The Y14.5 standard is considered the
authoritative guideline for the design language of geometric dimensioning
and tolerancing (GD&T.)
It establishes uniform practices for stating
and interpreting GD&T and related requirements for use on engineering
drawings and in related documents.
GD&T is an essential tool for communicating
design intent — that parts from technical drawings have the desired form,
fit, function and interchangeability.
By providing uniformity in drawing
specifications and interpretation, GD&T reduces guesswork throughout the
manufacturing process — improving quality, lowering costs, and shortening
Now, a consensus committee of experts has
revised Y14.5 for 21st-century applications.
Important changes address: concept of
feature of size; datum references and degrees of freedom; composite position
tolerances; surface boundaries and axis methods of interpretation; profile
tolerances; and symbology and modifiers tools.
Additionally, the subject matter has been
restructured for better readability, with profile, orientation, and form now
in separate sections, and material within sections reorganized.