Christiansen: How to measure the effectiveness of preventive maintenance

April 29, 2020
As processors make the switch to preventive maintenance, they will want to measure the effectiveness of the program using intelligent indicators. Here, we look at more robust methods of evaluating the maintenance department.

The move from reactive to preventive maintenance is one many processing companies strive for. After all, preventive maintenance delivers many benefits. A 2017 study found that 60% of “best-in-class” operations were using some form of a preventive maintenance strategy. On average, they saw an 11% reduction in year-on-year maintenance cost and a 9% reduction in year-on-year unplanned downtime.  

As processors make the switch to preventive maintenance, they will want to measure the effectiveness of the program using intelligent indicators. Here, we look at more robust methods of evaluating the maintenance department.

Switching to preventive maintenance

The most traditional and simplistic maintenance strategy has been a reactive approach. Simply put — when a machine breaks down, the maintenance staff goes to action in repairing it. This is a problematic strategy for many reasons:

  • Production schedules are interrupted by unplanned downtime, causing many downstream effects to the operation.
  • Spare parts are not optimized — either you must rush in parts at higher cost or hold too much inventory.
  • The maintenance staff is mostly working to fix the issue of the moment, rather than thinking long-term.
  • Failures and unplanned downtime will continue to occur.

As a result, operations have moved to a preventive maintenance strategy. With preventive maintenance, technicians work to optimize equipment and perform regular tasks before breakdowns occur. This approach reduces downtime, increases asset life and improves the value of the maintenance organization. Furthermore, preventive maintenance can improve your site safety.

As a processor moves to preventive maintenance it wants to understand the efficiency of its newest systems. But how does a company measure the effectiveness of its preventive maintenance program?

Why cost should not be your top indicator

A traditional way of measuring maintenance effectiveness is simply department cost over time. This method, however, misses many aspects of maintenance and does not provide clear direction to a maintenance team, other than “reduce your cost.”

Of course, maintenance spend is an important number to track — but just as a portion of maintenance performance, and not the ultimate indicator. By simply tracking maintenance spending, the goal becomes a cheap maintenance staff, which tries to drive down costs and not necessarily support the operational goals. Furthermore, unplanned downtime is often significantly more costly to an operation — and driving down maintenance spend does not affect unplanned downtime.

That is why more intelligent measures must be employed. By tracking more effective indicators, the efficiency of the maintenance staff will improve, and cost will decrease as a result.

CMMS for data generation and analysis

One step in a preventive maintenance program is to install and deploy a Computerized Maintenance Management System (CMMS). Along with helping to schedule and manage your maintenance tasks, a CMMS will help to generate data that can be made into reports on the maintenance efficiency. Without a CMMS, consistently collecting accurate data for these advanced indicators could be extremely difficult and time-consuming.

Once you establish your baseline data with the help of a CMMS, you can start establishing metrics, indicators and goals you want to track.

KPIs versus performance metrics

First, understand that performance metrics and Key Performance Indicators (KPIs) are not the same. Where KPIs measure progress toward a key maintenance objective, performance metrics follow the status of a specific process. Think of a KPI as a more strategic measure, and a performance metric as a tactical measure.

For example, a KPI may be maintenance backlog, and a performance metric may be overtime or work order completion percentage. With that stated, let’s get into some maintenance KPIs that you can track for maintenance effectiveness.

KPIs to consider

  1. Planned Maintenance Percentage — The amount of maintenance time being spent on preventive maintenance versus reactive maintenance. A best-in-class operation will spend 90% of time on preventive tasks.
  2. Maintenance Work Efficiency — Assuming you have an idea of how long a task should take, you can see if your technicians are spending the appropriate amount of time on work. This can lead to theoretical workloads, overtime plans and other metrics.
  3. Overall Equipment Effectiveness (OEE) — OEE is one metric many businesses use for a comprehensive measure of the operation. Put simply, this measure is calculated by multiplying availability (inverse of downtime), performance (how much output versus target) and quality (yield of good output).
  4. Mean Time to Repair (MTTR) — MTTR is calculated by dividing the downtime length by the total number of downtime events. MTTR can be used to determine criticality of an asset or areas in which preventive tasks need to be added.
  5. Mean Time Between Failure (MTBF) — MTBF is the average time between failures on an asset. This is an important indicator to determine preventive maintenance priorities.
  6. Maintenance cost as a percentage of replacement asset value — World-class operations have a percentage less than 2%
  7. Maintenance Cost Per Production Unit — With the caveat about maintenance spend tracking, this is perhaps a better measure of maintenance efficiency.
  8. Maintenance Backlog — The backlog in work orders or labor time. The backlog should not be growing over time, so this KPI could indicate a further issue.
  9. Maintenance Schedule Compliance — A measure of how much the schedule was followed and a potential indicator of how well the preventive maintenance program is working.
  10. Spare Part Inventory Turns — Measuring the inventory turns will indicate whether the inventory is needed or potentially tying up capital on the shelf.
  11. Maintenance Emergency Events (or Percentage Emergency Work) — Tracked over time to see how many breakdowns are happening. With a preventive maintenance program, this number should be decreasing.

Setting goals

Armed with these more meaningful KPIs, you can start to set maintenance goals that can take your maintenance department to the next level. Rather than trying to improve all KPIs, focus and set specific goals. When setting a goal, make it a measurable and achievable (use the SMART rubric, for example). Some examples of SMART goals include:

  • Improve OEE on one asset by 25% in one year
  • Decrease MTBF by 50% on a critical asset in one year
  • Reduce the maintenance backlog by 40 man-hours in one month


Whether just starting a preventive maintenance strategy or a 10-year veteran, you will want to measure the effectiveness of the program. Preventive maintenance should reduce unplanned downtime and increase asset life and equipment efficiency. These can be difficult things to measure in the short term, so other KPIs are needed.

Relying on a tactic of only tracking overall maintenance spend does not give you the entire picture of maintenance performance. More nuanced measures are needed. Once you get more meaningful KPIs established, you can use them to set specific goals for your team. With these actions in place, you can start to drive your maintenance program to a best-in-class level.

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