What is GD&T?
Geometric Dimensioning and Tolerancing, (GD&T) is a set of guidelines for dimensioning a print that can be correctly interpreted and applied. The GD&T on the print gives the guidelines for dimensional inspection. The standard that is most commonly used is published by ASME (formerly ANSI). The most current ASME standard is the ASME Y14.5M-2009. Click here to obtain a copy of the standard. A very useful chart with information on all 14 Geometric symbols is available at the bottom of the page.
Why?
If properly used, GD&T has significant benefits; here are just a few:
- Clearly define the part’s design intent
- Optimally use the part’s available tolerance
- Increase correlation between customer and supplier
- Provides the basis to correctly determine whether a part is acceptable or not.
If geometric dimensioning and tolerancing is not used, or not used properly, the potential consequences are manifold, such as
- The parts fail inspection but are still functional
- The parts pass inspection but do not work
- Lack of correlation between customer/supplier and difficult to determine why
- Unable to make correct pass/fail analysis
How?
Getting a print with properly defined GD&T is just the beginning to being successful. By far, the largest hindrance to the success of implementing GD&T is lack of training. GD&T training is critical for designers, manufacturers, and QC inspectors. Here at AIS, all of our QC inspectors go through basic and advanced GD&T training through the International Institute of Geometric Dimensioning & Tolerancing (IIGDT) and we also have a Senior Level GD&T Professional (ASME GDTP-S) in-house to support our metrology. At AIS we have the knowledge, equipment and software to correctly evaluate even the most complex GD&T requirements.
Click here to see GD&T Definitions
*For more information on dimensional inspection and GD&T, click here for a PDF.
Please contact us for more information on geometric dimensioning and tolerancing and dimensional inspection services. Or Request a Quote today!