Imperfect Maintenance Models, from Theory to Practice

Abstract

The role of maintenance in the industrial environment changed a lot in recent years, and today, it is a key function for long-term profitability in an organization. Many contributions were recently written by researchers on this topic. A lot of models were proposed to optimize maintenance activities while ensuring availability and high-quality requirements. In addition to the well-known classification of maintenance activities-preventive and corrective-in the last decades, a new classification emerged in the literature regarding the degree of system restoration after maintenance actions. Among them, the imperfect maintenance is one of the most studied maintenance types: it is defined as an action after which the system lies in a state somewhere between an "as good as new" state and its pre-maintenance condition "as bad as old." Most of the industrial companies usually operate with imperfect maintenance actions, even if the awareness in actual industrial context is limited. On the practical definition side, in particular, there are some real situations of imperfect maintenance: three main specific cases were identified, both from literature analysis and from experience. Considering these three implementations of imperfect maintenance actions and the main models proposed in the literature, we illustrate how to identify the most suitable model for each real case.

Optimization of equal-cycle maintenance strategy considering imperfect preventive maintenance

“…To improve the reliability of the repairable equipment, extend the service life of the equipment, reduce the number of accidents, and reduce the loss in the production process, preventive maintenance is essential and plays an extremely important role in the use of repairable equipment. 1,2 At present, maintenance strategy mainly can be divided into two types 3 : preventive maintenance strategy and corrective maintenance strategy. Corrective maintenance is to repair the equipment after failure [4][5][6] ; preventive maintenance generally refers to taking corresponding maintenance actions to delay the occurrence of the failure before the equipment fails.…”

“…The quality of maintenance is of great concern to people. In terms of the effectiveness of maintenance, maintenance can be divided into five types 3,28 : worst maintenance, worse maintenance, minimal repair, imperfect maintenance, and perfect maintenance. In practice, preventive maintenance actions for repairable products usually include lubrication, cleaning, adjustment, replacement, etc.…”

“…At present, maintenance strategy mainly can be divided into two types 3 : preventive maintenance strategy and corrective maintenance strategy. Corrective maintenance is to repair the equipment after failure 4–6 ; preventive maintenance generally refers to taking corresponding maintenance actions to delay the occurrence of the failure before the equipment fails.…”

“…Therefore, imperfect preventive maintenance actions are mostly adopted for most repairable or expensive products. Imperfect maintenance models mainly include the following categories 3,29 : (p, q) rule method and its variants, improvement factor method, virtual age method, shock model method, (α, β) rule method, and hybrid hazard rate method. There is some related literature that has studied the equal-cycle maintenance strategy considering imperfect preventive maintenance.…”

Asset maintenance optimisation approaches in the chemical and process industries – A review

“…The common assumption in maintenance modelling is that the maintenance is ‘imperfect’ (see the latest British Standards of risk inspection ( BS-EN-13306, 2017 ). Carlo and Arleo (2017) conducted reviews on the applications of ‘perfect’ maintenance into real practises in the industry and provided guidelines to select the proper ‘imperfect’ maintenance model. de Jonge and Scarf (2019) presented a comprehensive review of different mathematical approaches used by researchers in generic systems up until 2018 in maintenance planning…”