Obrabotka Metallov / Metal Working and Material Science

Introduction. One way to enhance the efficiency of the cutting process is to develop new effective compositions of metalworking fluids (MWFs), which will reduce cutting force and temperature, while increasing the durability of the cutting tool and the quality of the processed surface. One approach to address this challenge is the chemical activation of MWF using additives based on nanoclay minerals, which are characterized by low cost and abundant reserves in-Earth. In this regard, the theoretical rationale for the selection of this additive and its impact on the tribological properties of the MWF is given. The purpose of the work is to determine the effect of oil-based additives with nanoclay minerals on reducing the cutting force, as well as improving the quality of the processed surface when drilling corrosion-resistant steel. Research methods. Experimental investigations were conducted during a drilling operation, in which the components of the cutting force were recorded using a three-component dynamometer M-30-3-6k. The aim of the experiment was to determine the effect of oil-based MWF containing additives from nanoclay minerals on the component of the cutting force, as well as the roughness of the processed surface. A formula for calculating the friction coefficient in the drilling process was derived using mathematical modeling. Results and Discussion. The experimental investigations yielded results demonstrating the effectiveness of using oil-based MWF with additives made from nanoclay minerals. Experimental data was obtained for the friction coefficient, cutting force component, as well as the roughness of the processed surface during drilling. These results were obtained using the experimental MWF, supplied to the cutting zone. The results of the study showed the effectiveness of using the modified MWF compared to traditional compositions. Conclusions. The modified MWF, which includes sunflower oil and nanoclay minerals as additives, significantly reduces the friction coefficient, cutting force, as well as the roughness of the processed surface, which opens up further prospects for its use in the metalworking industry.

Introduction. The paper presents the results of an experimental study on the quantitative and qualitative evaluation of the surface after wire electrical discharge machining (WEDM). The purpose of this study is an experimental investigation with qualitative and quantitative analysis of surface defects in samples made of a heat-resistant nickel alloy VV751P after WEDM. Methods of research. Samples for the study with a specific geometry were obtained by the wire electrical discharge machining method in 4 modes. The operating parameters were: workpiece height (h, mm), pulse-on time (Ton, μs), and pulse-off time (Toff, μs). The samples were studied using a Hitachi S-3400N electron microscope in backscattered electron mode at 25 kV. Surface topography after electrical discharge machining was evaluated using a laser scanning microscope (LSM) LextOLS4000. Cyclic tests were performed on a universal testing machine Biss-00-100 at a test frequency of 20 Hz in a symmetrical cycle (R = −1). Results and discussion. The defective (white) layer of samples was analyzed. It is established that during wire electrical discharge machining the thickness of defective white layer is within 10 µm, both after processing in minimum and maximum mode. The surface quality index (surface roughness Ra) was analyzed. It was found that the average value of surface roughness parameter Ra is 1.62 μm when processing samples with a height of 10 mm. When the sample height increases, the surface roughness value reaches 2.6 μm after processing in minimum mode and 3.4 μm after processing in maximum mode. It is established that with an increase in workpiece height, the number of microcracks on the surface of the product increases, which is associated with the intensification of the interaction of single pulses with the processed surface. As a result of the study, it is found that at a loading amplitude of 400 MPa, an average value of the number of cycles reaches 1.50E + 05 cycles. A decrease in the number of cycles is observed with an increase in the amplitude of the loading cycles.

Introduction. Additive manufacturing technologies, in particular wire arc additive manufacturing (WAAM), have been gaining increasing popularity recently. This method allows for the production of blanks with significantly increased hardness compared to traditional methods such as forging, which in turn significantly increases the cutting force during subsequent machining. The present study is aimed at investigating the cutting forces during milling of samples made from the high-strength, heat-resistant alloy Inconel 625 obtained by WAAM. The aim of the work is to investigate the influence of microstructure and properties of Inconel 625 fabricated by WAAM, on cutting forces during milling. Particular attention is paid to the search for optimal cutting modes, providing minimization of cutting forces and vibrations in the “machine-utility-tool-part” system. Methods of research. Samples were produced by WAAM using wire made from heat-resistant nickel-based alloy Inconel 625. A comprehensive analysis of the microstructure of the obtained samples was carried out using modern materials science methods. The main attention is paid to the experimental study of cutting forces during milling using different machining modes (cutting speed, feed rate, and depth of cut) and types of cutters. Results and Discussion. The microstructure of Inconel 625 samples obtained by WAAM is characterized in detail. Optimal milling modes will be determined to ensure efficient machining of the material, taking into account its high hardness and strength. It is expected that machining of Inconel 625 blanks will require high-strength carbide milling cutters, possibly of special geometry and with increased wear resistance, with a larger diameter compared to milling of steel 0.4 C-13 Cr. The results of the study allow developing recommendations for selecting optimal cutting modes minimizing cutting force, cutting edge temperature, tool wear and vibrations in the “machine-utility-tool-part” system, thereby improving processing productivity and accuracy.

