A simulation model for maintenance planning

The author discusses the application of simulation models to evaluate maintenance policies for an automated production line in a steel rolling mill. This production line is a multistage transfer machine that converts black wire reel stock into ground and polished steel rods of standard length using multistage processing. In order to characterize subsystem failure and repair mechanisms, the entire multistage machine is subdivided into seven major independent subsystems. Three classes of maintenance policies, opportunistic, failure, and block, were simulated and compared in order to determine the best maintenance policy. The objective criterion applied to evaluate policies was availability percent. It was determined that the opportunistic maintenance policy was far superior to existing maintenance policies. Existing maintenance policies were a haphazard combination of failure maintenance and block maintenance actions. Using past data on types of maintenance activities performed, a compilation of detailed preventive maintenance procedures was developed in the form of a checklist