Geometric tolerancing is a form of annotation that you can use to provide additional information about the features of a part. While dimensions and their associated tolerances give information about the acceptable variation in the size or location of a feature on a part, geometric tolerancing establishes the relationships between features on a part. For example, you can define the tolerance for the position of a hole in a part in relation to other features, or datums, on the part.
In the Draft environment, you can define the geometric tolerances with the following commands:
The Feature Control Frame command specifies the necessary tolerance on a feature in relation to reference letters for other features of a part, called datums.
You can identify the datums on your part using the Datum Frame command.
You can specify datum points, lines, planes, or areas for special function or manufacturing and inspection using the Datum Target command.
Note:
Solid Edge supports the ASME Y14.5-2009 ANSI and ISO drafting standards for geometric dimensioning and tolerance callouts. The between and statistical tolerance symbols are supported in the TrueType symbol fonts.
A feature control frame is composed of two or more rectangular compartments that contain information about tolerances. The first block always contains a geometric characteristic symbol. Subsequent compartments contain tolerance values and symbols representing part variations, such as maximum material condition. You can create the feature control frame by typing text and selecting symbols from a dialog box.
You can refer to up to four datums in a feature control frame.
A feature control frame has the following parts:
|
(A) |
Geometric characteristic symbol |
|
(B) |
Tolerance |
|
(C) |
Datum reference |
|
(D) |
Tolerance zone symbol |
|
(E) |
Tolerance value |
|
(F |
Material condition symbol |
A valid feature control frame must contain these two components:
Geometric characteristic symbol
Tolerance
Some geometric characteristics also require a reference to a datum in the feature control frame. You can apply material conditions to the tolerance and datum references. You can also apply a diametral tolerance zone to the tolerance.