15 research outputs found
The Effect of Cellulose Nanocrystal-Based Nanofluid on Milling Performance: An Investigation of Dillimax 690T
No full textMachining high-strength structural steels often requires challenging processes. It is essential to improve the machinability of such materials, which are frequently needed in industrial manufacturing areas. Recently, it has become necessary to enhance the machinability of such materials using different nanopowders. In this study, different cooling/lubricating (C/L) liquids were prepared with cellulose nanocrystal (CNC) nanopowder. The aim was to improve the machinability properties of Dillimax 690T material with the prepared CNC-based cutting fluids. CNC nanopowders were added to 0.5% distilled water by volume, and a new nanofluid was produced. Unlike previous studies, base synthetic oil and CNC-based cutting fluid were sprayed on the cutting area with a double minimum quantity lubrication (MQL) system. Machinability tests were carried out by milling. Two different cutting speeds (Vc = 120–150 m/min), two different feed rates (f = 0.05–0.075 mm/tooth), and four different C/L environments (dry, MQL oil, CNC nanofluid, MQL oil + CNC nanofluid) were used in the experiments. In the study, where a total of 16 experiments were performed, cutting temperature (Tc), surface roughness (Ra), tool wear (Vb), and energy consumption results were analyzed in detail. According to the test results, significant improvements were achieved in the machinability properties of the material in the experiments carried out using CNC nanofluid. In particular, the hybrid C/L environment using MQL oil + CNC nanofluid improved all machinability metrics by over 15% compared to dry machining. In short, using CNC nanopowders offers a good milling process of Dillimax 690T material with effective lubrication and cooling ability
Development and analysis of performance characteristics of a new type of external gear pump using curvilinear involute gears
No full textGünümüzde dıştan dişli pompaların kolay üretilebilir olması, üretim maliyetinin düşük olması, hidrolik sistemlere kolay entegre edilebilmesi, yüksek basınçlarda çalışabilmesi, viskozitesi yüksek akışkanları iletebilmesi ve geniş devir sayılarına sahip olmalarından dolayı endüstride kullanımı oldukça yaygındır. Bunun yanı sıra pompa gürültü seviyesi, pompa girişinde ani basınç düşüşünden kaynaklanan kavitasyon oluşumu, pompa elemanlarında zamanla meydana gelen aşınma ve ayrıca aşınmadan kaynaklanan ters akış oluşumu pompa performans ve ömrünün azalmasına yol açarak bu tip pompalar için dezavantaj olmuştur. Bu gibi dezavantajların giderilebilmesi için araştırmacılar birçok çalışma yapmışlardır ve halen bu çalışmalar devam etmektedir. Bu tez çalışmasında da literatürde yapılan çalışmalarla verimliliği kanıtlanmış fakat dıştan dişli pompalar için kullanılmamış eğrisel evolvent dişli çarkların kullanımı araştırılmıştır. Bu kapsamda referans evolvent profil ve asimetrik evolvent profil dişililer, farklı eğrilik yarıçaplarında (R90-135-180-225) eğrisel evolvent profil olarak yeniden tasarlanmıştır. Yeni tip dıştan dişli pompa tasarımları geliştirilmiş, HAD analizleri gerçekleştirilmiş, doğrulama deneyleri yapılmış ve pompa elemanlarının imalatı gerçekleştirilmiştir. Ayrıca dişli çarkların imalatında kullanılan AISI 5140 malzemesi için farklı soğutma/yağlama koşulları altında işlenebilirlik deneyleri gerçekleştirilmiş ve işlenebilirlik metriklerinin iyileştirilmesi sağlanmıştır. Çalışma sonucunda R180 eğrilik yarıçapına sahip profil diş ile tasarlanan dişli pompanın, referans olarak kullanılan düz dişli pompaya göre hidrolik çalışma performansı (hacimsel verim, akış dalgalanması ve kavitasyon durumu) iyileştirilmiştir. Ayrıca işlenebilirlik deneyleri için endüstride yaygın olarak kullanılmayan sıvılaştırılmış azotun, soğutma/yağlama koşullarında kullanılmasıyla AISI 5140 malzemesinin işlenebilirlik metriklerinde önemli gelişmeler sağlanmıştır.Today, external gear pumps are widely used in the industry due to their easy production, low production cost, easy integration into hydraulic systems, ability to operate at high pressures, transmitting fluids with high viscosity, and wide speed range. In addition, the noise level of the pump, the formation of cavitation caused by the sudden pressure drop at the pump inlet, the wear of the pump elements over time, as well as the reverse flow formation caused by the wear, have been a disadvantage for this type of pumps by reducing the pump performance and life. In order to eliminate such disadvantages, researchers have carried out many studies and these studies are still continuing. In this thesis, the use of curvilinear involute gears, whose efficiency has been proven by studies in the literature but not used for external gear pumps, were investigated. In this context, reference involute profile and asymmetrical involute profile gears were redesigned as curvilinear evolvent profiles with different radii of curvature (R90-135-180-225). New types of external gear pump designs were developed, CFD analysis were performed, validation experiments were carried out and pump components were manufactured. In addition, for the AISI 5140 material used in the manufacture of gears, machinability tests were carried out under different cooling/lubrication conditions and the machinability metrics were improved. As a result of the study, the gear pump designed with a profile tooth with a radius of curvature of R180, the hydraulic operating performance (volumetric efficiency, flow fluctuation and cavitation) was improved compared to the pump used as the reference gear pump with involute gear. In addition, significant improvements were achieved in the machinability metrics of AISI 5140 material by using liquid nitrogen, which is not widely used in the industry, for machinability tests under cooling/lubrication conditions
