Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/2079
  Ultrasonic-assisted high-speed micro-milling of Ti6Al4V

  Mahmat, Aybars; Agar, Salih; Tosun, Nihat

  In this study, the effects of different cooling techniques and process parameters on the performance characteristics of ultrasonic and conventional micro-milling (1-micron fixed amplitude, 20 and 30 kHz frequencies) of Ti6Al4V alloy were experimentally investigated. The impact of independent factors on tool life, cutting force, surface topography, surface roughness and cutting temperature was determined in order to find out machinability characteristics in this paper. Machining operations were performed under 20,000, 40,000 and 60,000 rpm revolution speed. The cutting depth and feed rate of the machining were kept fixed at 0.02 mm and 0.66 mm/s, respectively. Uncoated carbide and TiSiN-coated carbide cutting tools were used in machining operations. Dry machining and two different minimum quantity of lubrication (MQL) methods were used as cooling methods. According to the results achieved in the existing study, the ultrasonic micro-milling improved the surface roughness, reduced cutting forces, cutting zone temperature, and cutting tool wear. It was also found that MQL methods among other methods used in the present study have a greater effect on performance characteristics. As the spindle speed increased, the workpiece surface roughness, cutting force and tool life decreased, while the cutting zone temperature increased.

  AtıfScopus4·WoS4·OpenAlex4

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/1375
  Investigation of Mechanical Properties of Jute and Tea Waste-Reinforced Epoxy Composite Material Produced by Vacuum Assisted Resin Infusion Molding

  Dogan, Akar; Mahmat, Aybars; Agar, Salih

  Recently, the production of materials obtained from plant sources has been increasing due to their environmentally friendly and sustainable sources. Natural fibers and waste materials offer a remarkable alternative in composite production due to their biodegradability, low cost and renewability. In this study, composite materials were produced using hybrid Jute and industrial tea waste-reinforced epoxy materials by vacuum assisted resin infusion molding. In this context, the reason for using natural and industrial resources such as jute fiber and tea waste is to contribute to both the improvement of mechanical properties and the reduction of environmental impacts. It was observed that tensile and flexural strength decreased as the amount of tea waste increased. Conversely, the energy absorbed during the quasi-static punch shear and Charpy impact tests increased, unlike the tensile and flexural strength. Approximately 50% decrease was observed in the tensile strength of the 60% tea waste reinforced material compared to the pure jute composite material. In Charpy impact and quasi-static punch shear tests, a 5% increase in the energy absorbed in the 60% tea waste reinforced composite materials was obtained.

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  AtıfScopus2·WoS1·OpenAlex1

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/1196
  Experimental comparison of conventional and ultrasonic-assisted high-speed drilling of glass fiber reinforced epoxy composites

  Ağar, Salih; Mahmat, Aybars; Doğan, Akar

  Glass fiber reinforced epoxy composites are favored in several industries, including automotive and aerospace, owing to their superior strength-to-weight ratio. Drilling is a prevalent machining procedure employed to add fasteners for laminate assembly. Nonetheless, drilling these composites presents significant challenges due to the abrasive characteristics of the reinforcement, necessitating an examination of machining performance. During the drilling of composites, cutting temperature, thrust force, and delamination damage are primary concerns. In recent years, high-speed ultrasonic drilling, an innovative machining technique designed to address these challenges, has garnered significant interest. This investigation involved high-speed ultrasonic drilling and conventional drilling of glass fiber reinforced epoxy material. In the studies, optimal conditions were studied by evaluating thrust force, cutting temperature, and delamination damage by varying speeds, feed rates, and frequencies. The thrust force was 11 N in the traditional approach at 40,000 rpm, but it was recorded at 9 N with the ultrasonic method. Moreover, with ultrasonic drilling, cutting temperatures decreased by over 25% relative to traditional drilling, attributable to the harmonic motion that dissipates heat in the drilling zone. Analysis of the drilling region revealed a notable enhancement in damage, particularly in delamination, with the application of ultrasonic drilling. The experimental results indicate that ultrasonic machining enhances machining performance.