Introduction. When manufacturing critical parts from high-strength and difficult-to-process steels in various industries, the final quality is usually formed during finishing operations. The efficiency of the process is significantly higher when using combined, hybrid methods of influencing the surface being processed. When processing some complex-shaped parts, more attention in finishing operations is usually paid to reducing roughness while maintaining previously achieved dimensional accuracy indicators. For this purpose, abrasive tools on a rigid base are often used, placing it in a less rigid technological system. To increase the efficiency of the process, it is necessary to establish optimal modes of mechanical and electrochemical processing of parts. In the absence of the possibility of using industrial equipment for hybrid technologies at the initial stage, taking into account the need to modernize existing technological equipment for the implementation of the electrochemical grinding process, it is advisable to study this process by simulating it on simulator devices. The purpose of the work is to develop a device for studying and simulating the process of electrochemical grinding of conductive parts with abrasive heads on a metal bond. Research methodology. To simulate the process of electrochemical grinding of conductive parts using abrasive heads on a metal bond, we have developed a special device. It allows for the basing of the workpiece and the tool, implementation the electrochemical grinding process, its kinematic and electrical conditions: main motion, linear displacement of working bodies, mechanical and electrical modes, ensuring the necessary conditions for the implementation of the technology, and implementing a control system. Results and discussion. To determine the influence of mechanical cutting modes on the roughness of the machined surface of a part made of corrosion-resistant steel 0.12 C-18Cr-10 Ni-Ti, empirical studies were carried out on the designed device. Planning and processing of experimental results were carried out using standard methodology for preparing and conducting a full factorial experiment. The resulting model makes it possible to determine rational mechanical cutting conditions and evaluate its influence on the quality of the surface being processed.

Introduction. The primary goal of food processing equipment manufacturing is to create highly efficient process equipment that can increase labor productivity while reducing energy costs. Improving existing and creating new high-performance equipment for food production is one of the main trends in the development of modern mechanical engineering. The term “homogenization” literally means “increasing uniformity”. In the context of emulsions, homogenization refers to the process of treating emulsions, which leads to the fragmentation of the dispersed phase. Homogenization is the process of grinding liquid or mashed foods by passing it at high speed and pressure through narrow annular slots. The authors propose to use cam-type mechanisms for homogenization. Cam-type mechanisms allow for a more efficient allocation of the time for the product suction and injection. The homogenization process benefits from the potential to reduce the speed during product injection. The purpose of the work is to reduce power consumption during homogenization. The research methods are based on the theory of machines and mechanisms. These methods enabled developing a methodology for synthesizing the homogenizer drive mechanism and designing a machine that ensures its operation in accordance with the proposed cycle diagram. Results and discussion. The synthesis of mechanisms is executed with consideration for the workload, which was calculated for existing domestic machines in the production of processed cheese. Thus, with a given production capacity of 550 l/h and a plunger diameter of 28 mm, the technological force is F = 12315 N. In accordance with the authors' proposals, the design of the homogenizer is modified by introducing cam mechanisms. In the design of this drive, a novel cycle diagram is proposed, enabling an increase in product injection time and a reduction in suction time. According to the novel cycle diagram, 280° is proposed for product injection and 80° for suction. In this case, the power on the drive shaft is equal to P = 2.5 kW instead of 3.5 kW for the existing design, driven by a crank mechanism. The power consumption is decreased by 26 %.

Introduction. Cast iron is a material that is widely used in various industries. It possesses high heat capacity, relatively high hardness, and a number of other physical, mechanical and technological properties. Due to the significant operational stress experienced by the working surfaces of cast iron parts and its frequent exposure to aggressive environments, additional surface treatment is required to enhance wear resistance, corrosion resistance, and other properties. There are many different methods of surface modification. One of the most promising and modern ones is ion implantation with various ions. The purpose of the work is thus to study the effect of ion implantation on the surface of cast iron and the resulting changes in its mechanical properties. Methods. Cast iron samples were implanted with nitrogen ions of different doses (optimal dose of implanted nitrogen ions as a nitride-forming element). The surface microstructure of cast iron samples was investigated using a scanning electron microscope Stereoscan S-180 at a magnification of ×2,900 and ×5,000. Microdurometry analysis of the samples was carried out using a Neophot-2 metallographic microscope equipped with an attachment for measuring microhardness, at a load of 10 g after implantation of cast iron samples with various doses of nitrogen ions. In addition, X-ray diffraction analysis was performed on a DRON-3 diffractometer to determine the phase composition and fine structure of modified cast iron samples. Results and Discussion. Ion implantation of cast iron samples significantly increases microhardness. Thus, the conducted study reveals that the best mechanical properties (specifically microhardness) are observed in cast iron samples after implantation by N+ ions with a dose of 5×1017 ions/cm2 with energy of 40 KeV. X-ray diffraction analysis demonstrated that the ion implantation with nitrogen results in the formation of Fe2N and Fe2N nitrites, and also revealed changes in fine structure (average dislocation density and size of mosaic blocks).

