What does "Geometric Dimensioning and Tolerancing" (GDandT) define?

"Geometric Dimensioning and Tolerancing" (GD&T) is a symbolic language used on engineering drawings and provides a clear and concise way to communicate the allowable variations in the size and location of part features. The primary purpose of GD&T is to define how much a feature can deviate from its ideal geometry, ensuring that parts will fit together correctly during assembly and function as intended.

Tolerances are critical in engineering design because they allow for manufacturing variability while ensuring that the final product meets functional requirements. GD&T offers a standardized set of symbols and rules that specify the permissible limits of sizes and geometric relationships, which is essential for maintaining quality control in production processes. By using GD&T, engineers can ensure that parts are produced to the necessary specifications, minimizing potential assembly issues and improving overall product quality.