This study introduces an analytical model for determining a economic preventive maintenance period of a production system, considering changes in the product quality level due to deterioration. The economic preventive maintenance period is optimal if the expected cost rate, comprising failure, maintenance, and quality costs, is minimized under an age-dependent maintenance policy. The quality cost is evaluated based on the precision of the product using the concept of a loss function.
The model is developed assuming that a system can experience failure and deterioration during production, and that the deterioration comes with the quality-down of processed products. Failure and deterioration are assumed to follow a Poisson process with parameters λf and λd, respectively. In addition, maintenance activities are assumed to restore the system conditions when the system is initially set.