# Research on Improved OEE Measurement Method Based on the Multiproduct Production System
## 2 Mainstream OEE Measurement Methods and Their Deficiencies
### Introduction of Mainstream OEE Measurement Methods  
Overall Equipment Efficiency. OEE was officially put forward by [PERSON] [24]. The primary arithmetic of OEE is:  
\[OEE\ =\ AR\ \times\ PE\ \times\ QR \tag{1}\]\[AR\;=\;\frac{OT}{LT} \tag{2}\]  
\[PE\;=\;\frac{SCT\;\times\;TO}{OT} \tag{3}\]  
\[QR\;=\;\frac{QP}{TO} \tag{4}\]  
where,  
\(AR\) is Availability Rate (the degree of utilization of production planning time). \(PE\) is Performance Effectiveness (the degree of exertion of equipment's design performance). \(QR\) is Quality Rate (the proportion of qualified products in all of the products produced). \(LT\) is Loading Time (calculated by Factory Planning Working Time minus Factory Planning Downtime). \(SCT\) is Single Cycle Time. \(OT\) is Operating Time (calculated by that Loading Time minus Equipment Downtime including Adjustment Time, Failure Time, and so on). \(TO\) is Total Output. \(QP\) is Qualified Products (given by Total Output minus Defect Amount). Therefore, the detailed arithmetic of OEE is:  
\[OEE\;=\;\frac{OT}{LT}\;\times\;\frac{SCT\;\times\;TO}{OT}\;\times\;\frac{QP}{ TO} \tag{5}\]  
The arithmetic can be simplified as:  
\[OEE\;=\;\frac{SCT\;\times\;QP}{LT} \tag{6}\]  
The further simplified form is:  
\[OEE\;=\;\frac{QOCT}{LT} \tag{7}\]  
QOCT means Qualified Output Cycle Time. The ultimate arithmetic is a ratio of time, which is used to reflect the production effectiveness of the factory within the statistical time. OEE, as a tool to measure actual production effectiveness by focusing on single equipment or single production line, is universally acknowledged all over the world [25]. The Total Equipment Effectiveness Performance (TEEP) was put forward by [PERSON] [26] and the arithmetic of TEEP is:  
\[TEEP\;=\;EU\;\times\;OEE \tag{8}\]  
\(EU\) means Equipment Utilization. TEEP can reflect the equipment effectiveness comprehensively by considering all the factors. It can also assess whether the utilization of the equipment is maximized. Production Equipment Effectiveness (PEE). [PERSON] proposed the concept of PEE by assigning weight coefficients to the three indicators in the OEE arithmetic in 1994 [27] and the specific calculation is:  
\[PE\;=\;AR\;\times\;w_{1}\;\times\;PE\;\times\;w_{2}\;\times\;QR\;\times\;w_{3} \tag{9}\]  
Overall Factory Effectiveness (OFE). [PERSON] and [PERSON] developed the OFE [28], which focused on the existing correlation among the equipment, production process, order plan, and so on. It could be used to measure the overall production effectiveness of the factory and arrange the production process. In addition, it could be adopted to coordinate the production line scheduling and factory scheduling. Actually, there is no general calculation method for OFE until now. [PERSON] and [PERSON] hold the idea that composite indicators (reworkrate, inventory turnover rate, on-time delivery, and the like) should be set and weighted. In 2003, [PERSON] et al. developed an OFE metric and adopted simulation analysis to integrate these metrics for the improvement of manufacturing productivity based on the analysis of metrics [29]. Overall Asset Effectiveness (OAE) and Overall Production Effectiveness (OPE). Based on OEE, OAE and OPE were expanded, which were widely used to identify and measure losses in the overall manufacturing environment [30]. Total Equipment Effectiveness (TEE). [PERSON] and [PERSON] designed TEE in 2006. From the TEE, it could be learned that various resource inputs were considered in the production process [31]:  
\[TEE\ =\ \sum_{i=1}^{I}\omega_{i}e_{i}\ \times\ OEE \tag{10}\]  
where, \(e_{i}\) is the ratio of actual input resources and theoretical input resources in the \(i\)th process, \(I\) represents the number of all processes, and \(\omega_{i}\) is its weight (\(\sum\ \omega_{i}\ =\ 1\)). Modified OEE.