Delay-time-based model of optimization grouping maintenance type and case study

There are many kinds of defects occurred in production plant, and those defects have different effects on the performance of production plant. So many kinds of inspection activities, or maintenance types such as daily inspection, weekly inspection, monthly inspection, yearly maintenance, and overhaul as well, are simultaneously applied on a production plant. The current research about inspection modeling pays more attention on the calculation of inspection cycle which is only for one maintenance type, not on the modeling of multiple nested inspection cycle. This has caused the serious problems of either over maintenance or insufficient maintenance. In this paper, all kinds of inspection activities are firstly given, and the relationship between different maintenance types is described. Secondly, a model of optimization grouping maintenance type at different inspection cycles for production plant is established. Based on the delay time maintenance theory, the key two terms, namely the expected failures number occurred in inspection cycle T and the expected defects number identified in inspection activities, are calculated. Thirdly, a new heuristic algorithm is proposed for solving the established model. As the proposed algorithm is very simple and easy to use, so it is better than branch-and-bound procedure to solve the nonlinear target function of integer variables. Finally, a case study is given to demonstrate the modeling and solution processes.