What is geometric dimensioning and tolerancing (GD&T)?
GD&T is a design and manufacturing mechanism that helps engineers communicate to manufacturers how to build a part that matches the drawing and is precisely what the customer desires.
Machinists and designers use GD&T, print dimensions, and notes to create a manufacturing process that results in a high-precision component replicating the designer's original vision. Proper detailing on the drawing enhances the communication between the customer and vendor.
Using symbolic language, GD&T shows how much a part's features may deviate from the geometries listed in the design model. This symbolic language has all the pertinent details involved in the manufacturing process, such as dimensions, tolerances, definitions, rules, and symbols communicating a component's functional requirements.