Tool handling and scheduling in a two-machine flexible manufacturing cell

In this paper we examine the issue of tool management in a flexible manufacturing cell. The type of system considered here is typical of mechanical manufacturing, in which large metallic parts are loaded on the machines and are not moved until processing completion. The architecture of the cell is characterized by the absence of on-board tool magazines on the machines. Although this permits the continuous maintenance and inspection of the tools and typically results in cost and workspace savings, it calls for more complex tool handling procedures. We present a heuristic to address the overall problem of assigning parts to machines, sequencing parts on each machine, and synchronizing tool movements. The results indicate that our method provides near-optimal solutions in terms of makespan and mean flow time. Further, we observe that the solution procedure is at least one order of magnitude faster than the approach currently used and also results in a much better mean flow time.