Metric Screw Threads:

M Profile

A N A M E R I C A N N A T I O N A L S T A N D A R D

ASME B1.13M-2005

(Revision of ASME B1.13M-2001)

Metric Screw Threads:

M Profile

AN AMERICAN NATIONAL STANDARD

Three Park Avenue • New York, NY 10016

Date of Issuance: March 10, 2006

The next edition of this Standard is scheduled for publication in 2010. There will be no addenda or written interpretations of the requirements of this Standard issued to this edition.

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The American Society of Mechanical Engineers Three Park Avenue, New York, NY 10016-5990

Copyright © 2006 by

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS

All rights reserved Printed in U.S.A.

CONTENTS

Foreword vi

Committee Roster viii

1. Designation of Thread Fit 20

2. Designation of Rounded Root External Thread 20

3. Designation of Threads Having Modified Crests 20

4. Designation of Special Threads 20

5. Designation of Multiple Start Threads 20

6. Designation of Coated or Plated Threads 20

7. Designation of Threads With Adjusted Size Limits 20

1. Dimensional Accommodation of Coating or Plating for 60 deg Threads 21

   1. Introduction 21

   2. Material Limits for Coated Threads 21

   3. Dimensional Effects of Coating 21

   4. External Thread With Allowance Available for Coating 21

   5. External Thread With No Allowance for Coating 23

   6. Internal Threads 24

   7. Electrodeposited Coatings 24

   8. Other Considerations 25

10 Lead and Flank Angle Tolerances 37

10.1 Lead and Flank Angle Acceptance 37

Figures

1. Basic M Thread Profile (ISO 68-1 Basic Profile) 4

2. Internal Thread, Design M Profile With No Allowance (Fundamental

   Deviation) (Maximum Material Condition) 5

3. External Thread, Design M Profile With No Allowance (Fundamental

   Deviation) (Flanks at Maximum Material Condition) 5

4. Metric Tolerance System for Screw Threads 6

5. M Profile, External Thread Root, Upper and Lower Limiting Profiles for

   r min.p0.125P and for Flat Root Form (Shown for Tolerance Position g) 7

6. Ratio of Pitch Diameter Change to Thickness of Coating on 60 deg

   Threads 22

7. Effects of Electrodeposited Coating on 60 deg External Threads 23

8. Internal Thread — Limiting M Profile, Tolerance Position H 34

9. External Thread — Limiting M Thread Profile 37

   
   

   Tables

   1. General Symbols 2

   2. Thread Data, M Profile 3

   3. Limit Values for M Profile Minimum Rounded Root Radius 8

   4. Standard Coarse Pitch M Profile General Purpose and Mechanical

      Fastener Series 8

   5. Standard Fine Pitch M Profile Screw Threads 8

   6. ISO 261 Diameter/Pitch Combinations From Which the Standards

      Were Selected 9

   7. Length of Thread Engagement (ISO 965-1) 13

   8. Examples of Tolerance Classes Required for Normal Gage Length Contacts

      With Various Thread Engagement Lengths 14

   9. Minor Diameter Tolerances of Internal Thread, TD1 (ISO 965-1) 14

   10. Major Diameter Tolerances of External Thread, Td (ISO 965-1) 15

   11. Pitch Diameter Tolerance of External Thread, Td2 (ISO 965-1) 16

   12. Pitch Diameter Tolerance of Internal Thread, TD2 (ISO 965-1) 17

   13. Allowance (Fundamental Deviation) for Internal and External Threads

       (ISO 965-1) 18

   14. External Thread — Limiting Dimensions M Profile 26

   15. Internal Thread — Limiting Dimensions M Profile 35

16A Example of External Screw Thread, Standard Size 39

16B Example of Internal Metric Screw Thread, Standard Size 41

16C Example of External Metric Screw Thread, Non-Standard Size 43

16D Example of Internal Metric Screw Thread, Non-Standard Size 45

1. Allowable Variations in Lead and Equivalent Change in Functional

   Diameter 47

2. Allowable Variations in 30 deg Basic Half-Angle of Screw Threads 50

   Nonmandatory Appendices

   1. Standard Rules for Rounding 51

   2. Thread Strength Design Formulas 52

   3. Limiting Dimensions M Profile Screw Threads — Inch Translation 53

   4. Basic Dimensions for ISO Series Metric Screw Threads From ISO 724 64

   5. Overtapped Nut Thread Class 6AX 68

   6. Internal Thread Allowance (Fundamental Deviation) Tolerance Position E 70

FOREWORD

In 1966, ANSI Standards Committee B1 — Standardization and Unification of Screw Threads — started preparation of a document for ISO Metric Screw Threads based on the current ISO recommendations and draft documents. Since there were some uncertainties as to the acceptance of this thread by American industries, the information was published in August 1967 with the title, “Interpretative Document Metric Screw Threads B1.13.” This document was never approved as an ANSI standard.

