- Geometrical Dimensioning and Tolerance is language of accurately communicate geometry requirement for associated features on assembly and individual manufacturing component drawings.
- GD&T consist of dimensioning, tolerances, symbols, definition, rules and it is used for precisely communicate the functional requirements for the location, orientation, size, and form of each feature of the design models.
GDT-Symbols
- GD&T symbols provides accurate dimension from point to point of requirement of model. Manufacturing of the drawing having concise of GD&T symbols to help of understanding the drawing.
| Name of the Symbols | Control Type | Description |
| Straightness | FORM | Where an component of a surface is a straight line |
| Flatness | FORM | Surface having all elements in one plane |
| Circularity | FORM | The form of surface of revolution (cone, Cylinder, Sphere) where all points of the surface intersected by any plane. |
| Cylindricity | FORM | Like circularity, but applies simultaneously to the entire part of the surface. |
Profile of a line | PROFILE | Uniform amount of profile variation, either unilaterally or bilaterally, along a line element of a feature. |
Profile of a surface | PROFILE | Uniform amount of profile variation, either unilaterally or bilaterally, along a line element of a surface. |
| Perpendicularity | ORIENTATION | Which is 90 deg perpendicular to the primary datum of its datum reference frame. |
| Angularity | ORIENTATION | Which is having specific angle in relation to the primary datum of its datum reference frame. |
| Parallelism | ORIENTATION | Which is having a equidistant at all points from datum plane. |
| Position | LOCATION | Orientation of a features relation to its datum reference frame. |
| Concentricity | LOCATION | In which two or more features having a same axis. |
| Symmetry | LOCATION | Symmetry of two planes about a center datum. |
Circular run out | RUNOUT | Circularity and co-axiality of each circular segment of a surface independently about a center datum |
| Total run out | RUNOUT | Circularity, straightness, co – axiality and taper of a cylindrical surfaces about a center datum to rotated 360(deg). |