A (r,r,Q) inventory model for spare parts involving equipment criticality

Demand for spare parts can sometimes be classified into critical and non-critical demand, depending on the criticality of the equipment for production. To effectively handle this situation in spare parts inventory control, we propose a (r,r,Q) inventory model for spare parts where some of the stock is reserved for critical demand. A solution procedure to determine the reorder point r, which is equal to the critical level, and the reorder quantity Q is presented. Finally, some numerical examples of the spare parts of semiconductor equipment are presented to illustrate the results of using the proposed policy.