The machine layout within a TFT-LCD bay with a multiple-stacker crane in-line stocker

In this paper, we study the machine layout problem in a TFT-LCD (thin-film transistor liquid-crystal display) bay with a multiple-stacker crane in-line stocker. Unlike other material-handling systems, such as automated guided vehicles and conveyors that only have a transportation function, in-line stockers have both transportation and storage functions. They rely on stacker cranes to perform their transportation function. The in-line stocker in a TFT-LCD bay is often divided into zones. Each zone is served by a stacker crane. 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 minimisation 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 layout design found by the proposed layout procedure was validated with computer simulations. It was also compared with layouts obtained by approaches proposed by other researchers. 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 with a multiple-stacker crane in-line stocker.