Fig Positional Tolerancing Of Slots

5.10.1 Noncircular Features at MMC. Where a positional tolerance of a noncircular feature applies at MMC, the following apply.

(a) In Terms of the Surfaces of a Feature. While maintaining the specified width limits of the feature, no element of its side surfaces shall be inside a theoretical boundary defined by two parallel planes equally disposed about true position and separated by a distance equal to that shown for W in Fig. 5-45.

(b) In Terms of the Center Plane of a Feature. While maintaining the specified width limits of the feature, its center plane must be within a tolerance zone defined by two parallel planes equally disposed about true position, having a width equal to the positional tolerance. See Fig. 5-46. This tolerance zone also defines the limits within which variations in atti tude of the center plane of the feature must be confined.

(c) In Terms of the Boundary for an Elongated Feature. While maintaining the specified size limits of the elongated feature, no element of its surfacc shall be inside a theoretical boundary of identical shape located at true position. The size of the boundary is equal to the MMC size of the elongated feature minus its positional tolerance. To invoke this concept, the term BOUNDARY is placed beneath the feature control frames. See Fig. 5-47. In this example, a greater positional tolerance is allowed for its length than for its width. Where the same positional

Feature Control Frame ExamplesPositional Tolerance Slots Tabs

Slot position may vary as shown, but no point on either side surface shall be inside of W

' Theoretical boundary (equal to minimum width of slot minus the positional tolerance)

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  • filmon
    When is equal distance plane used with positional tolerance?
    1 year ago

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