A nearly optimal inspection policy for productive equipment

Abstract

SUMMARY Recently a maintenance policy (so-called ‘on condition’ ) has increased in importance. Such a policy is based on the systematic control of equipment: preventive action starts on the basis of the information gathered from inspections. To determine an optimal on-condition maintenance policy means to determine the sequence of inspection times which can allow the lowest maintenance intervention and inspection cost. In this paper, the authors show a mathematical model of a nearly optimal inspection policy suitable for production plant equipments. Unlike most previous studies, the model states the hypothesis of two different rates of wear of the equipment, corresponding to two different stages of the failure process, before and after the alarm threshold is exceeded. The model is applied to a real case by examining various intervention policies in different operative situations, with maintenance cost dependent on the plant utilization level.