GROUP SCHEDULING PROBLEMS IN FLEXIBLEFLOW SHOPS

摘要

Flexible flow shops are becoming increasingly common in industry practice because of higher workloads imposedrnby jobs on one or more stages, thus requiring two or more units of the same machine type. We present arnmethodology for solving this important problem, namely group scheduling, within the context of cellularrnmanufacturing systems in order to minimize the total completion time of all groups of jobs considered in thernplanning horizon. Two different setup options, namely single setup and multiple-setups, are investigated for jobsrnwithin the same group. A combined heuristic solution algorithm, comprised of single- and multiple-pass heuristics,rnis used for solving the problem. An example problem, consisting of three different problem instances of the samernstructure, is used to not only demonstrate the applicability of the solution algorithm, but also to identify the setup tornaverage job run time ratios that should simultaneously prevail across all stages represented by two or more identicalrnunits in order to select multiple-setups over single setup or vice versa.