Investigation of microstructure and hardness properties of Cu matrix composite materials produced by powder metallurgy using CrC particle reinforcements at different ratios
No full textBu çalışmada, toz metalürjisi (T/M) yöntemikullanılarak farklı oranlarda CrC partikülleri, Cu matrisi içerisindekullanılarak Cu matrisli kompozit malzeme üretimi amaçlanmıştır. Bu amaçla SafCu tozu içerisine CrC partikülleri ağırlıkça %5, %10, %15 ve %20 olmak üzere farklı oranlardakatılmıştır. Hazırlanan karşımlar 450 MPa basınç altında şekillendirilmiştir.Şekillendirilen parçalar 950 0C’de 60 dakika boyuncasinterlenmiştir. Sinterleme işleminin başarısı yoğunluğun ve SEM görüntülerininincelenmesi ile değerlendirilmiştir. Üretilen kompozit malzemelerin mikroyapıve mekanik özellikleri incelenmiştir. Mikroskop incelemeleri taramalı elektronmikroskobu (SEM) kullanılarak yapılmıştır. Yapılan SEM incelenmesinde, eşeksenli tanelerden oluşan Cu matrisi içerisinde CrC fazının dengeli dağıldığıgözlenmiştir. Yapılan sertlik ölçümlerinde, CrC oranı arttıkça buna bağlıolarak sertliğin arttığı gözlenmiştir
Tribological aspects, optimization and analysis of Cu-B-CrC composites fabricated by powder metallurgy
No full textTribological 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 °C) were used. Taguchi’s L16 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 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °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
Evaluation of Mechanical and Tribological Aspect of Self-Lubricating Cu-6Gr Composites Reinforced with SiC–WC Hybrid Particles
No full textBecause 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 × 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
Machinability of different Cu-Gr composites in milling: Performance parameters prediction via machine learning models
No full textThe machinability of copper-graphite (Cu-Gr) composites has gained significant attention due to their unique thermal, electrical, and mechanical properties. This study experimentally investigates the machinability performances (such as surface roughness, flank wear, cutting temperature, and energy consumption) of Cu-Gr hybrid composite materials during milling. It predicts these parameters with machine learning models. The study aims to contribute to sustainable and optimized manufacturing processes by analyzing the effects of different cutting parameters and cooling/lubrication conditions on this performance. Furthermore, advanced artificial intelligence-based models predict machining outcomes, providing a robust framework for process enhancement and industrial implementation. Although there are comprehensive studies on the machining performances of metal matrix composites in the literature, there is limited information on Cu-Gr composites' mechanical and thermal behaviors in milling processes. To address this deficiency, a full factorial experimental plan was applied on six different Cu-Gr composites and the effects of different cutting speeds, feed rates and cooling/ lubrication environments (Dry, MQL, cryogenic LN2) on flank wear, surface roughness, cutting temperature and energy consumption were analyzed. The materials used in the study were prepared by mixing graphite and hard phases (Al2O3 and Cr3C2) in specific proportions, and these composites were compared in terms of machinability. Afterward, the output parameters of the experimental results are predicted by employing the well-known machine learning models and the experimental results. The results manifested that Gradient-Boosted Decision Tree Regression performs better than the other ten machine learning models in predicting machinability parameters. Finally, this study highlights potential areas for future research and provides a practical guide for optimizing CuGr composites in manufacturing processes and achieving sustainability goals. It has engineering value in efficiency, cost reduction, and developing environmentally friendly applications, especially for the automotive, aerospace, and energy sectors
Investigation of the Effects of Cooling and Lubricating Strategies on Tribological Characteristics in Machining of Hybrid Composites
