Machines. Technologies. Materials.
Vol. 19 (2025), Issue 3

Table of Contents

  • MACHINES

    • Choice and calculation of ball screw for linear actuator

      pg(s) 83-86

      The selection of an appropriate ball screw for a linear actuator is a critical factor in ensuring precision, efficiency, and durability in automated systems. This paper presents a systematic approach to selecting a ball screw based on key operational requirements, including axial load, travel distance, linear speed, acceleration time, accuracy, backlash tolerance, and service life expectancy. By analyzing and calculating the technical specifications, we determine optimal parameters for high-performance linear actuation.

  • TECHNOLOGIES

    • Features of diamond crystal processing by pulsed laser radiation in microelectronics technologies

      pg(s) 87-90

      Diamond is currently one of the main reserves for the development of microelectronics. It is with it that tangible progress of this industry is possible, allowing it to reach new technical frontiers, associated primarily with an increase in the speed and power of electronic components. Of the many laser technologies for processing materials in the production of electronic components, the following processes are distinguished: cutting, ablation and welding. For short and ultra-short laser pulse durations, the above processes are applicable under certain conditions, e.g., the thickness and linear size of the element are mainly in the micrometer range. High accuracy of part processing is achieved by using the size of the laser spot on the surface > 0.5 μm and a power density of about 109 W/cm2. This can be realized by increasing the uniformity of the laser beam, controlling the pulse shape, and selecting the wavelength of the laser radiation. Laser ablation, especially on metal structures, is implemented using nano-, pico- and femptosecond pulses. If the laser power density values are much higher than the threshold for ablation, treatment occurs at 120 fs < tp <150 fs using wavelengths of 800 and 1064 nm. The features of laser ablation in metals, semiconductors, and dielectrics are to reduce the threshold power flux density if the pulse duration is reduced from nano- to femtoseconds. The main promising areas of predominant application of diamond and diamond-containing materials in the production of components of electronic equipment are presented.

    • Thermal Effects of High-Speed Machining: Analysis of Cutting Zone Temperatures, Tool Behavior, and Cutting Forces in C45 Steel Turning at Elevated Speeds

      pg(s) 91-94

      High-speed machining (HSM) significantly influences the thermal dynamics of the cutting process, particularly in the toolworkpiece interaction zone. At elevated cutting speeds, the reduced tool-workpiece contact time minimizes heat transfer to the workpiece, concentrating thermal energy in the cutting zone. This results in localized material softening, reduced cutting forces, and enhanced process efficiency. This study investigates the thermal effects of HSM by experimentally turning C45 steel using a cubic boron nitride (CBN) tool at cutting speeds ranging from 800 m/min to 1800 m/min. Cutting forces were measured and analyzed in conjunction with temperature distributions within the cutting zone and tool. The experimental results were compared against predictions from the analytical Oxley machining model and numerical simulations using DEFORM software. The analysis revealed the dependence of cutting speed on cutting zone thermal properties, providing insights into material behavior under high-speed conditions. Furthermore, the study identified optimal cutting speeds that balance thermal effects and cutting process stability. These findings contribute to the definition of appropriate high-speed machining parameters, ensuring effective heat dissipation and stable tool performance.

    • Plasma jet surface hardening of tool steel – computational investigation using different modelling approaches

      pg(s) 95-100

      The article presents a comparison of different computational approaches used to study the surface treatment of a NiCrMoV steel with 0.55% Carbon content by a plasma jet. Metallographic observations show formation of martensite layer due to high cooling rate by heat transfer into the bulk steel. Heat affected zone (HAZ) was 1 mm deep and 10-12 mm wide. The treated surface maximum hardness was measured at 763 HV0.1 whereas untreated steel was at 210 HV 0.1. The computation indicates a hardening sink near the surface that went undetected in the experimental observations. The ability of the different computational approaches to explore the process related phenomena and to give reliable results is put into discussion.

    • Composite modifications obtained through various technological approaches based on inorganic binders and foam glass materials

      pg(s) 101-104

      Composite structural modifications based on hydraulic inorganic binders and foam glass aggregate fractions were prepared. Formwork moulds were developed for the moulding of composite test bodies using different technological approaches. A series of experimental specimens meeting the requirements for standard laboratory tests were obtained. The role of the technological regimes used in the formation of the structural characteristics and performance of the composites is examined. The existing possibilities for further modification and potential application of the obtained composite materials are analysed.