Introduction. Hip joint replacement is considered the most complex and critically important orthopedic surgical procedure compared to knee and shoulder joint replacements. Over the past few decades, there has been significant advancement in hip joint replacement technology, and various biomaterials have been substantially improved. An increasing number of hip joint replacement surgeries are now successful, assisting individuals in regaining normal daily activity and work capacity comparable to their pre-fracture state. However, the need for revision surgery, specifically for implant replacement, is still observed in active patients several years following the initial operation. This underscores the need to develop durable biomaterials and customized hip joint implants to reduce implant wear and the risk of dislocation. This research study explores a novel PEEK-in-acrylate composite biomaterial with varied weight percentages of PEEK (0 %, 5 %, and 10 %) in an acrylate-based matrix. Tests were conducted to determine its properties, biocompatibility, and 3D printability. Based on the developed material, pins (in accordance with the ASTM standard) were fabricated using 3D printing for subsequent wear rate studies. The potential use of the developed composite materials for hip-joint applications was also thoroughly investigated. The purpose of this study is to develop and investigate a new PEEK in Acrylate composite biomaterial with varied weight percentages of PEEK (0 %, 5 %, and 10 %) in an acrylate-based matrix. The research includes an assessment of the material's properties, biocompatibility, and 3D printability. Using digital light processing (DLP) 3D printing technology at room temperature, pins (in accordance with the ASTM standard) were fabricated. An experimental study of dry sliding wear resistance was conducted on the resulting samples to determine the effect of PEEK weight fraction on the wear rate and frictional performance against an SS 316 steel disk. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to analyze the surface structure and element distribution within the material. The Methods of Investigation. Digital Light Processing (DLP) 3D Printing technique was used to 3D Print the ASTM pins and Acetabular liner with different weight fraction of PEEK in acrylate. Dry sliding wear tests were carried out using a pin-on-disk tribometer. During testing, the disk rotation speed and the normal load on the pin were varied. The studies were designed to determine the influence of input parameters on the wear rate. A total of nine experiments were conducted for each PEEK weight fraction, with a sliding distance of 4 km per experiment. The load ranged from 20 to 100 N, and the sliding speed varied from 450 to 750 rpm. Surface structure and element distribution were analyzed by Energy-dispersive X-ray spectroscopy (EDS) and Scanning electron microscopy (SEM). Result and Discussion. Current study demonstrates the advantages of varying the weight fraction of PEEK in Acrylate for DLP-fabricated biomaterials. Analysis of the SEM, EDS, and wear testing results indicated that the composite with 10 wt % PEEK in Acrylate exhibited superior microstructural integrity, elemental homogeneity, and significantly improved wear resistance. The 10 wt % PEEK in Acrylate composite, fabricated via DLP 3D printing, is suitable for biomedical implant and healthcare applications

Introduction. This study investigates the influence of key operating parameters (load, sliding velocity, and sliding distance) on the wear behavior of composites made of 40 % glass fiber and polyphenylene sulphide (PPS), with varying weight fractions of bentonite clay. The main purpose was to evaluate how different experimental conditions affect the wear characteristics. To achieve this, experiments were conducted using a Taguchi L9 orthogonal array at three levels of complexity. The tribological tests were performed on a pin-on-disc setup, following ASTM G99 standards, with six material samples containing different weight fractions of bentonite clay. The results show that wear of the original (virgin) sample increases with an increase in the applied average load. In contrast, samples containing bentonite clay exhibit a decrease in wear with increasing average load. Furthermore, an increase in the bentonite clay content leads to a significant reduction in wear, but a further increase to 7 % clay results in a noticeable increase in wear values. Research Methods. This study investigates the effect of load, sliding velocity, and weight fraction of bentonite clay on the wear and coefficient of friction (COF) of a composite material. Composite samples with varying clay content were tested using a pin-on-disc setup, and wear and COF were measured as dependent parameters. Scanning electron microscopy (SEM) was used to analyze the wear surfaces after testing to reveal the influence of independent parameters on wear mechanisms and surface morphology. The results revealed important trends in the friction and wear behavior under different conditions. Comparative analysis provided insights into optimizing the tribological performance of the material by balancing load, velocity, and clay content. Result and Discussion. This study investigates the effect of bentonite clay addition on the wear behaviour of PPS + GF composites. The findings reveal that wear decreases by up to 3 % with an increase in the weight percentage of bentonite clay, but increases again with a further increase in clay content. It is noted that a higher weight fraction of bentonite clay leads to an increase in the specific wear rate and a decrease in the coefficient of friction due to the manifestation of an abrasive wear mechanism caused by clay agglomeration. Conversely, a lower clay weight fraction promotes a reduction in the wear rate while increasing the coefficient of friction.This work intends to address the dual challenge of performance optimization and cost reduction in friction and wear applications. The need of the work. The purpose of this research is to develop an organic polymer composite that exhibits both high performance and cost-effectiveness. One of the key objectives is to create such a composite material using bentonite clay, an organic and readily available material that can be sourced at a low cost. This will enable the production of a competitively priced composite without compromising quality. Another goal of the research is to replace existing friction materials in brake and clutch systems with the newly developed composite, potentially improving its performance and durability. Furthermore, this work aims to create a composite material suitable for use in sliding bearings, particularly those operating in corrosive environments. Such a composite should possess increased resistance to chemical degradation, ensuring an extended lifespan and reliability under severe operating conditions.