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    A Comparative Study on Friction Performance and Mechanical Properties of Printed PETG Materials With Different Patterns
    (Wiley, 2025) Aslan, Enes; Akincioglu, Gulsah; Sirin, Emine
    Investigating the mechanical and wear properties of widely used PETG (polyethylene terephthalate glycol) filaments is important to understanding the material's performance, reliability, and suitability in different application areas. This study performed tensile and wear tests on PETG samples produced with a 3D printer using four infill patterns (honeycomb, grid, triangular, and gyroid). The study aimed to investigate the effect of infill patterns on the tensile and wear properties of the samples. In the evaluations, friction coefficient, wear rate, SEM microscope images, hardness test, temperature measurement during tensile, diameter accuracy value, Young's modulus, and yield values were analyzed. The mechanical results present that the triangular pattern showed 133% higher mechanical strength compared to other patterns with the highest Young's modulus. As a result of the wear tests, horizontal patterns showed more homogeneous wear, while vertical patterns caused irregular wear by creating more brittle structures. It was found that dense patterns, such as honeycomb and grid, were more resistant to wear. The triangular pattern samples can be preferred for high strength and thermal stability, while gyroid and grid pattern samples can be used in the flexibility field. The results revealed that different infill patterns significantly affect the mechanical and tribological performances of the materials and that appropriate pattern selection can optimize performance in engineering applications.
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    Comprehensive analysis of cutting temperature, tool wear, surface integrity and tribological properties in sustainable milling of Ti6Al4V alloy: LN2, nanofluid and hybrid machining
    (Elsevier Sci Ltd, 2024) Sirin, Emine; Yildirim, Cagri Vakkas; Sirin, Senol; Kivak, Turgay; Sarikaya, Murat
    Despite being expensive and difficult to process, the Ti6Al4V alloy is a vital component for crucial industries. To improve its machinability and accomplish sustainable production, environmentally friendly cooling and lubricating agencies are used. Studies on the machinability of the alloy are still necessary because of its unique features and significance in vital industries like aerospace, defense, and medicine. Therefore, this investigation focuses on tool wear, temperature, and surface integrity for sustainable milling Ti6Al4V under various machining environments, i.e., dry, pure-MQL, LN2, 2 , hBN, CuO-doped nanofluids, and hybrid methods. The produced nanofluids' thermophysical and rheological characteristics were examined in the study's initial phase. Because of the results from the first stage, machining performance indicators were assessed in the subsequent milling experiments. As a result, CuO-doped nanofluids gave improved results in terms of viscosity and pH. The best results obtained in the LN2 2 + CuO hybrid cooling lubrication environment in important machinability outcomes such as tool wear and surface integrity were attributed to the rheological properties of CuO-doped nanofluid and its harmonious cooperation with LN2-cryogenic 2-cryogenic cooling.
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    The Effect of Environmentally Friendly Cooling Techniques in Hard Turning: Comparison of Nanofluid, Vortex, GQDs and Hybrid Cooling Methods
    (Springer Heidelberg, 2024) Ayhan, Muhammed Omer; Sirin, Emine; Yildirim, cagri Vakkas
    Conventional cutting fluids have negative impacts on the environment, worker health and production costs. Thus, both researchers and manufacturers are doing many studies to obtain alternative methods. The main purpose of these studies is to obtain alternative cooling conditions that are both sustainable and efficient. For this purpose, the current study investigates the effects of different cooling and lubrication techniques on machining performance during hard turning of AISI D3 cold work tool steel. Thus, 10 different conditions such as MQL, vortex tube, graphene-doped nanofluid (GPN), graphene quantum dots doped nanofluid (GQDs) and hybrid cooling conditions including their interaction were applied. The effects of these methods on machining outputs such as surface roughness, cutting temperature, power consumption, flank wear and tool wear characterization were analyzed. Thermal conductivity and pH values were measured to see the relationship between the effect of cutting fluids on machining efficiency and homogeneity/thermal conductivity. The results showed that the vortex + GPN/GQDs hybrid cooling technique gave the best results at all outputs. Compared to dry machining, vortex + GPN/GQDs provided decreases of 53.63%, 49.01%, 56.52% and 46.47% in average surface roughness, cutting temperature, energy consumption and flank wear, respectively.
