Research On Integrated Scheduling Problem Of Single-machine Production And Preventive Maintenance Based On Machine Condition

In traditional production scheduling research,it is assumed that the machine is always available.But in practice,the machine is gradually worn out due to use,which reduces the production efficiency and even causes failure.Although the machine preventive maintenance can reduce the failure rate,improve the performance and extend the service time of machine,it takes up resources.Therefore,considering the maintenance and production separately will cause scheduling conflicts.The problem of integrated scheduling of production and maintenance has been paid attention by more and more scholars for its coordination.Especially with the development of condition monitoring technology,the integrated scheduling problem of production and preventive maintenance based on machine condition has become one of hot-points in the research.The integrated scheduling problem of single-machine production and maintenance based on machine condition with the goals of minimizing the makespan and the total completion time is studied in this paper.The specific contents are as follows:1.The integrated scheduling problem of production and maintenance which considering preventive maintenance duration based on the machine condition before and after maintenance is studied.In the case that the condition of machine depends on job and age,two condition-based maintenance strategies,such as maintenance restores the machine to initial condition and maintenance restores the machine to satisfactory interval condition,are adopted.The nature of the problem is analyzed and proved,and the ordering rules are put forward.Combined with the characteristics of the problem,a mathematical model is established and an improved genetic algorithm is designed.The integrated scheduling problem of production and maintenance instances of different sizes are studied and analysed.The feasibility and stability of the algorithm are verified.The applicability of maintenance strategies are compared.The results show that the preventive maintenance strategy of restores the machine to satisfactory interval condition can achieve better scheduling objectives than restores the machine to initial condition.2.The integrated scheduling problem of production and maintenance which considering deteriorating effect is studied.The process time is a function based on the condition of machine.In the case that the condition of machine depends on job and age,two condition-based maintenance strategies which durations based on the machine condition before and after maintenance,such as maintenance restores the machine to initial condition and maintenance restores the machine to satisfactory interval condition,are adopted.The nature of the problem is analyzed.Using the improved genetic algorithm to study and analyze the problem instances of different sizes.The applicability of two preventive maintenance strategies are compared.The results show that the maintenance restores the machine to satisfactory interval condition can achieve better scheduling objectives in small-scale,and maintenance restores the machine to initial condition can achieve better scheduling objectives in large-scale.3.The integrated scheduling problem of production and maintenance which considering the unexpected failures is studied.The condition of machine depends on the age.The condition-based maintenance strategy which maintenance restores the machine to satisfactory interval condition is adopted when no failure occurs but the preventive maintenance condition is reached.When failure occurs,different corrective maintenance methods,such as minor repair,medium repair and overhaul,are adopted by monitoring the condition of the machine at the time of the breakdown happened.Combined with preventive maintenance strategy and corrective maintenance methods,four maintenance strategies are proposed,such as preventive maintenance-minor repair,preventive maintenance-minor repair,preventive maintenance-minor repair-medium repair,preventive maintenance-minor repair-overhaul and preventive maintenance-minor repairmedium repair-overhaul.The preventive maintenance duration and corrective maintenance duration are determined according to the condition of the machine before and after the maintenance except the minor repair method.The nature of the problem is analyzed.Using the improved genetic algorithm to study and analyze the problem instances of different sizes under different failure rates.The applicability of maintenance strategies are compared.