Talep tedarik süresi ve kritik seviye politikası ile yedek parça envanter yönetimi

ABSTRACTSPARE PARTS INVENTORY MANAGEMENT WITHDELIVERY LEAD TIMES AND RATIONINGYaşar Levent Koşağas cgM.S. in Industrial EngineeringSupervisor: Assist. Prof. Dr. Alper SenşMay, 2004We study the spare parts service system of a major semiconductor equipmentmanufacturer facing two kinds of orders of different criticality. The more criticaldown orders need to be supplied immediately, whereas the less critical mainte-nance orders allow a given demand lead time to be fulfilled. For this system,we propose a policy that rations the maintenance orders. Under a one-for-onereplenishment policy with backordering and for Poisson demand arrivals for bothclasses, we first derive expressions for the service levels of both classes and thenconduct a computational study to illustrate superior system performance com-pared to a system without rationing. We also conduct a case study with 64representative parts and show that significant savings are possible through incor-poration of demand lead times and rationing.Keywords: Inventory models, spare parts planning, multiple demand classes, ra-tioning, demand lead time.iii