Estimating arrival times of transportation jobs for automated material handling in LCD fabrication facilities

A modern LCD fabrication facility uses state-of-art automation technology to enhance manufacturing competitiveness driven by shorter cycle times, faster deliveries, and higher quality products. All transportation jobs from a process toolset to other toolsets during fabrication are done by automated material handling systems such as industrial robots, automated cranes, and AGVs (automated guided vehicles) in the industry. Estimating transportation times are important since the information can be used to improve the performance of the material handling systems by providing the expected arrival time of a job compared to its arrival due time, which can be used to change the priority of the transportation more dynamically. This paper develops a new heuristic method based on a stochastic approach to estimate the arrival times of transportation jobs to their final destinations in an LCD fabrication facility. To analyze the performance of the new method, the author collected a set of actual transportation data from the industry and the analysis shows that the new method outperforms an existing method that uses simple statistics based on historical data.