GD&T is the symbolic language of mechanical part design. It communicates design intent and acceptable variation without ambiguity.
Back in the day a company’s design and manufacturing activities would be located on the same site, sometimes in the same building. Design drawings acted more as high-level guides to manufacturing rather than hard and fast functional specifications, and few items would be sourced externally. GD&T may have been regarded as something that was either not required, of limited value, or applicable only to a few specialised industries. When issues of assembly, functionality or conformity and ambiguity relating to the specifications arose they would be resolved through local interpretation and agreement. A certain level of scrap, rework and, dare we say it - poor quality, was deemed acceptable. Wind things forward into the 21st century and it's all change.
In today’s world of global product realisation, the design, manufacturing and assembly of a single product may take place utilising teams spread over three or even four continents. Customer expectations of quality and functionality have grown, and a company can only beat the competition if it can bring a better quality product to the market .......... faster ........... and, ideally at lower cost. Ambiguity of specification, function and conformance is no longer permissible. The parts must be guaranteed to fit and function first time. The drawings must represent the functional product. The design intent and functional requirements must be satisfied.
The Benefits of GD&T
-
Guaranteed assembly of parts and functionality of product
-
Shorter development lead times, fewer problems and change requests
-
Larger manufacturing tolerances
-
Reduced tolerance stack-ups
-
Reduced non-conformances, scrap and rework
-
Fewer conformity disputes with suppliers
-
Compliance with national and international standards, BS 8888, ASME Y14.5, ISO GPS
-
Compliance and uniformity with customer utilised standards
-
Highly skilled design, manufacturing and quality engineering teams
-
The drawing represents the functional part. Design intent is communicated
"When GD&T is applied correctly the drawing represents the functional part. Tolerances are increased without affecting functionality.
All functional are parts accepted and all non-functional parts are rejected."
e i q o p d f g h jk l n m