The machine layout within a TFT-LCD bay with an in-line stocker system and an RGV system

There are many factors that can affect a TFT-LCD (Thin-Film-Transistor Liquid-Crystal-Display) plant's material flow efficiency. Among them, a TFT-LCD plant's intra-bay machine layout is a critical one. The way that material flow is handled in a TFT-LCD bay is different from that in a semiconductor bay due to the difference between their automated material handling systems. For example, a stocker in a semiconductor fab is located at a bay's end and only has the storage function. However, a stocker in a TFT-LCD plant can extend all the way into the bay it belongs to. A TFT-LCD stocker has not only the storage function, but also the transportation function. This type of stocker is referred to as in-line stocker. Furthermore, for the purpose of improving transportation reliability, some TFT-LCD plants also have RGVs (Rail Guided Vehicles) to assist in-line stockers in transporting glass panels. Because of the unique combination of the in-line stocker and RGVs, the machine layout problem within a TFT-LCD bay will be different that within a semiconductor bay or a TFT-LCD bay with only the in-line stocker. In this paper, we propose a layout method for the machine layout problem within a TFT-LCD bay. The objective is to minimize the total flow distance and at the same time balance the workload of stocker cranes in the in-line stocker. An example problem will be solved to illustrate the proposed method. The result of our study shows that the proposed method is able to design feasible and good-quality machine layouts within a TFT-LCD bay.