Overall Equipment Effectiveness, or OEE, has long been considered one of the best metrics for benchmarking productivity available to manufacturers today.
With 100% being a perfect score, it allows you to take a look at quality, performance and availability. As you inch closer to that high score, it means that you’re manufacturing A) only high quality parts, B) as quickly as you can, with C) little to no stop time to speak of. As you implement measures for improvement and optimization, you can see that score improve in real-time – thus allowing you to see exactly which of your efforts are working as soon as possible.
Which, of course, demands the question – what happens if that score isn’t actually increasing? What if you’re making strategic moves, only to see it start to slide in the other direction? All told, there are a number of reasons why your OEE score may be on the decline – and reversing these trends requires you to understand as much about them as possible.
Understanding Declining OEE Scores: An Overview
By far, two of the biggest reasons why OEE scores may be declining have to do with both planned and unplanned stops. Planned stops include things like changeovers and inspections, while unplanned stops are obviously related to unexpected periods of downtime.
To be fair, some type of stoppage is inevitable – it’s a big part of the reason why nobody ever achieves a true OEE score of 100%. But if planned stops are taking too long, and they’re getting longer all the time, it could cause your OEE score to decline. Likewise, even if you don’t think unplanned stops are taking too long, if they’re increasing in frequency it could create the same trend.
Another major reason why OEE scores tend to decline has to do with slow speeds of the equipment being measured. In order to increase your score, particularly in terms of availability, a machine or system needs to be hitting its maximum productivity. If it isn’t, it could point to a number of different issues.
Sometimes, machines begin to slow down because they’re being feed poor quality materials. Other times, its human error – operators simply need more training or access to resources that they don’t have. However, it could also be due to the machine’s age – illustrating the dangers of inadequate maintenance programs.
Ultimately, it’s relatively easy for your OEE score to start to decline – especially if you’re not paying attention to the data you’re getting. Prioritizing maintenance for equipment and ongoing training and education for employees is one way to combat this, but there are many others. If nothing else, this serves as a reminder of the fact that OEE is not something you “do once and forget about.” There are always opportunities for improvement and if you don’t start to capitalize on them, you could start to see a negative trend that is much, much harder to correct than it otherwise should be.