A new mathematical model for integrated production planning and scheduling problem in capacitated flexible flow shop with sequence-dependent setups

The main contribution and novelty of this paper is proposing a more efficient mathematical model for integrated lot-sizing and scheduling in a multi-product multi-period capacitated flexible flow shop with sequence-dependent setups. A new approach for modeling the problem has been proposed and its complexity compared with former models. In comparison to the former models, because of fewer continuous and binary variables and constraints of proposed model makes it easy to be solved. Comparison between new model and former models proves the superiority of proposed model. Due to the complexity of the problem, three mixed-integer programming based heuristics all based on iterative resolutions of reduced-size MIPs and rolling horizon have been implemented to solve model. To evaluate the performance of the proposed model and solution method, problems of different scales have been studied. The used algorithms search the solution space for both lot-sizing and scheduling and find a combination of production planning and scheduling that is feasible and close to optimum. Computational results show that HA2 is superior for this problem and can find good quality solution for the problem in a reasonable computational time. Also, sensitivity analysis is used to clarify the problem and ensure suitability of the proposed model.