Abstract
In order to define and measure the overall performance of equipment, Overall Equipment Efficiency (OEE) has been proposed to consider the trade-off between traditional stand-alone metrics. OEE represents a comprehensive index for single equipment performance. Due to the growing of the number of equipment in factories, it becomes more difficult to manage single machine OEE one by one. In this study, group OEE (GOEE) is proposed to observe the equipment performance on group level. In addition, existing studies focus on the analysis of equipment OEE during a period of observing time. Nevertheless, it is also essential to continuously monitor OEE from time to time. This study aims to construct a framework for monitoring equipment performance and diagnosing root causes of performance losses. In particular, we define OEE-related metrics that consider two dimensions: equipment group and time. Longitudinal analysis on OEE monitors the long-term equipment performance by statistical efficiency control charts. After several critical time intervals are found to have OEE down, root cause analysis is then utilized to identify possible performance detractors: crucial machine statuses. By prioritizing the performance loss factors according to their proportion of OEE loss, analyzers can determine that which machine or machine group should be the focus for management. Improvement actions can be triggered on those critical machine statuses to promote equipment performance.