Calculate and Apply OEE

The topic of overall equipment effectiveness (OEE) is a perennially hot topic in automation. We see it every month in the traffic search data that leads users to the automationworld.com site. Considering that OEE is a straightforward and decades-old formula, the number of searches being conducted about OEE indicate that workers in industry still have lots of questions about how to use it.

To address those questions, we connected with Jim Toman, senior manufacturing execution system advisor with system integrator Grantek, for a recent episode in the Automation World Gets Your Questions Answered podcast series. 

In that discussion, Toman provided an example of how to calculate OEE for a standard manufacturing line. His example focused on a single production line that included filling, wrapping, sealing, weighing and cartoning of a food product.

“So what we would basically do [for a line like this] is measure how many packs we fill in a shift, how many were rejected for quality issues, and how much time the line was running versus being down or stopped,” he said. “We won’t take into account things like changeover or cleaning time. There’s a lot of complexity you can add, but for simplicity we’ll ignore those for right now and we’ll look at the OEE for the line as a whole.”

To get the OEE availability percentage, Toman said to take the number of minutes that the machine or line was running divided by the total minutes available for the shift minus the cleaning and change over time to simplify this example.

“Let’s say that the line was down for equipment issues for a couple of hours in an eight-hour scheduled run. That gives us eight hours of time available. We had two hours down. That means our availability was 75%.”

For the OEE performance percentage, Toman said to take the ideal cycle time of the filler, multiply that by the total number of packs filled and divide it by the running time. In this case, we’ll say the line ran at full speed the entire shift when it was operating, so performance would be 100%.

To get the OEE quality percentage, Toman said take the number of packages that were rejected for quality issues and subtract that from the number of total packages. That tells you how many good packages were made. 

“We would divide that by the total packs, so if we lost 50 out of 1,000 packs, our quality number in this case is 95%,” explained Toman.

That’s basically how you get each of the components of OEE. Take 75% for availability, multiply that by 100% for performance and multiply that by 95% for quality, which would give you an OEE of 71% for that shift.

Original Article: https://www.automationworld.com/factory/oee/article/55000841/calculate-and-apply-oee