Integration of material handling devices assignment and facility layout problems

Facility layout problems focus on the assignment of departments into the facility layout by considering the minimization of total costs. A well-designed facility result in efficient material flows in transportation. For this reason, the problem should be considered with the changes in demands that cause different material flows between departments. While the aim of the static facility layout problem is to obtain the optimal facility layout, the dynamic facility layout problem includes the multi-periods dealing with the changes in material flows between departments. Furthermore, the material handling devices may affect the facility layout decisions although it is omitted in general. In this study, three different facility layout problems concern static, dynamic and flexible bay structure and material handling device assignment problems are considered simultaneously. Three mixed integer programming models are proposed for the addressed problems with integrated decisions. The proposed models are compared with a two-stage approach composed of solving the classical facility layout problems first, then solving material handling devices assignment problems. The comparative results show that the integrated decision affects the facility layout and decreases the total costs. Eleven test instances are considered and the integrated model provides cost efficiency for these test instances.