“ Scheduling Mechanism for Dynamic Discrete Manufacturing ”

It is vital for manufacturing companies not only to cope with frequent product changes and fluctuating demands, but also to reduce the impact of disturbances on the overall manufacturing performance. In this paper a real-time scheduling mechanism for dynamic discrete manufacturing is presented. Modified mean flow time performance for different scheduling approaches is compared through off-line simulation experiments, under dynamic manufacturing environments that are subjects to disturbances such as machine breakdowns. These experimental results are used as reference indices for the real-time scheduling mechanism to select the better scheduling approaches for further evaluation based on the actual manufacturing conditions. Discrete event simulation is used on-line to evaluate the selected approaches and the corresponding schedules to determine the best solution. The selected schedule is used until the deviation of actual performance from the estimated one exceeds a given limit, or when a major event occurs. A new simulation is then performed with the remaining operations to select a new schedule.