Overall Equipment Effectiveness(OEE) is a set of metrics used by manufacturing facilities. This method of measurement is used to improve operations, increase financial gain and improve productivity. To calculate overall equipment effectiveness the availability, performance, and quality of the facility's equipment first need to be determined.
The first measurable factor of OEE is a manufacturing facility's Availability. This measurement is based on the facilities' net available time for production and the amount of production's downtime. Downtime includes maintenance, machine failure, and break time.
To find the percentage of Availability needed to calculate overall equipment effectiveness, this equation is used:
Hours equipment is used/hours available=machine's availability
For example, if a machine is used 10 hours a day, but is available for operation 20 hours a day, its availability is 50%.
The performance of a machine is another factor used to measure operations OEE. To calculate the performance, the current speed of the operation and the speed it is capable of need to be known.
To find the performance percentage needed to calculate overall equipment effectiveness, this equation is used:
Actual number of products produced/Machine's capability=Performance
For example, if the machine is producing 110 products per day, but it is capable of producing 200 products a day, its performance percentage is 55%.
The quality of production also needs to be determined to calculate overall equipment effectiveness. To calculate the percentage of quality, the number of rejected products produced and the total number of products it has made need to be known.
To find the quality percentage needed to calculate OEE, this equation is used:
Quality products made/Total number of products=Quality
An example of this would be a machine made a total of 200 good units, but 300 total were made. The quality percentage is 67%.
Once the facilities Availability, Performance and Quality are determined, the overall equipment effectiveness can be calculated.
To Find the OEE, these three factors are multiplied.
OEE= Availability x Performance x Quality
In the examples above, the equipment's availability was 50%, the performance was 55% and the quality was 66%. Using the above equation, the overall equipment effectiveness is 18.43 %.( 50 x 55 x 67= 18.43%)
Now that the overall equipment effectiveness has been calculated, improvement opportunities can be determined. The numbers the overall equipment effectiveness equation produces does not solve a machine's current problem, however, calculating the losses can be analyzed and new performance standards can be set.