Strategic options for conducting maintenance

While reading the literature on maintenance management, it becomes clear that many papers refer to the principally same subjects with varying terminology. Especially the distinction between maintenance strategy, methodology, technique or policy is not clear. If different papers are compared, for example, Tsang (2002, p. 23-26) refers to the terms below (in the table 4) as methodologies, Wang et al. (2007, p. 153-154) de-fine them maintenance strategies, and Garg et al. (2006, p. 214) declare them niques. Anyway, table 4 summarizes the relevant strategies, methodologies and tech-niques found in the field of maintenance and a short description is given on what each term means in principal terms. This classification in the table 4 is mainly based on the classification made by Garg et al. (2006, p. 214-219), and the definitions for each term are adapted from a few different sources.

Table 4. Different maintenance strategies, methodologies and techniques combined and briefly explained.

Options Explanations CM and

RTF

Corrective maintenance means maintaining equipment after a failure has happened, aiming to restore the equipment to a specific condition. (Wang 2002, p. 470) Another term called run-to-failure (RTF) is linked to CM, as it means that only routine maintenance is being conducted until a system fails.

(Tsang 2002, p. 23) CMMS

Computerized maintenance management systems provide information technology tools for storing, retrieving and analyzing information. They also facilitate communication and coordination of activi-ties. (Garg et al. 2002, p. 217; Swanson 1997, p. 11)

CBM and PdM

Condition-based maintenance means making maintenance decisions based on the state of the system, which is being monitored or inspected constantly. Maintenance tasks are aimed to be done prior to predicted failures. (Chen et al. 2002, p. 43; Garg et al. 2002, p. 216; Grall et al. 2002, p. 167; Jardine et al. 2006, p. 1483; Marseguerra et al. 2002, p. 151-152) In addition to CBM, predictive mainte-nance (PdM) is also about predicting the need for maintemainte-nance based on data collected through monitoring systems. (Chu et al. 1998, p. 285; Garg et al. 2002, p. 217-218; McKone et al. 2002, p.

109-110) That means these two terms are somewhat interchangeable.

ECM

Effectiveness-centered maintenance puts emphasis on doing the right maintenance tasks in terms of systems functions and customer service. The basic goal is to prioritize maintenance tasks based on the importance of system functions. ECM is composed of people participation, quality improvement, maintenance strategy development, and performance measurement. (Garg et al. 2006, p. 218; Pun et al. 2002; p. 346-347)

MO

Maintenance outsourcing refers to outsourcing those maintenance activities, which are not reasona-ble to conduct in-house. (Garg et al. 2002, p. 218; Martin 1997, p. 83-84; Murthy et al. 1999, p. 259-261)

PCM

Profit-centered maintenance puts emphasis on reducing the need for maintenance and re-engineering of maintenance activities, in order to eliminate non-value adding activities and maximizing profits and minimizing maintenance costs. (Bond et al. 1997)

PM

Preventive maintenance refers to maintaining equipment before a breakdown, thus preventing a sys-tem failure. The frequency of maintenance is dictated by the passage of time (time-based mainte-nance, TBM), the amount of production, or machine condition (CBM). (Garg et al. 2002, p. 214-215;

McCall 1965, p. 496; Takata et al. 2004; Wang 2002, p. 470) RBM

Risk-based maintenance means taking into account the related risks of equipment failures and risks are being minimized or optimized in parallel with other objectives for maintenance, primarily cost effectiveness. (Garg et al. 2002, p. 218-219; Khan et al. 2003, p. 561-566)

RCM

Reliability-centered maintenance means determining a maintenance plan for an asset during its life-cycle, while balancing the reliability criteria for the asset and cost effectiveness of maintenance tasks. The main focus in RCM is minimizing costs through focus on the most important functions of the equipment and avoiding or removing maintenance actions that are not strictly necessary. (Fran-gopol et al. 2001, p. 27; Garg et al. 2002, p. 217; Rausand 1998, p. 121-122; Tsang 2002, p. 24-25)

SMM

Strategic maintenance management views maintenance as a multidisciplinary and a core business activity. Decisions on maintenance activities should be made in parallel with other strategic business decision. SMM takes a quantitative approach to modeling maintenance activities. (Garg et al. 2002, p. 218; Murty et al. 2002, p. 290)

TPM

Total-productive maintenance takes a comprehensive view on maintenance: a system, covering the whole life-cycle of equipment and all aspects related to maintenance tasks, is established in a com-pany. All employees from top-management to line staff and all company departments are encouraged to participate in promoting TPM. Maintenance is conducted through autonomous cross-functional team work. TPM aims not only to minimize costs of maintenance, but to maximize equipment effec-tiveness and profitability from customer’s perspective. (Chan et al. 2005, p. 72; Garg et al. 2002, p.

216-217; McKone et al. 1999, p. 124; Tsang 2002, p. 25-26)

As the above terms are referred to with differing terminology, maintenance policies are a bit more clearly defined and referred concept. However, we can notice some

overlap between policies and the above terms as well. Examples of maintenance poli-cies are age replacement, block replacement, repair limit, failure limit, sequential and repairs counting policy. Age replacement policy means a unit is repaired or replaced in relation to its age. Block replacement policy means individual parts of a system are replaced at prescribed times. Repair limit policy means a unit is repaired if the cost of repair is acceptable. Failure limit policy means repair is conducted if failure rate of a system rises above an unacceptable level. Sequential PM policy means a unit is pre-ventively maintained at unequal and usually shortening time intervals as time passes.

Repairs counting policy means a unit is replaced after some number of failures have occurred. (Wang 2002, p. 469-483)

Now, if we look at the presented strategies, methodologies, techniques and policies in parallel, the conclusion is that they all deal with the same subject from quite similar viewpoints. All of them can be regarded as strategic options for conducting mainte-nance. And all of these take into account several maintenance strategy elements pre-sented in the table 3 (previous chapter), but not all if any can be regarded as a com-plete maintenance strategy. In this study, it is not thoroughly argued, whether any of the above strategies is really a maintenance strategy or rather a methodology, tech-nique or policy. However, they all are just regarded as strategic options. And later in the AB model description, the strategic dimensions and options being modeled are clearly defined, based on the concepts presented in the previous tables.

In general, proactive maintenance strategies such as CBM, PM, PdM, and TPM are better in terms of performance compared to reactive maintenance strategies such as CM. By performance it is meant improved quality of products, equipment availability and reduction in production costs. (McKone et al. 2001, p. 39-58; Swanson 2001, p.

239-243)