How can I optimize an existing preventive maintenance plan?

There are a few different approaches to preventive maintenance optimization (PMO).

One of the easiest methods is simply asking your technicians. Odds are, they’ve been performing the same PM tasks for a while, and they’d probably have some insight on what could be done better. If any of their tasks seems irrelevant, they’ll let you know if you ask.

While this is the simplest way to track down superfluous PM tasks, it’s not the most precise, and it is pretty subjective. That said, it’s easy to do when you’re just starting to optimize PM in your facility.

The next way is a bit more precise, though it is based on some industry assumptions. A few decades ago, a maintenance and engineering manager named John Day, Jr. proposed the 6:1 rule. This rule asserts that for every 6 PM tasks you perform, you should be finding one corrective maintenance task.

This rule isn’t perfect, but it can give you a good starting point for optimizing your PM. If you’re performing more than six PMs for each CM, you may want to scale back a bit, but only after doing some research. if it looks like your PM:CM ratio is too high, I’d advise analyzing the types of failures you’re preventing. If they don’t pose too much of a threat, scaling back relevant PM tasks could be a good idea.

On the other hand, if you have more CM than the ratio dictates, you might be facing one of these two possibilities:

  1. You’re not doing enough PM.
  2. You’re doing too much of the wrong PM.

Again, some extra analysis will help you make the right choice here. Do some digging into the kinds of preventive maintenance tasks you’re performing and see if those are addressing the right issues. If they are, your PM timing or quantity may be off. If they’re not, then you’ll want to scale those back and replace them with more relevant tasks.

A similar approach involves tracking hours performed on PM and emergency maintenance for a single asset. If you have more emergency repair hours than PM hours, you’ve probably got a problem and will want to do some analysis on the root cause.

These last two approaches give you more precision, but they do take more planning, so keep that in mind when you start streamlining your PM.