Dim. and Tolerance ASME standard

1. MAHAM KAMRAN
UZAIR AHMED
ASFAND ALI TARIQ
SHAHEER AHMED
KHALID QASEEM
HASEEB UR REHMAN
ASME Y14.5-2018
(REVISION OF ASME Y14.5-2009)
Dimensioning
and Tolerancing

2. Tolerancing, Interpretation of Limits,
Limits of Size, Material and Symbology

3. Introduction
•Establishes different symbols, rules, definitions, requirements,
defaults, for the recommended practices.
•It helps in stating and interpreting dimensioning, tolerancing,
and related requirements for use on engineering drawings,
models defined in digital data files, and related documents.

4. Unilateral dimensions Tolerancing
Bilateral dimensions Tolerancing
Limit dimensions tolerancing
Basic Dimension Tolerancing
Angular dimension Tolerancing
Dimensioning of Units

5. Limit Dimensioning
Plus and Minus Dimensioning

6. Symbols
Symbols for Diameters and Radiuses
Symbology
Material/Boundary Condition Symbols

7. Counter Sink Symbol Depth Symbol
Counter Sunk Hole Symbol

8. Counterbore and Spotface symbols

9. Counter Bore Symbols
Size Meaning

10. Extreme Variations of Form Allowed by a Size Tolerance

11. Taper and Slope Symbols

12. Datum Referencing
Frames

13. Degrees of Freedom
The three translational degrees of freedom are termed x, y, and z.
The three rotational degrees of freedom are termed u, v, and w.

14. Definition
A datum reference frame is a coordinate system against which the geometric
dimensions and tolerances of a part are defined.
The main function of the datum reference frame is to specify a foundation for the
inspection of the part.
It is the common coordinate system of all tolerance zones. Without this common
coordinate system, product definition is unclear, rendering the inspection results
unreliable.
Symbols of a Datum Feature

15. Datum line and Feature Control
Datum line examples in drawings
Feature Control Frame

16. Precedence
of Datum
Features

17. Mutually Perpendicular Frames Number of Datum Reference Frames
Example of Datum Reference Frame

18. Example of Datum Reference Frame
There is a specific order of precedence of
datum features
Priority Datum

19. TOLERANCES OF FORM
SPECIFICATION OF FORM TOLERANCES
Form tolerances critical to function or interchangeability are specified
where the tolerances of size do not provide sufficient control.
A tolerance of form may be specified where no tolerance of size is given
FORM TOLERANCES
1. Straightness
2. Flatness
3. Circularity (Roundness)
4. Cylindricity
Figure 1 Types of Form Tolerences

20. FORM TOLERANCES-STRAIGHTNESS
1. Straightness of Line Elements
Straightness on flat surface shall lie between two parallel lines separated
by the amount of the prescribed straightness tolerance and in a direction
indicated by the orthographic view.
Figure 2 Specifying Straightness of a Flat Surface

21. FORM TOLERANCES-STRAIGHTNESS
2. Straightness of Line Elements on the Surface of
Cylindrical Features
Each longitudinal element of the surface shall lie between two parallel
lines separated by the amount of the prescribed straightness tolerance.
Figure 3 Specifying Straightness of a Surface Elements

22. FORM TOLERANCES-STRAIGHTNESS
3. Derived Median Line Straightness
When the feature control frame is associated with the size dimension or
attached to an extension of the dimension line of a cylindrical feature, the
straightness tolerance applies to the derived median line of the cylindrical
feature.
Figure 4 Specifying Straightness RFS

23. FORM TOLERANCES-STRAIGHTNESS
4. Applied on a Unit Basis
Straightness may be applied on a unit basis as a means of limiting an
abrupt surface variation within a relatively short length of the feature.
Figure 5 Specifying Straightness at MMC

24. FORM TOLERANCES-FLATNESS
1. Application of Flatness RFS, MMC, or LMC to Width
Flatness may be applied on an RFS, MMC, or LMC basis to width
features of size, and the tolerance value may be greater than the size
tolerance
Figure 6 Specifying Flatness per unit length RFS, with
no specified total

25. FORM TOLERANCES-FLATNESS
2. Applied on a Unit Basis
Flatness may be applied on a unit basis as a means of limiting an abrupt
surface variation within a relatively small area of the feature. The unit
variation is used either in combination with a specified total variation or
alone.
Figure 7 Specifying Flatness on Unit basis

26. FORM TOLERANCES-CIRCULARITY
A circularity tolerance specifies a tolerance zone bounded by two
concentric circles within which each circular element of the surface shall
lie, and applies independently at any plane.
Figure 8 Specifying Circularity

27. FORM TOLERANCES-CYLINDRICITY
A cylindricity tolerance specifies a tolerance zone bounded by two
concentric cylinders. The surface shall be within these two concentric
cylinders.
Figure 9 Specifying Cylindricity

28. AVERAGE DIAMETER
An average diameter is the average of several diametric measurements
across a circular or cylindrical feature.
Figure 10 Specifying Circularity With Average Diameter Figure 11 Specifying restraint for non-rigid parts

29. Orientation Control
•Control angular relationship such as parallelism, angularity and perpendicularity.
•It does not control the location of features.
•Tolerance zone shall be related to one or more datums.
•Constrained in rotational degrees of freedom not translational.

