## 1 Introduction  
Obtaining appropriate reliability and quality of products requires proper methods of enterprise management, production, and the means necessary for its implementation [1]. These methods allow for the coordination and integration of all company functions [2]. One of the elements affecting the high quality of a product is the condition of technological machines maintained in enterprises [3; 4; 5]. Its suitability and technical condition largely determine the quality and competitiveness of a product. Maintenance management is a critical issue amongst management activities of manufacturing organizations [6; 7; 8]. Therefore, in recent years, intensive efforts have been made to propose and improve maintenance strategies that aim to extend the useful life of every piece of existent equipment, increase its availability, and guarantee higher levels of reliability [9; 10; 11]. In recent decades, maintenance was regarded as a necessary evil in managing an organization, because it was limited to the appropriate functions that are usually performed in emergency situations, such as a machine failure. However, this practice is no longer acceptable, because the role of maintenance has been recognized as a strategic element of generating revenues for the organization [1]. The maintenance process in enterprises was not always carried out in a way that ensures the minimization of outlays while maximizing the achieved effects in service and maintenance processes. In practice, obtaining the maximum benefits from the operation of a technological machine system requires an optimal solution to a number of tasks [12; 13]. For a larger number of machines, it creates the need for appropriate system modelling, simulation research, and optimization of partial and complex tasks based on the adopted optimization criteria [14]. Accordingly, the company must establish a maintenance system that enables these activities to be carried out in an optimal manner from the point of view of resource pro-vision and its effectiveness [15]. These activities are usually carried out in accordance with a specific exploitation strategy that has been developed with the development of production systems. Most of the enterprises with foreign capital managed to organize effective maintenance [16]. However, small and medium enterprises are still looking for the right method for their reorganization as well as for the right way of supervising technological machines and equipment that would allow for improving effectiveness as well as for using it in a manufacturing process. That is why, some organizations have started implementing lean methods and tools in the area of maintenance defined as lean maintenance [17]. Lean maintenance is a proactive maintenance strategy whose main goal is to support reliability in the most effective, cost-effective way possible, which means keeping costs to a minimum while ensuring high efficiency and productivity. This philosophy is mainly based on the concept of total productive maintenance (TPM), the idea of which is to involve all employees at every level of the organization in maintenance and management tasks [18]. This paper presents the possibilities of using intelligent systems to support decision-making processes in the implementation of the lean maintenance concept. The aim of the article is to indicate the methods and tools of lean maintenance, which have the greatest impact on increasing the effectiveness of the enterprise. The obtained research results indicate which lean maintenance methods and tools should be implemented in the company in the first place to increase the efficiency, quality, and availability of its production processes. This problem is particularly important from the point of view of small- and medium-sized enterprises, which do not always have adequate human or financial resources to implement modern concepts in a wide range.