Geometrical Dimensioning
and Tolerancing is a system for defining and communicating engineering design
with tolerances. Using symbols on engineering drawings and computer-generated
three-dimensional solid models it explicitly describes the geometry of the part
and its allowable variation, explaining, the manufacturing staff and machines,
the degree of accuracy and precision needed. GD&T is defining the
theoretically perfect geometry of parts and assemblies, There are several
standards worldwide t0 describe symbols and define the rules used in GD&T.
One such standard being American Society of Mechanical Engineers (ASME)
Y14.5-2009. The uniqueness in Y14.5 standard is that it provides a fairly
complete set of standards for GD&T in a single document.
Importance of GD&T
Tolerance analysis and GD&T of designs bring robustness and accuracy to
product designs, significantly improving product quality while drastically
reducing production costs. Industries that make use of mechanical designing,
like, Aerospace & Defense, Heavy Industry, Automotive, HVAC, Consumer
Products, Medical Devices, Electronics & Power, Safety & Security
Systems, etc, GD&T is an integral part of their operation. The production
uses the language to interpret the design intent, and inspection looks to the
language to determine the setup. By providing uniformity in drawing
specifications and interpretation, GD&T reduces controversy, guesswork, and
assumptions throughout the manufacturing and inspection process, and hence
plays a contributing factor to many industries.
Why GD&T
GD&T is part of the designing process which is an effective tool to
● communicate design features between the designer and the manufacturer.
● It simplifies inspection
● forces the designer to totally consider function, manufacturing process, and
inspection methods.
It is the most important tool for a designer to learn and a manufacturer to
understand. This course offers all the information needed for a designer to
initiate his career as a mechanical designer.