1. DPT 312 METROLOGY CHAPTER 3 MEASUREMENT AND TOLERANCES
ROSHALIZA HAMIDON (DPT /09)

2. Introduction Geometric dimensioning and tolerancing
DEFINITION
Engineering design
What is to be manufactured?
Product
What has been manufactured?
Part inspection
How we compare the product
with the engineering design?
Geometric dimensioning and tolerancing
Ensure the most economical and effective production of the parts
ROSHALIZA HAMIDON (DPT /09)

3. ROSHALIZA HAMIDON (DPT 312 08/09)
Tolerance
The total amount that a specific dimension is permitted to vary
In dimensional metrology, tolerances are applied to both position (where) and size (how big) dimensions (see figure 3.1)
Both types of dimensions must have tolerances for economical manufacture
ROSHALIZA HAMIDON (DPT /09)

4. ROSHALIZA HAMIDON (DPT 312 08/09)B D C E A B D C E A B D C E A B D C E
Figure 3.1 Tolerances apply to both dimensions of size (A,B, E) location and dimensions of location ( C and D)
ROSHALIZA HAMIDON (DPT /09)

5. Geometric dimensioning and tolerancing (GD&T)
GD&T is a means of dimensioning and tolerancing a drawing with respect to the actual function or relationship of part features that can be most economically produced
It is a language of symbols used on mechanical drawings to efficiently, and accurately communicate geometry requirements for features on parts and assemblies.
This type of dimensioning and tolerancing should be used when:
Features are critical to be functionality or interchange ability of the part
Datum references are desirable to ensure consistency between design, manufacturing and inspection
Computerization techniques in design and manufacturing are being used or are desirable
Standard interpretation or tolerance is not already implied
ROSHALIZA HAMIDON (DPT /09)

6. ROSHALIZA HAMIDON (DPT 312 08/09)
Key terms in GD&T
Feature – general term applied to a physical portion of a part such as a surface, hole or slot
Datum- a theoretically exact plane, point axis from which a dimension is measured
Datum feature – part feature that contacts a datum (use as the origin for measurement)
Datum reference plane- a set of three mutually perpendicular datum planes (see figure 3.2)
Feature of size- one cylindrical or spherical surface, or a set of two opposed parallel surface associated with a size dimension
i. internal – the diameter of a hole or the width of a slot
ii. External – the width or length of a block or a shaft diameter
ROSHALIZA HAMIDON (DPT /09)

7. Figure 3.2: Datum Reference Plane
ROSHALIZA HAMIDON (DPT /09)

8. ROSHALIZA HAMIDON (DPT 312 08/09)
SYMBOL AND MODIFIERS
The language of geometric tolerancing is a set of symbols.
This symbols are divided into five types of dimensioning control
Form
Profile
Orientation
Location
Runout
* Geometric controls of form never use a datum reference.
*Form control (straightness, flatness, circularity or cylindricity) are always relative to themselves and not other features.
*some geometric controls (orietation, location, or runout) must have a datum reference
ROSHALIZA HAMIDON (DPT /09)

9. ROSHALIZA HAMIDON (DPT 312 08/09)
1. Form tolerance
State how far an actual surface or feature is permitted to vary from the desired form implied by the drawing
ROSHALIZA HAMIDON (DPT /09)

10. ROSHALIZA HAMIDON (DPT 312 08/09)
2. Profile tolerance
States how far an actual surface or feature is permitted to vary from the desired form on the drawing and/ or vary relative to a datum
ROSHALIZA HAMIDON (DPT /09)

11. 3. Orientation tolerance
States how far an actual surface or feature is permitted to vary relative to a datum
ROSHALIZA HAMIDON (DPT /09)

12. ROSHALIZA HAMIDON (DPT 312 08/09)
4. Location tolerance
States how far an actual size feature is permitted to vary from the perfect location implied by the drawing as related to a datum or other feature
ROSHALIZA HAMIDON (DPT /09)

