Preventive Maintenance & Replacement Scheduling Model for Repairable and Maintainable Systems

Maintenance plan is required when there is a need to decide on production rate and preventive maintenance (PM) scheduling for complex production systems in industry. The more complex the system is, the more components that may fail and cause the entire piece of equipment to be taken out of service, that in turn could affect production rate.
Usually, most of equipment has its PM schedule set during plant design phase and generally follow recommendation from equipment manufacturer. After years of operation (operation and maintenance phase), the PM schedule might not be optimised due to various reasons – lack of full information on failure rate, repair rate, maintenance cost, etc. Thus, the objectives of this project are to develop an appropriate model for preventive maintenance and replacement scheduling using Mixed Integer Non – Linear Programming (MINLP), and also to analyze the results and effectiveness of the optimized model through trade – offs curves, that are one of the project deliverables. The project is initiated by identifying problem and objectives, study on literature review regarding various types of preventive maintenance and replacement scheduling model, and then come out with a model concept. It was found out that various parametric change effects were observed in component age graphs and scheduling tables in two developed models. In Model 1, three different trends were seen for each three cases such as cost increment was observed as required reliability increased where no changes happened in required reliability when shutdown cost varied and required reliability increased when time period was decreased respectively. In Model 2, it can be also seen that as time period decreased required reliability increased where higher amount of given budget can also increase required reliability of components. After all, these studies should be useful for maintenance planners and engineers tasked with the problem of developing maintenance plans for complex systems of components.