The effect of activation of oil coolants with ionized air on increasing the resistance of high-speed

Abstract

Keywords: Durability; high-speed cutting tool; ionized air; lubricating and cooling process environment.

Introduction

Metalworking is one of the most common methods of obtaining a finished product, and plays a leading role in mechanical engineering. An integral part of a metal working operation are cutting tools, which have various design and geometric parameters. The quality of the parts obtained and the cost of their manufacture directly depend on the choice of tool material, geometry, and tool productivity methods [1]. The most common method of increasing productivity and quality of processing is the use of lubricating and cooling process media (LCPM) of various compositions, which have cooling, lubricating, cutting and plasticizing, cleaning, protective and strengthening properties [2–5]. Mineral oils and LCPM based on them are widely used in machine-building enterprises, however, the profitability of using such oils is significantly reduced due to the increase

in auxiliary costs associated with transportation, storage, regeneration and disposal, in turn, widely used industrial oils and emulsions based on them negatively affect the health of production personnel, and are also one of the main pollutants of the environment [5–7]. Taking into account all of the above, in the world practice of metalworking, ways have been determined to reduce the negative impact of the applied cutting fluids, such as: a complete rejection of them and a transition to "dry" cutting, processing with a metered supply of a minimum amount of the process medium, and the creation of new, environmentally friendly compositions [6]. Today, a complete rejection of the use of cutting fluids is not possible. The metered supply of the process medium is not suitable for all process operations and does not completely resolve the issue of environmental safety. Therefore, the third option is more rational. Western manufacturers Blaser Swisslube (Switzer-

*Corresponding author. *E-mail address: eshrebdzhemilov@gmail.com Published by Yıldız Technical University Press, İstanbul, Türkiye This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

Figure 1. Experimental stand. land) and Houghton (USA) have extensive experience and proven technologies for creating such compositions. These companies are engaged in the development and production of compositions that do not contain chlorine and sulfur compounds, while the tribological properties are preserved, and in some cases they increase, due to the introduction of esters of carboxylic saturated acids that do not have aromatic bonds. These acids are contained in large quantities in vegetable oils, taking this into account, it is possible to select for a specific type of processing. Nowadays, machine-building enterprises often use oil coolants and emulsions based on them, the composition of which contains antifriction, extreme pressure and anti-fog additives, corrosion inhibitors, which in turn are organic compounds of nitrogen, chlorine, sulfur and phosphorus. When cutting metals, changes occur in these additives, especially during their evaporation and combustion, with the subsequent formation of hazardous compounds (CO, SO2, HCI and others), negatively affecting the environment and the health of workers [7–10]. The rising prices and limited resources of petroleum products and mineral products and their impact on environmental pollution make it necessary to explore alternative and environmentally friendly process media for industrial purposes. In recent years, it has been shown that the use of vegetable oils as cutting fluids has undoubtedly improved the performance of mechanical processing due to the adsorption and chemisorption phenomena. In fact, these oils significantly improve the environmental performance of the cutting process compared with mineral cutting fluids [5–8].

The combined use of a metered minimum supply of sprayed cooling lubricants using special minimum quantity lubrication (MQL) devices affects the chip formation process in the cutting zone more effectively than traditional (flooding) supply. Using MQL technology to supply lubricant with a minimum consumption of process fluid, the lubricating effect of the medium becomes predominant, which directly affects the contact stresses in the working area of the tool, as well as the specific friction work, the load on the cutting system, plastic deformation, surface quality and wear rate of the cutting tool. Most machining operations involve heating of tools, workpieces, chips and the environment. Cooling of the contact zone by the tool with the chips is relevant. In the context of the application of MQL technology and the decisive measure of this, ionized air will be used to form an air-droplet mixture. The efficiency of cooling the processing zone by supplying air passed through a corona discharge, in the works [9–11]. The penetrating effect of ionized agents is higher due to the directed movement of ions under the influence of electromagnetic fields as a result of exposure. Formed when an air flow occurs through a corona discharge, is a very popular method of joining and a strong oxidative transition to the formation of oxide films on the surface of the cutting tool, which, in turn, prevent wear. Theory During laboratory studies on measuring the content of ionized air in combination with oils (rapeseed and mineral I-20) on a SAMAT 400M screw-cutting lathe, increased accuracy was achieved, and an Altivar 71 frequency converter

Figure 3. General view of the MQL and the SATVA OL 102 compressor unit. was installed on the machine, allowing for a constant peripheral measurement speed. The general appearance of the stand for conducting experimental studies is shown in Figure 1. The research was conducted on the following materials: steel 45 and stainless steel grade 12X18N10T. Multifaceted replaceable cutting plates ISO SPUN120308 made of high-speed steel grade HSSCo5 were used as the cutting tool (Fig. 2). The supply of the cooling liquid was carried out in the form of an aerosol (containing a lubricant and ionized air) using a special dosing device. The general appearance of the device is shown in Figure 3.

