Ordering Policies under Minimal Repair

Many maintenance policies in the literature have assumed that whenever a unit is to be replaced, a new unit is immediately available. However, if the procurement lead time is not negligible, an ordering policy should determine when to order a spare and when to replace the operating unit. This paper proposes and analyzes two ordering policies for replacement with minimal repair which include the ´periodic replacement with minimal repair at failure´ of Barlow & Hunter as a special case. If the failure rate is monotonic, the objective functions representing the cost rates for the two policies are unimodal.