Location Tolerance (Location Deviation)

Location tolerance determines the location (true position) of the feature in relation to a reference. A datum is always necessary to indicate location tolerance; as such, it is a geometric tolerance for features related to datums.

Position

Position

The position requirement specifies the accuracy of the position in relation to the datum (reference plane or line).

Sample indication
Position
a
Within 0.1 mm dia.
Explanation of drawings
The center of the circle indicated by the indication arrow must be within a circle with a diameter of 0.1 mm.

Coaxiality

Coaxiality

The coaxiality requirement specifies the coaxiality of the axes of two cylinders (no deviation of the central axis).

Sample indication
Coaxiality
Explanation of drawings
The axis of the cylinder indicated by the indication arrow must be within a cylinder with datum axis line A as the axis and a diameter of 0.03 mm.

Concentricity

Concentricity

The concentricity requirement specifies the accuracy of concentricity of the axes of two cylinders (no deviation of the center). Unlike coaxiality, the datum is the center point (plane).

Sample indication
Concentricity
a
Within a circle with 0.05 mm dia.
Explanation of drawings
The axis of the cylinder indicated by the indication arrow must be within a cylinder with datum axis line A as the axis and a diameter of 0.05 mm.

Symmetry

Symmetry

The symmetry requirement specifies the accuracy of how symmetrical a target is to the datum (reference plane).

Sample indication
Symmetry
a
Within 0.05 mm from the theoretical center plane
b
Theoretical center plane
Explanation of drawings
The center plane indicated by the indication arrow must be between two parallel planes symmetrical to the datum center plane A and separated from each other by 0.05 mm.

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