In this video, Lindsey Shepard will walk you through the OEE calculation itself and how you can utilize it to help improve your process.
The basis of the OEE calculation is as simple as it is brilliant. It assumes a theoretical maximum capacity on the one hand and the actual output on the other. The OEE calculation maps out the loss landscape clearly in a way that everyone can understand.
The OEE calculation poses these 3 questions:
Is the machine operating or not? (Availability)
How fast is the machine running: (Performance)
How many products met the specifications? (quality)
We start this calculation with Availability.
If the machine is producing the product while it was available to the production-team we know it was running. The ‘availability rate’ indicates the relationship between the time that the machine could theoretically have been in operation and the time that there was actual output.
For example: If the machine delivers 360 minutes of output regardless of speed and quality during an 8-hour shift which is 480 minutes, then the availability rate is 360/480= 75%. In other words, 25% of the available time is “lost”.
OEE now asks the second question of Performance
Say that the machine is designed to produce 10 pieces a minute, in which case you would expect to have 3,600 pieces after 360 minutes. Of course, this is only possible if the machine ‘performs’ while it is running, at 100% speed. The performance rate determines whether this is true:
In the performance rate, ‘theoretical output’ is the output that the machine could have made in theory if the machine had operated at maximum speed during the time that it actually operated.
For example, the machine operates 360 minutes and production speed is 10 pieces per minute. The theoretical output is 360 x10 or 3600 pieces.
Actual output which includes both good AND rejected pieces though is only 2880 pieces. So performance is 2880/3600 or 80%.
So when we know how long the machine ran and how fast it ran, the next question is Quality.
Once we have measured the time and speed losses, we focus our attention on the quality of the products that are being made.
The relationship between the number of units produced and the number of the units produced that meet the specification is called the ‘quality rate’.
For example, we know that during the production time, 2880 pieces were produced, but 144 of those pieces were rejected giving us a total of 2736 good pieces. To calculate the quality rate, we take 2736 divided by 2880 which equals 95%.
The OEE is calculated by multiplying the availability rate, by the performance rate, by the quality rate.
Availability rate is b divided by A 360 minutes divided by 480 minutes which equal 75%.
Performance rate is d divided c or 2880 pieces divided by 3600 or 80%.
Quality rate is f divided by e or 2736 units divided by 2880 units or 95%.
So the OEE is 75% times 80% times 95% which gives us 57%.
So in this example, your machine is running at 57% Overall Equipment Effectiveness. You can take this information and begin to look at options for improving availability, performance or quality and see how small changes can make a big difference in your machine’s OEE.
To learn more about OEE, watch this video:
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