Key Points
Parallelism is the condition of a surface, axis, or center plane, oriented at 0˚/180˚ to the datum reference frame.
Example Drawing
How to Read It
All points of the surface must lie within two parallel planes .005 apart which are parallel to datum plane A. In addition, the surface must be within the limits of size or profile tolerance. Since parallelism is a refinement of the size or location, the value must be smaller. Note that parallelism on a planar surface also controls the flatness.
Since the above parallelism specification is a surface control, the material condition modifiers MMC, LMC, and RFS are not applicable.
Sample Inspection for Parallelism
Both the datum feature and indicator stand are mounted on the surface plate and the dial indicator is placed on the surface. As the indicator traverses the feature, the full indicator movement (FIM) or total indicator reading (TIR) can be no more than .005 (max-min).
