An Inspection Model with Minimal and Major Maintenance for a Flexible Manufacturing Cell using Generalized Stochastic Petri Nets

This paper provides an inspection maintenance model for a production system which is subjected to deterioration and random failures. A Markov model for preventive maintenance of such a continuously operating device whose condition deteriorates with time in service has been proposed by Sim and Endrenyi (1993). This model incorporates deterioration and so-called Poisson failures, minimal repair, periodic minimal maintenances, and major maintenance after a given number of minimal maintenance. In this study, the Sim and Endrenyi model is represented by Generalized Stochastic Petri Net (GSPN). This model then has been developed into a condition based maintenance model aimed to develop a more comprehensive model for maintenance of Automated Manufacturing Systems such as Flexible Manufacturing Systems or Cells. In this model instead of periodic maintenance, after inspection based on the condition of the system the repairman can choose one of the following three choices: 1) performing a minimal maintenance, 2) performing a major maintenance, 3) doing no maintenance action. Taking into account the performability, rather than reliability of the system, the throughput of the manufacturing system is chosen as performance measure. By solving and analyzing GSPNs model, the obtained results indicate that the system performs better under inspection policy. A number of different policies, then are examined that illustrate how performance of the system could further be improved by making better decision between minimal, major and no maintenance action, considering the condition of the system after inspection. Further numerical analyses has been carried out to investigate the effect of varying parameters such as mean duration of minimal maintenance, major maintenance and major repair.