Machines. Technologies. Materials.
Vol. 16 (2022), Issue 7

Table of Contents

  • MACHINES

  • TECHNOLOGIES

    • Study on the influence of cutting fluid on flat grinding process

      pg(s) 231-233

      In the paper is presented a study regarding the influence of different factors on the roughness of machined surfaces obtained by manufacturing process of flat grinding. The workpieces that were used on the experimental tests were radial bearing ring with needles made of steel hardened to 60-64 HRC. It were taken into consideration factors like, the size of the machined surface, the traverse speed, the grain size of abrasive grinding wheels, cutting fluid.
      During the experiments was used the method of the Box-plot graphical representation that aims to observe and characterize the distribution of values obtained on these tests.

    • The influence of tool path strategies for 3- and 5-axis milling on the accuracy and roughness of shaped surfaces

      pg(s) 234-237

      Free form or shaped surfaces are found on a large number of modern engineering products. 3- or multi-axis CNC milling is usually used in their production. CAM systems are almost exclusively used in the creation of control programs. The aim of the presented research was to compare the quality of shaped surfaces made by 3- and 5-axis milling using three frequently used strategies. A sample with hemispherical surfaces was designed for the experiment. The surfaces predicted by the CAM system were compared with the surfaces actually produced. The disagreement of the predicted surface deviations with the deviations of the produced surfaces was demonstrated. In the evaluation of surface roughness, the advantage of 5-axis milling was partially demonstrated when one of the strategies achieved lower roughness, at two strategies the roughness was identical to 3-axis milling.

    • Disposal of Spent Ionizing Radiation Sources Cobalt-60

      pg(s) 238-240

      The paper discusses the experience of work of specialists of the consortium as part of the INP AS (Tashkent, Uzbekistan), JSC “National Technical Physics and Automation Research Institute” and CJSC “Mounting Firm “Radiy” (Moscow, Russia) at utilization of 96 pieces of sources GIK-7-2 Co-60 of gamma installations of “RKhM-gamma-20” and “Issledovatel”, including 2 emergency sources Co-60, their burial in specialization point for radioactive waste. Also, the experience of specialists in the elimination of emergency situation with recharge a highly active source of GIK 8-4 Co-60 for radiation gamma therapy from emergency holder with crack to a new holder from depleted uranium. The reason for the appearance of a crack on the body of the Co-60 source holder is discussed.

    • Investigation of the interface of two-layer diamond plates for drilling tools

      pg(s) 241-242

      Two-layer diamond-hard alloy plate is the cutting element of the drill bit and consists of a layer of polycrystalline diamond compact (PDC) binded with the superhard alloy substrate (WC-Co). PDC tools are now actively used in the drilling of mineral resources for the search and production of hydrocarbons.
      Full-scale tests of PDC cutters in PDC bits have shown that their strength, wearability, and especially heat resistance, are determined by the quality of the contact layer (interface) between the PDC and the substrate. In the work, the interface of the diamond layer and the substrate of two-layer diamond plates made on the installation based on a multi-punch press GY850 was investigated by laser-ultrasonic flaw detection.

  • MATERIALS

    • About corrosion damage of the railway wheels

      pg(s) 243-247

      Corrosion mechanism and rate of different chemical composition and structural condition of wheel steel were investigated. It was shown that “white layers”, variation in grain size and banding of wheel steel structure results in corrosion rate. Microstructure of steel from different elements of railway wheels after operation with corrosion was investigated. Wheel steel with addition of vanadium corroded more quickly than steel without vanadium. Non-metallic inclusions are the centres of corrosion nucleation and their influence on corrosion depends on type of inclusion. Mechanism of corrosion of wheel steel corrosion was discussed.

    • Analytical approach to crack tip plasticity of dental CoCrMo alloy

      pg(s) 248-250

      In this paper, a thin infinite plate of CoCrMo alloy with a straight crack was loaded perpendicularly to the crack plane. CoCrMo alloys are due to their suitable mechanical and corrosion properties widely used for dental applications. The importance of good mechanical properties is reflected in ensuring the functional and technical durability of dental appliances. The intention of this paper is to use a mathematical approach in analyzing a thin infinite plate with a straight crack to the rather complex occurrences within the cohesive zones around the crack tips. The dependence of plastic zone magnitude around the crack tip on an external load of dental CoCrMo alloy plate was considered in this paper. Static tensile tests were carried out to determine the mechanical properties of dental CoCrMo alloy. At plastic deformation, the dental CoCrMo alloy is nonlinearly hardened in accordance with the Ramberg-Osgood equation which parameters were determined using a least-squares method from experimental data. The application of the Dugdale model the plastic zone magnitude around the crack tip was determined. The stress intensity coefficient from the cohesive stresses was calculated using Green functions. The analytical methods, assuming a small plastic zone around a crack tip, were used in the analysis. The results were obtained by means of a commercial software package and presented in the form of diagrams.

    • Nanophase structures in vacuum multilayer coatings formed on tool and high-speed steels

      pg(s) 251-254

      The most common coatings for metalworking tools include titanium nitride, titanium carbide, titanium carbonitride, zirconium nitride, zirconium carbide, zirconium carbonitride, compounds based on chromium, titanium, aluminum, diamond-like coatings that are formed in vacuum using PVD, CVD, PCVD methods or a combination of the above methods. The current trend in the deposition of vacuum coatings is the production of multifunctional coatings, which can significantly increase operational characteristics compared to the starting materials. To form multifunctional coatings, the creation of “sandwich” structures is used, since each layer performs various functions – forming, antiwear, anticorrosion. Thus, the use of a composite multilayer coating containing layers of titanium nitride, titanium, diamondcontaining compounds with a thickness of one layer from 0.1 to 2 microns makes it possible to increase the wear resistance of a metalworking tool by 1.5-5 times.

    • Features of the tribological behavior of the magnesium alloy Mg -1% ca depending on the structural state

      pg(s) 255-259

      This paper presents experimental data on the tribological properties of the Mg-1%Ca magnesium alloy with different microstructures (coarse-grained microstructure in the initial state, and ultrafine-grained and nanocrystaline microstructures after severe plastic deformation via two processes – equal-channel angular pressing and high pressure torsion) in contact with an indenter made of the Fe-18W-4Cr- 0.8C steel without any coating and with applied hydroxyapatite, which is the main mineral component of bones. An indenter with hydroxyapatite on the surface was used as a bone simulator. As a result of the experiments, it was found that the shear strength of adhesive bonds and the adhesive component of the friction coefficient are structurally sensitive parameters. For all the samples in the considered contact pairs, when using a bone tissue simulator the strength of adhesive bonds was lower than that when using a steel indenter. It is noted that ultrafine-grained and nanocrystalline structures produced as a result of severe plastic deformation via two processes, equal-channel angular pressing and high pressure torsion, contribute to a decrease in the shear strength of adhesive bonds and the adhesive component of the friction coefficient due to strengthening resulting from grain size reduction from originally 100 μm to 1.4–4 μm on average in the investigated Mg-Ca magnesium alloy.

    • Recent developments and regulations in fire resistance of wood and wood-based composites

      pg(s) 260-262

      This study focused on the fire-retardant treatment of wood and wood-based composites using various methods. The recent developments in the fire-retardant standards and classification of wood and wood-based composites were reviewed. Most commonly used fire-retardants and commercial application methods of fire retardants such as boron compounds and phosphates to improve fire resistance of wood and wood based composites were explained. Furthermore, fire-retardant mechanism was informed. Novel nanomaterials used in the fire resistance of wood and wood-based composites were introduced. Significant criteria in choosing of the suitable fire retardants for wood and wood-based composites were explained