The M × N Flowshop Problem with Separable, Sequence-independent Setup Times
نویسندگان
چکیده
This paper presents an MILP model for the permutation flowshop wherein the setup times are both separable from the job processing times and independent of a job’s position in the processing sequence. Two experiments were conducted to estimate the computer times necessary to solve problems with up to 9 machines and 15 jobs, and to then compare these solution time requirements to those required to solve the same sets of problems solved as regular (NSIST) flowshop problems. The resultant data were then used to assess the impact on two optimal sequence performance measures, makespan and mean flowtime when setup times were separated from their jobs and allowed to begin as soon as the machine was free from the preceding job. This impact of separated setup times was found to increase with increasing numbers of machines, but to decrease slightly with increasing numbers of jobs for a given number of machines. Lastly, the data were used to analyze the impact on mean flowtime when makespan is minimized, and the impact on makespan when mean flowtime is minimized. KeywordsInteger programming, Flowshop, Setup times, Sequence-independent setup times, Makespan, Mean flow time ∗Corresponding author’s email: [email protected] International Journal of Operations Research 1813-713X Copyright 2006 ORSTW
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