No 1 (163) (2025)
Materials science in mechanical engineering
ANALYZING THE MORPHOLOGY OF WORN SURFACES IN POLYMER MATRIX FRICTION COMPOSITES
Abstract
This study examines the surface topography and wear mechanisms of polymer matrix friction composites used in brake pads. By analyzing microscopic images and three-dimensional surface wear profiles, the study identifies key wear processes and the formation of third body particles that influence the behavior of friction. The research used samples prepared by traditional methods of powder metallurgy based on phenol-formaldehyde. The experiments included friction tests under various conditions, and the results evidentiated distinct phases in the variation of friction coefficient, being illustrative of the composite's response to various stresses. The morphology of the surface after testing revealed several wear mechanisms, including abrasive and adhesive wear.
Science intensive technologies in mechanical engineering. 2025;(1 (163)):3-8
3-8
APPLICATION OF METALLOPHYSICAL METHODS OF CERTIFICATION OF ROLLER DRIVE MATERIALS
Abstract
The paper is devoted to the selection of methods for determining the materials used for the manufacture of roller drive in the framework of import substitution. Modern research methods were used such as optical and scanning electron microscopy, microhardness measurements using an automatic microhardness tester. As a result of measuring the microhardness of the roller drive material, the authors obtained an increase from 779HV in the center to 835HV on the teeth of the part. Based on metallographic studies, the microstructure of fine-needled martensite with well-defined chains of chromium, molybdenum, and vanadium carbides with a microhardness of 1200…1500 HV has been obtained. In case of microrentgenospectral analysis using a TESCAN LYRA 3 scanning electron microscope with the Ultim MAX microanalysis system, information was obtained on the point chemical composition of the sample material, traces of precipitation of carbides from a matrix with low visco-plastic properties were observed. Recommendations are given on suitable domestic analog materials. The research results can be used in constructive solutions for the design and modernization of machines and mechanisms.
Science intensive technologies in mechanical engineering. 2025;(1 (163)):9-16
9-16
Welding, related processes and technologies
SPEAKING OF MECHANISM RESPONSIBLE FOR A COMPOSITE MATERIAL MICROSTRUCTURE FORMATION UNDER WELDING OF HETEROGENEOUS COMPONENTS IN A FRICTION WITH STIRRING MODE
Abstract
The problem of joint formation under friction treatment of composite materials based on immiscible components is viewed. The role of adiabatic shear bands (AShB) in the interaction with the elements forming the composite material is shown. The effects of migration of heavy low-melting components compared to adiabatic shear bands at speeds much higher than the speeds of traditional diffusion are described, making possible to take a fresh look at the possibilities of the effect of friction welding with stirring not only as an effective welding method, but also as the basis for an alternative technology for the production of alloys for immiscible components in bulk samples. It was found that the temperature in the stirring zone was high enough for intensive formation of solid solutions and intermetallic phases. The structure of such particles was formed under the influence of heating and intense plastic deformation under the conditions of the possible implementation of two mechanisms of component migration – diffusion and migration ones along AShB, reproduced with each rotation of the tool. An increase in the lead content in the composite material from 5 to 44 % led to a decrease in the coefficient of friction from 0,28 to 0,13. The main reduction in the coefficient of friction of the composite material of the Al – Pb system is achieved in the range of lead content of 0…30 wt. %. The development of the alternative technology for the production of special–purpose composite materials (CM) discussed above provides for two interrelated directions - expanding the range of new functional CM using the unique capabilities of FSW technology and clarifying the mechanism of structural and phase transformations underlying this technology. In particular, it is obvious that the mechanism and kinetics of AShB formation and their role in the formation of the microstructure and properties of composites need additional research.
