PRODUCTION SCHEDULING RESCHEDULING IN FLEXIBLE MANUFACTURING/

Scheduling of production in flexible manufacturing systems (FMSs) has been extensively researched over the past years and it continues to at tract the interests of both academic researchers and practitioners. Th e generation of new and modified production schedules is becoming a ne cessity in today's complex manufacturing environment. Genetic algorith ms are used in this paper to obtain an initial schedule. Uncertainties in the production environment and modelling limitations inevitably re sult in deviations from the generated schedules. This makes rescheduli ng or reactive scheduling essential. Four different types of uncertain ties that normally cause discrepancies between the actual output and t he planned output are considered in this paper. These include unforese en machine breakdowns, increased order priority, rush orders arrival a nd order cancellations. In this paper, the current status of the shop is considered while rescheduling. The proposed algorithms revise only those operations that must be rescheduled and can, therefore, be used in conjunction with the existing scheduling methods to improve the eff iciency of flexible manufacturing systems.