Ramazan Hakkı Namlu

Namlu, Ramazan Hakkı

Name Variants

Ramazan Hakki, Namlu
Ramazan Hakkı Namlu
N., Ramazan Hakkı
Namlu,R.H.
R.H.Namlu
N.,Ramazan Hakkı
Namlu, Ramazan Hakki
Ramazan Hakkı, Namlu
R. H. Namlu
R.,Namlu
Namlu R.
N., Ramazan Hakki
N.,Ramazan Hakki
Namlu, Ramazan Hakkı
R., Namlu
Namlu,Ramazan Hakki

Job Title

Doktor Öğretim Üyesi

Email Address

ramazan.namlu@atilim.edu.tr

Scholarly Output

13

Articles

8

Citation Count

37

Supervised Theses

2 Scholarly Output Search Results

Now showing 1 - 10 of 13

Citation Count: 2
An Experimental Study on Ultrasonic-Assisted Drilling of Inconel 718 Under Different Cooling/Lubrication Conditions
(Springer London Ltd, 2024) Erturun, Omer Faruk; Tekaut, Hasan; Cicek, Adem; Ucak, Necati; Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, S. Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing Engineering
Ultrasonic-assisted drilling (UAD) is one of the efficient and innovative methods to improve the drillability of difficult-to-cut materials. In the present study, the UAD of Inconel 718 was investigated under different cooling and/or lubrication conditions. The drilling tests were carried out at a constant cutting speed (15 m/min) and a feed (0.045 mm/rev) using uncoated and TiAlN-coated solid carbide drills under dry, conventional cutting fluid (CCF), and minimum quantity lubrication (MQL) conditions. The applicability of UAD to drilling Inconel 718 was evaluated in terms of thrust force, surface roughness, roundness error, burr formation, subsurface microstructure and microhardness, tool wear, and chip morphology. The test results showed that, when compared to conventional drilling (CD), UAD reduced the thrust force and improved the hole quality, tool life, and surface integrity under all conditions. Good surface finish, lower roundness error, and minimum burr heights were achieved under CCF conditions. MQL drilling provided lower thrust forces, better tool performance, and good subsurface quality characteristics. In addition, the simultaneous application of CCF-UAD and MQD-UAD showed significantly better performance, especially when using the coated tool.
Havacılık Endüstrisinde Kullanılan Kesilmesi Zor Malzemeler Üzerinde Nanoakışkan Minimum Miktar Yağlama ile Çok Eksenli Ultrasonik Titreşi̇m Destekli Frezelemenin Etkileri Üzerine Bir İnceleme
(2023) Namlu, Ramazan Hakkı; Lotfi, Bahram; Kılıç, Sadık Engin; Mechanical Engineering; Department of Mechanical Engineering
Havacılık sektörü, modern dünyanın önde gelen endüstrilerinden biri olarak öne çıkmaktadır. Bu sektörde Ti-6Al-4V malzemesinin yaygın olarak kullanılması, mükemmel mukavemet-ağırlık oranına ve iyi korozyon direnci gibi özelliklerine sahip olmasından kaynaklanmaktadır. İşleme, malzemeyi nihai şekline dönüştürmek için havacılık sektöründe vazgeçilmez bir süreçtir. Bununla birlikte, Ti-6Al-4V'nin işlenebilirliği, Geleneksel İşleme (Gİ) kapsamında, düşük termal iletkenliği, kesici takımlara yapışma eğilimi ve talaş kaldırmayla ilgili zorluklarla karakterize edilmekte ve bundan dolayı genellikle 'işlenmesi zor' bir malzeme olarak adlandırılmaktadır. İşleme verimliliğini artırmak için, Ultrasonik Titreşim Destekli İşleme (UTDİ) umut vaat eden bir teknik olarak ortaya çıkmıştır. UTDİ, yüksek frekansta, düşük genlikli titreşimleri çeşitli kesme yönlüklerine entegre ederek verimliliği artırmayı amaçlayan hibrit bir işleme yaklaşımıdır. Hibrid işleme stratejileri ile beraber, Ti-6Al-4V'nin işleme performansını artırmak için başka bir yol da soğutma sistemlerini içermektedir. Bu sistemler, malzemenin düşük termal iletkenliğinden kaynaklanan kesme bölgesindeki ısı birikimini azaltmayı amaçlar. Ancak, Geleneksel Kesme Sıvıları'nın (GKS) kullanımı, sınırlı performans artışları ve çevresel ve mesleki sağlık riskleri nedeniyle alternatif tekniklerle değiştirilmektedir. Bu alternatifler arasında, Minimum Miktar Yağlama (MMY), kesme bölgesine yüksek basınçlı hava ile birlikte minimum miktarda yağın aerosol formunda verilmesini içeren bir yöntem olarak ortaya çıkmıştır. Aerosol form, GKS'ye kıyasla kesici takım ile iş parçası arasına daha iyi penetre ederek verimliliğin artmasına katkıda bulunur. Ayrıca, MMY'nin avantajları, Nanoakışkan-MMY (NMMY) olarak bilinen nanoparçacıkların eklenmesi ile daha da artırılmaktadır. NMMY, MMY'de kullanılan yağa nanoparçacıkların entegre edilmesini içerir ve bunların termo-fiziksel özelliklerini kullanarak saf MMY'ye kıyasla üstün işleme verimliliği elde etmeyi amaçlar. Özellikle, en büyük gelişmeler, çeşitli nanoparçacık türlerini birleştiren Hibrid-NMMY (HNMMY) uygulamasıyla elde edilebilir. Bu tez, optimum konsantrasyonları ve uygulama metodolojilerini belirlemek amacıyla, değişik nanoparçacık konsantrasyonları ve bunlara karşılık gelen etkilerle karakterize edilen çeşitli nanoakışkanların kapsamlı bir incelemesini amaçlar. Daha sonra, tez, çok eksenli UTDİ ve NMMY yaklaşımlarının birleşik etkilerini araştırır. Mevcut literatüre göre, daha önce hiçbir araştırma, Ti-6Al-4V üzerinde kanal frezeleme operasyonlarında çok eksenli UTDİ ve NMMY/HNMMY uygulamalarını incelememiştir. Araştırma bulguları, çok eksenli UTDİ ve NMMY'nin birleşik kullanımının Ti-6Al-4V'nin işleme performansında önemli gelişmelere yol açtığını göstermektedir, bu da daha etkili ve sürdürülebilir bir uygulama sağlamaktadır.
