Geometric dimensioning and tolerance- form tolerance

Gd and t

1. Geometric Dimensioning and
Tolerancing (GD&T)

Form Tolerance

2. Straightness Tolerance
•A straightness tolerance is a geometric
tolerance that defines the straightness
deviation permitted on individual surface
elements or on a derived median line.

5. Types of Straightness Deviations

6. Rule#1’s Effect on Straightness Deviation of
a Derived Median Line

7. Applications of Straightness Tolerances

8. Straightness Applied to a Surface

9. Straightness Tolerance Application

10. Straightness Tolerance Applied to a
Feature of Size (FoS)

11. Significant Questions on Straightness Tolerance

12. •Verifying a
straightness Tolerance
Zone

13. Straightness Tolerance (at MMC)
applied to a FoS

14. Flatness
•Flatness Tolerance is a geometric tolerance
that defines the allowable flatness deviation
permitted on a planar surface or derived
median plane.

15. How Rule#1 affects the Flatness on a Surface

16. Flatness applied to a Surface

17. Flatness @MMC applied to a FoS

18. Significant Questions on Flatness Tolerance

19. Verifying a Flatness Tolerance applied to a Planar
Surface

20. Verifying Flatness Tolerance @ MMC applied to a FoS

21. Circularity Tolerance
•A circularity tolerance is a geometric tolerance that
limits the circularity deviation (radial deviation
between highest and lowest points) on individual
circular elements. A circularity tolerance:
–Is one of the four direct form tolerances.
–Never uses a datum feature reference.
–Can only be applied to a single feature with circular cross
sections (eg sphere, cylinder, cone, etc).
–Applies to each circular element of a surface
independently.

22. Rule # 1 Effects on Circularity
Tolerance

23. Circularity Deviations

24. Circularity Tolerance applied to a
Surface

25. Circularity Tolerance and its Tolerance
Zone

26. Significant Questions Applied to a
Circularity Tolerance

27. Roundness Gage

28. Cylindricity Tolerance
•A cylindricity tolerance is a geometric tolerance
that defines the deviation permitted on a
cylindrical surface. A cylindricity tolerance
applies along the entire cylindrical surface
simultaneously.
•A cylindricity tolerance:
–Is one of the four direct form tolerances
–Never uses a datum feature reference
–Can only be applied to a single cylindrical feature
–Applies to the entire surface simultaneously.

29. Cylindricity Tolerance Zone may contain any
Combination of these Form Deviations

30. Cylindricity Tolerance and Tolerance Zone

31. Rule #1 effects on Cylindricity Deviation of a Surface

32. Significant Questions applied to a Cylindricity Tolerance