Prioritizing equipments for preventive maintenance (PM) activities using fuzzy rules Amir Khanlari, Kaveh Mohammadi, Babak Sohrabi * Department of Information Technology Management, School of Management, University of Tehran, P.O. Box 14155-6311, Tehran, Iran Received 3 August 2006; received in revised form 8 July 2007; accepted 12 July 2007 Available online 19 July 2007 Abstract Maintenance, as a support function in businesses, plays an important role in backing up any emerging business and operation strategies. It is required to maximize the reliability of equipment and systems. Among them, preventive main- tenance (PM) involves the repair, replacement, and maintenance of equipment in order to avoid unexpected failure during use. The objective of any PM program is the minimization of the total cost of inspection and repair, and equipment down- time (measured in terms of lost production capacity or reduced product quality). Maintenance activities have been regarded as a necessary expense that belongs to the operating budget. But since, organizational resources are limited and scarce, prioritizing equipments for assigning resources is essential. In this paper, fuzzy rules used to interpret linguistic variables for determination of priorities. Using this approach, such verbal expressions, which cannot be explicitly analyzed or statistically expressed, are herein quantified and used in decision making. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Preventive maintenance; Priority; Rule base; Fuzzy 1. Introduction Once a system or a piece of equipment has been purchased, it must be maintained. Tsang (2002) argues that experience, judgment and vendor recommendations are the common bases for determining the con- tent and frequency of a maintenance task. Maintenance can be defined like the activities intended to pre- serve or promptly restore the safety, performance, reliability, and availability of plant structures, systems, and components to ensure superior performance of their intended function when required (Weinstein & Chung, 1999). Production and service systems are heavily affected by their respective maintenance systems. Mainte- nance systems operate in parallel to the production systems to keep them serviceable and safe to operate at minimum cost. One way to reduce the cost of operation and production is to optimize utilization of maintenance resources (Duffuaa & Al-Sultan, 1997). Historically, maintenance activities have been 0360-8352/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.cie.2007.07.002 * Corresponding author. Tel.: +98 2188008969. E-mail address: bsohrabi@ut.ac.ir (B. Sohrabi). Available online at www.sciencedirect.com Computers & Industrial Engineering 54 (2008) 169–184 www.elsevier.com/locate/dsw