Capacitated production planning problem considering the detailed scheduling constraints in a flow shop environment

In this paper, a multi-product multi-period production system organized as a flow shop is considered. To overcome the shortcomings of hierarchical production planning, detailed production planning scheduling and sequencing constraints are integrated. A new integrated mixed-integer programming (MIP) model, capable of simultaneously performing production planning and nonpermutation scheduling, is proposed for the considered problem. For precise machine workload calculation, detailed scheduling constraints are used to determine a feasible production plan. The objective function includes production, inventory, backlog, set-up costs, and the costs associated with machine idle time and overtime. A hybrid simulated annealing (HSA) algorithm with dispatching rules and an exact solution method is proposed to solve the integrated model. The proposed algorithm searches the solution space for both problems and finds a combination of production planning and scheduling that is feasible and close to optimum. To evaluate the performance of the proposed model and solution method, problems of different scales are studied. The total costs of the proposed solution method are smaller than the results of hierarchical production planning.