Skip to main content

Overall Equipment Effectiveness

Definition​

Overall Equipment Effectiveness (OEE) is an essential piece of information for any production facility that wants to get on-board with Industry 4.0. It is used to assess what percentage of the production time is truly productive on a system. OEE can be calculated for machines, but it can also be calculated for a set of machines and even a whole plant. It is the product of 3 factors, that each range from 0% to 100%:

  • Availability
  • Performance
  • Quality

Therefore, OEE is also a number that ranges from 0 to 100%, a value of 100% meaning that the system is fully productive.

Availability​

Availability is a measure of how much of the time that is planned for production is spent producing.

For example, if a machine is supposed to be working every day between 7AM and 7PM, it has a planned production time of 12 hours. If, some day, the machine has been down between 10AM and 1PM (3 hours), it means its uptime for the day is 9 hours and therefore its availability for the day is 9/12 = 75%.

To measure the availability of a machine, you will need to configure Machine State events. This way, the K2 application knows when your machine is up and when it is down. When it is down, you can set it to prompt your operators for a stop cause, so that you can have a better idea of what causes downtimes in your factory and act upon it.

Performance​

Performance is a measure of how fast parts are being produced compared to the theoritical time needed to produce one part.

For example, if the operator works for 5 hours on a machine to produce parts that each take 30 minutes to produce, the unit completion time is 30 minutes and the production goal is 10 parts. If only 9 parts were produced during the 5-hour period, the performance ratio is 9/10 = 90%.

Since machines can produce different types of parts that each have their own theoritical production time, you need to configure SKU numbers for your machines if you wish to know about their performance. You also need to configure Part events, so that the application knows when parts are being made. When the operator is using the machine, they need to indicate what SKU number they are working on, so that the application knows what is the theoritical rate at which parts are supposed to be produced.

Quality​

Quality is the ratio of the number of good output parts to the number of input parts. When a part enters a machine, it is an input part. When it exits the machine, it becomes an output part. If the part is rejected for quality reasons, it can be classified as a defect. Good output parts are output parts that are accepted or, in other words, that are not tagged as defect.

For example, if 10 parts enter the machine and they all come out, that's 10 input parts and 10 output parts. If, out of the 10 parts that exited the machine, 2 are marked as defects, that leaves us with 8 good output parts and a quality ratio of 8/10 = 80%.

To measure the quality ratio of a machine, you will need to configure Part events. This way, the K2 application knows what goes in and out of your machine. Using the rules engine, output parts can be marked as a defect automatically (if there is such a signal that provides this information), or manually (for example, an operator that clicks a button following visual inspection).