No full textEngineering materials are expected to contain physical and mechanical properties to meet the requirements and to improve the functionality according to their application area. In this direction, hybrid composites stand as an excellent option to fulfill these requests thanks to their production procedure. Despite the powder metallurgy method that allows for manufacturing products with high accuracy, machining operations are still required to obtain a final product. On the other hand, such materials are characterized with uncertainties in the structure and extremely hard reinforcement particles that aggravate the machinability. One of the prominent solutions for better machinability of composites is to use evolutionary cooling and lubricating strategies. This study focuses on the determination of tribological behavior of Cu-based, B-Ti-SiCP reinforced, about 5% wt. hybrid composites under milling of several environments, such as dry, minimum quantity lubrication (MQL)-assisted and cryogenic LN2-assisted. Comprehensive evaluation was carried out by considering tool wear, temperature, energy, surface roughness, surface texture and chips morphology as the machinability characteristics. The findings of this experimental research showed that cryogenic cooling improves the tribological conditions by reducing the cutting temperatures, flank wear tendency and required cutting energy. On the other hand, MQL based lubricating strategy provided the best tool wear index and surface characteristics, i.e., surface roughness and surface topography, which is related to spectacular ability in developing the friction conditions in the deformation zones. Therefore, this paper offers a novel milling strategy for Cu-based hybrid composites with the help of environmentally-friendly techniques
Numerical Study on the Effect of Different Types of Impeller Blades in Centrifugal Heart Assist Pump
No full textBu çalışmada, kalp yetmezliği hastalıklarında tedaviye destek amaçlı olarak kullanılan santrifüj kalp destek pompaları için farklı çark kanat geometrilerinin pompa performansına olan etkisi sayısal olarak incelenmiştir. Pompa tasarım parametreleri olarak, yetişkin bir insan kalbinin çalışma parametreleri baz alınmıştır. Bu parametreler ışığında pompa tasarımı yapılmış ve CFD (Computational Fluid Dynamics) yazılımı aracılığıyla 3 farklı çark kanat tipi için (radyal, eğik ve eğri) dört farklı debide (3, 4, 5 ve 6 l/dk.) ve üç farklı dönme hızında (3500, 3850 ve 4250 dev/dk.) pompa performansları tespit edilerek pompa performans eğrileri oluşturulmuştur. Elde edilen bulgulara göre tasarım noktası parametrelerine, eğri çark tipinde ve 3850 dev/dk. dönme hızında ulaşılmıştır. Bu noktada pompa hidrolik verimi ise %34 olarak tespit edilmiştir. En yüksek basınç farkı yaklaşık 180 mm-Hg ve 2 l/dk. debide elde edilmiştir. Ayrıca bu çalışmada parametrelerin ve çark kanat tiplerinin kan hasarına (hemoliz) olan etkilerini inceleyebilmek için cidar kayma gerilmeleri de tespit edilmiştir.In this study, the effect of different impeller blade types on pump performance for centrifugal heart support pumps used to support treatment in heart failure diseases was investigated numerically. The pump design parameters were based on the operating parameters of an adult human heart (flow rate of 5 l/min and a pressure load of 100 mm-Hg). By considering these parameters, pump design has been made and by means of CFD (Computational Fluid Dynamics) software for 3 different impeller blade types (radial, straight and curved) at four different flow rates (3, 4, 5 and 6 l / min) and three different rotational speeds (3500, 3850 and 4250 rpm) pump performance curves were determined. According to the findings, the design point parameters were reached at the curved impeller blade type and 3850 rpm. At this point, the hydraulic efficiency of the pump was determined as 34%. The highest pressure difference was obtained at approximately 180 mm-Hg and 2 l/min. In addition, in this study, wall shear stresses were determined in order to investigate the effects of parameters and impeller blade types on blood damage (hemolysis)
Evaluation of Machinability and Energy Consumption of CK45 Steel Using Synthetic-Based Nanofluid and Minimum Quantity Lubrication Cutting Fluid
No full textCK45 steel has various industrial uses due to its durability, wear resistance and strength. It is generally used in machinery, automotive industry, hydraulic cylinders, bearings, gears and similar applications. It is important to investigate the machinability properties of CK45 steel, which is frequently used in the manufacturing industry, in different cooling/lubrication environments. This study focused on the effects of a synthetic-based nanofluid cooling strategy and different cutting parameters during the milling of CK45 steel. Additionally, Taguchi analysis was performed to reduce the number of experiments and costs. Sustainable cooling/lubrication techniques were used during milling. A three-axis computer-controlled machine was used for the milling process. According to the findings, flank wear, surface roughness, and energy consumption were reduced by machining in the nanofluid environment. It was observed that Cu nanoparticles added into the nanofluid increased the machinability properties. Furthermore, statistical analysis was employed to ascertain the predominant control variables influencing the response parameters. Machinability efficiency can be increased by using nanoparticulate fluids as a coolant during milling. In addition, costs can be reduced by identifying the most effective factors in the experiment through statistical analysis
