A scheduling system is proposed and developed for a special type of flow shop. In this flow shop there is one machine at each stage. A job may require multiple operations at each stage. The first operation of a job on stage j cannot start until the last operation of the job on stage j - 1 has finished. Pre-emption of the operations of a job is not allowed. The flow shop that the authors consider has another feature, namely time lags between the multiple operations of a job. To move from one operation of a job to another requires a finite amount of time. This time lag is independent of the sequence and need not be the same for all operations or jobs. During a time lag of a job, operations of other jobs may be processed. This problem originates from a flexible manufacturing system scheduling problem where, between operations of a job on the same workstation, refixturing of the parts has to take place in a load/unload station, accompanied by (manual) transportation activities. In this paper a scheduling system is proposed in which the inherent structure of this flow shop is used in the formulation of lowerbounds on the makespan. A number of lowerbounds are developed and discussed. The use of these bounds makes it possible to generate a schedule that minimizes makespan or to construct approximate solutions. Finally, some heuristic procedures for this type of flow shop are proposed and compared with some well-known heuristic scheduling rules for job shop/flow shop scheduling.
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References
Aanen, E. (1988) Planning and scheduling in a flexible manufacturing system, Ph.D. Thesis, Faculty of Mechanical Engineering, University of Twente.
Aanen, E., Gaalman, G. J. C. and Nawijn, W. M. (1993) A scheduling approach for a flexible manufacturing system. International Journal of Production Research, 31, 2369–2385.
Cao, J. and Bedworth, D. D. (1992) Flow shop scheduling in serial multi-product processes with transfer and set-up times. International Journal of Production Research, 30, 1819–1830.
Garey, M. R. and Johnson, D. S. (1979) Computers and Intractability: a Guide to the Theory of NP-Completeness, Freeman, San Francisco.
Johnson, S. M. (1954) Optimal two- and three-stage production schedules with set-up times included. Naval Research Logistics Quarterly, 1, 61–68.
Kern, W. and Nawijn, W. M. (1991) Scheduling multi-operation jobs with time lags on a single machine, Working paper University of Twente, Holland.
Mitten, L. G. (1958) Sequencing n jobs on two machines with arbitrary time lags. Management Science, 5, 293–298.
Monma, C. L. (1979) The two-machine maximum flow time problem with series parallel precedence relations: an algorithm and extension. Operations Research, 27, 792–798.
Morton, T. E. and Pentico, D. W. (1993) Heuristic Scheduling Systems, with Applications to Production Systems and Project Management, John Wiley & Sons, New York.
Szwarc, W. (1983) Flow shop problems with time lags. Management Science, 29, 477–481.
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Riezebos, J., Gaalman, G.J.C. & Gupta, J.N.D. Flow shop scheduling with multiple operations and time lags. J Intell Manuf 6, 105–115 (1995). https://doi.org/10.1007/BF00123682
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DOI: https://doi.org/10.1007/BF00123682