Orientation Checks
Angularity, Perpendicularity and Parallelism
Orientation checks require at least a single datum for evaluation. The measurements of the datum are first aligned to the datum features and then the measurements of the check feature are evaluated rela- tive to that alignment.
Perpendicularity and Parallelism are special cases of an angularity check where the angle is either 90 or 0 degrees respectively and are therefore evaluated in the same way. Angularity checks ensure that all the specified points lie at approximately a specified angle relative to the datum features. The tolerance zone can be defined as planar region or as the deviation between two axes.
Evaluation Process within SA:
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Planar Evaluation. The minimum distance between two parallel planes at the specified angle containing the measurements of the feature.
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Axial Evaluation. The minimum diameter of a cylindrical zone at the specified angle containing the measurements of the feature.