This Standard establishes uniform practices for stating and interpreting dimensioning, tolerancing, and related requirements for use on engineering drawings and in related documents. For a mathematical explanation of many of the principles in this Standard, see ASME Y14.5.1M. Practices unique to architectural and civil engineering and welding symbology are not included.
Author(s): The American Society of Mechanical Engineers
Series: Engineering Drawing and Related Documentation Practices
Year: 2009
Language: English
Pages: 227
City: New York
Tags: Drafting;Technical Drawing; Engineering Drawing; Engineering Graphics, Standard
Foreword .............................................................................................................................................................................. vi
Committee Roster ................................................................................................................................................................ viii
Correspondence With the Y14 Committee ...................................................................................................................... ix
Section 1 Scope, Definitions, and General Dimensioning ...................................................................................... 1
1.1 Scope ................................................................................................................................................................ 1
1.2 References ....................................................................................................................................................... 1
1.3 Definitions ...................................................................................................................................................... 2
1.4 Fundamental Rules ........................................................................................................................................ 7
1.5 Units of Measure ............................................................................................................................................ 8
1.6 Types of Dimensioning ................................................................................................................................. 9
1.7 Application of Dimensions .......................................................................................................................... 10
1.8 Dimensioning Features ................................................................................................................................. 13
1.9 Location of Features ...................................................................................................................................... 20
Section 2 General Tolerancing and Related Principles .......................................................................................... 24
2.1 General ............................................................................................................................................................ 24
2.2 Direct Tolerancing Methods ......................................................................................................................... 24
2.3 Tolerance Expression ..................................................................................................................................... 25
2.4 Interpretation of Limits ................................................................................................................................. 26
2.5 Single Limits ................................................................................................................................................... 26
2.6 Tolerance Accumulation ............................................................................................................................... 26
2.7 Limits of Size .................................................................................................................................................... 27
2.8 Applicability of Modifiers on Geometric Tolerance Values and Datum Feature References ............. 29
2.9 Screw Threads ................................................................................................................................................ 31
2.10 Gears and Splines .......................................................................................................................................... 31
2.11 Boundary Conditions .................................................................................................................................... 31
2.12 Angular Surfaces ........................................................................................................................................... 31
2.13 Conical Tapers ................................................................................................................................................ 35
2.14 Flat Tapers ....................................................................................................................................................... 35
2.15 Radius .............................................................................................................................................................. 36
2.16 Tangent Plane ................................................................................................................................................. 36
2.17 Statistical Tolerancing ................................................................................................................................... 36
Section 3 Symbology .............................................................................................................................................. 38
3.1 General ............................................................................................................................................................ 38
3.2 Use of Notes to Supplement Symbols ........................................................................................................ 38
3.3 Symbol Construction ..................................................................................................................................... 38
3.4 Feature Control Frame Symbols .................................................................................................................. 44
3.5 Feature Control Frame Placement ............................................................................................................... 46
3.6 Definition of the Tolerance Zone ................................................................................................................. 46
3.7 Tabulated Tolerances ..................................................................................................................................... 46
Section 4 Datum Reference Frames ........................................................................................................................ 48
4.1 General ............................................................................................................................................................ 48
4.2 Degrees of Freedom ....................................................................................................................................... 48
4.3 Degrees of Freedom Constrained by Primary Datum Features
Regardless of Material Boundary ............................................................................................................ 48
4.4 Constraining Degrees of Freedom of a Part ............................................................................................... 48
4.5 Datum Feature Simulator ............................................................................................................................. 53
4.6 Theoretical and Physical Application of Datum Feature Simulators ..................................................... 53
4.7 Datum Reference Frame ............................................................................................................................... 53
4.8 Datum Features .............................................................................................................................................. 57
4.9 Datum Feature Controls ............................................................................................................................... 58
4.10 Specifying Datum Features in an Order of Precedence ........................................................................... 58
4.11 Establishing Datums ..................................................................................................................................... 59
4.12 Multiple Datum Features ............................................................................................................................. 65
4.13 Mathematically Defined Surface ................................................................................................................. 69
4.14 Multiple Datum Reference Frames ............................................................................................................. 69
4.15 Functional Datum Features .......................................................................................................................... 69
4.16 Rotational Constraint About a Datum Axis or Point ................................................................................ 70
4.17 Application of MMB, LMB, and RMB to Irregular Features of Size ...................................................... 74
4.18 Datum Feature Selection Practical Application ......................................................................................... 75
4.19 Simultaneous Requirements ........................................................................................................................ 76
4.20 Restrained Condition .................................................................................................................................... 79
4.21 Datum Reference Frame Identification ...................................................................................................... 79
4.22 Customized Datum Reference Frame Construction ................................................................................. 81
4.23 Application of a Customized Datum Reference Frame ........................................................................... 81
4.24 Datum Targets ................................................................................................................................................ 83
Section 5 Tolerances of Form .................................................................................................................................. 91
5.1 General ............................................................................................................................................................ 91
5.2 Form Control .................................................................................................................................................. 91
5.3 Specifying Form Tolerances ......................................................................................................................... 91
5.4 Form Tolerances ............................................................................................................................................. 91
5.5 Application of Free-State Symbol ................................................................................................................ 95
Section 6 Tolerances of Orientation ....................................................................................................................... 99
6.1 General ............................................................................................................................................................ 99
6.2 Orientation Control ....................................................................................................................................... 99
6.3 Orientation Symbols ...................................................................................................................................... 99
6.4 Specifying Orientation Tolerances .............................................................................................................. 99
6.5 Tangent Plane ................................................................................................................................................. 103
6.6 Alternative Practice ....................................................................................................................................... 103
Section 7 Tolerances of Location ............................................................................................................................ 108
7.1 General ............................................................................................................................................................ 108
7.2 Positional Tolerancing ................................................................................................................................... 108
7.3 Positional Tolerancing Fundamentals: I ..................................................................................................... 108
7.4 Positional Tolerancing Fundamentals: II .................................................................................................... 119
7.5 Pattern Location ............................................................................................................................................. 127
7.6 Coaxial Feature Controls .............................................................................................................................. 148
7.7 Tolerancing for Symmetrical Relationships ............................................................................................... 156
Section 8 Tolerances of Profile ............................................................................................................................... 158
8.1 General ............................................................................................................................................................ 158
8.2 Profile .............................................................................................................................................................. 158
8.3 Tolerance Zone Boundaries .......................................................................................................................... 158
8.4 Profile Applications ....................................................................................................................................... 165
8.5 Material Condition and Boundary Condition Modifiers as
Related to Profile Controls ....................................................................................................................... 167
8.6 Composite Profile .......................................................................................................................................... 167
8.7 Multiple Single-Segment Profile Tolerancing ............................................................................................ 175
8.8 Combined Controls ......................................................................................................................................... 175
Section 9 Tolerances of Runout .............................................................................................................................. 180
9.1 General ............................................................................................................................................................ 180
9.2 Runout ............................................................................................................................................................. 180
9.3 Runout Tolerance ........................................................................................................................................... 180
9.4 Types of Runout Tolerances ......................................................................................................................... 180
9.5 Application ..................................................................................................................................................... 182
9.6 Specification ................................................................................................................................................... 182
Nonmandatory Appendices
A Principal Changes and Improvements ................................................................................................. 185
B Formulas for Positional Tolerancing ..................................................................................................... 191
C Form, Proportion, and Comparison of Symbols .................................................................................. 194
D Former Practices ...................................................................................................................................... 199
E Decision Diagrams for Geometric Control .......................................................................................... 200
Index ..................................................................................................................................................................... 207
