Cost and availability functions using imperfect maintenance policy for a serial system

This paper deals with imperfect preventive maintenance (PM) for a serial production system. PM is carried out periodically at a fixed interval. PM can not restore the machines as new, but between as-good-as-new and as-bad-as-old (imperfect). PM decreases virtual age of the machines which may different for one machine to another. The failure occurred between PM is repaired minimally. The optimal coordinated PM interval is obtained to meet the availability target at minimum cost. The coordinated PM results are compared with those of independent PM. Numerical examples are given to illustrate the model solution.