Technology Transfer Services Blog

There really is some truth to the old adage “If it ain’t broke, don’t fix it.”  Such a phrase seems naïve or misplaced in the context of preventive maintenance, but is it really?

 A great article by Drew Troyer of Noria Corporation discusses some of the issues that arise with preventive maintenance and how to avoid them.

  “Preventive maintenance is among the most common root causes leading to the need to perform corrective maintenance. It need not be. Evaluate your PMs and eliminate tasks that fail to add value or actually create failure. Eliminate the waste and ambiguity and properly assign the tasks at the proper interval, and avoid the temptation to knee-jerk react to failures by simply adding new PMs to the system or increasing the frequency with which tasks are executed without proper cause analysis. You’ll find yourself spending less money on preventive maintenance and, at the same time, increase the reliability of your manufacturing systems.”

 The steps to build a PM procedure have been described in many books, corporate policies, etc.  The process is typically data driven and mechanical to determine PM frequency.  However, the “art” is to consider the following three aspects of preventive maintenance:

1. Human Factors – Anyone who has performed routine maintenance on different models of cars can relate to this issue easily. On some cars, it may be simply a matter of lifting the hood or opening the glove box to access a fuse box. On other cars, accessing the fuse box might be equivalent to the twelve labors of Hercules. The harder it is to reach, the more likely something else will break accidently. The same issue applies to plant equipment.  Different motors, pumps, etc., may have the same basic PMs that need to be performed, but have varying degrees of access and ease of maintenance.  The “art” is to evaluate the likelihood of accidental damage to something else during the process of performing a PM based on physical location and workforce skill.
2. Domino Effect – As noted in the linked article, equipment failure probability generally increases immediately following preventive maintenance. So what happens after such a failure? Add another PM of course!  The best response to such a failure is to go back and evaluate why it happened and rethink the frequency of the original PM procedure. The right course of action might be to reduce the frequency of the PM, not to add another PM.
3. Collateral Damage – Wear and tear on components removed or accessed during preventive maintenance is a certainty.  An often overlooked aspect of PM program design is the interaction and impact of multiple PMs as it applies to wear and tear. Certainly maintenance planning involves scheduling of related PMs for labor efficiency and to minimize downtime of equipment. However, another factor to consider is the impact of the inevitable worn threads, sheared bolts, broken latches, etc.   The impact of such anticipated failures over time needs to factored into the frequency of PMs and should be planned for.

The bottom line is to temper the science of PM design with the art of considering the very real (yet hard to quantify) three aspects noted above.

Author: David Brent, Vice President