Position Tolerances

• Deviations in relative locations of surfaces

– Misalignment• Deviation of axes which should normally coincide with the

geometrical axis• Can be axial misalignment or angular misalignment

– Non-parallelism of axes– Incorrect location of intersecting axes

• Angular deviation from the specified angle of intersection and the deviation from the point of intersection

– Non-perpendicular surfaces• Amount of angular deviation between two orthogonal surfaces

Datum

• Defined as the ideal geometrical reference to which the geometrical tolerance features are related

• Indicated by a filled inverted triangle and a leader line

• Shown by a capital letter enclosed in the triangular frame

Representation of Geometrical Tolerance on a Drawing

• Geometrical tolerance zone is an imaginary area or volume in which the actual component should be enclosed

• Geometrical tolerances are represented by symbol, tolerance and datum enclosed in the rectangular frame

• Symbol M indicates maximum material condition of feature size

Geometrical Characteristic Symbols

Surface Texture