Electrical Testing
Tip of the Week: Have you customized your PM procedures?

Tip of the Week: Have you customized your PM procedures?

Maintain your equipment based on actual conditions and usage, not “typical” applications assumed by manufacturers.

A large manufacturing facility decided to hire a maintenance consultant because it just could not get any traction in reducing equipment failures.

The first thing the maintenance consultant did was look at a representative sample of the Preventive Maintenance (PM) procedures. They seemed fine. He then went through the maintenance schedule with the maintenance department’s scheduling person. Again, everything seemed fine.

His next step was to review a representative sample of the repair logs, but they didn’t really tell him anything. The documentation was skimpy, to say the least. There were no As Found photos and no As Left photos. There was no mention anywhere of root cause analysis. He asked the scheduling person, who also maintained these logs, where that information was. Maintenance personnel didn’t collect that information.

Photo credit: wichai leesawatwong/iStock/Thinkstock

The consultant then discussed his findings (and lack thereof) with the plant engineer and concluded with the question: “How do you determine which PM activities to do and when to do them?”

The plant engineer said the procedures all followed the manufacturer’s recommendations. “No sense reinventing the wheel,” he said.

But it’s not reinventing the wheel. It’s making sure you have a steering wheel. In this case, there was no feedback from the repairs to modify the PMs for the actual failure causes. Because these causes were not addressed, the failures continued.

In another plant, four different drive motors on a long, complicated line blew their overloads in the same week. In each case, the whole line stopped. Obviously, the manufacturer-recommended PMs weren’t doing the trick anymore. Something had changed, and an engineer was tasked to determine what that was. He began by monitoring the current draw on several motors.

The problem turned out to be a drift in a particular set of mechanical adjustments. It increased the load on certain motors, and with enough variance from that (and from production itself) a motor could get overloaded. This problem happened twice more during the investigation phase, but never again after that because the mechanical arm of the maintenance department added another task to its PMs. You can easily guess what that task was.

Maintain based on your actual conditions and usage, not on some “typical” application assumed by manufacturers whose recommendations are really a starting point.

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