Determination of temperature of maximum operability of replaceable cutting hard-alloy inserts based on study of electromagnetic properties change

OBRABOTKAMETALLOV Vol. 23 No. 1 2021 TECHNOLOGY Introduction Today, under the conditions of sanctions, the Russian Federation needs the development of energy- saving technologies in various industries more than ever. The tasks for designing machine parts, for example in aviation or oil and gas engineering, determine the use of heat-resistant and dif fi cult-to-process materials, including new ones. Metallurgy is constantly developing; there appear new grades of materials with strength, hardness, plasticity, heat resistance properties that are many times superior to their analogs, for example, Russian grades of alloys such as VVP or American alloy martensite. In this regard, in the manufacture of such machine parts, there are many problems with the assignment of technological parameters of the manufacturing process. Primarily, this is due to the implementation of new materials at the start of the product manufacturing or general overhaul and preventive repairs, i.e. custom production of various units and machines. In Tyumen Oblast, gas turbine engines used for pumping gas undergo capital and emergency repairs. Many dif fi cult-to-process heat-resistant materials are used in their design. Studies have shown that the choice of tool material, as well as the appointment of processing modes (cutting), are the major issues in the processing of steels and alloys that belong to the group of hard-to-process materials [1]. Choosing the rational manufacturing parameters of the cutting process allows building an energy-ef fi cient process for the production and repair of machine parts. Cutting is a multifactorial process that is very dif fi cult to predict, especially when processing heat- resistant and dif fi cult-to-process materials. However, there is no doubt that under the in fl uence of temperature and cutting forces, there occurs a change in the structure and, accordingly, the properties of the tool and the processed material, with this change affecting the machining process. The study of how the changes in the properties of these materials in fl uence the process of their cutting will allow for a reasonable assignment of rational processing modes. When assigning cutting modes for new materials, tool companies conduct tests for the destruction of replaceable cutting inserts during cutting, with the obtained numerical values published in catalogs [2]. However, these numerical values do not always correspond to the optimal cutting modes. In practice, the operating conditions for the tool are divided into workability groups [3]. To date, tool companies use seven workability groups in their catalogs. The group may include a large number of processed materials grades, but only a few grades of tool material may be recommended for processing. According to these recommendations, it is not possible to determine which tool material will provide the longest service life when processing the chosen material. The problem of ensuring the longest service life of the cutting tool was studied from various positions in the works of S. A. Vasin [4], S. N. Grigoriev [5], S. V. Gruby [6], I. Carceanu, G.Cosmeleat ǎ [7], C. Ferri [8], J. Kümmel [9], Munish Kumar Gupta [10], K. S. Murthy [11], R. Neugebauer [12], I. Jaafar[13], S. Tangjitsitcharoen [14], A. Patwari [15], W. Tillmann [16], H. Zhang[1 7], and C. L. Zhang [18]. A literary analysis of the works of world-renowned scientists in edge cutting machining has shown that the temperature factor has a resultant effect on the cutting process of hard-to-process materials [4–18]. Tool materials (TM), like other materials, have physical and mechanical properties that can change under the in fl uence of external factors. These properties have a decisive in fl uence on the operability and service life of the tool made of these materials. Studies have shown that the physical and mechanical properties of tungsten hard alloys change symmetrically under the in fl uence of high temperatures during operation, namely during the cutting of hard-to-process materials [19]. The study of the processes occurring inside tool materials, including tungsten hard alloys, will allow for determining and assigning operating modes of this material on a scienti fi cally based methodology taking into account the material’s internal changes. It will increase the service life of the cutting tool and provide conditions for the cutting tool to have maximum cutting properties when machining hard-to-process materials [20]. The aimof thework is to determine the cutting speed that ensures themaximumservice life of replaceable cutting inserts made of tungsten hard alloy B35 during turning of the chromium-nickel alloy EI867-VD