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Öğe Determination of machinability metrics of AISI 5140 steel for gear manufacturing using different cooling/lubrication conditions(Elsevier, 2022) Usca, Usame Ali; Uzun, Mahir; Sap, Serhat; Giasin, Khaled; Pimenov, Danil Yurievich; Prakash, ChanderAISI 5140 steel is mostly used in gear manufacturing for variety of industries. Those gears can be manufactured via casting, powder metallurgy or forging techniques. Nevertheless, machining (via turning and milling processes) remains the most common manufacturing method to fabricate them. Milling of gears made from 5140 steel can be challenging due to the excessive energy consumption, rapid tool wear and poor surface finish. Therefore, traditional and environmentally friendly coolants are usually applied during machining to improve the surface finish and prolong tool life. The current study aims to investigate machinability performance of 5140 steel under different cooling/lubrication conditions. Several machinability metrics were investigated and analyzed (surface roughness, cutting temperature, tool wear, chip morphology, and energy consumption). Milling tests were performed under different cutting speeds (75 and 100 m/min), different feed rates (0.15 and 0.2 mm/rev) and dry, minimum quantity lubrication (MQL), and cryogenic liquid cooling/lubrication conditions (dry, MQL and cryo-LN2). The results showed that using Cryo-LN2 cooling/lubrication tended to improve all the investigated machinability metrics compared to dry condition. The surface roughness was reduced by approximately 54%, while the cutting temperature was reduced by 87%. Similarity, the cutting tool flank wear was reduced by 20% thus energy consumption was minimized by 15%. The current study shows the importance of cryogenic machining in industry for difficult to cut materials. (C) 2022 The Authors. Published by Elsevier B.V.Öğe Development of the hardness, three-point bending, and wear behavior of self-lubricating Cu-5Gr/Al2O3-Cr3C2 hybrid composites(Sage Publications Ltd, 2023) Sap, Serhat; Usca, Usame Ali; Uzun, Mahir; Giasin, Khaled; Pimenov, Danil YuThis research aims to assess the mechanical characteristics of high-performance copper composites made utilizing powder metallurgy. The composites were produced by adding reinforcement elements (Al2O3-Cr3C2) at different rates (3-6-9 wt.%) into copper-graphite (Cu-5Gr) via hot pressing technique. The microstructure, hardness, three-point bending and wear performance were analysed. The results determined that hybrid reinforced composites exhibited higher density, hardness and bending strength compared to Cu-Gr composites. The highest hardness of 73.02 HB was found in the CG-4 (copper graphit-4) sample. The maximum bending stress of 151.06 MPa occurred in sample CG-2. In addition, it was observed that the wear resistance increased significantly with the addition of the hybrid reinforcements. The lowest specific wear rate of 7.961 x 10(-7) mm(3)/N.m occurred in sample CG-6. As a result, 15.92%, 58.16% and 83.21% improvements were achieved in hardness, bending strength and wear performance, respectively. The current work indicates that certain mechanical properties of copper can be improved via the powder metallurgy process and the addition of reinforcements which could expand the applications and use of this metal in different industries.Öğe Evaluation of Mechanical and Tribological Aspect of Self-Lubricating Cu-6Gr Composites Reinforced with SiC-WC Hybrid Particles(Mdpi, 2022) Usca, Usame Ali; Sap, Serhat; Uzun, Mahir; Giasin, Khaled; Pimenov, Danil YurievichBecause of their high thermal conductivity, good corrosion resistance, and great mechanical qualities, copper matrix composites are appealing materials utilized in a variety of industries. This study investigates the mechanical properties of copper-graphite (Cu-Gr) matrix composites reinforced with silicon carbide (SiC) and tungsten carbide (WC) particles by hot pressing using powder metallurgy method. The goal is to investigate the influence of the reinforcement ratio on the mechanical characteristics of copper composite materials generated (density, hardness, flexural strength, and wear resistance). SEM, EDS, and X-RD analysis were used to perform metallographic examinations. The highest relative density with a value of 98.558% was determined in the C3 sample. The findings revealed that when the reinforcement ratio was raised, the hardness rose. The highest hardness value was observed in the C6 sample with an