A SIMULATION-BASED SCHEDULER FOR FLEXIBLE FLOWLINES

A flexible flowline is a generalized production model employed in a wi de variety of manufacturing assembly applications to produce a range o f products in small batch quanitites. The MRP systems, which are commo nly used in such environments, lack the detail to carry out daily sche duling. Recently, finite capacity planning tools have been suggested a s a means of generating short-term production schedules. These tools e mploy techniques that take a global view of the problem and are based on static 'snapshots' of the manufacturing system. However, they ignor e any inherent dynamics and therefore are inadequate in managing disru ptions that can be very costly in terms of the inability to meet throu ghput requirements and prior delivery commitments. A simulation-based scheduler, on the contrary, is effective in accommodating the dynamic and/or stochastic nature of the system in arriving at a sheduling solu tion. In this paper, we introduce a simulation-based scheduler which i s used to study a general class of parametric dispatching rules for fl exible flowlines, under a variety of shop loading conditions. A scaled model of an actual manufacturing system is used to study the apparent tardiness cost based scheduling rule. The simulation-based scheduler has the facility to model a variety of manufacturing scenarios ranging from PCB lines to complex flexible flowlines. The scheduler is design ed on pragmatic considerations and provides a test platform for studyi ng static as well as dynamic scheduling rules for real manufacturing e nvironments. It serves as an expedient to evaluating the practical eff ectiveness of scheduling rules. Additionally, it can also be used to d evelop detailed short-term capacity plans that form the basis for fini te capacity scheduling.