A revision of the information based on the then current ISO standards and recommendations was published in April 1972 with the title “B1 Report — ISO Metric Screw Threads.” Again, the document was never approved as an ANSI standard. The document number was therefore removed and the status changed to a report.

Interest in metric screw threads has grown at a rapid pace over the past several years with the advent of greater import and export business. The American National Standards Institute, in April 1971, established a committee, ANSI Special Committee to Study Development of an Optimum Metric Fastener System (OMFS). Included in the scope was metric screw threads. Recommendations were submitted to a joint ISO/TC1/TC2 working group established in Septem- ber 1973 to study the OMFS proposals.

An ISO/TC1/TC2 Ad Hoc Advisory Panel meeting in April 1975 in Munich reached a compro- mise between the OMFS recommendations and the existing ISO screw thread system. This compromise was approved, in the main, by the ISO/TC1 in its eleventh plenary meeting in Stockholm, June 1976.

1. The first issue of this Standard, designated ANSI B1.13M, was approved as an American National Standard on February 12, 1979. It provided a system of metric screw threads for general fastening purposes in mechanisms and structures and was in basic agreement with ISO screw thread standards and resolutions current at that time. It featured detailed information for diameter- pitch combinations selected as preferred standard sizes.

2. The 1983 issue of this Standard was designated ANSI/ASME B1.13M-1983 and was approved as an American National Standard on August 5, 1983. It updated the 1979 issue to include

   1. the addition of the new ISO tolerance position f

   2. the addition of a section on dimensional accommodation of coating or plating

   3. the addition of a section on lead and flank angle tolerances

3. The 1995 issue of this Standard was designated ASME B1.13M-1995 and was approved as an American National Standard on February 20, 1995. It updated the 1983 issue to include

   1. the addition of an 8 mm pitch series

   2. the addition of standard size M10 1

   3. the provision for adjustment of internal thread tolerance class for short and long lengths of thread engagement, which may be used instead of external thread class adjustment

   4. changes in rounding procedures that follow the principles of ASME B1.30M

4. The 2001 issue of this Standard was designated ASME B1.13M-2001 and was approved as an American National Standard on May 22, 2001. It updated the 1995 issue to include

   1. incorporation of changes made in the 1998 issue of ISO 261, including addition of diame- ters 125, 130, and 140 in the 8 mm pitch series; and changing of the 7 mm diameter from 3rd to 2nd choice in Table 6.

   2. recognition of changes made in the 1998 issue of ISO 965-1, including the stating of when International practice permits thread designation without thread class (not USA practice); and modifying the designation of multiple lead threads to be more in line with ISO practice.

   3. incorporation of the new 1998 International Standard, ISO 965-5, by adding Nonmanda- tory Appendix E for Class AX threads.

   4. minor changes in some thread root diameters due to modified calculation and rounding procedures added in ASME B1.30. ASME B1.30 uses rounding upward when the digit following

      the last rounded place is a 5 followed by zeros. Prior to issue of ASME B1.30, rounding was to the nearest even digit. Tabulated values appearing in ISO Standards are not subject to rounding rules of ASME B1.30.

   5. changes in Circular Runout tolerances.

   6. other required updates and corrections.

5. This issue updates the 2001 edition and includes

   1. addition of a new Nonmandatory Appendix F to provide a new tolerance position E

   2. addition of tolerance class 6h as a preferred class

   3. addition of M8 x 1.25 – 6AX to Nonmandatory Appendix E

   4. revision of section 8 on “Dimensional Accommodation of Coating or Plating...” to include allowances at thread roots and to expand the information on internal threads

   5. revision of section 7 to provide thread designations in accordance with ASME Y14.6-2001

   6. revision of some tabulated inch translation values in Nonmandatory Appendix C and the examples of calculation of thread size values in para. 9.4, in accordance with ASME B1.30-2002

   7. addition of para. 7.9 for designation of a thread with adjusted size limits

   8. other required editorial updates and corrections

      Suggestions for improvement of this Standard are welcome. They should be sent to Secretary, ASME B1 Standards Committee, Three Park Avenue, New York, NY 10016-5990.

      This revision was approved as an American National Standard on September 29, 2005.

      
      

      ASME B1 COMMITTEE

      Standardization and Unification of Screw Threads

      (The following is the roster of the Committee at the time of approval of this Standard.)

      
      