Citation Count: 4
Investigation of the Effects of Axial Ultrasonic Vibrations on Chatter Stability in Milling With Bull Nose Cutters
(Elsevier B.V., 2023) Namlu,R.H.; Kiliç,Z.M.; Lorain,R.; Kiliç,S.E.; Mechanical Engineering
Ultrasonic vibrations-assisted machining has positive effects on the chatter stability and surface integrity of the process. Radial vibration-assisted milling is effective but it needs an advanced control of vibration trajectory hence is not easy to implement. The aim of this paper is to investigate the effects of axial ultrasonic vibrations on stability through disturbing the chip regeneration. A simple way of predicting the stability increase is proposed using missed-cut effect that reduces the effective number of teeth in cut. The axial vibrations are shown to introduce radial runout such that a regular cutter will show the characteristics of a serrated tool. For a 2-tooth bull nose cutter, the proposed method was verified by milling of Ti-6Al-4V material. The results showed that the axial ultrasonic vibrations increased limit axial depth of cut by more than 40%. Therefore, applying axial vibrations would be a simple solution to improve chatter resistance in machining difficult-to-cut materials while avoiding the cost and complexity of serrated rounded edges. The attention on using axial ultrasonic vibrations in milling is increasing, hence further research on modelling the machining dynamics combined with the velocity effects will be needed following this study. © 2023 Elsevier B.V.. All rights reserved.
Citation Count: 11
An Experimental Study on Surface Quality of Al6061-T6 in Ultrasonic Vibration-Assisted Milling With Minimum Quantity Lubrication
(Elsevier B.V., 2022) Namlu,R.H.; Yilmaz,O.D.; Lotfisadigh,B.; Kiliç,S.E.; Mechanical Engineering; Manufacturing Engineering
Al6061-T6 is frequently used in the automotive and aerospace industries, where milling is an essential process, due to its high strength-to-weight ratio. In order to achieve improved surface quality in milling, Ultrasonic Vibration-Assisted Milling (UVAM) has been introduced recently. Besides, Minimum Quantity Lubrication (MQL) is another advanced method to enhance the surface properties of the cutting by improving the coolant performance. However, the effects of simultaneous implementation of UVAM and MQL methods has not yet been studied sufficiently. This paper investigates the effects of applying UVAM in tandem with MQL in cutting of Al6061-T6. The results showed that surface quality enhanced with this combination. © 2022 The Authors.
Citation Count: 0
An Experimental Study of the Effects of Ultrasonic Cavitation-Assisted Machining on Ti-6al
(Inderscience Publishers, 2024) Koçak,B.; Canbaz,H.İ.; Zengin,N.N.; Mumcuoğlu,A.B.; Aydın,M.B.; Namlu,R.H.; Kılıç,S.E.; Mechanical Engineering; Manufacturing Engineering
Ti-6Al-4V has extensive applications in high-tech industries like aviation, defence and biomedical. However, the cutting of Ti-6Al-4V is challenging due to its poor machinability. Recently, ultrasonic cavitation-assisted machining (UCAM) has emerged as a cutting process that utilises high-frequency and low-amplitude vibrations to induce the formation of cavitation bubbles, thereby improving cutting performance. Despite the benefits of UCAM, there is lack of research investigating its application in Ti-6Al-4V. This study aims to investigate the efficacy of UCAM in improving the cutting performance of Ti-6Al-4V and compare it with conventional methods. Specifically, the study compares UCAM with conventional machining (CM) under conventional cutting fluid. The study reveals that UCAM can reduce cutting forces by up to 49.5% and surface roughness by up to 51.9%. Additionally, UCAM yields more uniform, homogeneous surfaces with reduced surface damage compared to CM. These results demonstrate the potential of UCAM for enhancing cutting performance of Ti-6Al-4V. Copyright © 2024 Inderscience Enterprises Ltd.
Citation Count: 0
Multi-Axial Ultrasonic Vibration-Assisted Machining of Inconel 718 Using Al2o3-Cuo Hybrid Nanofluid Mql
