The multi-period multi-level capacitated lot-sizing and scheduling problem in the dairy soft-drink industry

ABSTRACT Lot-sizing and scheduling are a well-known problem. However, there are only few works addressing the problem in the food industry. We propose a mixed-integer-programming model for the lot-sizing and scheduling problem in a dairy production process. The latter is composed of standardisation tanks that can store different types of flavours and ultra-high temperature (UHT) lines. The model considers limited shelf life of liquid flavours in standardisation tanks and production bottleneck that can alternate between stages. Ten representative instances using real data are addressed with an exact method and a relax-and-fix heuristic. The results show that the assignment strategies increase the production costs. Moreover, these assignment strategies do not only reveal the total production capacity related to some industrial settings but also show the limit at which the bottleneck capacity of a given setting moves from the UHT line to the tanks.