EFFECTS OF EQUIPMENT FAILURE UNCERTAINTY IN BATCH-PRODUCTION SCHEDULING

This paper deals with production scheduling of multipurpose batch plan ts in the presence of equipment failure uncertainty. Uncertainty analy sis is incorporated at the production scheduling stage to improve the probability of performing the resulting schedule. This probability wil l depend on forecasts of equipment failure. The effects of equipment f ailure on the production schedule are minimised by means of reliabilit y indexes for each plant unit. Avoiding the use of equipment with low reliability indexes is balanced against production requirements (deman d). Preventive maintenance tasks may be also introduced to compensate for possible delays produced by equipment with low reliability indexes . The system Operates from an on-line data-base management system whic h is continuously updated with plant status information. The incorpora tion of these methodologies into the overall planning framework is als o shown and illustrated with case studies.