is based on standard hole tolerances. The tabulated drill and hole sizes of Table 2 list the inch fastener clearance ho
36、le recommendations. 3.2 Metric Fasteners The recommended drill and hole sizes for metric fasteners are tabulated in Table 3. The minimum recom- mended hole is the drill size and the maximum recom- mended hole size is based on standard tolerances. 3.3 Tolerances The clearance hole tolerances for both
37、 inch and metric holes are based on IS0 286, IS0 System of Limits and Fits, using tolerance class HI2 for close-fit, H 13 for normal-fit, and H 14 for loose-fit clearance holes. 3.4 Clearances The clearances provided by the three classes of fit are based on regularly stepped clearances as listed in
38、Table 1 for inch and Table 4 for metric. 1 ASME B18.2.8-1999 CLEARANCE HOLES FOR BOLTS, SCREWS, AND STUDS TABLE 1 INCH CLEARANCE HOLE ALLOWANCES Nominal Fit Classes Screw Size Normal Close Loose #0-#4 164 0.008 132 #5-/16 132 l164 3/64 l/2 I “8 11 6 132 “4 I 18 11 6 132 132 1 3/32 132 5/32 1 1/8 , 1
39、94 3/32 132 4 6 131 , 1 l18 /16 15 164 GENERAL NOTE: Dimensions are in inches. TABLE 2 CLEARANCE HOLES FOR INCH FASTENERS Fit Classes Normal Close Loose Screw Nominal Hole Diameter Nominal Hole Diameter Nominal Hole Diameter Size Drill Size Min. Max. Drill Size Min. Max. Drill Size Min. Max. #O #1 #
40、2 #3 #4 #5 #6 #8 #10 14 5/16 78 4 6 /2 78 “/4 18 1 /a 1 1/4 1 “/E 1 112 1 #48 0.076 #43 0.089 #38 0.102 #32 0.1 16 #30 0.128 #18 0.170 #9 0.196 #2 0.221 132 0.281 3/32 0.406 0.562 0.688 0.812 1 3/32 1.094 1132 1.219 %2 0.156 I32 0.344 15 132 0.469 6 11 13 15 116 11 6 11 6 0.938 1 “132 1.344 1 112 1.
41、500 1 518 1.625 0.082 0.095 0.108 0.122 0.135 0.163 0.177 0.203 0.228 0.290 0.354 0.416 0.479 0.572 0.698 0.824 0.950 1.106 1.235 1.360 1.516 1.641 #5 1 #46 3/32 #36 #3 1 #23 #15 #5 %4 0.067 0.081 0.094 0.106 0.120 0.141 0.154 0.180 0.206 0.266 0.328 0.391 0.453 0.531 0.656 0.781 0.906 1.031 1.156 1
42、.281 1.438 1.562 0.071 0.085 0.098 0.110 0.124 0.146 0.159 0.185 0.21 1 0.272 0.334 0.397 0.460 0.538 0.663 0.789 0.914 1.039 1.164 1.291 1.448 1.572 3/32 0.094 #37 0.104 #32 0.116 #30 0.128 #27 0.144 /sa 0.172 #13 0.185 #3 0.213 B 0.238 0.297 0.359 11 19 23 27 164 164 164 0.422 164 0.609 164 0.734
43、164 39 47 29 132 0.906 1 132 1.031 0.484 1 5/32 1.156 1 5/16 1.312 1 116 1.438 147/64 1.734 1 “164 1.609 0.104 0.114 0.126 0.140 0.156 0.184 0.197 0.225 0.250 0.31 1 0.373 0.438 0.500 0.625 0.754 0.926 1.051 1.181 1.337 1.463 1.634 1.759 GENERAL NOTE: Dimensions are in inches. 2 CLEARANCE HOLES FOR
44、BOLTS, SCREWS, AND STUDS ASME 818.2.8-1999 TABLE 3 CLEARANCE HOLES FOR METRIC FASTENERS Fit Classes Normal Close Loose Nominal Hole Diameter Nominal Hole Diameter Nominal Hole Diameter Screw Size Drill Size Min. Max. Drill Size Min. Max. Drill Size Min. Max. Nominal M1.6 M2 M2.5 M3 M4 M5 M6 M8 MI0 M
45、I2 MI4 MI6 M20 M24 M30 M 36 M42 M48 M56 M 64 M72 M80 M90 MlOO 1.8 2.4 2.9 3.4 4.5 5.5 6.6 9 11 13.5 15.5 17.5 22 26 33 39 45 52 62 70 78 86 96 107 1.8 2.4 2.9 3.4 4.5 5.5 6.6 9 11 13.5 15.5 17.5 22 26 33 39 45 52 62 70 78 86 96 107 1.94 2.54 3.04 3.58 4.68 5.68 6.82 9.22 11.27 13.77 15.77 17.77 22.3
46、3 26.33 33.39 39.39 45.39 52.46 62.46 70.46 78.46 86.54 96.54 107.54 1.7 2.2 2.7 3.2 4.3 5.3 6.4 8.4 10.5 13 15 17 21 25 31 37 43 50 58 66 74 82 93 104 1.7 2.2 2.7 3.2 4.3 5.3 6.4 8.4 10.5 13 15 17 21 25 31 37 43 50 58 66 74 82 93 104 1.8 2.3 2.8 3.32 4.42 5.42 6.55 8.55 10.68 13.18 15.18 17.18 21.2
47、1 25.21 31.25 37.25 43.25 50.25 58.3 66.3 74.3 82.35 93.35 104.35 2 2.6 3.1 3.6 4.8 5.8 7 10 12 14.5 16.5 18.5 24 28 35 42 48 56 66 74 82 91 101 112 2 2.6 3.1 3.6 4.8 5.8 7 10 12 14.5 16.5 18.5 24 28 35 42 48 56 66 74 82 91 101 112 2.25 2.85 3.4 3.9 5.1 6.1 7.36 10.36 12.43 14.93 16.93 19.02 24.52 2
48、8.52 35.62 42.62 48.62 56.74 66.74 74.74 82.87 91.87 101.87 1 12.87 GENERAL NOTE: Dimensions are in millimeters. 3 ASME B18.2.8-1999 CLEARANCE HOLES FOR BOLTS, SCREWS, AND STUDS TABLE 4 METRIC CLEARANCE HOLE ALLOWANCES Nominal Fit Classes Screw Size Normal Close Loose M1.6 M2 M2.5 M3 M4, M5 M6 M8 M1
49、0 M12-Ml6 M20, M24 M30 M36, M42 M 48 M56-M72 M80 M90 MlOO 0.2 0.4 0.4 0.4 0.5 0.6 1 1 1.5 2 3 3 4 6 6 6 7 0.1 0.1 0.1 0.2 0.3 0.4 0.4 0.5 1 2 2 2 3 4 0.25 0.3 0.3 0.6 0.8 1 2 2 2.5 4 5 6 8 10 11 11 12 GENERAL NOTE: Dimensions are in millimeters. 4 ASME 818.2.8-1999 MANDATORY APPENDIX I NONSYSTEM DRILLS 1-1 RECOMMENDED SUBSTITUTE DRILLS If the clearance hole application is dimensioned in metric drill sizes for inch fasteners or inch drill sizes for metric fasteners, Tables 1-1 and 1-2 lis