13. ROSHALIZA HAMIDON (DPT 312 08/09)
5. Runout feature
States how far an actual surface or feature is permitted to vary from the desired form implied by the drawing during full 360 degree rotation of the part on a datum axis
ROSHALIZA HAMIDON (DPT /09)

14. ROSHALIZA HAMIDON (DPT 312 08/09)
Material condition
Maximum material condition (MMC)
The condition in which a feature of size contains the materials within its stated tolerance limit
Least material condition (LMC)
LMC is the condition in which a feature of size contains the least amount of material within its permissible limits
Regardless of Feature Size (RFS)
Indicates a geometric tolerance that applies at any increment of size of the feature within its permissible limits.
ROSHALIZA HAMIDON (DPT /09)

15. APPLICATION OF GEOMETRIC TOLERANCING
Form tolerance
Straightness
Flatness
Circularity (Roundness)
Cylindricity
Profile tolerance
Profile of line
Profile of surface
Orientation tolerances
Angularity
Perpendicularity
Parallelism
Location tolerance
Position
Concentricity
Symmetry
Runout tolerances
Circular runout
Total runout
ROSHALIZA HAMIDON (DPT /09)

16. ROSHALIZA HAMIDON (DPT 312 08/09)
1. Form Tolerance
State how far an actual surface or feature is permitted to vary from the desired for
Straightness , flatness, circularity, and cylindricity are most frequently applied to single features or portions of a feature.
ROSHALIZA HAMIDON (DPT /09)

17. ROSHALIZA HAMIDON (DPT 312 08/09)
i. Straightness
The condition where one line element of an axis, or surface is in straight line. (see figure 3.3)
Straightness tolerances can be applied to an axis or to a surface
ROSHALIZA HAMIDON (DPT /09)

18. Figure 3.3: Straightness tolerance
ROSHALIZA HAMIDON (DPT /09)

19. The tolerance zone is a space between two parallel straight lines
When applied to an axis, straightness is specified in the view where the axis is in straight line
The tolerance zone is a space between two parallel straight lines
MMC of LMC
Figure 3.4: Straightness tolerance applied to an axis
ROSHALIZA HAMIDON (DPT /09)

20. Figure 3.5: Straightness tolerance applied to a surface
When a surface is to be controlled, the feature control frame is attached to the surface with leader or extension line
RFS
Figure 3.5: Straightness tolerance applied to a surface
ROSHALIZA HAMIDON (DPT /09)

21. ROSHALIZA HAMIDON (DPT 312 08/09)
ii. Flatness
The condition of surface having all elements in one plane
When flatness is specified, the feature control frame is attached directly to the surface or to an extension line of the surface
The flatness tolerance zone is defined by two parallel planes
All points of the surface must be within the limits of the tolerance zone defined by these two planes. (see figure 3.6)
The smaller the tolerance zone, the flatter the surface
Always applied RFS, no feature modifier such as MMC or LMC are allowed T
ROSHALIZA HAMIDON (DPT /09)

22. Flatness (cont’) Figure 3.6: Flatness tolerance
ROSHALIZA HAMIDON (DPT /09)

23. iii. Circularity (roundness)
Circularity is identified with any given cross section taken perpendicular to the axis of a cylinder or cone or through the center of sphere
The tolerance is bounded by two concentric circles
Each circular element of the surface must be contained within these concentric circles
The circularity tolerance must be less than the size tolerance, except for parts subject to free state variation
For RFS
ROSHALIZA HAMIDON (DPT /09)

24. ROSHALIZA HAMIDON (DPT 312 08/09)
Figure 3.7: Circularity tolerance
ROSHALIZA HAMIDON (DPT /09)

25. ROSHALIZA HAMIDON (DPT 312 08/09)
iv. Cylindricity
Defined as the condition of a surface of revolution in which all points of the surface are equidistant from a common axis
The tolerance zone for cylindricity is bound by two concentric cylinder
All surface elements must lie within these concentric circles
The tolerance applies simultaneously to both the circular and the longitudinal elements of the surface
For RFS
ROSHALIZA HAMIDON (DPT /09)

