Committee Personnel
T. D. Benoit. Alternate. Pratt b Whitney CEB R. A. Chaddecdon, Southwest Consultants F. A. Christiana, ASEA Brown Boveri Combustion Engineering Systems M. E. Curtis, Jr., Rexnord Corp. R. W. DaBolt, Motorola Inc., Government and Space Technology Group H. L. Dubocq L. W. Foster, L W. Foster Associates, Inc. C. J. Gomez, The American Society of Mechanical Engineers D. Hagler, E-Systems, Inc., Garland Division E. L Kardas, Pratt Whitney CEB C. G. Lance, Santa Cruz Technology Center W. J. McGee,...
Info Cto
FIG. 5-18 MULTIPLE PATTERNS OF FEATURES, SEPARATE REQUIREMENTS the use of a composite feature control frame. See para. 3.4.4 and Fig. 3-22 a . The position symbol is entered once and is applicable to both horizontal segments. Each complete horizontal segment in the feature control frames of Figs. 5-19 and 5-20 may be verified separately, but the lower segment is always a subset of the upper segment. a Pattern-Locating Tolerance Zone Framework PLTZF . Where composite controls are used, the upper...
Fig Foreshortened Radii 1
arrowhead between the radius center and the arc, it may be placed outside the arc with a leader. Where the center of a radius is not dimensionally located, the center shall not be indicated. See Fig. 1-20. 1.8.2.1 Center of Radius. Where a dimension is given to the center of a radius, a small cross is drawn at the center. Extension lines and dimension lines are used to locate the center. See Fig. 1-21. Where location of the center is unimportant, the drawing must clearly show that the arc...
Fig Datum Feature Symbol 1
is not sufficient space within the compartment, the area size may be placed outside and connected to the compartment by a leader line. See Fig. 4-29. 3.3.4 Basic Dimension Symbol. The symbolic means of indicating a basic dimension is shown in Fig. 3-7. 3.3.5 Material Condition Symbols. The symbolic means of indicating at maximum material condition and at least material condition are shown in Fig. 3-8. The use of these symbols in local 3.3.6 Projected Tolerance Zone Symbol. The symbolic means of...
Fig Profile Of A Line And Size Control
thecretical boundary shaped identically to the basic profile. For an internal feature, the boundary equals the MMC size of the profile minus the positional tolerance, and the entire feature surface must lie outside the boundary. For an external feature, the boundary equals the MMC size of the profile plus the positional tolerance, and the entire feature surface must lie within the boundary. To invoke this concept, the term BOUNDARY is placed beneath the positional tolerance feature control...
Profile Control
A profile is the outline of an object in a given plane two-dimensional figure . Profiles are formed by projecting a three-dimensional figure onto a plane or by taking cross sections through the figure. The elements of a profile are straight lines, arcs, and other curved lines. If the drawing specifies individual tolerances for the elements or points of a profile, these elements or points must be individually verified. Such a procedure may be impracticable in certain cases, particularly where...
Fig Specifying Runout Relative To Two Datum Oiameters
of sufficient length. Figure 6-47 incorporates the principle of circular runout tolerancing and illustrates the control of circular elements of a surface. Figure 6-48 incorporates the principle of total runout tolerancing and illustrates the control of an entire surface. 6.7.1.3.2 Two Datum Diameters. Figure 6-49 illustrates application of runout tolerances where wo datum diameters collectively establish a single datum axis to which the features are related. 6.7.1.3.3 Diameter and Face Datums....
Bidirectional Positional Tolerancing Of Features
Where it is desired to specify a greater tolerance in one direction than another, bidirectional positional tolerancing may be applied. Bidirectional positional tolerancing results in a noncylindrical tolerance zone for locating round holes therefore, the diameter symbol is omitted from the feature control frame in these applications. FIG. amp -36 NONPARALLEL HOLES INCLUDING THOSE NOT NORMAL TO SURFACE FIG. 5-37 SAME POSITIONAL TOLERANCE FOR HOLES AND COUNTERBORES, SAME DATUM REFERENCES FIG....