(Elsevier B.V., 2024) Namlu,R.H.; Lotfi,B.; Kiliç,S.E.; Mechanical Engineering; Department of Mechanical Engineering
Inconel 718 is a widely used superalloy in the aerospace industry, owing to its exceptional creep and corrosion resistance, as well as its ability to retain strength at elevated temperatures. However, its machinability presents challenges due to its low thermal conductivity and high work hardening rate during conventional machining, resulting in inadequate surface quality. To address this issue, a recent technique known as Ultrasonic Vibration-Assisted Machining (UVAM) has emerged. UVAM involves applying high-frequency, low-amplitude vibrations to the cutting tool or workpiece. Additionally, Minimum Quantity Lubrication (MQL) has been considered as an alternative cooling technique to enhance machining performance. Optimizing the performance of UVAM can be achieved by employing various vibration axes. Additionally, the effectiveness of MQL can be enhanced through the utilization of nanofluids. This study investigates the combined application of multi-axis UVAM and Al2O3-CuO added Hybrid Nanofluid MQL (HNMQL) during the milling of Inconel 718. The evaluation parameters include surface roughness, topography, burr formations, and cutting forces. The results demonstrate that the simultaneous use of multi-axis UVAM and HNMQL significantly improves the machining performance of Inconel 718. This combination leads to better surface quality and overall process efficiency, offering promising prospects for the aerospace industry and other applications involving difficult-to-cut materials. © 2024 The Authors. Published by Elsevier B.V.
Citation Count: 1
Enhancing Machining Efficiency of Ti-6al Through Multi-Axial Ultrasonic Vibration-Assisted Machining and Hybrid Nanofluid Minimum Quantity Lubrication
(Elsevier Sci Ltd, 2024) Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, S. Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing Engineering
Ti-6Al-4V offers a balance of good strength with lightweight properties. Yet, Ti-6Al-4V poses machining challenges, including low thermal conductivity, chemical adhesion to cutting tools, and chip removal difficulties. To improve machining efficiency, Ultrasonic Vibration-Assisted Machining (UVAM) has emerged as a promising approach. UVAM has demonstrated reduced tool wear, cutting forces, and improved surface quality compared to Conventional Machining (CM). Additionally, Minimum Quantity Lubrication (MQL) methods offer sustainable coolant alternatives, with recent research focusing on Nanofluid-MQL (NMQL) and Hybrid Nanofluid-MQL (HNMQL) for enhanced performance. Although there exists a body of literature showcasing the promising effects of UVAM and MQL methods individually, comprehensive investigations into the synergistic effects of these methodologies remain limited. This study addresses these critical research gaps by conducting a systematic examination of combined application of multi-axial UVAM and HNMQL. Specifically, it delves into the comparison of different vibration directions within UVAM, evaluates the effectiveness of UVAM when combined with cutting fluids incorporating Al2O3 and CuO nanoparticles in NMQLs and HNMQLs, and contrasts these novel approaches with conventional machining methods. The study unfolds in three distinct stages. The first stage examines the ultrasonic cutting mechanism and its combined application with the MQL technique. In the second stage, the study investigates the physical properties of the cutting fluids, including contact angle and surface tension. The final stage encompasses slot milling operations, where an array of parameters such as cutting forces, surface roughness, surface topography, surface texture, and the occurrence of burr formations are rigorously analyzed. The results demonstrate that the combination of multi-axial UVAM with HNMQL yields substantial advantages over traditional machining methods. Notably, it leads to a remarkable reduction in cutting forces (up to 37.6 %) and surface roughness (up to 37.4 %). Additionally, this combination engenders the production of highly homogeneous and uniform surface textures, characterized by minimal surface defects and a significantly diminished occurrence of burr formations. These findings underscore the potential of multi-axial UVAM combined with HNMQL as a promising approach in enhancing the machining of Ti-6Al-4V, thus offering a pathway to enhance the efficiency and precision of aerospace component manufacturing processes.
Citation Count: 1
Combined Use of Ultrasonic-Assisted Drilling and Minimum Quantity Lubrication for Drilling of Niti Shape Memory Alloy
(Taylor & Francis inc, 2023) Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, S. Engin; Yilmaz, Okan Deniz; Akar, Samet; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing Engineering
