Geometric Tolerancing is used Things like:
•Straightness •Flatness •Circularity •Cylindricity
•Angularity
Geometric Tolerances are shown on a to specify the shape of features. •Profiles
•Perpendicularity •Parallelism •Concentricity •And More...
drawing with a feature control frame.
The Feature Control Frame
This feature control frame is read as: "The specified feature must lie perpendicular within a tolerance zone of 0.05 diameter at the maximum material condition, with respect to datum axis C. In other words, this places a limit on the amount of variation in perpendicularity between the feature axis and the datum axis. In a drawing, this feature control frame would accompany dimensional tolerances that control the feature size and position.
Geometric Characteristic Symbols
TYPE OF TOLERANCE |
CHARACTERISTIC |
SYMBOL |
SEE: | |
STRAIGHTNESS |
- |
6.4.1 | ||
INDIVIDUAL FEATURES |
FORM |
FLATNESS |
CJ |
6.4.2 |
CIRCULARITY (ROUNDNESS) |
O |
6.4.3 | ||
CYLINDRICITY |
// |
6.4.4 | ||
INDIVIDUAL |
PROFILE |
PROFILE OF A LINE |
r^ |
6.5.2 (b) |
OR RELATED FEATURES |
PROFILE OF A SURFACE |
6.5.2 (a) | ||
ANGULARITY |
6.6.2 | |||
ORIENTATION |
PERPENDICULARITY |
_L |
6.6.4 | |
PARALLELISM |
// |
6.6.3 | ||
RELATED FEATURES |
POSITION |
5.2 | ||
LOCATION |
CONCENTRICITY |
© |
5.11.3 | |
SYMMETRY |
5.13 | |||
RUNOUT |
CIRCULAR RUNOUT |
6.7.1.2.1 | ||
TOTAL RUNOUT |
6.7.1.2.2 | |||
♦ ARROWHEADS MAY BE FILLED OR NOT FILLED |
13.3.1 |
FIG. 3-1 GEOMETRIC CHARACTERISTIC SYMBOLS
A feature control frame gives information about geometric tolerances on the feature. 15
Straightness Example
THIS ON THE DRAWING
MEANS THIS (a)
0.02 wide tolerance zone
016.00 MMC
— 0.02 wide tolerance zone
016.00 MMC
Each longitudinal element of the surface must lie between two parallel lines (0.02 apart) where the two lines and the nominal axis of the part share a common plane. The feature must be within the specified limits of size and the boundary of perfect form at MMC (16.00).
Note: Waisting (b) or barreling (c) of the surface, though within the straightness tolerance, must not exceed the limits of size of the feature.
Straightness at MMC
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