Unit sized transfer batch scheduling in an automated two-machine flow-line cell with one transport agent

The process of splitting a job lot comprised of several identical units into transfer batches (some portion of the lot), and permitting the transfer of processed transfer batches to downstream machines, allows the operations of a job lot to be overlapped. The essence of this idea is to increase the movement of work in the manufacturing environment. In this paper, the scheduling of multiple job lots with unit sized transfer batches is studied for a two-machine flow-line cell in which a single transport agent picks a completed unit from the first machine, delivers it to the second machine, and returns to the first machine. A completed unit on the first machine blocks the machine if the transport agent is in transit. We examine this problem for both unit dependent and independent setups on each machine, and propose an optimal solution procedure similar to Johnson's rule for solving the basic two-machine flowshop scheduling problem.