26. Figure 3.8: Cylindricity tolerance
ROSHALIZA HAMIDON (DPT /09)

27. ROSHALIZA HAMIDON (DPT 312 08/09)
2. Profile tolerance
Allows us to control the form or shape of a surface
A profile is the outline of an object represented by a cross section through the part or by and end view of the part
Basic dimensions are generally used to define a profile
Profile tolerance can be applied as either a profile of line, or profile or a surface
ROSHALIZA HAMIDON (DPT /09)

28. ROSHALIZA HAMIDON (DPT 312 08/09)
i. Profile of line
Used where parts have a change in the cross section through the length
The tolerance zone is two dimensional, extending along the length of the applicable feature
See figure 3.9
ROSHALIZA HAMIDON (DPT /09)

29. Figure 3.9: Profile of a line with all around symbol
ROSHALIZA HAMIDON (DPT /09)

30. ROSHALIZA HAMIDON (DPT 312 08/09)
ii. Profile of a surface
Use to control the entire surface of single entity
The tolerance zone is three dimensional, extending along the total length and width or circumference of the part or feature
ROSHALIZA HAMIDON (DPT /09)

31. Figure 3.10 Application of profile of a surface
ROSHALIZA HAMIDON (DPT /09)

32. 3. Orientation tolerance
Orientation tolerance control features in relation to one another; therefore a datum reference is required
Orientation controls can be applied to the surface or the axis of the part feature.
Angularity, parallelism, and perpendicularity are orientation tolerances
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33. ROSHALIZA HAMIDON (DPT 312 08/09)
i. Angularity
Angularity is the condition of a surface, center plane, or axis at a specific angle from a datum plane or axis.
The tolerance zone is established by two parallel planes or a cylindrical zone at any specified angle other than 90%, to a datum plane or an axis
Where angularity is applied to a surface, the feature control frame is connected to the surface by a leader
See figure 3.11
The angle is specified by a basic angle from the datum plane
For RFS
ROSHALIZA HAMIDON (DPT /09)

34. Angularity tolerance applied to a surface
Angularity tolerance applied to an axis
Figure 3.11
ROSHALIZA HAMIDON (DPT /09)

35. ROSHALIZA HAMIDON (DPT 312 08/09)
ii. Perpendicularity
Perpendicularity is the condition when a surface, center plane or axis is at exactly 90 degree to a datum
The tolerance zone for perpendicularity is established by two parallel planes or cylindrical zones that are 90 degree to a specified datum plane or axis
Perpendicularity can be applied to a surface or an axis
When applied to a surface, the shape of the tolerance zone is parallel planes that are at a 90 degree angle to a datum plane.
See figure 3.12
The tolerance value identifies the size of the tolerance zone
All elements of the surface must lie within this tolerance zone
For RFS
ROSHALIZA HAMIDON (DPT /09)

36. Perpendicularity tolerance applied to surface
Figure 3.12
Perpendicularity tolerance applied to surface
Perpendicularity tolerance applied to an axis
ROSHALIZA HAMIDON (DPT /09)

37. ROSHALIZA HAMIDON (DPT 312 08/09)
iii. Parallelism
Parallelism is the condition where a surface, center plane or axis is exactly parallel to a datum.
Parallelism may be applied to a surface, resulting in a tolerance zone of two parallel planes, or applied to an axis resulting in a cylindrical tolerance zone.
When surface is controlled parallel to a datum, all elements of that surface must lie within two parallel planes, parallel to the datum
Parallelism may be applied to the axis of two or more features where a parallel relationship is required.
See figure 3.13
ROSHALIZA HAMIDON (DPT /09)

38. Parallelism tolerance applied to a surface
Figure 3.13
Parallelism tolerance applied to a surface
Parallelism tolerance applied to an axis
ROSHALIZA HAMIDON (DPT /09)

39. ROSHALIZA HAMIDON (DPT 312 08/09)
Location tolerance
Location tolerance are used to locate or position features from datums
Location tolerances include position, concentricity and symmetry
Position tolerancing provides the maximum benefit of GD&T, allowing increase in tolerance of the feature by 57% and reducing scrap
Location tolerances can be used to control position, symmetry and coaxiality
ROSHALIZA HAMIDON (DPT /09)

