Acronyms Are Hard: OEE Overall Equipment Effectiveness

Basic OEE Calculation

The following is a continuation of our Acronyms Are Hard: MES edition series, which you may want to catch up on before reading this.

Overall Equipment Effectiveness

Overall Equipment Effectiveness is used to calculate the efficiency of a line, facility, or anything in-between. The equation

OEE = A x P x Q

A being Availability (Uptime)

Availability is the actual uptime divided by the expected uptime. So if we are expecting to run 50 minutes in the hour, and we’ve run for 45 minutes, we are 90% efficient

P being Performance (Speed)

So we would compare the speed that the line runs in conjunction with the speed at which it runs. For this post say that we ran at 90.1% of our target speed

Q being Quality (Waste/Scrap)

Which almost always is no scrap. So let's say there were not any issues and the quality was 100%.

OEE = .9 x .91x 1.0

OEE = .81 or 81%

Downtime

Downtime is one of the easier components of OEE to quantify. Part of what Corso Systems puts in place is a combination of reason codes pulled from the PLC as well as the option for manually inputting reason codes by operators. We pull as much information as possible from the PLC because it is more efficient and removes the opportunity for human error. The more automated we can make the line and the process, the more information we can pull from the PLC.

The downtime report is a good place to start finding where you can become more efficient. A typical example report might include the top five reasons the line has gone down. This information will expose the low hanging fruit for maintenance and operations to fix first. Perhaps they need to do more preventive maintenance, or there was an issue with raw material supply. Or there could be a bottleneck because the best operators are being asked to do extra tasks they would otherwise need to complete at the same time as running the plant.

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Updated - 6/14/2022