Multi-purpose scheduling on parallel machines under breakdown

Planning and scheduling techniques have been discussed which are used nowadays by explaining planning and scheduling terms. Basic deterministic scheduling algorithms have been observed. Heuristic algorithms have been classified that include breakdown and not include breakdown. Also four articles have been researched in this subject. A heuristic scheduling algorithm with n parallel machines under breakdown has been developed. Fitting of statistical data to distribution is used for calculating of intervals between breakdowns. Repair time is determined by using discrete probability distribution. This algorithm consist of three phase like assigning of the jobs to the machines, for each machine independently, optimization of the jobs to minimize number of setup and adding of breakdown times to existing schedule. Codes of the algorithm have been written by using VBA (Visual Basic for Application) with MS EXCEL interface. This developed algorithm has been applied to a real case as an experimental study. Improvements which have been observed from this study have been compared with previous case before optimization. In order to determine of the performance level of the algorithm, numbers of iterations and optimization times have been calculated for respectively 50, 100, 150, 200, 250, 300, 350 and 400 jobs. These data also visualized by graphically. Keywords: Multi-purpose scheduling, heuristic algorithm, parallel machines, breakdown, setup