Direct Tolerancing Methods
Limits and directly applied tolerance values are specified as follows. a Limit Dimensioning. The high limit maximum value is placed above the low limit minimum value . When expressed in a single line, the low limit precedes the high limit and a dash separates the two values. See Fig. 2-1. b Plus and Minus Tolerancing. The dimension is given first and is followed by a plus and minus expression of tolerance. See Fig. 2-2. 2.2.1 Metric Limits and Rts For metric application of limits and fits, the...
Info Khc
Feature-relating tolerance zone cylinder Pattern-locating tolerance zone cylinder Actual feature pattern. All feature axes must simultaneously lie within both the pattern and feature locating tolerance zones Pattern-locating tolerance zone cylinder Feature-relating tolerance zone cylinder relative to datum plane A One possible displacement of actual feature pattern. relative to datum plane A One possible displacement of actual feature pattern. FIG. 5-23 POSITIONAL TOLERANCING WITH MULTIPLE...
General
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. 1.1.1 Section 1, General. This Section establishes definitions, fundamental rules, and practices for general dimensioning that...
Zero Positional Tolerance at MMC In
the preceding explanation, a positional tolerance of some magnitude is specified for the location of features. The application of MMC permits the tolerance to exceed the value specified, provided features are within size limits, and the feature locations are such as to make the part acceptable. However, rejection of usable parts can occur where these features are actually located on or close to their true positions, but produced to a size smaller than the specified minimum outside of limits ....
Datum Features
A datum feature is selected on the basis of its geometric relationship to the toleranced feature and the requirements of the design. To ensure proper assembly, corresponding interfacing features of mating parts should be selected as datum features. However, a datum feature should be accessible on the part and be of sufficient size to permit its use. Datum features must be readily discernible on the part. Therefore, in the case of symmetrical parts or parts with identical features, physical...
Fig Hole Patterns Of Fig Two Singlesegment Feature Control Frames With
pattern, and Fig. 5-20 f for the six-hole pattern of features shown in Fig. 5-20. 5.4.1.3 Two Single-Segment Feature Control Frames. Where it is desired to invoke basic dimensions along with the datum references, single-segment feature control frames are used. See Fig. 3-22 b . Figure 5-21 shows two single-segment feature control frames. The lower feature control frame repeats datums A and B. Figure 5-21 c shows that the tolerance cylinders of the FRTZF as a group are free to be displaced to...
I Nkt
FIG. 5-29 RELATIONSHIPS OF FEATURE-RELATING TOLERANCE ZONE FRAMEWORK FRTZF TO PATTERN-LOCATING TOLERANCE ZONE FRAMEWORK PLTZF One possible displacement of Feature-relating tolerance cylinders Tolerance zones of PLTZF as a group are One possible displacement of Feature-relating tolerance cylinders Datum center plane C Pattern-locating tolerance cylinders Pattern-locating tolerance zone framework PLTZF - Tolerance zones of PLTZF as a group are perpendicular to A, positioned to B. arid fixed on C...
L 1
Smallest pair of coaxial circumscribed cylinders- RG. 4-21 TWO DATUM FEATURES AT RFS, SINGLE DATUM AXIS ders. as explained in para. 4.5.3 a . A datum axis established by coaxial datum features is normally used as a primary datum. For one possible method of controlling the coaxiality of these diameters, see para. 6.7.1.3.4 4.5.8 Pattern of Features. Multiple features of size, such as a pattern of holes at MMC, may be used as a group to establish a datum when part function dictates. See Fig....
Units Of Measurement
For uniformity, all dimensions in this Standard are given in SI units. However, the unit of measurement selected should be in accordance with the policy of the user. 1.5.1 SI Metric Linear Units. The commonly used SI linear unit used on engineering drawings is the millimeter. 1.5.2 U.S. Customary Linear Units. The commonly used U.S. customary linear unit used on engineering drawings is the decimal inch. 1.5.3 Identification of Linear Units. On drawings where all dimensions are either in...
