Inventory models for fast moving spare parts subject to ''sudden death'' obsolescence

Simple inventory models are developed for fast moving spare parts subject to the risk of unexpected, immediate obsolescence. The approach does not require a precise knowledge of the probability distribution of the moment of obsolescence, as is the case for models discussed in the literature. A rough estimate of the obsolescence risk for the next order cycle is sufficient. The models call be seen as extensions of the EOQ-formula. Following cases are studied: 1. Constant obsolescence risk; no shortages allowed 2. Varying obsolescence risk; no shortages allowed 3. Varying obsolescence risk; shortages allowed It appears that the models are practicable and, in the proper circumstances, lead to a substantial reduction of cost.