Overall equipment effectiveness (OEE) is a performance indicator Seiichi Nakajima developed in the 1960s to evaluate the effectiveness of a given manufacturing operation. OEE is the most frequent indicator found in manufacturing industries. While OEE measures effectiveness against scheduled hours, TEEP measures effectiveness against calendar hours (24/7/365 days per year).
OEE and TEEP are not, however, absolute measures and are best used to identify priority improvement levers. The value of these indicators are relative to a baseline for a given piece of equipment and therefore specific to that equipment and not necessarily comparable across departments or plants. Maximizing OEE or TEEP doesn’t necessarily mean reaching the global optimum.
There’s no international consensus on this kind of performance indicator. However, it’s easy to find examples of well-built OEE metrics both in manufacturing companies and from national normalization organizations.