Fig Different Positional Tolerance At Each End Of Long Hole
NOTE A further refinement of perpendicularity within the positional tolerance may be required. NOTE A further refinement of perpendicularity within the positional tolerance may be required. 5.9.1 Rectangular Coordinate Method. For holes located by rectangular coordinate dimensions, separate feature control frames are used to indicate the direction and magnitude of each positional tolerance relative to specified datums. See Fig. 5-41. The feature control frames are attached to dimension lines...
Fig Sequence Of Datum Features Relates Part To Datum Reference Frame
mary datum feature relates the part to the datum reference frame by bringing a minimum of three points on the surface into contact with the first datum plane. See Fig. 4-3 a . The part is further related to the frame by bringing at least two points of the secondary datum feature into contact with the second datum plane. See Fig. 4-3 b . The relationship is completed by bringing at least one point of the tertiary datum feature into contact with the third datum plane. See Fig. 4-3 c . As...
B Limits And Fits
The formulas for positional tolerancing are also applicable where requirements for the size and fit of mating features are specified by symbols. See ANSI B4.2, which explains the use of symbols. For preferred sizes and fits, tables are provided therein giving the appropriate MMC limits. For other fit conditions, these limits must be calculated using tables in the appendix that list deviations from the basic size for each tolerance zone symbol alphanumeric designation . EXAMPLE Given the parts...
Info Nsf
Each longitudinal element of the surlace must lie between two parallel lines 0.02 apart where the two lines and the nominal axis of the part share a common plane. The feature must be within the specified limits of size and the boundary of perfect form at MMC 16.00 . Each longitudinal element of the surlace must lie between two parallel lines 0.02 apart where the two lines and the nominal axis of the part share a common plane. The feature must be within the specified limits of size and the...
May Be Applied As A Means Of Preventing An Abrupt Surface Variation Within A
0.1 diameter tolerance zone in each 25 mm of length The derived median line of the feature's actual local size must lie within a cylindrical tolerance zone of 0.4 diameter for the total 100 mm of length and within a 0.1 cylindrical tolerance zone for any 25 mm length, regardless of feature size. Each circular element of the surface must be within the specified limits of size. The derived median line of the feature's actual local size must lie within a cylindrical tolerance zone of 0.4 diameter...
Definitions
The following terms are defined as their use applies in this Standard. Additionally, definitions throughout the Standard of italicized terms are given in sections describing their application. Their location may be identified by referring to the index. 1.3.1 Boundary, Innar. A worst case boundary that is, locus generated by the smallest feature MMC for an internal feature and LMC for an external feature minus the stated geometric tolerance and any additional geometric tolerance if applicable...
Coaxiauty Controls
Coaxiality is that condition where the axes of two or more surfaces of revolution are coincident. The amount of permissible variation from coaxiality may be expressed by a positional tolerance or a runout tolerance. Selection of the proper control depends on the nature of the functional requirements of the design. 5.11.1 Positional Tolaranca Control. Where the surfaces of revolution are cylindrical and the control of the axes can be applied on a material condition basis, positional tolerancing...
Fig Positional Tolerancing At Mmc Relative To Datum Feature Center Planes
5.3.1 Material Condition Basis. Positional tol-erancing is applied on an MMC, RFS, or LMC basis. When MMC or LMC is required, the appropriate modifier follows the specified tolerance and applicable datum reference in the feature control frame. See para. 2.8. 5.3.2 MMC as Related to Positional Toler-ancing. The positional tolerance and maximum material condition of mating features are considered in relation to each other. MMC by itself means a feature of a finished product contains the maximum...
