Performance Metric
The performance portion of the OEE Metric represents the speed at which the Work Center runs as a percentage of its designed speed. The Performance Metric is a pure measurement of speed that is designed to exclude the effects of Quality and Availability. The losses due to wasted performance are also often called speed losses. In practice it is often difficult to determine speed losses, and a common approach is to merely assign the remaining unknown losses as speed looses.
Calculation: Performance = (Parts Produced * Ideal Cycle Time) / Operating time [2]
Example:
A given Work Center is scheduled to run for an 8-hour (480 minute) shift with a 30-minute scheduled break.
Operating Time = 450 Min Sched – 60 Min Unsched Downtime = 390 Minutes
The Standard Rate for the part being produced is 40 Units/Hour or 1.5 Minutes/Unit
The Work Center produces 242 Total Units during the shift. Note: The basis is Total Units, not Good Units. The Performance metric does not penalize for Quality.
Time to Produce Parts = 242 Units * 1.5 Minutes/Unit = 363 Minutes
Performance = 363 Minutes / 390 Minutes = 93.0%
Quality
The Quality portion of the OEE Metric represents the Good Units produced as a percentage of the Total Units Started. The Quality Metric is a pure measurement of Process Yield that is designed to exclude the effects of Availability and Performance. The losses due to defects and rework are called quality losses.
Calculation: Quality = (Units produced – defective units) / (Units produced)
Example:
242 Units are produced. 21 are defective.
(242 units produced – 21 defective units) = 221 units
221 good units / 242 total units produced = 91.32%
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