Overall Equipment Effectiveness (OEE)

An ideal machine would run continuously, always at maximum performance, and without any defects. However, this ideal scenario rarely occurs in reality. The Overall Equipment Effectiveness (OEE) serves as a metric to determine how close the equipment is to this ideal state. It combines time, quantity, and quality to provide an effectiveness assessment. We refer to the product of these three factors as overall equipment effectiveness, or OEE.

Starting with the maximum available time, for example, assumed to be 24 hours, the theoretically available production time is used as the basis for further calculations. This potential production time is derived from the total time in the observation period minus all planned downtimes, such as maintenance, repairs, or non-utilization of the equipment due to the order situation.

Three types of losses are distinguished for OEE calculation:

• Availability losses
• Performance losses
• Quality losses

Availability losses: These occur due to unplanned downtimes during the potential production time, such as breakdowns, setup processes, or waiting times. Subtracting availability losses from the potential production time yields the actual production time.

Performance losses: These represent the difference between the potential output of the equipment based on the actual production time and the actual output. This difference arises from short stoppages, such as jammed parts, or from reduced equipment speed.

Quality losses: These include all non-conforming products produced by the equipment. Any product requiring rework or considered scrap is deducted from the actual output for calculating the OEE.

Overall, the OEE is calculated by multiplying the availability rate (actual production time / potential production time) by the performance rate (actual output / potential output) by the quality rate (good products / actual output).