increase of 12.52%. Sample C4 (with the lowest SiC and WC particles ratio) had the highest bending stress (233.18 MPa). Bending stress increased by 35.56% compared to the C1 sample. The lowest specific wear rates were found in the C4 sample, with a decrease of 82.57% compared to the C1 sample. The lowest wear rate (6.853 x 10(-7) mm(3)/Nm) also occurred in the C4 sample. The microstructural analysis showed that the hybrid reinforcement particles exhibited a homogeneous distribution in the copper matrix. X-RD analysis showed that there was no intermediate reaction between the parent matrix and the hybrid reinforcements. A good interfacial bond was observed between the matrix structure and the hybrid reinforcements. The motivation of this research was to utilise the advantages of the unique features of SiC-WC hybrid particles to improve the performance of newly developed Cu-6Gr composites for wear-resistance applications.Öğe Investigation of machinability of Ti-B-SiCp reinforced Cu hybrid composites in dry turning(Elsevier, 2022) Sap, Serhat; Uzun, Mahir; Usca, Usame Ali; Pimenov, Danil Yu; Giasin, Khaled; Wojciechowski, SzymonMMCs (metal matrix composites) are widely used in many industrial applications thanks to their high specific strength. Nevertheless, this also poses a great challenge to their machinability due to rapid tool wear and poor surface finish caused by the added reinforcement particles. Improving the machinability of MMCs is of great importance as it will increase their performance and areas of applications. In this study, the machinability of Cu composites reinforced with Ti-B-SiC powder particles (0-2-4-6-8 wt.%) produced at different rates using powder metallurgy method was investigated. Cutting speed (V-c: 100-150 m/min) and feed rate (f(n): 0.2-0.4 mm/rev) were used as cutting parameters. The effects of these parameters on surface roughness, flank wear, and cutting temperature were investigated. As a result of the turning experiments, it was observed that the surface roughness decreased with increasing reinforcement ratio, and thus the best surface roughness (R-a = 0.22 mu m) was observed in the 8 wt.% reinforced sample. The cutting temperature and flank wear values increased as the reinforcement ratio increased. It was observed that cutting temperature at the chip-tool interface was the lowest (76 degrees C) in MMCs sample with 2 wt.% reinforcement. The lowest flank wear (0.93 mm) was also observed in the 2 wt.% reinforced sample. In addition, the chip morphologies of all samples produced at different ratios were investigated after the turning process. (C) 2022 The Authors. Published by Elsevier B.V.Öğe Investigation on microstructure, mechanical, and tribological performance of Cu base hybrid composite materials(Elsevier, 2021) Sap, Serhat; Uzun, Mahir; Usca, Usame Ali; Pimenov, Danil Yu; Giasin, Khaled; Wojciechowski, SzymonCopper matrix composites (CMC) are frequently used in the automotive, aerospace, construction, and electrical-electronics industries. Properties such as low density, improved fatigue strength, high hardness, and high specific strength are the factors that make copper matrix composites important. The development of these factors is important for the industrial use of copper matrix composites. SiCp doped metal matrix composites have better mechanical properties than pure alloys. It is also known that Ti, B powder particle additives improve the mechanical properties of the main matrix. In this study, Cu hybrid composites reinforced with Ti-B-SiCp powders, which were not produced before, were obtained and their microstructure, density, hardness, and wear behavior were investigated. Composite materials produced by powder metallurgy method were prepared at 2-8 wt. % mixing ratios. Then each material was sintered at temperatures of 950-100-1050 degrees C. Microstructural images showed homogenous distribution in the composite material. The highest relative density of 93% was obtained in the composite material with a 2% reinforcement rate at 1050 degrees C. It was found that the hardness increased with the increase of the reinforcement rate up to 6 wt.% and then decreased after that. It was observed that the specific wear rate increased with the increasing reinforcement ratio. In addition, the lowest friction coefficient and wear temperature occurred at a sintering temperature of 1050 degrees C. In this study, it was reported that the sinter temperature value of 1050 degrees C is the optimum temperature value in terms of the tribological and mechanical performance of the materials. (C) 2021 The Authors. Published by Elsevier B.V.