  • MATERIALS

    • Classification of modern armor steels, history, material properties and heat treatment procedures

      pg(s) 105-109

      Modern armor steels are essential in safeguarding military and civilian assets from ballistic threats. This paper provides a comprehensive classification of contemporary armor steels, examining their material properties, including hardness, impact resistance, and the influence of chemical composition, particularly carbon equivalent (CE), on their performance. The classification considers chemical composition, alloying elements, and mechanical properties, with a focus on their ballistic effectiveness and suitability for various armored platforms. Additionally, the paper delves into the historical evolution of armor steel, tracing its origins from early military applications to the sophisticated alloys used today. It also highlights the importance of MIL-DTL specifications in establishing a standardized language for armor steel grades, ensuring uniformity in quality and performance across the defense sector. Furthermore, the paper discusses the role of heat treatment procedures, such as quenching and tempering, in influencing the microstructure and mechanical properties of armor steels, directly affecting their resistance to penetration and impact. Through a review of armor steel classifications, historical context, and their technological advancements, this paper offers valuable insights into the ongoing efforts to improve the performance and reliability of armored materials.

    • Application of thermal-derivative analysis to study phase transformation in AlSi7Mg alloy with different iron content

      pg(s) 110-113

      Using an increasing share of aluminum scrap (production and post-production) requires paying special attention to its impurities. Gaseous inclusions (e.g., hydrides) can be removed from the liquid alloy by refining, but the situation is worse with metallic impurities. In Al-Si alloys, one of the worst is iron, which goes into solution due to its low solubility in the solid state, at a content of over 0.4wt.%, it crystallizes in morphologically unfavorable phases, which worsen the functional properties and increase the porosity of aluminum alloys, limiting their use. The crystallization of these phases causes thermal effects that various methods can record. The paper presents studies of phase transformation, especially iron phases, using thermal-derivative analysis occurring in the AlSi7Mg alloy with different iron content. The studies were performed on Crystaldigraph NT3-8K coupled with the MLab program. It was found that the most unfavorable phase is β- Al5FeSi, which crystallizes preeutectic (and mainly primary crystallize) dimensions of up to 1000 μm, causing the formation of shrinkage porosities.

    • Force-Stroke Analysis of Metallic Materials using the Upper Bound Method

      pg(s) 114-118

      All plastic deformation applied to metallic materials create a metal flow. The main factors affecting metal flow are the friction conditions between the metallic material and the mold. In addition upset forces are closely related to the geometric shapes of the metallic materials that changes deformation rates. It is possible to express the formation rates with mathematical approaches in shaping metallic materials. However obtaining these mathematical approaches can be done with very complex methods. Numerical and analytical expressions are generally used in the mathematical approaches. Some of the approaches applied to obtain more accurate results are slip lines methods, finite elements analysis, finite difference methods and Boundary element methods. In this study the upper bound method was applied for metallic materials. The force-stroke diagrams were obtained by the investigation of deformation energy and friction losses. The analyzed parts were prismatic specimen with arbitrary profiles and the results obtained were supported by graphics.

    • Phase transformations in titanium biomedical materials

      pg(s) 119-122

      New types of materials have been developed for years, including titanium-based alloys, which have the potential for various applications. Due to the combination of their very good mechanical properties with outstanding corrosion resistance and excellent biocompatibility, titanium alloys are developing into materials that can be used in aerospace, automotive, energy systems and especially in medicine. A fundamental understanding of the phase transformations that occur at high temperatures in all these cases, especially during cooling from elevated temperatures, is necessary to achieve optimal mechanical properties of titanium alloys. It is known that the mechanical properties of titanium alloys depend on a significant extent upon the microstructure. Therefore, it is very important to understand the nature of the phase transformations that occur under different heat treatment conditions the leads to microstructure development of titanium alloys microstructure. The aim of this article is to review the current state of knowledge and previous research and to point out some of the most interesting phase transformations of titanium alloys.

    • Structure and properties of magnetostrict materials of the Fe-Ga AND Fe-Ga-Al systems

      pg(s) 123-125

      Abstract. The structure and some properties of magnetostrictive powder materials of the Fe .Ga and .Fe-(Ga+Al) systems, obtained by sintering at a temperature of 1150 oC in a neutral Ar environment for 1 h, were studied. The structure and phase composition of the obtained materials were studied. Mechanical tests of the samples were carried out, corrosion resistance was determined and magnetostrictive properties of samples of the composition Fe-Ga and Fe-1.7Al-19.3Ga were evaluated as the most promising for use as magnetostrictive materials. An increase in hardness and level of compressive strength of the material of the composition Fe-1.7Al-19.3Ga compared to materials of the composition Fe-21.4Ga was revealed. In terms of corrosion resistance, these materials are corrosion-resistant materials (3-4 points on a 10-point scale of corrosion resistance). The highest level of magnetostriction is possessed by materials of the dual composition Fe 21.5 wt.%Ga (>210 ppm). The material with the composition Fe 19.3 wt. % Ga-1.75 wt. % Al, which had a lower level of compressive elasticity, also differed in a lower value of magnetostriction (130 ppm). The level of magnetostriction of the studied materials is within the requirements for commercial deformed Fe-Ga alloys (galfenols).