GD&T is an acronym that stands for Geometric Dimensioning and Tolerancing. It is a symbolic language used by designers to communicate manufacturing constraints and tolerances clearly. This information is conveyed in the form of annotations included in the design of the part.
To start, the designer encodes the information into the model, using GD&T’s specific grammar and syntax rules. This eliminates the lengthy notes in a drawing that used to be used to describe the form. With GD&T we have a broad range of tolerances, giving the designer a certain flexibility to communicate dimensional constraints based on the requirements of the part.
When it is time to validate the part, the Inspector then decodes the information, which describes tolerances for the fit, form, and function of the part.
The goal of implementing Geometric Dimensioning and Tolerancing is to avoid confusion, scraps, and rework, all of which lead to a loss of profit.