Stephen Hawking once said, “The enemy of knowledge is not ignorance it is the illusion of knowledge.”
Think about that for a moment. What is the “illusion of knowledge?” Hawking suggests that what impedes a greater understanding is the tendency of people to believe they already possess knowledge of it.
When we apply that to GD&T, we see engineers and designers use GD&T incorrectly because they think they are defining their parts and geometry correctly. In reality, they have simply failed to learn the current definitions of how to apply controls.
Design Mistakes Reflect Poorly on Our Industry
Experts estimate that at least 50% of drawings that employ GD&T use it incorrectly. This is unacceptable. Machine shops must not just strive to improve their manufacturing skills, but pursue excellence in achieving their goals. Anything short of that is a failure.
Consider this in the context of a machine shop. If 50% of the designs—and hence the drawings—that come through the doors are beset with mistakes and problems, then how does that reflect on us as manufacturers?
Inaccuracies Go Unchecked
GD&T allows us to define precise part geometry. Everything the designer needs to say about a part’s form, fit, and function can be outlined to a nearly infinite degree of detail. So, if the designer includes inaccuracies on the drawings that we then estimate and build on a daily basis, then perhaps our inability to understand the convention sufficiently allows these problems to go unchecked. The “Illusion of knowledge” is winning the battle.
Inaccuracies Go Unchecked, So What?
Parts still get made. Machinists and technicians still work their eight hours a day. We don’t make any less money as a business or as workers when we’re less than excellent. If the parts are inaccurate, but we maintain our operations, then, “so what?”
The “so what” translates to the countless hours spent accomplishing work on parts that don’t need it.
If the parts we make pass both the shop floor’s interpretations of the call outs and the quality department’s interpretations of the call outs, and both teams made decisions based on a less-than-perfect interpretation of the job requirements, then there is overcompensation going on.
Vague Tolerance Interpretations Push Back the Goal Post
Remember, meeting any particular tolerance can only be accomplished by being “slightly” better than the call out. But, being exactly in-tolerance is not a real-world possibility.
A part feature is either better than or less than a given tolerance, so if the exactness of the given tolerances’ interpretation is vague or blurred, the distance to exceed it is harder to reach.
Create a Culture of Questioning
Often, inspectors and customers quote explanations of why a feature was inspected in a certain fashion, only to realize they have no idea why they were doing something for that call out.
Creating a playing field that questions how we interpret the tolerances that govern our performance will help shops find the most efficient way to ship good parts. After all, that’s how we compete.
Study the Standards. Look for Correctness. Know Your Tolerance Zones.
Know what you absolutely have to know to meet your drawing tolerances to help machine your parts correctly, and know what you absolutely do not have to do to meet those same tolerances.
The truth is, we as builders and designers only begin to excel on the world stage when we do exactly what we’re supposed to.
The “Illusion of Knowledge” can be the biggest hurdle we face in our pursuit of excellence. Remember, however, excellence is not a goal, it’s a journey, and achievement is not an outcome, it’s a process.
Partner with Metalcraft
Our engineer-minded machinists prioritize staying up-to-date with the latest GD&T standards. We examine part drawings to find the most efficient way to produce your product at the lowest price point. Are you looking for a metal manufacturing partner with a reputation for precise accuracy and tight tolerances? Contact us for a bid, today.