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• MakaleAçık Erişim2024Scopus SJRQ3/r/munzur/1944
  Effects of vibration conditions on machinability of aisi 52100 bearing steel

  Agar, Salih; Tosun, Nihat; Mahmat, Aybars

  This study focused on determining the effects of the cooling condition in the conventional and ultrasonic-assisted turning of AISI 52100 steel. AISI 52100 steel has been widely used in the bearing, mold, and automotive industries because of its superior wear resistance and mechanical properties. However, its high wear resistance caused poor machinability in conventional machining methods. Low surface quality, rapid tool wear, high cutting temperature, and high cutting force are the main difficulties in the conventional machining of AISI 52100 steel. On the other hand, ultrasonic-assisted machining has become widely used in the past decades for the machining of materials that have low machinability in conventional methods. Conventional turning and ultrasonic-assisted turning were selected as machining methods. Ultrasonic-assisted turning experiments were conducted under 20 and 30 kHz vibration frequencies. Cubic Boron Nitride (CBN) cutting tools were used in machining experiments. In machining operations 50, 100, and 150 m/min cutting speeds were selected, and feed rate (0.1 mm/rev) and depth of cut (0.5 mm) were kept constant in experiments. Minimum quantity lubrication technique which used 1% Al2O3 nanoparticle additives cutting fluid and dry cooling methods were used. CBN insert was used as a cutting tool. The effects of cutting speed, cutting method, and cooling condition on surface quality, cutting force, cutting zone temperature, and cutting tool wear were studied experimentally. Analysis of Variance (ANOVA) was carried out to determine the significance of the effects of input variables on process outputs. As a result of this study, it is determined that combined UAT and nanoMQL have significant effects on the process outputs.

  AtıfScopus3·WoS3·OpenAlex3

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• MakaleAçık Erişim2023/r/munzur/6449
  AISI 52100 Rulman Çeliğinin Ultrasonik Tornalama Yöntemi ile Kesici Takım Ömrünün İncelenmesi

  Tosun, Nihat; Mahmat, Aybars; Ağar, Salih

  Bu çalışmada, AISI 52100 çeliğinin geleneksel ve ultrasonik tornalanmasında işlem parametrelerinin performans karakteristikleri üzerindeki etkileri yani AISI 52100 çeliğinin işlenebilirliği deneysel, sayısal ve istatistiksel olarak araştırıldı. Çalışmada, işlenebilirliğin tespit edilmesi amacıyla, bağımsız değişkenlerin takım ömrü üzerine olan etkileri belirlendi. Deneysel çalışmalar, 50, 100 ve 150 m/dak kesme hızları, 0.1 mm/devir sabit ilerleme ve 0.5 mm sabit talaş derinliği gibi işleme şartları altında, sementit karbür ve kübik bor nitrür (CBN) kesici takımlar kullanılarak yürütüldü. Ultrasonik tornalamada, kesici takıma iki farklı titreşim genliği (5 ve 10 µm) ve iki farklı titreşim frekansı (20 ve 30 kHz) uygulandı.

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• MakaleAçık Erişim2023Scopus SJRQ3/r/munzur/1875
  EFFECT of the COOLING with AIR and WATER VAPOR on MILLING PERFORMANCES

