The hidden cost of Preventive Maintenance mismatches

In a perfect world, the cradle that starts the existence of preventive maintenance (PM) starts from a Failure Mode Effects Analysis (FMEA). Whether it is usage-based, condition-based, or time-based, these proactive activities sometimes result from a reactive event, but most are design by an FMEA. From the FMEA, the necessary proactive work identified sets the stage for the asset to achieve an expected life-cycle cost and the desired reliability. We then create the PM's attributes for an employee in the future to effectively perform repeatable work within a condition-based maintenance program.

From a frequency interval perspective, in most applications, time-based is used to determine when the PM is done due to the complexities associated with usage-based. We then take these into the computerized maintenance management system (CMMS) to establish the PM at the identified calendar interval. What a journey this set of instructions has taken. We set the stage for future success, but too often insert a ticking time-bomb. Nowhere in this process do we say to insert the frequency interval in the preventive maintenance work order’s title. I want to rant.

Preventive maintenance plans are no small feat. If you’re accustomed to reacting to unexpected breakdowns and critical emergency repairs, a preventive maintenance plan will force you to think months, even years ahead. Bryan Christiansen - MaintWorld

Here we go

If you were to search in your browser errors of a PM program and you will see all kinds of things that systematically impact the effectiveness of your asset management program. However, an error that is never noted and gets under my skin the fastest is when people place the frequency interval of the PM within the title of the PM. Within the preventive maintenance plan’s title for the asset, we emotionally feel like we should write “weekly PM” or “Q1 inspection” to display the importance of the PM or remind performer of the PM the frequency interval. This is wrong! Stop! Don’t! How can something so simple impact reliability so much? How can something so simple hide cost so significantly?

Over the life-cycle of an asset, criteria may change requiring modifications to the frequency interval of performing preventive maintenance. Best practices would have your work on a usage-interval functionality, but most organizations maintain a time base interval for these proactive activities. Therefore, the frequency intervals should breathe, remain organic, and be malleable to correlate to utilization levels and intended reliability of the collection of assets designed for intended functionality. Therefore the preventive maintenance frequency intervals should indeed change over time.

Let's relate to this

Personalizing this breathable metaphor, I am assuming you didn’t change the oil in your automobile at the same time-based frequency in 2020 as you did in 2019. You extended this PM, because of the COVID impact on your automobile’s utilization. Your PM you use to do every 180 days on average turned to every 360 days most likely. PMs should breathe if you are running them at time-based intervals. Consider this example in your CMMS. If you wrote the interval in the title, you would have to change it in the title and the program that creates the PMs. Guaranteed petri dish of errors.

So let’s do an activity together. Look at your current backlog of work within your computerized maintenance management system (CMMS) and note the frequency interval of your preventive work within the title, description, and/or instructions. Document if it says things like quarterly, weekly, or monthly. Now correlate this free-text field to the frequency interval that automatically creates or activates the work order. I have high confidence you will see errors and mismatches. For example, a quarterly PM will have a title of monthly. Most times when I ask an organization to do this type of activity, the mismatch is anywhere between 2% to 5% of all PMs have a mismatch. These errors don't only cost a lot due to waste, it creates the potential for violations of code and catastrophic breakdowns because of a wrong interval.

I understand that each error could be favorable or unfavorable in the current business conditions you are in. Regardless, this there is a waste. You may be saving some cost by doing something less frequently because of the mismatch, or you could have just freaked out because you aren’t doing a PM as often as the “title” of the work order may say. Assume code states that a PM should be conducted, not to exceed, on an annual basis. You have in the title, “Annual PM.” This free-write field has zero influence on when the PM will be automatically generated. The program that generates the PM could be set up at a 2-year interval. Mismatch. Oh crap!

It’s important to remember that a good PM program will help work to ensure the inherent designed reliability of your equipment. It’s also important to ensure the people who manage this program have a thorough understanding of where Preventive Maintenance should be applied. - Doug Plucknette - Plant Engineering

Then why do we put some unit of measure indicating the “time” in the title? Why does it say “weekly” or ”bi-annual” in the PM’s title? Does Y2 mean twice per year or once every two years? Ok, then what about M3 versus 1Q in the title? What the heck? How did we get here? I have seen two planners in an area write Y2 to mean once every six months and once every two years. And I assume you have the same problem.

Many individuals will argue that it helps them balance their workloads and schedule work activities. Responding, I say it allows them to superficially connect this string of characters in a free-write field to some siloed and internal prioritization process. Other individuals say it benefits the technician to know the level of detail expected to be conducted. I call bologna. These type of biases removes the intentions of the prioritization process, criticality analysis, and FMEA. It removes the intentions of your CMMS’s module to create active proactive work order to properly go through the planning stages. Saying “weekly” in a PM’s title creates zero benefits for the organization, instead, it is only a siloed emotional high of disorderliness for the planner.

Examples of why not

Example one. Consider ASME B30 as a reference guide as a good practice to emulate. ASME B30 denotes that you should perform different levels of inspection on cranes based on their severity and type. The different levels of inspection exist in the form of frequent or periodic. The vagueness of these words allows the program that calculates the PM to achieve the credentials of the standard. Inserting “Annually” within the title of a periodic PM doesn’t work for an overhead crane with a severity ranking of “severe.” It requires a PM not to exceed a quarterly interval. Whereas a severity ranking “normal” on an overhead crane requires a PM not to exceed an annual interval.

Example two. You are laying out your maintenance costs for the year on a specific collection of assets. You download your data to correlate the costs over the year within your regimented preventive maintenance optimization process. You multiply the cost of an occurrence against the frequency interval of the proactive activity. You are not writing code to look for a string of characters in the description to denote the frequency interval.

Example three. You want to change the preventive maintenance interval due to an incident, change in utilization, or a change in the desired reliability. If you denote the interval in the title and the program that generates the PM, you are entrusting that the individual will always revise both fields. When you write “weekly” or “monthly” within the title field, you are expecting your Planner to revise it along with the program that issues new PMs. And over time, I guarantee that these Planners will miss this one of the two fields, and your “weekly PM” in the title will be contradicting the PM being created monthly. I can just hear the maintainer looking at a problem and saying, “We will see what it looks like next week when we do the weekly PM.” Not knowing that it won’t be done until next month.

What should we change?

The practice I recommend is to insert words that correlate with standards that are being referenced or the depth of the expectation. Back to the ASME example, the application of words like “frequent” or “periodic” are very useful and are referenced often throughout other standards. However, using descriptives like “thorough,” “reoccurring”, or “detailed” allows the power of the interval to remain within the program and not a string of characters of the title.

I understand that this is a rant. I also know that this is invalid if the organization is utilizing usage-based functionality to conduct its preventive maintenance. However, I will continue to be in the camp that putting a time base interval within the title or description is either a duplication of another field creating the potential of mismatch or a lack of utilization until someone proves me wrong.


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