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    Effects of mono/hybrid nanofluid strategies and surfactants on machining performance in the drilling of Hastelloy X
    (Elsevier Sci Ltd, 2021) Sirin, Emine; Kivak, Turgay; Yildirim, Cagri Vakkas
    This study examined the effects of dry, base fluid, mono and hybrid nanofluid cooling/lubrication conditions on machining performance in drilling of nickel based Hastelloy X superalloys. Nanofluids were prepared by adding 0.6 vol% graphene nanoplatelets (GNP) and/or hexagonal boron nitride (hBN) with or without addition of 0.25 wt% sodium dodecyl sulfate (SDS) and/or gum arabic (GA) as surfactants into the cutting lubricant. Drilling experiment were performed at two different cutting speeds (20 and 30 m/min), two different feed rates (0.04 and 0.06 mm/rev) and a constant drilling depth (13.5 mm). Cutting force, hole quality (surface roughness and de-viations in diameter, circularity and cylindricity), cutting temperature, burr height, tool wear and tool life were selected as the performance criteria. The best results with regard to cutting force, hole quality, burr height, and tool wear were obtained under SDS added hBN/GNP hybrid cutting, whereas the best results for cutting tem-perature were achieved under hBN/GNP hybrid cutting condition without surfactants. In terms of tool wear, after 10 holes under dry cutting, flank wear on the drill was measured as 0.281 mm, whereas after 60 holes under hBN/GNP-SDS cutting condition, it was measured as 0.135 mm. This indicated a 51.96% improvement in tool wear compared to dry cutting. Among the mono nanofluids, the hBN-SDS cutting condition delivered the best performance, whereas among the hybrid nanofluids, the hBN/GNP-SDS cutting performed the best. Finally, evaluation of the surfactants added to the nanofluids revealed that SDS surpassed GA in terms of machining performance.
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    Evaluation of tribological performance of MQL technique combined with LN2, CO2, N2 ecological cooling/lubrication techniques when turning of Hastelloy C22 superalloy
    (Elsevier Sci Ltd, 2023) Sirin, Emine
    Sustainability specifically addresses using ecological cooling/lubrication techniques in the manufacturing industry. Dry, MQL, CO2, LN2, N2, CO2 +MQL, LN2 +MQL, and N2 +MQL techniques were preferred for ecological cooling/lubrication. To determine the effects of cooling/lubrication techniques on machining performance, cutting speed (Vc 80 m/min), feedrate (f 0.12 mm/rev), and cutting depth (ap 0.5 mm) were taken as constants. Cutting tool wear and mechanisms, surface roughness and topography, cutting temperature, and vibration peak values are preferred as machining performance characteristics. At the end of the turning experiments performed with sustainable cooling/lubrication techniques: N2 +MQL hybrid cooling/lubrication technique performed better performance in cutting tool wear (0.226 mm), surface roughness (1.658 & mu;m), and vibration (48.017 m/ sec2), while LN2 cooling technique showed the best performance (87 degrees C) in cutting temperature. Compared to dry condition, the N2 +MQL hybrid cooling/lubrication technique reduced tool wear, surface roughness, and vibration by 73.50%, 53.9%, and 42.4%, respectively.