30. a tolerance zone defined by two parallel planes at the specified basic angle from, parallel to, or
perpendicular to one or more datum planes or datum axes, within which the surface, axis, or center plane
of the considered feature shall be contained.
Orientation Tolerance

31. a cylindrical tolerance zone at the specified basic angle from, parallel to, or perpendicular to one or more
datum planes or datum axes, within which the axis of the considered feature shall be contained.
Orientation Tolerance

32. Position Tolerance
•Position may be used to control the following relationships.
•center distance between features of size such as holes, slots, bosses, and tabs
•location of features of size as a group, from datums
•coaxial relationships of features of size
•symmetrical relationships of features of size

33. Components of Position
Tolerances
Dimensions used to locate true position shall be basic and defined
A feature control frame is added to the notation used to specify the size and number of features. Which
show different types of feature pattern dimensioning. Feature control frame

34. TOLERANCING FOR
SYMMETRICAL RELATIONSHIPS
FIGURE. POSITIONAL TOLERANCE AT MMC FOR SYMMETRICAL FEATURES

35. POSITIONAL TOLERNACE AT MMC
Zero Positional Tolerance
at MMC for Symmetrical
Relationships
Positional Tolerancing
RFS
FIGURE. POSITIONAL TOLERANCING RFS FOR
SYMMETRICAL FEATURES

36. TOLERNACES OF PROFILE
Types Of Profile Tolerances
Profile Of a Surface
Profile Of a Line
FIGURE. PROFILE OF A SURFACE APPLICATION

37. TOLERNACES OF PROFILE
PROFILE SPECIFICATION
PROFILE TOLERANCE AS A
GENERAL REQUIREMENT
FIGURE. PROFILE OF A LINE AND SIZE CONTROL

38. TOLERNACES ZONE BOUNDARIES
Uniform Tolerance Zone
BILATERAL PROFILE TOLERANCE
ZONE
Unequally Disposed Profile
Tolerance
All Around and All Over
Specification
FIGURE. SPECIFYING PROFILE OF A SURFACE

39. TOLERNACES ZONE BOUNDARIES
Non-Uniform Tolerance Zone
Drawing Indication
ZONES TO SMOOTH THE
TRANSITIONS
Alternative Practice
FIGURE. NON-UNIFORM PROFILE TOLERANCE ZONE

40. PROFILE APPLICATIONS
Profile Tolerance For Plane
Surfaces
Coplanarity
Offset Surfaces
Conical Surfaces
FIGURE. SPECIFYING PROFILE FOR PLANE SURFACES AND
CONICAL SURFACES

41. PROFILE APPLICATIONS
Profile on Non Size Datum
Features
Applications on Continuous
Features
FIGURE. SPECIFYING PROFILE FOR DATUM FEATURES AND
CONTINUOUS FEATURES

42. Composite Profile
Composite Profile Tolerancing of an Irregular Feature
Composite Profile Tolerance for a Single Feature.

43. Pattern Located by Composite Profile Tolerancing-
Repeated Primary Datum Feature Reference
 PLTZF. When composite controls are used, the uppermost
segment is the profile pattern-locating control. The PLTZF
specifies the larger profile tolerance for the location of the
pattern of profiled features as a group.
 FRTZF. Each of the lower segments is referred to as a
“profile feature-relating control.” They govern the smaller
tolerance for size, form, orientation, and location within the
pattern of features and may include constraints on rotation
of an FRTZF to specified datums

44. Pattern Located by Composite Profile Tolerancing- Repeated
Primary Datum Feature Reference

45. Irregular Shaped Feature with a Profile Size/Form Control and the Pattern
Located by Composite Profile Tolerance
• When the design requires that the size and form of one or more features be controlled independently of the
composite profile tolerance, a separate single-segment profile feature control frame is used followed by the term
“INDIVIDUALLY.”
• The size/form tolerance specified shall be less than the tolerance in the lower segment (FRTZF) of the
composite profile control

46. COMBINED CONTROLS
• Profile tolerancing may be combined with other types of geometric tolerancing.
• Profile tolerancing may be combined with positional tolerancing when it is necessary to control the boundary
of a noncylindrical feature.

47. PROFILE OFA LINE AS A REFINEMENT
• When it is a requirement to control individual line elements of a surface, a profile of a line tolerance is specified.
• This permits control of individual line elements of the surface independently in relation to the datum reference
frame and does not limit the total surface to an encompassing zone.

48. Dynamic Profile Tolerance
Controlling Form
• When the dynamic tolerance modifier is applied to a lower segment of a composite tolerance without datum
feature references,
• The tolerance zone controls the form but not the size of the feature and it uniformly progresses (expands or
contracts) normal to the true profile.

49. Dynamic Profile Tolerance Applied
to a Surface of Revolution
The dynamic profile tolerance may be applied to
surfaces of revolution to maintain the shape of the
considered feature while allowing its size to vary.

50. THANK YOU
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