Science intensive technologies in mechanical engineering. 2025;(1 (163)):17-25
17-25
Technologies of mechanical processing of workpieces
INCREASING THE EFFICIENCY OF COAL MASS GRINDING BY CHANGING THE GEOMETRY OF THE IMPACT SURFACE OF THE GRINDING WHEEL
Abstract
In hammer mills, fuel is ground by the impact of the beaters on the coal pieces entering the mill, as well as by the abrasive action of the beaters on the coal in the space between the beaters and the mill body. A disadvantage of hammer mills is the rapid wear of the beaters, requiring their frequent replacement. It is known that the greater the mass of the material being worn, the longer the beater can work, all other things being equal. The mass of the metal being worn can be increased by increasing the mass of the beater itself or the degree of metal utilization. As practice shows, increasing both has its limits. The optimal mass of the beater for medium-capacity mills with a diameter of up to 1,6 m is 8…10 kg, for high-capacity mills with a rotor diameter of
2…2,5 m, the optimal mass of the beater is 12…14 kg. Increasing the mass of the beater beyond these values does not lead to a significant increase in the service life of the beaters, since this reduces the degree of metal utilization. In addition, replacing beaters weighing more than 14 kg significantly increases the labor intensity of beater replacement operations. The paper investigates the dependence of specific beater wear on the angle of impact with the crushed material and shows the sequence of changes in the shape of the working surface of the beaters. The abrasion of the beaters at different angles of attack of abrasive coal particles is considered, the particle ejection velocity from the working element is calculated, and a mathematical model of the forces arising during the working movement of the beaters is compiled. A methodology for designing the geometric shape of the working element of a tangential hammer mill – a beater – has been developed, which allows for ensuring stable mill efficiency due to uniform wear of the striking part of the beater while maintaining its effective working area.
Science intensive technologies in mechanical engineering. 2025;(1 (163)):26-32
26-32
Additive technologies and laser processing
WORKABILITY OF INDUSTRIAL PRODUCTS OBTAINED BY FULLY ADDITIVE TECHNOLOGIES
Abstract
Methods for evaluating workability of industrial products obtained by fully additive technologies are viewed. The study of the concept of workability and applicability of existing developments for additive manufacturing is being analyzed.
Qualitative approach and quantitative aspect are used simultaneously for evaluating the workability. The qualitative aspect is based on experience and recommendations, but requires adaptation to the specifics of additive technologies. A quantitative approach through the determination of workability coefficients is preferable, as it allows managing of the production process and is quickly adaptable to changes. Various quantitative evaluation techniques of workability, developed by domestic and foreign authors, have been analyzed. It is concluded that flexible ways require additional adaptation to the specific characteristics and capabilities of additive manufacturing, such as the creation of complex geometric structures, optimization in terms of weight and material consumption. The need for a comprehensive multidisciplinary approach to the development of a workability evaluation concept, taking into account the economic, environmental and technical factors of additive technologies, is emphasized. This will increase production efficiency, reduce costs and risks when launching new products.
Science intensive technologies in mechanical engineering. 2025;(1 (163)):33-37
33-37
Technological support of operational properties of machine parts and their connections
A RENDERING METHOD OF TECHNOLOGY OPTIONS FOR MACHINING EQUIPMENT THROUGH GRAPH THEORY ATTRIBUTES
Abstract
A technical approach to information support for the machine work process design is presented, which is aimed at creating intelligent computer-aided design systems and implementing technological processes, taking into account the real production situation. The introduction of computer-aided design of manufacturing activity is slowed down due to the lack of available scientific and methodological principles and practical methods for designing databases that meet the basic requirements for ensuring the necessary quality of information processing and focusing on the needs for solving problems in real production conditions. The main reason for this is the lack of initial information, which can be formalized from design and technological documentation without the involvement of an engineer. Including data on processing machines and technological equipment, which makes it possible, based on a comparison of the available real technological capabilities of each piece of equipment and the characteristics of parts (workpieces), to carry out the necessary design procedures for the development of manufacturing activities. The structure of the interrelationships between the individual parameters and characteristics of the surfaces of the machined part and the means of technological equipment, the sequence of the formalized description of the presented scheme using graph theory as a mathematical tool technique, is developed. The elements of connections are designed that describe: the influence of the process used for the quality indicators change in case of the treated surface within the framework of a separate technological transition; the maximum dimensions, the qualitative characteristics of the base surfaces used and the requirements for their relative spatial arrangement for the equipping variant of the selected technological equipment in the coordinate system of the equipment; the ranges of the working area of processing, taking into account the set of parameters of the bases and operating surfaces of the part with the elements of the technological equipment. The result of the graphing, on the basis of which a relational database is formed, is a clearly structured information support for the implementation of a set of design procedures, focused on the analysis of definitive and operational dimensional relationships. The development of a procedural framework of the information support base for the creation of automated technological preparation systems ensures both: real state of existing systems and the current situation in the field of process development management, are taken into account.
Science intensive technologies in mechanical engineering. 2025;(1 (163)):38-48
38-48