GD&Ts: What you Need to Know to Enhance your Profitability
Geometric Dimensioning and Tolerancing (GD&T) are tolerances in 3D. For example, they specify how the centers of two bores can differ.
Drawings with many tight GD&Ts are costly to manufacture. Ignoring this information will affect your profitability. Keep reading to get some tips to enhance it.
Different Types of GD&T
Datum
A datum is theoretical exact plane, axis or point location that GD&T or dimensional tolerances are referenced to. You can think of them as an anchor for the entire part; where the other features are referenced from. A datum feature is usually an important functional feature that needs to be controlled during measurement as well.
All GD&T symbols except for the form tolerances (straightness, flatness, circularity and cylindricity) can use datums to help specify what geometrical control is needed on the part. When it comes to GD&T, datum symbols are your starting points where all other features are referenced from.
Here, A and B are the datum. These are used as reference surfaces to control any other feature on the component.