Fundamental Rules
Dimensioning and tolerancing shall clearly define engineering intent and shall conform to the following. a Each dimension shall have a tolerance, except for those dimensions specifically identified as reference, maximum, minimum, or stock commercial stock size . The tolerance may be applied directly to the dimension or indirectly in the case of basic dimensions , indicated by a general note, or located in a supplementary block of the drawing format. See ANSI Y14.1. b Dimensioning and...
B Coaxial Features
The formula previously given for the floating fastener case also applies to mating parts having two coaxial features where one of these features is a datum for the other. See Fig. B-3. Where it is desired to divide the available tolerance unequally between the parts, the following formula is useful This formula is valid only for simple two-feature parts as shown here. Consideration must be given for other geometric conditions that may be required for ftinction. EXAMPLE Given the information...
Fig Positional Tolerancing Of Slots 1
5.10.1 Noncircular Features at MMC. Where a positional tolerance of a noncircular feature applies at MMC, the following apply. a In Terms of the Surfaces of a Feature. While maintaining the specified width limits of the feature, no element of its side surfaces shall be inside a theoretical boundary defined by two parallel planes equally disposed about true position and separated by a distance equal to that shown for W in Fig. 5-45. b In Terms of the Center Plane of a Feature. While maintaining...
Parts With Cylindrical Datum Features
A cylindrical datum feature is always associated with two theoretical planes intersecting at right angles on the datum axis. The datum of a cylindrical surface is the axis of the true geometric counterpart of the datum feature for example, the actual mating envelope or the virtual condition boundary , and simulated by the axis of a cylinder in the processing equipment. This axis serves as the origin of measurement from which other features of the part are located. See Figs. 4-5. 4-11, and 4-12....
Multiple Datum Reference Frames
More than one datum reference frame may be necessary for certain parts, depending upon functional requirements. In Fig. 4-24, datum features A, B, and C establish one datum reference frame, while datum features D, B, and C and datum features D, E, and B establish different datum reference frames. 4.5.11.1 Functional Datum Features. Only the required datum features should be referenced in feature control frames when specifying geometric tolerances. An understanding of the geometric control...
Fig E Datum Selections
in the diagrams. When datums are applicable, the user is referred to Fig. E-7. E7.1 Datum Modifiers. When a feature of size has been selected as a datum, a material condition modifier must be considered. See Fig. E-7 and para. 2.8. E7.2 Multiple Datums. Some applications require only a primary datum, while others may need secondary and tertiary datums. When more than one datum is needed, the diagrams loop back until the datum reference framework is complete. See Fig. E-7.
Runout 1
Runout is a composite tolcrance used to control the functional relationship of one or more features of a pan to a datum axis. 6.7.1 Runout Tolerance. The types of features controlled by runout tolerances include those surfaces constructed around a datum axis and those constructed at right angles to a datum axis. See Fig. 6-46. 6.7.1.1 Basis of Control. The datum axis is established by a diameter of sufficient length, two diameters having sufficient axial separation, or a diameter and a face at...
Calculating Positional Tolerance
Figure 5-9 shows a drawing for one of two identical plates to be assembled with four 14 mm maximum diameter fasteners. The 14.25 minimum diameter clearance holes are selected with a size tolerance as shown. Using conventional positional tolerancing, the required tolerance is found by the equation as given in para. B3 of Appendix B. T H - F 14.25 - 14 0.25 diameter Cylindrical tolerance zone equal to positional tolerance Axis of hole at true position Axis of hole Is Axis of hole Is located Axis...
Specifying Datum Features at MMC
Where a datum feature of size is applied on an MMC basis, machine and gaging elements in the processing equipment that remain constant in size may be used to simulate a true geometric counterpart of the feature and to establish the datum. In each case, the size of the true geometric counterpart is determined by the specified MMC limit of size of the datum feature, or its MMC virtual condition, where applicable. 4.5.4.1 Size of a Primary or Single Datum Feature. Where a primary or single datum...
