Simulation of G/G/m-queue with multiple preventive maintenance schedules

Abstract

Preventive maintenance (PM) is an important activity in semiconductor manufacturing to maintain its equipment to keep stable manufacturing condition for the long term. The longer the durations of PM`s are, the larger their impact is on the cycle time (CT) and line performance. The reason why we consider segregating original PM into smaller ones. However, each preventive maintenance requires each setup time which causes potentially increasing CT. Thus, to determine segregating PM work is critical to optimize cycle time. This research finds out optimal PM work to optimize cycle time in G/G/m-Queue with multiple PM by simulation work. This study treats semiconductor manufacturing and failures as G/G/m-Queue and multiple PM respectively. Also we assume that we know time schedule of all failure and repair time. Thereby this research can use scheduling issue to find optimal PM work to optimize cycle time. There are two contribution from this research.First, we use same notation for cycle time of G/G/m-queue with single PM by simulation. In earlier research, when PM splits was 1, a researcher assumed that PM contained setup time. When PM splits was more than 2, he divided PM and setup time and segregated PM into smaller ones. In this research, we divide PM and setup time even PM splits is 1. We use same notation after segregating PM and we compare result of equation to result of simulation. This research provides equation and simulation that have same trend.Second, we show cycle time of G/G/m-queue with multiple PM by simulation. Since there is no equation for cycle time of G/G/m-queue with multiple PM, this study describes approximated cycle time with simulation. The result of simulation provides base of future research of G/G/m-queue with multiple PM.