Öğe Skull Thickness Calculation Using Thermal Analysis and Finite Elements(Mdpi, 2021) Calisan, Mucahit; Talu, Muhammed Fatih; Pimenov, Danil Yurievich; Giasin, KhaledIn this study, the skull bone thicknesses of 150 patients ranging in age from 0 to 72 years were calculated using a novel approach (thermal analysis), and thickness changes were analyzed. Unlike conventional thickness calculation approaches (Beam Propagation, Hildebrand), a novel heat transfer-based approach was developed. Firstly, solid 3D objects with different thicknesses were modeled, and thermal analyses were performed on these models. To better understand the heat transfer of 3D object models, finite element models (FEM) of the human head have been reported in the literature. The FEM can more accurately model the complex geometry of a 3D human head model. Then, thermal analysis was performed on human skulls using the same methods. Thus, the skull bone thicknesses at different ages and in different genders from region to region were determined. The skull model was transferred to ANSYS, and it was meshed using different mapping parameters. The heat transfer results were determined by applying different heat values to the inner and outer surfaces of the skull mesh structure. Thus, the average thicknesses of skull regions belonging to a certain age group were obtained. With this developed method, it was observed that the temperature value applied to the skull was proportional to the thickness value. The average thickness of skull bones for men (frontal: 7.8 mm; parietal: 9.6 mm; occipital: 10.1 mm; temporal: 6 mm) and women (frontal: 8.6 mm; parietal: 10.1 mm; occipital: 10 mm; temporal: 6 mm) are given. The difference (10%) between men and women appears to be statistically significant only for frontal bone thickness. Thanks to the developed method, bone thickness information at any desired point on the skull can be obtained numerically. Therefore, the proposed method can be used to help pre-operative planning of surgical procedures.Öğe Tool wear, surface roughness, cutting temperature and chips morphology evaluation of Al/TiN coated carbide cutting tools in milling of Cu-B-CrC based ceramic matrix composites(Elsevier, 2022) Usca, Usame Ali; Uzun, Mahir; Sap, Serhat; Kuntoglu, Mustafa; Giasin, Khaled; Pimenov, Danil Yu; Wojciechowski, SzymonCeramics-based composites are a special class of materials carrying combined properties that belongs to alloys and metals according to market demands. This makes composites completely different and paves the way for new applications that requires the utmost properties. Machining of such composites is of great importance to finalize the fabrication process with improved part quality; however, the process implies several challenges due to the complexity of the cutting processes and random material structure. The current study aims to examine the machinability characteristics when milling novel material, Cu-B-CrC composites using Al/TiN coated carbide tools. Further, the influence of machining parameters along with the different weight ratios of the powders amounts used to fabricate the machined reinforced samples on output parameters namely surface roughness, tool wear, chip morphology and cutting temperatures was investigated. One of the key findings of the study is the dominant effect of reinforcement ratio (Cu, B, CrC) on machinability, which showed that 5% additive (2% B, 3% CrC) provides improved properties such as surface roughness, tool wear and cutting temperature. Cutting speed alterations play an important role in the machinability characteristics, i.e., increasing value increases flank wear and cutting temperatures and reduces surface roughness. Increasing feed rate in-creases the surface roughness meanwhile its effect shows changing behavior on the flank wear and cutting temperatures according to cutting speed and reinforcement ratio.(c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Öğe Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy(Mdpi, 2021) Usca, usame Ali; Uzun, Mahir; Kuntoglu, Mustafa; Sap, Serhat; Giasin, Khaled; Pimenov, Danil YurievichTribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 degrees C) were used. Taguchi's L-16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 degrees C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 degrees C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 degrees C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.
