A total productive maintenance (TPM) measure of how effectively
equipment is being used.
OEE is calculated from three elements: The availability rate measures downtime losses from equipment failures and adjustments as a percentage of scheduled time. The performance rate measures operating speed losses—running at speeds lower than design speed and stoppages lasting a few seconds. The quality rate expresses losses due to scrap and rework as a percentage of total parts run.
These elements are multiplied to obtain OEE:
Availability Rate x Performance Rate x Quality Rate = OEE
If Availability is 90%, Performance is 95%, and Quality is 99% then 0.90 x 0.95 x 0.99 = 84.6% OEE
OEE typically focuses on what are termed the six major losses—failures, adjustments, minor stoppages, reduced operating speeds, scrap, and rework—but some companies add other measures judged important to their business.