Basics of geometric dimensioning and tolerancing according to ISO standards

Programme and exercises

1 Introduction:

• Structure of ISO versus ASME Standards.
• Classification of dimensions and tolerances.
• Basic principles of dimensioning.
• How GD&T was created.
• Disadvantages of coordinate dimensioning.
• Examples of proper and improper use of coordinate dimensioning.
• What is GD&T, advantages of its use.
• The advantages of using a convention in a serious sense.

2 Basic concepts and symbols:

• Key concepts.
• Theoretical dimension symbol.
• Tolerance frame.
• Symbols for basing.
• Classification and symbolism of geometric tolerances.

3 Additional symbols:

• Symbols for material conditions.
• Free status condition.
• Identifiers of the tolerated element.
• Identifiers of ancillary elements.
• Symbol associated with size tolerance.
• Symbols defining how the tolerance relates to several elements at the same time.
• Symbol defining a specific asymmetrical tolerance distribution.
• Symbols defining an unspecified tolerance offset.
• Symbols defining the application of a tolerance to a characteristic directly related to the actual outline of the component being tolerated.
• Symbols defining the application of a tolerance to a characteristic not directly related to the actual outline of the component being tolerated.
• Modifiers defining the method of determining the characteristics of a tolerated element.
• Modifiers defining the parameters for determining the characteristics of a tolerated element.
• Symbols typical of the ASME standard.

4 Shape tolerances:

• Straightness.
• Flatness.
• Roundness.
• Cylindricality.
• Line and surface profile without reference to bases.

5 Orientation tolerances:

• Parallelism.
• Perpendicularity.
• Inclination.
• Line and surface profile with reference to bases.

6 Position tolerances:

• Position tolerance.
• Coaxiality tolerance.
• Symmetry tolerance.
• Line and surface profile with reference to bases.

7 Run-out tolerances:

• Circular run-out (axial and radial).
• Total run-out (axial and radial).

8 Conclusion:

• Myths associated with the use of GD&T.
• Returning to the topic from the introduction.