Raw material procurement with fluctuating prices

Increasing global competition and cost pressure force enterprises and supply chains to discover undetected cost-saving potentials. In particular, interfaces to the raw materials' market are a promising field for improvement. This paper presents a deterministic optimal control approach optimizing the procurement and inventory policy of an enterprise that is processing a raw material when the purchasing price, holding cost, and the demand rate fluctuate over time. Applying Pontryagin's maximum principle, the optimal policy turns out to be of a bang-bang type involving impulse and just-in-time procurement. Numerical examples illustrate the solutions obtained and compare the optimal policy with simple replenishment strategies.