A method of creating production schedules regarding production lines with parallel machines is presented. The production line setup provides for intermediate buffers located between individual stages. The method mostly concerns situations when part of the production machines is unavailable for performance of operations and it becomes necessary to modify the original schedule, the consequence of which is the need to build a new schedule. The cost criterion was taken into account, as the schedule is created with the lowest possible costs regarding untimely completion of products (e.g. fines for delayed product completion). The proposed method is relaxing heuristics, thanks to which scheduling is performed in a relatively short time. This was confirmed by the presented results of computational experiments. These experiments were carried out for the rescheduling of machine parts production.
Rescheduling is a frequently used reactive strategy in order to limit the effects of disruptions
on throughput times in multi-stage production processes. However, organizational deficits
often cause delays in the information on disruptions, so rescheduling cannot limit disruption
effects on throughput times optimally. Our approach strives for an investigation of
possible performance improvements in multi-stage production processes enabled by realtime
rescheduling in the event of disruptions. We developed a methodology whereby we
could measure these possible performance improvements. For this purpose, we created and
implemented a simulation model of a multi-stage production process. We defined system
parameters and varied factors according to our experiment design, such as information delay,
lot sizes and disruption durations. The simulation results were plotted and evaluated
using DoE methodology. Dependent on the factor settings, we were able to prove large improvements
by real-time rescheduling regarding the absorption of disruption effects in our
experiments.
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