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    Experimental research on sustainable drilling of Hastelloy X superalloy: Impact of hBN, GNP, LN2 and hybrid eco-friendly cooling/ lubrication strategies
    (Elsevier Sci Ltd, 2024) Sirin, Emine; Yildirim, Cagri Vakkas; Kivak, Turgay; Sirin, Senol; Sarikaya, Murat
    In this study, the effect of sustainable cooling and lubrication strategies such as MQL, LN2, LN2 +MQL, LN2 +hBN/GA, LN2 +GNP/GA, LN2 +hBN-GNP/GA on drilling nickel-based Hastelloy X alloy was examined. The environmental impacts and health risks of traditional petroleum-based cutting fluids used in drilling operations have led researchers to look for ecological alternatives. In this context, combinations of nanofluids enriched with minimum quantity lubrication (MQL), liquid nitrogen (LN2), and nanosized hBN and GNP particles have been tested. The experiments were carried out at cutting speeds of 20 and 30 m/min and feed rates of 0.04 and 0.06 mm/rev. Nanofluids characteristics i.e., viscosity, Ph, thermal conductivity and wettability, and drilling performance were evaluated with criteria such as cutting force, surface roughness, hole quality and tool wear. The results obtained showed that the hybrid methods combining LN2 and nanofluid-based MQL provided superior performance in terms of both cooling and lubrication, and the condition directly positively affected the processing outputs. This study contributes to the literature by revealing the potential of ecological cooling/lubrication methods in the sustainable production of difficult-to-machine materials such as Hastelloy X.
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    An Investigation of Deep Wear Status Assessment of AISI 329 Material Under Green Nanofluid Conditions
    (Springer Heidelberg, 2025) Sirin, Emine; Uysal, Emrah; Khanna, Navneet; Sirin, Senol
    One of the main goals in sustainability is to reduce the environmental effects of boundary and mixed lubrication on rubbing surfaces. Petroleum-based fluids are at the center of environmental concerns and have attracted the attention of researchers in recent years. Vegetable-based oils are a good alternative to petroleum-based oils, and their tribological performance is a matter of curiosity. For the last 10 years, nanoparticle additives have been used to increase the tribological effect of plant-based oils. Green tribology is an integrated concept that includes the terms nanotribology and biotribology. In this study, nanofluid was prepared by adding SiO2 and TiO2 nanoparticles into the vegetable-based oil to examine green tribology performance. Friction/wear tests were applied to AISI 329 stainless steel material with a ball-on-disc tester. In the green tribology performance evaluation, pH, thermal conductivity, surface roughness, topography, microhardness deviations, coefficient of friction (CoF), track width, SEM analysis, and power consumption results were taken into consideration. As a result of the tests, the SiO2 nanofluid condition provided a reduction of 40.76%, 13.69%, 66.77%, 5.98% in surface roughness, microhardness, CoF, track width, and power consumption results, respectively, compared to the dry condition. In other words, the SiO2 green nanofluid condition exhibited superior performance compared to other conditions in all performance criteria.
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    Performance and wear analysis in machining of Co-based Haynes 25/L605 superalloy using sustainable cooling/lubrication agencies
    (Elsevier, 2025) Sarikaya, Murat; Yildirim, cagri Vakkas; Sirin, Senol; Kara, Muhammed Ikbal; Sirin, Emine; Kivak, Turgay; Krolczyk, Grzegorz M.
    The cobalt-based Haynes 25 superalloy is a key material in sectors such as aerospace, medical, and energy, known for its outstanding high-temperature strength, wear and corrosion resistance. However, its low thermal conductivity and rapid work hardening rate make it inherently difficult to machine, highlighting the need for new cooling and lubrication methods. This work investigates the machinability of Haynes 25 under various sustainable cooling and lubrication techniques, including dry conditions, minimum quantity lubrication (MQL), nanofluids, and cryogenic COQ. Additionally, hybrid systems combining cryogenic COQ with nanofluids are also being investigated. The effectiveness of these approaches was ascertained by thorough investigations of surface roughness, cutting temperature, tool wear, and its mechanisms, and power consumption. Experimental results show that hybrid cooling systems especially those including nanofluids and cryogenic COQ significantly improve machining performance. Compared to dry machining, these methods minimized tool wear by 38 % and achieved up to a 44 % reduction in cutting temperature and a 32 % reduction in power usage. These results were a result of the enhanced thermal and tribological characteristics of nanofluids along with COQ's fast cooling capacity. This work provides a route toward sustainable and high-performance manufacture of challenging-to-machine materials by highlighting the possibilities of hybrid cooling strategies to maximize machining efficiency, extend tool life, and lower environmental impact.