The drilling of shape-memory alloys based on nickel-titanium (Nitinol) is challenging due to their unique properties, such as high strength, high hardness and strong work hardening, which results in excessive tool wear and damage to the material. In this study, an attempt has been made to characterize the drillability of Nitinol by investigating the process/cooling interaction. Four different combinations of process/cooling have been studied as conventional drilling with flood cooling (CD-Wet) and with minimum quantity lubrication (CD-MQL), ultrasonic-assisted drilling with flood cooling (UAD-Wet) and with MQL (UAD-MQL). The drill bit wear, drilling forces, chip morphology and drilled hole quality are used as the performance measures. The results show that UAD conditions result in lower feed forces than CD conditions, with a 31.2% reduction in wet and a 15.3% reduction in MQL on average. The lowest feed forces are observed in UAD-Wet conditions due to better coolant penetration in the cutting zone. The UAD-Wet yielded the lowest tool wear, while CD-MQL exhibited the most severe. UAD demonstrated a & SIM;50% lower tool wear in the wet condition than CD and a 38.7% in the MQL condition. UAD is shown to outperform the CD process in terms of drilled-hole accuracy.
Citation Count: 2
Machining Performance and Sustainability Analysis of Al₂o_{3< Hybrid Nanofluid Mql Application for Milling of Ti-6al}
(Taylor & Francis inc, 2024) Lotfi, Bahram; Namlu, Ramazan Hakki; Kilic, S. Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing Engineering
Machining of Ti-6Al-4V presents challenges due to its low thermal conductivity, and conventional cutting fluids (CCF) are inadequate in providing a productive and sustainable solution. This study aims to achieve more sustainable and productive machining of Ti-6Al-4V by utilizing Al2O3 and CuO-added Nanofluid Minimum Quantity Lubrication (NMQL) individually and in hybrid form with different concentrations. A comparison is made with pure-MQL, CCF and dry conditions. The study consists of three stages. In the first stage, the physical properties of the coolants, like contact angle and surface tension, are investigated. The second stage involves slot milling operations, and various outputs including cutting forces, surface roughness, surface topography, surface finish, and subsurface microhardness are analyzed. In the last stage, a sustainability analysis is conducted based on the Pugh Matrix Approach. The results indicate that Al2O3-NMQL exhibits lower contact angles and surface tensions compared to other conditions. Furthermore, HNMQL applications result in lower cutting forces (up to 46.5%), surface roughness (up to 61.2%), and microhardness (up to 6.6%), while yielding better surface finish and topography compared to CCF. The sustainability analysis demonstrates that HNMQL application is the most suitable option for achieving sustainable machining of Ti-6Al-4V.
Citation Count: 0
Investigation of the Combined Effects of Ultrasonic Vibration-Assisted Machining and Minimum Quantity Lubrication on Al7075-T6
(Hindawi Ltd, 2024) Namlu, Ramazan Hakki; Cetin, Baris; Lotfi, Bahram; Kilic, S. Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing Engineering
The aluminum alloy Al7075-T6 finds extensive application in the aviation and automotive industries, where machining plays a pivotal role. Emerging techniques such as Ultrasonic Vibration-Assisted Machining (UVAM) and Minimum Quantity Lubrication (MQL) hold promise for enhancing machining efficiency. In this study, the combined use of UVAM and MQL for slot milling of Al7075-T6 was investigated. The results demonstrate that UVAM reduced cutting forces by an average of 10.87% in MQL and 8.31% in Conventional Cutting Fluid (CCF) conditions when compared to Conventional Machining (CM). In addition, UVAM yielded significantly improved surface finishes, characterized by an average reduction in surface roughness of 41.86% in MQL and 32.11% in CCF conditions relative to CM. Furthermore, surfaces subjected to UVAM exhibited fewer instances of burn marks and tool-induced markings, reduced chip splashing, and more uniform surface integrity compared to those manufactured with CM. Lastly, chips generated through UVAM exhibited distinct characteristics, notably shorter length, curvier shape, and a distinctive half-turn morphology when compared with the irregular chips produced through CM. In conclusion, our findings underscore the potential of UVAM in synergy with MQL to augment the machining of Al7075-T6 alloy, thereby yielding superior-quality machined components with enhanced operational efficiency.