8 / 2018-11-16 11:27:39

Integrated Unit Exchange Spare Parts Inventory Management Model under Imperfect Maintenance

Imperfect repair, Reorder point, Optimal Order Quantity, Backorder downtime, Stock out downtime, Repair process

The purpose of this paper is to provide an integrated model for repairable unit exchange spare parts. The repairable spare parts (RSP) management is way different than the non-repairable spare parts management. The term unit exchange describe the life cycle of RSP as they traverse through three sections in a cyclic manner i.e. (1) failure (2) repair and (3) inventory. The common practice follows the respective analysis in isolation for RSP in these three sections neglecting the visible linkage through the RSP. The paper integrates failure process, repair process and inventory under two policies to model the real world RSP operating scenario and to analyze the inventory variation for respective policies. The paper utilizes the generalized renewal process maximum likelihood estimators (GRP MLEs) to estimate the expected number of failures of RSP. Various downtimes associated with the repair process are defined and estimated. Downtime based inventory model is then developed to estimate optimal repaired lot sizes and reorder point. Three RSPs are considered for model development and validation. Detailed sensitivity analysis between various inventory related parameters of the developed models are carried out to ascertain their variations with respect to each other.