dc.description.abstract | Building a thin-film transistor liquid-crystal display (TFT-LCD) plant is a huge investment, thus it is very important to increase the production efficiency of a TFT-LCD plant. One important factor that affects a TFT-LCD plant’s production efficiency is the plant’s material flow efficiency. Many factors can affect a TFT-LCD plant’s material flow efficiency. Among them, a TFT-LCD plant’s intra-bay facility layout and the dispatching control of the plant’s intra-bay automated material handling systems (AMHSs) are two critical ones. The way that material is handled in a TFT-LCD bay is different from that in a wafer-fab bay. The stocker of a wafer-fab bay is located at one end of the bay and only provides the storage function. However, the stocker of a TFT-LCD bay is extended all the way into the bay. Furthermore, the stocker of a TFT-LCD bay not only has the storage function, but also can transport cassettes between machines, ports and storage cells. This type of stocker is referred to as ‘stocker direct handling system’ also known as ‘in-line stocker.’ In some TFT-LCD plants, rail guided vehicles (RGVs) are also used to assist in-line stocker transporting cassettes. The unique way that an in-line stocker handles cassettes and the possible presence of RGVs have made the layout problem of a TFT-LCD bay different from that of a wafer-fab bay. In the first part of this paper, we study the machine layout problem in a TFT-LCD bay with a multiple-stacker crane in-line stocker. Furthermore, the machine layout within a TFT-LCD bay with an in-line stocker system and an RGV system is further investigated. Due to its multiple-zone in-line stocker, solving a TFT-LCD bay’s machine layout requires us to determine not only the positions of the machines, but also the zone division design. The objectives include the minimization of total flow distance and the workload balance between stacker cranes. We propose a layout procedure that adopts heuristic and mathematical approaches to assist us in accomplishing the aforementioned tasks. An example problem mimicking a real-case problem was solved to illustrate the proposed layout procedure. The simulation and comparison results demonstrate the capability of the proposed layout method in producing a feasible and good machine layout in a TFT-LCD bay. In the second part of this paper, we study the dispatching control problem of the stacker cranes of in-line stockers by identifying three control problems of stacker cranes and developing control rules for each of them. These three problems are task-determination problem, the port-clearing problem, and the cassette-delivery problem. Computer simulations were conducted to compare the performance of the rules proposed for each of these three problems. The objective of this paper is to optimize the material flow efficiency within a TFT-LCD bay. By doing so, it is hoped that the TFT-LCD plant’s operational efficiency can be improved, its production cost can be reduced and its competitiveness can be increased.
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