Optimal scheduling in a yogurt production line based on mixed integer linear programming

A Mixed Integer Linear Programming (MILP) model is proposed in this paper that targets the optimal production scheduling in a single yogurt production line. The model takes into account all the standard constraints encountered in production scheduling (material balances, inventory limitations, machinery capacity, labor shifts and manpower restrictions). Furthermore, it considers special features that characterize yogurt production, which are limitations in production sequencing mainly due to different fat contents and flavors of various products and sequence-dependent setup times and costs. The objective function that is minimized considers all major sources of variable cost that depend on the production schedule, i.e. changeover cost, inventory cost and labor cost. The model is applied to a yogurt production line of a major dairy industry and the results are presented and discussed.