A spare parts stocking policy based on equipment criticality

Demand for spare parts can sometimes be classified into critical and non-critical demand, depending on the criticality of the equipment in which it is installed. To effectively handle this situation in spare parts inventory control, we propose a stocking policy where some of the stock is reserved for critical demand. For Poisson demand and a lot-for-lot stocking policy with positive replenishment leadtime, approximations of the service levels for both classes of demand are derived, and verified by simulation. Finally, a numerical example is presented to illustrate the advantages of using the proposed policy.