Optimum Maintenance Policy for an Equipment Subject to Deterioration and Random Failure

Optimal maintenance policies for a machine with degradation in performance with age and subject to failure are considered. The optimal policies are shown to be generally of a bang-coast nature, except in the case where the probability of machine failure is a function of maintenance. It is also shown, in the case where machine failure is not taken into account, that a high depreciation rate tends to reverse this policy to coast-bang. The results obtained here extend and unify the recent results for this problem.