A joint optimization problem of spare ordering and preventive replacement is considered. Introducing the minimal repair, ordering, downtime, inventory costs and salvage value of unit, we derive the expected cost rate when the lifetime of unit is gener...
A joint optimization problem of spare ordering and preventive replacement is considered. Introducing the minimal repair, ordering, downtime, inventory costs and salvage value of unit, we derive the expected cost rate when the lifetime of unit is generally distributed. We show that the optimum ordering policy minimizing the expected cost rate is either one of the two typical policies: (1) the original unit is replaced as soon as the ordered spare is delivered, or (2) the delivered spare is put into inventory until the original unit fails.
Some properties regarding the optimum ordering policy are also presented.