In general, most engineers merely rely on the design of experiments (DOE) or their own process experiences in one of the machines with the same type to maintain the capacity of the production line and all of those machines of that same type. However, in this case, they cannot fully understand and control the whole process effects of those same-type machines, because the result of DOE can only represents a small part of the whole parameters. Besides, it merely reflects the condition of the specific machine at that moment. The time-varying effect and status between the different machines of the same type are the thorny problems in the production line, and these will result in variation of the product quality. To comprehend and control the time-varying effect and status of each single machine is usually a difficult and costly task.