Evaluation of maintenance policies for equipment subject to quality shifts and failures

• Published in: International journal of production research Vol. 46; no. 20; pp. 5761 - 5779
• Main Authors: Panagiotidou, S., Tagaras, G.
• Format: Journal Article
• Language: English
• Published: London Taylor & Francis 01.10.2008; Washington, DC Taylor & Francis LLC
• Subjects: Applied sciences; Economic models; Economic optimization; Economics; Exact sciences and technology; General aspects; Industrial metrology. Testing; Inventory control, production control. Distribution; Maintenance; Mechanical engineering. Machine design; Operational research and scientific management; Operational research. Management science; Optimization; Preventive maintenance; Product quality; Quality; Random variables; Studies; Production quality; Economic optimization; Optimal policy; Rupture; Maintenance equipment; Maintenance; Failures; Preventive maintenance; Economic model; Quality; Quality control; Profit; Delay time; Age; Production process; Physical Sciences
• ISSN: 0020-7543; 1366-588X
• DOI: 10.1080/00207540601182260

We develop an economic model for the optimization of maintenance procedures in a production process with two quality states. In addition to deteriorating with age, the equipment may experience a jump to an out-of-control state (quality shift), which is characterized by lower production revenues and higher tendency to failure. The times to quality shift and failure are allowed to be generally distributed random variables. We consider two types of maintenance: minimal maintenance (MM) that upgrades the quality state of the equipment without affecting its age and perfect preventive maintenance (PM) that fully upgrades the equipment to the as-good-as-new condition. We derive the expression for the expected profit per time unit and we investigate, through a large number of numerical examples, the type of the optimal solution. It is concluded that in practically every case the optimal maintenance policy is an extreme one: it either calls for immediate MM as soon as a quality shift occurs (active policy) or it allows operation in the out-of-control state until the time of a scheduled PM action (passive policy).