The experiments were carried out at a constant cutting depth of t = 0.5 mm and feed rate S = 0.2 mm/rev. The cutting speed was V=55 m/min when processing 45 steel, and V=27 m/min for AISI321 stainless steel. The wear values were measured on the rear surface using an ИМЦЛ 150x75(2)Б instrumental measuring microscope. The wear criterion for the cutting plate was hz = 0.35 mm in the normal wear zone on the rear surface of the tool (Fig. 4). Air ionization was carried out using the “Экотехнология-1” electrostatic cooling unit (Fig. 5). Air ionization was carried out using the “Ecotechnology-1” electrostatic cooling unit (Fig. 5).

Results And Discussion

The use of LCPM from the standpoint of reducing tool wear is primarily associated with a reduction in friction and temperature, which tend to preserve the original properties of the tool material and the conditions of contact interaction. Figures 6 and 7 show graphs of the effect of ionized air in combination with oil cooling lubricants on the durability of the cutting tool, from which it follows that ionized air in combination with vegetable (rapeseed) oil significantly exceeds the results of dry cutting and cutting in an ionized air environment in terms of durability. The obtained experimental data can be explained by the fact that ionized gases and ionized-oil mixtures significantly affect the contact interaction, reducing the occurrence of adhesive phenomena and the friction coefficient, which is due to a 1.5-2.0-fold decrease in the volume of inhibited layers and build-ups, as well as the length of contact of the cutting tool with the chips, compared to the action of mineral-based cooling fluids. It

was found that electrostatic air cooling promotes the formation of oxide and nitride films on the contact surface of the cutting tool, while reducing the contact area of the coming chips along the front surface. When using a combined method of feeding the cooling fluid to the cutting zone, a significant increase in the durability of the cutting tool is observed compared to dry cutting (Fig. 6, 7). The obtained experimental data show the presence of rather complex parallel physical and chemical processes both in the external environment itself and in the contact zone of the tool with the chips. Modified oil cooling lubricants with ionized gas create condensation centers and contribute to an increase in the entropy of the process. From which it follows that the ionized air-oil flow contributes to an increase in the durability of the cutting tool made of high-speed steel. In further research, it is planned to evaluate the combined influence of process fluids and activated gases when processing difficult-to-cut materials and for various technological operations.

Figure 6. Wear of the cutter when turning C45 steel in various environments.

Figure 7. Wear of the cutter when turning AISI321 steel in various environments.

Conclusion

Considering that the turning process takes place with the release of a large amount of heat, the influence of clean ionized air increases durability by up to 15% due to the formation of passivating films on the surfaces of the cutting tool. The formation of these films also reduces adhesive wear of the cutting tool. With the combined influence of ionized air and process fluids, an increase in the durability of cutting tools is observed up to 27% when processing structural steel and up to 43% when cutting stainless steel.

Based on experimental data, it has been established that the mechanism of action of the ionized air-oil mixture on the cutting process consists in changing the friction conditions in the contact zone of the tool and the workpiece. It has been shown that the process of air ionization in combination with the technology of minimum lubrication MQL, create the necessary conditions for increasing the durability and, accordingly, reducing the wear of the cutting tool, facilitating the process of plastic deformation during the cutting process.

Data Availability Statement

The authors confirm that the data that supports the findings of this study are available within the article. Raw data that support the finding of this study are available from the corresponding author, upon reasonable request. Author’s Contributions Eshreb Dzhemilov: Design, supervision, materials, data collection and processing. Shoir Karimov: Conception, analysis and interpretation, literature review.

Conflict of Interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Use of AI for Writing Assistance Not declared.

Ethics

There are no ethical issues with the publication of this manuscript.

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