40. ROSHALIZA HAMIDON (DPT 312 08/09)
i. Position
Position tolerance defines a condition where the center, axis or center plane of a feature of size is allowed to vary from true position
True position is the theoretically exact location of a feature.
The location of each feature is given by basic dimension and the location tolerance is indicated by the position symbol, a tolerance value, applicable modifiers and datum references
ROSHALIZA HAMIDON (DPT /09)

41. ROSHALIZA HAMIDON (DPT 312 08/09)
Figure 3.14: Position tolerance
ROSHALIZA HAMIDON (DPT /09)

42. ROSHALIZA HAMIDON (DPT 312 08/09)
ii. Concentricity
Concentricity is used to control the relationship between the axes of two or more cylindrical features.
When the axes of each cylinder fall on the same centerline, they are concentric. (see figure 3.15)
The tolerance zone for concentricity is a cylindrical tolerance zone whose axis coincide with the axis of the datum feature
Concentricity is a relative measurement, so it requires a datum specification
The tolerance can only be applied on an RFS basis
ROSHALIZA HAMIDON (DPT /09)

43. ROSHALIZA HAMIDON (DPT 312 08/09)
Figure 3.15: Concentricity tolerance. Concentricity is defined as the condition where all median points of diametrically opposed elements of a cylinder are congruent with the axis of a datum feature
ROSHALIZA HAMIDON (DPT /09)

44. ROSHALIZA HAMIDON (DPT 312 08/09)
iii. Symmetry
Symmetry is a positional tolerance where the median points of all opposed elements of two or more feature are congruent with the axis or center plane of a datum feature
Concentricity and symmetry are similar concepts
The difference is that they are applied to different geometric configurations- concentricity applies to cylindrical features while symmetry is applied to planar features
The tolerance zone is centered about the center plane of the datum
Symmetry is always used with a datum reference and applied on an RFS basis.
ROSHALIZA HAMIDON (DPT /09)

45. ROSHALIZA HAMIDON (DPT 312 08/09)
Figure 3.16: Symmetry tolerance
ROSHALIZA HAMIDON (DPT /09)

46. ROSHALIZA HAMIDON (DPT 312 08/09)
Runout tolerance
Runout tolerance are a combination of tolerances used to control the relationship of one or more features of a part to a datum axis.
The features can be surfaces perpendicular or surfaces around the datum axis
There are two types of runout control:
Circular runout
Total runout
ROSHALIZA HAMIDON (DPT /09)

47. ROSHALIZA HAMIDON (DPT 312 08/09)
Circular runout
Circular runout controls circularity and coaxiality (the condition where two or more features share a common axis)
The tolerance is measured by full indicator movement of a dial indicator placed at several locations while the part is rotated 360 degree.
Circular runout is measured as a single circular element at each measured location
ROSHALIZA HAMIDON (DPT /09)

48. Figure 3.17: Circular runout
ROSHALIZA HAMIDON (DPT /09)

49. ROSHALIZA HAMIDON (DPT 312 08/09)
Total runout
Total runout is used to provide total composite control of all surface elements. (see figure 3.18)
The total tolerance is applied to both circular elements and the profile
When applied to the surface around and at right angle to a datum axis, total run out may be used to control a combination of circularity, straightness, angularity, taper and profile.
ROSHALIZA HAMIDON (DPT /09)

50. ROSHALIZA HAMIDON (DPT 312 08/09)
Figure 3.18: Total runout
ROSHALIZA HAMIDON (DPT /09)

51. ROSHALIZA HAMIDON (DPT 312 08/09)
References
Dotson C.l., Fundamentals of Dimensional Metrology, Thomson Delmar Learning, 2006
Meadows J.D., Measurement of Geometric Tolerance in Manufacturing, Marcel Dekker, 1998
Griffith G.K, Geometric Dimensioning and Tolerancing, Prentice Hall, 2002.
ROSHALIZA HAMIDON (DPT /09)