comma CMMS equipment maintenance blog
The role of the CMMS to improve OEE - with practical examples.
Published 2024-04-05 by Alvaro Oberon (a 7.7 minute read) | Back to the main page
What is OEE?
OEE stands for Overall Equipment Effectiveness and it's a metric used in manufacturing organizations to assess equipment manufacturing productivity. It's expressed as a percentage and derives from a calculation that weighs in three key components: equipment availability, equipment performance and equipment production quality. Let's quickly look at each of these partial metrics and how they combine to form the OEE calculation along with some examples to help us understand all this better.
Equipment availability
This factor accounts for all events, expected or unexpected, that interrupt planned production and is expressed by the following equation:
Availability = Actual Run Time / Planned Production Time
Consider that the planned production time for machine A is 100 hours for a given week and that it broke down for 1 hour during that period, then
Availability (Machine A) = Actual Run Time (Machine A) / Planned Production Time => Availability (Machine A) = (100 - 1) / 100 = 0.99 * 100 = 99 %.
Machine A was available for 99% of the time during the period we're analyzing.
Equipment performance
For this parameter, let's start by considering the manufacturer specifications that state a production capacity of 30 items per hour. Therefore, for the analysis of the same period of 1 week (100 hours production time), the machine is capable of making 30 * 100 = 3,000 items.
The equipment performance equation, in what concerns production output is
Performance = number of parts produced / actual number of parts produced
Now let's assume the actual number of parts made during that week period was 2,855. It follows that
Performance (Machine A) = 2,500 / 3,000 = 0.8333 * 100 = 83.33 %.
Equipment production quality
This is simply the ratio between the number of parts that failed quality control and the total number of parts, good and not so good, produced on the time period under analysis. Continuing our example, consider that a total of 94 items failed the quality control test. As such,
Equipment production quality = 100 - Parts with defect / Total parts * 100 => Equipment production quality (Machine A) = 100 - (94 / 2,500) * 100 = 96.24 %.
Putting it all together
OEE is defined by the following equation that, when applied, yields the result we're looking for:
OEE = Equipment availability * Equipment performance * Equipment production quality => OEE = .99 * .83 * .96 = 0.7888 * 100 = 78.88 %.
Benchmarks
The overall equipment efficiency for our example is 78.88%. World-class manufacturers hover around 85% OEE but the reality is that most manufacturing organizations’ OEE scores are closer to 60-65% (see details for these numbers: https://evocon.com/articles/world-class-oee-industry-benchmarks-from-more-than-50-countries/). I hope the mathematics are clear: it is very difficult to achieve 85% OEE. For example, even with 90% on all three metrics used to calculate OEE, the resulting value is only 73% (.9 * .9 * .9 = 0.729).
The role of CMMS in OEE improvement
The CMMS in itself does nothing for OEE. It is simply a tool for the aggregation of data required for the calculation of the OEE components, specially equipment availability. It is also the support system for the implementation of maintenance management frameworks, such as RCM, whose sole purpose is the economical increase of equipment reliability which results in more availability, performance and operational quality which, as we have seen, result in OEE improvement. Let's look at some quick practical CMMS examples designed to support users through the logging of metrics that are important to a successful maintenance plan that directly benefits OEE.
Categorizing Failure Modes
During an FMEA, work orders classified as breakdowns for a given asset, can be further tagged by failure mode for later analysis. A failure mode identifies the various ways (e.g. excessive vibration, gasket failure, fracture, etc) in which equipment might malfunction or deviate from its intended function. Creating a list of tags and using those on breakdown work orders will result on an informed corrective action plan, improving OEE.
As a CMMS implementation example, consider the following work order that has been tag with "FMEA" (showing this is a component judged critical enough to be included on the failure mode analysis) and "SealLeak" (identifying the failure mode). Through time, filtering by tag and work order type for that asset will provide statistical data to measure the impact of failures by type providing key data to improve equipment reliability.
Tracking downtime
Calculating the time from the first report of the issue (creation date), all the way to the date and time the issue was resolved (complete date), will provide a duration for the unavailability of the item.
In comma CMMS, the best way to assess this is to export the work order data as csv and operate on the date columns to calculate the total time.
Scheduled maintenance
The CMMS automates preventive maintenance schedules, reducing downtime due to breakdowns. Well-maintained equipment performs better, positively affecting OEE.
For this, simply used the scheduler included in your CMMS to automatically trigger actions on a regular basis.
In comma CMMS, this is one on the maintenance plans module.
Analysis after a dip in OEE
The CMMS will help pinpoint root causes of OEE dips, whether it’s frequent breakdowns, low performance, or quality issues. The data that is naturally generated by the CMMS workflows will provide insights into these.
For example, in comma CMMS, filtering for work orders done on a given location (or group of locations by going higher on the functional location hierarchy) may show patterns and abnormalities that can assist in the investigation and clarify decisions on the preparation of an action plan to address the issues.
Inventory management
Efficiently managing spare parts ensures availability and reduces downtime. The CMMS streamlines inventory control by integrating spare usage and movements into the work order work flow.
In comma CMMS, technicians move equipment around and declare consumable usage inside work orders. Setting proper stock minimums, highlights all the items that need to be reordered. The goal is to never to have a piece of equipment run ant less than the intended performance levels for lack of spares.
Integration with Production Systems
In the points above there's an understandable emphasis on keeping the equipment running at its best. But we're looking at equipment availability as a component of the OEE calculation independently, other systems will have to be looked at independently in order to assess other OEE metrics.
On this point, we are considering the possibility of connecting the CMMS package to other systems in order to aggregate relevant information that comes from systems that provide their function the best way possible. The developer of the production management system is an expert on its field as is the quality control system designer. Continue to use each system for its optimized intended application and interconnect to extract and cross-analyze to come up with the very best OEE assessment possible.
Comma CMMS is expandable and is able to host additional custom modules that deal with the logic of communicating with other systems and can show custom dashboards with information coming from different sources. Additionally, there's an API that allows connection to external clients. That secure API makes most of the data available for analysis available to other systems.
Conclusion
The takeaway is that, while the CMMS itself does not directly impact OEE, it does serve as a crucial tool by collecting and aggregating data necessary for calculating OEE. Additionally, it acts as the backbone for implementing actions that come out of maintenance management frameworks like RCM, leading to increased availability, improved performance, and better operational quality which positively influencing OEE outcomes has we have seen.
Even if your company currently has other fires to put out and OEE is not actively analyzed and optimized to the depth described in this article, the (proper) use of a CMMS may still be of great help. In the short term, it can provide improvements simply by the fact that it is an organizational and event-logging tool at heart. In the long term, data collected now is still valuable in the implementation of more advanced maintenance management programs.
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