If we want to get into precision maintenance, we need to be aware of the differences between shaft alignment tolerances and coupling tolerances.

I just recently read an article from an online Reliability Maintenance website. It’s from a well-known organization that sells training for Reliability Centered Maintenance and Condition Based Maintenance programs. The title read:

“The precision maintenance revolution brings world-class reliability performance to your machinery and mechanical plants and equipment.”

Although the sentence isn’t very well written, it’s a good article that explains what precision maintenance is.

Is there a precision maintenance revolution? Or is it something that is just driven by marketing? Precision maintenance isn’t new, it’s been in our company name for many years. The PDM in BENCHMARK PDM stands for precision-driven maintenance. Apparently, the term precision maintenance was first used by some actual rocket scientists who worked for NASA in the sixties. I first heard the term from Ralph Buscarello of Update international who is the gentleman that taught me shaft alignment using dial indicators almost 40 years ago. So, what is precision maintenance? If you look at precision in the dictionary, we are told it is:

1. The state or quality of being precise; exactness.
2. The ability of a measurement to be consistently reproduced.

The two keywords for me is exactness and reproduced. As we know, a carpenter measures twice before cutting once. If the measurements are not the same (reproduced), he does not cut until he answers the question why?

Exactness makes statements such as “that’s close enough” redundant because we do not want “close”, we want it to be within tolerance.

That to me is how I define precision maintenance. It’s simply working to a tolerance. The reason we must work to an accepted tolerance range and not to an “exactness” is because in an environment such as rotating machinery, machines and mechanical parts are constantly subjugated to constant forces in which an exact measurement can’t be fulfilled. The problem is some people get confused by some of the tolerances that are out there in our maintenance world – especially when it comes to shaft alignment and the major mechanical parts involved.

Request your complimentary copy of our Shaft Alignment Fundamentals Wall Chart which highlights the ANSI/ASA Shaft Alignment Tolerances as well as information and guidelines for the implementation of good shaft alignment of rotating machinery, best practices, soft foot, tolerances, thermal growth, and much more!

Thank you John Lambert with Benchmark PDM for sharing this educational article with us! Click here to continue reading: “Are You Using Coupling Tolerances to Align Your Machines? You’re Doing It Wrong.” 

Choosing the Correct Alignment Tolerance Evaluation