Formulations and heuristics for scheduling in a Kanban flowshop to minimize the sum of weighted flowtime, weighted tardiness and weighted earliness of containers

The problem of scheduling in a Kanban flowshop is considered with the objective of minimizing the sum of weighted flowtime, weighted tardiness and weighted earliness of containers. The Kanban flowshop is characterized by the presence of separate input and output buffers between workstations, material handling between workstations, blocking mechanism due to part-type, Production and Withdrawal Kanbans, and setup times separated from process times of containers. First, mathematical formulations for time-tabling of containers for different types of problems are proposed. The development of a simple heuristic to minimize the sum of weighted flowtime, weighted tardiness and weighted earliness of containers is subsequently presented. An improvement scheme is supplemented to the proposed heuristic to enhance the quality of the final solution. The proposed heuristic and the existing heuristics are evaluated in a large number of randomly generated problems of different sizes.