      STANDARDS COMMITTEE OFFICERS

      1. L. Barrows, Chair

D. S. George, Vice Chair

A. L. Guzman, Secretary

G. L. Allen, The L. S. Starrett Co.

1. L. Barrows, Kennametal-IPG

   STANDARDS COMMITTEE PERSONNEL

2. Larzelere, Corresponding Member, Deltronic Corp.

L. L. Lord, Corresponding Member, Caterpillar, Inc.

F. G. Calderone, Corresponding Member, Quality Systems Implementers

L. N. Dixon, Jr., General Electric

R. Dodge, Pennoyer-Dodge Co.

1. A. Flannery, Corresponding Member, Mercury Gage Co.

2. N. Frost, Defense Supply Center Philadelphia

J. O. Gehret III, Vermont Thread Gage

D. S. George, Ford Motor Co.

J. R. Gervasi, Kerr Lakeside, Inc.

J. Greenslade, Greenslade and Co.

A. L. Guzman, The American Society of Mechanical Engineers

R. J. Hukari, SPS Technologies

L. C. Johnson, The Johnson Gage Co.

D. D. Katz, Precision Fittings

R. P. Knittel, Leitech-US Ltd.

M. H. McWilliams, PMC Lonestar

D. Skierski, Alternate, Sterling Gage and Calibration

D. Miskinis, Kennametal-Greenfield

W. R. Newman, Corresponding Member, Consultant

D. R. Oas, Seaway Bolt and Specials Corp.

M. W. Rose, Glastonbury Southern Gage

W. A. Watts, Alternate, Glastonbury Southern Gage

E. Schwartz, Consultant

R. H. Searr, Member Emeritus, Mak Tool and Gage

B. F. Sheffler, Dresser-Rand Co.

A. D. Shepherd, Jr., Emuge Corp.

R. D. Strong, General Motors Vehicle Engineering Center

A. F. Thibodeau, Member Emeritus, Swanson Tool Manufacturing, Inc.

R. E. Vincent, Jr., General Plug Manufacturing Co.

C. J. Wilson, Industrial Fasteners Institute

E. Schwartz, Chair

SUBCOMMITTEE 13 — METRIC SCREW THREADS

L. L. Lord, Corresponding Member, Caterpillar, Inc.

D. Miskinis, Vice Chair, Kennametal-Greenfield

A. L. Barrows, Kennametal-IPG

F. G. Calderone, Corresponding Member, Quality Systems Implementers

R. Dodge, Pennoyer-Dodge Co.

D. S. George, Ford Motor Co.

J. Greenslade, Greenslade and Co.

W. R. Newman, Corresponding Member, Consultant

R. D. Strong, General Motors Vehicle Engineering Center

A. F. Thibodeau, Corresponding Member, Swanson Tool Manufacturing, Inc.

R. E. Vincent, Jr., General Plug Manufacturing Co.

C. J. Wilson, Industrial Fasteners Institute

viii

ASME B1.13M-2005

METRIC SCREW THREADS: M PROFILE

1. GENERAL

   1. Scope

      This Standard contains general metric standards for a 60 deg symmetrical screw thread with a basic ISO 68-1 profile designated M profile. The M profile threads of tolerance class 6H/6g are intended for metric applica- tions where inch class 2A/2B have been used. At the minimum material limits, the 6H/6g results in a looser fit than the 2A/2B. Tabular data is also provided for a tighter tolerance fit external thread of class 4g6g, which is approximately equivalent to the inch class 3A but with an allowance applied. Formulation and tolerancing data is included for applications requiring other fits.

      NOTE: A 4H5H/4h6h is approximately equivalent to a class 3A/3B fit in the inch system.

   2. Interchangeability

      Threads produced to this Standard are fully inter- changeable with threads conforming to other National Standards that are based on ISO 68-1 basic profile and ISO 965-1 tolerance practices.

      1.2.1 Assembly. Threads produced in accordance with M profile and MJ profile (ASME B1.21M) design data will assemble with each other. However, external MJ threads will encounter interference on the root radii with internal M thread crests when both threads are at maximum material condition.

   3. References

      The latest issues of the following documents form a part of this Standard to the extent specified herein.

      ASME B1.3, Screw Thread Gaging Systems for Dimensional Acceptability — Inch and Metric Screw Threads (UN, UNR, UNJ, M, and MJ)

      ASME B1.7M, Nomenclature, Definitions, and Letter Symbols for Screw Threads

      ASME B1.16M, Gages and Gaging for Metric M Screw Threads

      ASME B1.21M, Metric Screw Threads: MJ Profile ASME B1.30, Screw Threads — Standard Practice for

      Calculating and Rounding Dimensions ASME B47.1, Gage Blanks

      ASME Y14.5, Dimensioning and Tolerancing

      Publisher: The American Society of Mechanical Engi- neers (ASME), Three Park Avenue, New York, NY 10016-5990; Order Department: 22 Law Drive, Box 2900, Fairfield, NJ 07007-2900

      ASTM F568M, Standard Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners Publisher: The American Society for Testing and Materi-

      als (ASTM), 100 Barr Harbor Drive, West Consho- hocken, PA 19428-2959

      ISO 3, Preferred Numbers — Series of Preferred Numbers

      ISO 68-1, ISO General Purpose Screw Threads — Basic Profile — Part 1: Metric Screw Threads

      ISO 261, ISO General Purpose Metric Screw Threads — General Plan

      ISO 724, ISO Metric Screw Threads — Basic Dimensions ISO 898-1, Mechanical Properties of Fasteners — Part 1:

      Bolts, Screws, and Studs

      ISO 965-1, ISO General Purpose Metric Screw Threads — Tolerances — Part 1: Principles and Basic Data

      Pu