Purpose The purpose of this paper is to provide comprehensive information on preventive maintenance (PM) planning and methods used in the industry in order to achieve an effective maintenance system. Design/methodology/approach The literature review is organized in a way that provides the general overview of the researches done in the PM. This paper discusses the literatures that had been reviewed on four main topics, which are the holistic view of maintenance policies, PM planning, PM planning concept and PM planning-based in developing optimal planning in executing PM actions. Findings PM policy is one of the original proactive techniques that has been used since the start of researches on maintenance system. Review of the methods presented in this paper shows that most researches analyse effectiveness using artificial intelligence, simulation, mathematical formulation, matrix formation, critical analysis and multi-criteria method. While in practice, PM activities were either planned based on cost, time or failure. Research trends on planning and methods for PM show that the variation of approaches used over the year from early 1990s until today. Practical implications Research about PM is known to be extensively conducted and majority of companies applied the policy in their production line. However, most analysis and method suggested in published literatures were done based on mathematical computation rather than focussing on solution to real problems in the industry. This normally would lead to the problems in understanding by the practitioner. Therefore, this paper presented researches on PM planning and suggested on the methods that are practical, simple and effective for application in the real industry. Originality/value The originality of this paper comes from its detail analysis of PM planning in term of its research focus and also direction for application. Extensive reviews on the methods adopted in relation to PM planning based on the planning-based such as cost-based, time-based and failure-based were also provided.

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Rail lubrication is vital in determines the friction, wear and noise level in the wheel and rail contacts. In general, the primary function of a rail curve grease is to minimize friction between the contact as well as to protect side wear of rails on a curved track. In this study, three commercially applied railway greases were identified and the wear and friction behavior, as well as the load-carrying ability, were investigated. Before that, the grease's physiochemical properties in terms of the consistency and drop point, as well as the element content, were also examined. The tribological investigation of the greases was also carried out using four-ball wear tester. In this test, the wear preventive (WP) and extreme pressure (EP) properties of the grease were measured under sliding actions between the balls, and the wear surface analysis was also carried out. The tests results explained that the rail curve greases are very soft in texture yet have stable structure over a high-temperature range. The greases also presenting low friction coefficient; ranges between 0.070 to 0.090, and acceptable wear scar diameter indicating the good anti-friction and anti-wear properties. High load-carrying ability up to 400 kg is also the significant properties for a rail curve grease to perform as the desired functions.

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Vegetable oils have been acknowledged to have significant potential as a substitute base fluid in grease formulation. The so-called biogreases are demanded especially in open applications where the greases are in contact with soil and water and lost to the environment. In this paper, formulation of a biogrease derived from palm-based ester as the base fluid and calcium complex soap as the thickener is discussed, with the main purpose to explore the potential of palm oil as an effective biodegradable fluid, and to investigate the possibility to improve the tribological properties by mixing calcium carbonate (CaCO3) and hydroxyapatite (HA) as green additives. The wear and friction properties as well as the load carrying capacity of the formulated bio-grease were extensively studied through the four-ball wear tester. The experimental results show that the average coefficient of friction of the palm based biogrease was improved by about 6.5% when 5% of CaCO3 and 3% of HA were added comparing to base grease. Besides, the load carrying capacity was also enhanced significantly by the addition of the additives. This demonstrated the good potential of palm ester as base fluid for grease and the CaCO3 and HA as lubricant additives, exhibited the good anti-friction and load carrying abilities.