  Mahmat, Aybars; Tosun, Nihat; AǦar, Salih

  This study aims to investigate experimentally and analytically the effects of different machining parameters such as cooling methods and cutting tool materials on surface roughness and chip thickness ratio for milling of AA7075-T6 aluminum alloy. The carbide and high-speed steel (HSS) end mills were used as cutting tools and the conventional, vapor, and compressed air were used as cooling methods in the experiments. The experiment conditions for compressed air at the cutting zone were 6 bar pressure and 30 m/s speed flow rate. A mixture of boron oil and water (1/20 mixture ratio) was used as cutting fluid in conventional cooling. The study was carried out using three levels of feed rates (20, 40, 80 mm/min), rotational speeds (780, 1330, 2440 rpm), and a constant 2 mm deep cut. As a result of the experiments, the surface roughness values increased with the increasing levels of feed rate. Besides surface roughness values decreased with increasing levels of the rotational speed. In addition, a better surface quality was obtained in milling processes by using carbide cutting tools compared to HSS tools. It was concluded that the most important parameter affecting the surface roughness and chip thickness ratio is feed rate and the rotational speed, respectively. Better surface roughness and chip thickness ratio were obtained from the vapor processing than the conventional and compressed air.

  AtıfScopus2·WoS1

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• MakaleAçık Erişim2021Scopus SJRQ3/r/munzur/2837
  Ultrasonic assisted turning of AISI 52100 steel using nanoparticle-MQL method

  Aǧar, Salih; Tosun, Nihat

  High cutting force and high cutting tool-chip interface temperature occur during machining of high strength materials like AISI 52100 by using conventional turning method and this makes to the difficult machining operation. Besides, in conventional turning (CT) of these materials, which has high abrasion resistance and hardness properties, an additional process such as grinding is required to achieve the desired surface quality. Ultrasonic assisted turning (UAT) method has been widely used in the machining industry in recent years, as it exhibits better surface quality, lower cutting forces, and cutting temperature than the CT method. This paper focused on experimentally and statistically determining the effects of different cutting parameters and cooling conditions (dry and minimum quantity lubrication-MQL) on surface roughness, workpiece surface texture, tangential direction cutting force, and cutting tool-workpiece interface temperature in the machining of AISI 52100 material by using UAT and CT methods. The experimental results revealed that significant improvements determined in the cutting forces and the surface roughness occurred in UAT compared to CT in all the cooling conditions. However, the increasing cutting speeds caused to observe higher interface temperature values in dry turning by the UAT method. Variance Analysis (ANOVA) was carried out to determine the significance grade of independent variables on dependent variables. According to ANOVA results, while the cutting speed is the most important factor on the surface roughness and the cutting zone temperature, and the cooling method is the most important factor on the cutting force. The effects of turning methods on corresponding surface topography, including surface defects, were evaluated. It is determined that in the surface topography analysis, feed marks are the main texture of the workpiece in the CT method while micro-level indentations and protrusions occurred on the workpiece surface in the UAT method.

  AtıfScopus14·WoS12·OpenAlex14

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• MakaleAçık Erişim2020/r/munzur/6723
  Metalografik Mikroyapı İncelemelerinde Kullanılmak Üzere Çok İstasyonlu Numune Zımparalama ve Parlatma Makinesinin Tasarımı ve İmalatı

  Tosun, Nihat; Mahmat, Aybars; Ağar, Salih

  Teknolojinin sürekli değişip gelişmesiyle birlikte, birçok alanda yeni makine ve cihazlar insanlığın kullanımına sunulmaktadır. Bu çalışmada, metalografik incelemeler yapmak için, numune hazırlama aşamalarından biri olan ve tam otomatik olarak çalışacak bir numune zımparalama ve parlatma makinesinin tasarımı ve imalatı yapılmıştır. Bu amaçla, daha önceden imal edilmiş numune zımparalama ve parlatma makineleri incelenerek, bu makinelerde görülen eksiklik ve aksaklıklar dikkate alınarak, yeni bir tasarım gerçekleştirilmiştir. Yapılan tasarımda, makinenin otomatik olarak beş farklı istasyonda numuneyi zımpara üzerinde tutan basınç değeri ve zımparalama süresi ayarlanabilmektedir. Beş farklı istasyonda ve her istasyonda arzu edilen tane büyüklüğünde farklı zımparalar yerleştirilmek suretiyle istenilen kalitede numune yüzeyi elde edilecektir.

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