Fig Projected Tolerance Zone Applied For Studs Or Dowel Pins 1
One feature control frame is placed under the callout specifying hole requirements and the other under the callout specifying counterbore requirements. See Fig. 5-38. Different diameter tolerance zones for hole and counterbore are coaxially located at true position relative to the specified datums. c Where positional tolerances are used to locate holes and to control individual counterbore-to-hole relationships relative to different datum features , two feature control frames are used as in b...
MEANS THIS Buh
Possible orientation of feature axis Possible orientation of feature axis Where the thread profile is at MMC, the feature axis must lie within a cylindrical zone 0.3 diameter which is perpendicular to and projects from datum plane A for the 14 specified height. The feature axis must be within the specified tolerance of location over the projected height. Note A threaded hole is located and gaged from Its thread profile at MMC. Consideration must be given to the additive tolerance which results...
MEANS THIS Gzx
Simulated datum feature Surface of manufacturing or verification equipment Simulated datum piano A Plane derived from the datum feature simulator Simulated datum feature Surface of manufacturing or verification equipment a Workplece amp datum feature simulator prior to contact Simulated datum plane A Plane derived from the datum feature simulator b Workplece amp datum feature simulator In contact FIG. 4-10 DATUM FEATURE. SIMULATED DATUM, AND THEORETICAL DATUM PLANE
Fig Symmetrical Outlines 1
1.8.9 Round Holds. Round holes are dimensioned as shown in Fig. 1-34. Where it is not clear that a hole goes through, the abbreviation THRU follows a dimension. The depth dimension of a blind hole is the depth of the full diameter from the outer surface of the part. Where the depth dimension is not clear, as from a curved surface, the depth should be dimensioned. For methods of specifying blind holes, see Fig. 1-34. 1.8.10 Slotted Holes. Slotted holes are dimensioned as shown in Fig. 1-35. The...
Projected Tolerance Zone 1
The application of this concept is recommended where the variation in perpendicularity of threaded or press-fit holes could cause fasteners, such as screws, studs, or pins, to interfere with mating parts. See Fig. 5-31. An interference can occur where a tolerance is specified for the location of a threaded or press-fit hole, and the hole is inclined within the positional limits. Unlike the floating fastener application involving clearance holes only, the attitude of a fixed fastener is governed...
A Figures
Figures have been revised to add a paragraph number s in the lower right corner. This notation is provided to assist users in locating the principal paragraph s that refers to the illustration. All figures have been revised, where applicable, to show the universal International Organization for Standardization ISO datum feature symbol being introduced in this issue of the Standard. All figures have been revised, where applicable, to remove the RFS symbol, which is no longer necessary. A3...
Radius
A radius is any straight line extending from the center to the periphery of a circle or sphere. 2.15.1 Radius Tolerance. A radius symbol R creates a zone defined by two arcs the minimum and maximum radii . The part surface must lie within this zone. See Fig. 2-18. NOTE This is a change from the previous editions of this Standard. See Appendix D. 2.15.2 Controlled Radius Tolerance. A controlled radius symbol CR creates a tolerance zone defined by two arcs the minimum and maximum radii that are...
A A 1
All Around Arc Length Basic Dimension SymboL 3.3.4 Between Counterbore or Spotface Symbol 3.3.12 Countersink Datum Feature Symbol 3.3.2, 3.4.6 Datum Target Depth Diameter and Radius Symbols 3.3.7 Dimension Origin Symbol 3.3.16 Free State Geometric Characteristic Symbols 3.3.1 Material Condition Symbols 3.3.5 Projected Tolerance Zone Symbol 3.3.6 Reference Square Statistical Tolerancing Symbol 3.3.10 Surface Texture Symbols 1.2. 3.3.21 Symbol Symbols for Limits and Fits 3.3.22 Tangent Plane...
