A condition-based maintenance policy with periodic inspections for a multi-unit system

This paper proposes a maintenance policy based on stochastic deterioration model for multi-unit systems, aiming at minimizing operation cost. First, critical level is introduced to conduct the proactive maintenance action, and to effectively reduce the excessive corrective maintenance cost and the loss from soft failure. Then, a model is established based on the random coefficient to work out a set of parameters which lead to a minimal cost. The method is simulated on the NC equipment FB260 to verify its rationality. And the impact of maintenance cycle on different operation cost rates, and the impact of failure level and critical level on different operation cost in different maintenance cycles is compared. Finally, the study shows that, compared with typical corrective maintenance policy only, the model we proposed can reduce up to 57.6% of the cost rate. Therefore, the strategy proposed has a great practical and heuristic significance for the practical engineering application.