The problem of generating is analyzed in science and practice in various ways by identifying it once as an element of the machine, and the second time as a part of production, that is, a final product. The nature of the materials of the machine elements, the loads in the contact zone, the relative velocities, the topography of the contact surfaces, and the temperature in the contact zone influence on the tribological characteristics of the elements, and hence on the characteristics of the tribo-mechanical systems. The surfaces of the tribo-mechanical elements of the machines through which mutual contact is realized are essentially thin layers of materials whose composition and properties differ significantly from the properties of the basic mass element material. There are a significant number of tribo-mechanical systems in the energy sector. Gear cutting is the most important operation in the production of gears. The quality of the gear cutting is one of the conditions for achieving the required quality of the work-piece. The gear is an element of a large number of tribo-mechanical systems. The geometrical parameters of the hob milling, the accuracy of the profiling and the accuracy of manufacture significantly affect the productivity and machining costs. In this paper, the topography and roughness parameters of lateral back surfaces of the model hob milling tools are analyzed before and after cylindrical gear cutting.

Abstract. The availability, adaptability, reliability and productivity of modern industrial complexes, maintenance costs, energy costs and industrial production costs depend also on the intensity of wear of the elements of tribo-mechanical systems. Gear cutting operations are usually a bottleneck of production, especially in higher types of production. Therefore, the necessity of researching the process of gear cutting by hob milling is obvious. In the paper a part of the results related to the possibility of direct measurement of the temperature in a very complex process of gear cutting of cylindrical gears by hob milling is given.

Abstract. The improvement of the gear cutting process by hob milling is also significant for the producers of gears as well as for the producers of hob milling tools. Due to the complexity of the process, the high values of the gears, and in particular the hob milling tool, the research of the bases for optimizing the process of gear cutting by hob milling requires significant financial resources and significant efforts of the researchers. In the modern production of gears there is a continuous demand for increasing the economy. In the gear cutting process improvements of the production equipment and materials for the cutting elements of the hob milling tools are necessary. In this paper an analysis of the tool life of coated hob milling tools for gear cutting of cylindrical gears is given. The experimental results have shown that the hob milling tools with inserted combs coated with TiAlN outperform the hob milling tools with inserted combs coated with TiN. They have higher resistance of 60.6 %.

Tribological processes and failure of plain bearings significantly affect the availability, adaptability, reliability and productivity of modern technology, maintenance costs, energy costs and the costs of modern production. The research of tribological processes and failure of plain bearings should indicate the possible causes and the necessary measures to be applied in order to reduce the tribological processes and failure of plain bearings. In this paper, possible causes of tribological processes and failure of plain bearings were analyzed. Having in mind the most important causes of tribological processes and failure, a proposal for monitoring the condition is given.

The need to increase productivity and cost-effectiveness of gear cutting of cylindrical gears with oblique teeth creates favorable conditions for the development of research in the field of tribology and the increasing application of tribological knowledge in industrial practice. Improving the gear cutting process by hob milling is important and useful for both gear manufacturers and hob milling tools manufacturers. Increasing productivity and increasing of the quality of serration are the basic directions of improving the process of gear cutting by hob milling. Technological parameters significantly affect the wear of cutters and taking into account the parameters for defining the economy of the process affect the achievement of optimal parameters of the cutting regimes. Based on experimental research, the paper presents an analysis of the influence of axial displacement, as one of the technological parameters, on the wear of hob milling tools in the gear cutting of cylindrical gears with oblique teeth.