Fig Specifying Restraint For Nonrigid Parts
forces are those that would be exerted in the assembly or functioning of the part. However, if the dimensions and tolerances are met in the free state, it is usually not necessary to restrain the part unless the effect of subsequent restraining forces on the concerned features could cause other features of the part to exceed specified limits. Free state variation of nonrigid parts may be controlled as described in the following paragraphs. 6.8.1 Specifying Geometric Tolerances on Features...
Fig Rectangular Coordinate Dimensioning Without Dimension Lines
1.9.1 Rectangular Coordinate Dimensioning. Where rectangular coordinate dimensioning is used to locate features, linear dimensions specify distances in coordinate directions from two or three mutually perpendicular planes. See Fig. 1-48. Coordinate dimensioning must clearly indicate which features of the part establish these planes. For methods to accomplish this, see Section 4. 1.9.2 Rectangular Coordinate Dimensioning Without Dimension Lines. Dimensions may be shown on extension lines without...
Fig Specifying Straightness Of Surface Elements
specified size tolerance. Each longitudinal element of the surface must lie between two parallel lines separated by the amount of the prescribed straightness tolerance and in a plane common with the nominal axis of the feature. The feature control frame is attached to a leader directed to the surface or extension line of the surface but not to the size dimension. The straightness tolerance must be less than the size tolerance. Since the limits of size must be respected, the full straightness...
Fig Symbol For All Around 1
3.3.17 Taper and Slope Symbols. The symbolic means of indicating taper and slope for conical and flat tapers are shown in Figs. 2-15 and 2-17. These symbols are always shown with the vertical leg to the left. 3.3.18 All Around Symbol. The symbolic means of indicating that a tolerance applies to surfaces all around the part is a circle located at the junction of the leader from the feature control frame. See Fig. 3-17. 3.3.19 Free State Symbol. For features subject to free state variation as...
Info Het
Datum plane B True geometric counterpart of datum feature B Perpendicular to datum axis A True geometric counterpart of datum feature A Smallest circumscribed cylinder Datum plane B True geometric counterpart of datum feature B -True geometric counterpart of datum feature A Smallest circumscribed cylinder perpendicular to datum plane B Datum plane B True geometric counterpart of datum feature B Datum plane B True geometric counterpart of datum feature B
Fig Radial Hole Pattern Located By Composite Positional Tolerancing
FIG. 6-24 RADIAL HOLE PATTERN LOCATED BY COMPOSITE POSITIONAL TOLERANCING CONT'D Tolerance Zones for Radial Hole Pattern FIG. 6-24 RADIAL HOLE PATTERN LOCATED BY COMPOSITE POSITIONAL TOLERANCING CONT'D Tolerance Zones for Radial Hole Pattern 4X 00.6 pattern-locating tolerance zone cylinders at MMC. Pattern-locating tolerance zone framework PLTZF la located and oriented relative to datum plane A and datum axis B no rotational requirements r 4X 00.25 feature-relating tolerance zone cylinders at...
Fig Specifying Profile Of A Surface For Coplanar Surfaces
for the features being controlled. The tolerance zone thus established applies to all coplanar surfaces including datum surfaces. See Fig. 6-21. 6.5.7 Profile Tolerance for Plane Surfaces. Profile tolerancing may be used to control form and orientation of plane surfaces. In Fig. 6-22, profile of a surface is used to control a plane surface inclined to a datum feature. 6.5.8 Profile Tolerance for a Conical Feature. A profile tolerance may be specified to control the conicity of a surface in...
First Part Of
CALLOUT MEANS THIS Datum plane A Pattern-locating tolerance zone framework PLTZF . 01 tolerance cylinders basically located and oriented relative to each other and to the specified datum reference frame. FIG. 5-22 COMPOSITE POSITIONAL TOLERANCING OF A CIRCULAR PATTERN OF FEATURES CONTD ADDITIONALLY, SECOND PART OF CALLOUT MEANS THIS One possible location and orientation of feature-relating tolerance zone framework FRTZF relative to pattern-locating tolerance zone framework PLTZF . FIG. amp -22...