Supporting Maintenance Scheduling: a case Study
Download 305.56 Kb. View original pdf
|
| 11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 T 1 t2 VT t ASY01 t t t t BUR T 2 t1 GP t t FCT50 t t VT T 3 t3 GP Fig. 5 - Gantt chart for technicians. In Fig. 5, it can be noticed that t and t were scheduled with delay due to equipment unavailability (BUR. In this example, the total tardiness obtained was ΣT j = 2 (days, there is 2 tardy jobs in total (ΣU j =2; t and t) and the maximum lateness (L max ) is one day. In this company the technicians are also allocated for production work and corrective maintenance. Therefore, although the distribution of preventive maintenance tasks and the total completion time (ΣC j ) are not equal between the three technicians (see Table 4), the remaining hours of the shifts could be occupied with production support and corrective maintenance interventions. Table 4 - Maintenance tasks scheduled to each technician Technician Number of maintenance tasks allocated ΣC j T 1 6 159 T 5 263 T 1 240 This instance was also solved by MILP and the same solution was obtained. It is a successful outcome since the PMS was able to provide an optimal solution. Through the analysis of this example, it is possible to identify some specific situations that need special attention and study • The maintenance tasks with small durations should first be scheduled on the gaps between the shifts and lunchtime, consequently the longer available intervals of equipment would be filled by the maintenance tasks with longer durations. 2130 Patrícia Senra et al. / Procedia Manufacturing 11 ( 2017 ) 2123 – 2130 • It would be interesting to apply the opportunistic maintenance concept, i.e. when a corrective maintenance intervention is performed, preventive maintenance tasks with small processing time could be performed, allowing the increase of the efficiency of the maintenance task execution. • The ordering of maintenance tasks adopted only considers the equipment’s criticality, it does not consider the impact of maintenance task non-achievement on the equipment performance. This can lead to situations that available time windows of equipment are totally occupied with maintenance tasks schedule with low impact on equipment performance that could be schedule later, instead of being occupied with maintenance tasks with higher impact on performance equipment. Therefore, this criterion will be considered in the ordering method. • The objective function only considers the tasks delays. Download 305.56 Kb. Share with your friends:
|