Abstract: The preventive maintenance (PM) decision-optimization problem of complex equipment is studied under imperfect repair context aiming at the deficiencies of residual life prediction and cost estimation. Based on the virtual age theory, we built the relationship between maintenance efficiency and equipment age. Furthermore, three different methods are put forward to calculate the relation between checking intervals and maintenance period. The quality fluctuation and variable maintenance cost caused by fault are considered to build a more concise overall cost estimation model. A multi-objective decision-making model for preventive maintenance is established to ensure high availability of equipment and low total cost. Numerical verification is performed using the production and maintenance history data of a machining center. The verification intends to compare the different overall cost rate and equipment availability under static, dynamic and failure limits calculation methods and various maintenance levels. In the same way, the applicability of the three methods is discussed. The influence of the quality cost on the optimal strategy is analyzed to prove the advanced nature of the method.

Key words: equipment; preventive maintenance; imperfect repair; quality cost; multi-objective decision