Q: Why GD&T?

A: Tolerance Zones

• Tolerances impact cost, quality, and customer satisfaction.
• Symbolic language
• Say what you mean

The number one reason to use GD&T is cost savings.

To put it simply, more parts pass inspection with GD&T.

By way of analogy, imagine you are a participant in a company target shooting contest at 300 yards. You get 10 shots at your target to represent your company well. Would you rather shoot at +/-50 mm square target of a 140 mm round target? Let’s add a cost componentto this analogy. Each shot that misses the target will cost your CEO $100.

When we issue a part for manufacturing in behalf of one of our customers, we know that GD&T tolerance zones make it easier for the supplier to hit the target. We effectively are giving a looser tolerance to the supplier so we can demand a lower cost becasue the machinist is able to run the job with higher feeds and speeds or on a lower cost lower precision machine. This is a win-win scenario for our customer becasue they get lower cost for their part with the same precision of fit.

GD&T allows designers to say what they mean and manufactures to interpret without ambiguity. The bottom line is that this geometric dimentioning standard yields less scrap which equates to cost savings.