Namlu, Ramazan Hakkı
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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
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Namlu R.
N., Ramazan Hakki
N.,Ramazan Hakki
Namlu, Ramazan Hakkı
R., Namlu
Namlu,Ramazan Hakki
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
Main Affiliation
Mechanical Engineering
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Sustainable Development Goals
14
LIFE BELOW WATER
0
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2
ZERO HUNGER
0
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11
SUSTAINABLE CITIES AND COMMUNITIES
0
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1
NO POVERTY
0
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12
RESPONSIBLE CONSUMPTION AND PRODUCTION
3
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7
AFFORDABLE AND CLEAN ENERGY
0
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5
GENDER EQUALITY
0
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3
GOOD HEALTH AND WELL-BEING
2
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9
INDUSTRY, INNOVATION AND INFRASTRUCTURE
8
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13
CLIMATE ACTION
0
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6
CLEAN WATER AND SANITATION
0
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10
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0
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4
QUALITY EDUCATION
0
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15
LIFE ON LAND
1
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16
PEACE, JUSTICE AND STRONG INSTITUTIONS
0
Research Products
17
PARTNERSHIPS FOR THE GOALS
0
Research Products
8
DECENT WORK AND ECONOMIC GROWTH
0
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Documents
19
Citations
207
h-index
8
Documents
15
Citations
173
Scholarly Output
22
Articles
13
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14/0
Supervised MSc Theses
2
Supervised PhD Theses
1
WoS Citation Count
172
Scopus Citation Count
206
WoS h-index
7
Scopus h-index
8
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0
Projects
1
WoS Citations per Publication
7.82
Scopus Citations per Publication
9.36
Open Access Source
6
Supervised Theses
3
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| Journal | Count |
|---|---|
| Procedia CIRP | 4 |
| Machining Science and Technology | 3 |
| Cirp Annals-Manufacturing Technology | 1 |
| International Journal of Advanced Manufacturing Technology | 1 |
| International Journal of Machining and Machinability of Materials | 1 |
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22 results
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Now showing 1 - 10 of 22
Conference Object Citation - WoS: 5Citation - Scopus: 6Investigation of the Effects of Axial Ultrasonic Vibrations on Chatter Stability in Milling with Bull Nose Cutters(Elsevier Science BV, 2023) Namlu, Ramazan Hakki; Kilic, Zekai Murat; Lorain, Raphael; Kilic, Sadik EnginUltrasonic 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. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)Article Comparative Analysis of Vibration Axis Effects on Ultrasonic Vibration-Assisted Machining of Inconel 718(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Namlu, R.H.; Kilic, Z.M.Inconel 718 is widely utilized in critical engineering sectors, particularly aerospace, owing to its exceptional creep resistance, corrosion resistance, and retention of mechanical strength at elevated temperatures. However, its high hardness, low thermal conductivity, and strong work-hardening tendency make it extremely difficult to machine using conventional techniques. Ultrasonic Vibration-Assisted Machining (UVAM) has emerged as an effective strategy to overcome these limitations by superimposing high-frequency, low-amplitude vibrations onto the cutting process. Depending on the vibration direction, UVAM can significantly change chip formation, tool–workpiece interaction, and surface integrity. In this study, the influence of three UVAM modes—longitudinal (Z-UVAM), feed-directional (X-UVAM), and multi-axial (XZ-UVAM)—on the machining behavior of Inconel 718 was systematically investigated. The findings reveal that XZ-UVAM provides the most advantageous outcomes, primarily due to its intermittent cutting mechanism. Compared with Conventional Machining (CM), XZ-UVAM reduced cutting forces by up to 43% and areal surface roughness by 37%, while generating surfaces with more uniform topographies and smaller peak-to-valley variations. Furthermore, UVAM enhanced subsurface microhardness as a result of the surface hammering effect, which may improve fatigue performance. XZ-UVAM also effectively minimized burr formation, demonstrating its potential for high-quality, sustainable, and efficient machining of Inconel 718. © 2026 by the authors.Doctoral Thesis 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 EnginHavacılık 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.Conference Object Citation - WoS: 11Citation - Scopus: 12Multi-Axial Ultrasonic Vibration-Assisted Machining of Inconel 718 Using Al2O3-CuO Hybrid Nanofluid MQL(Elsevier Science BV, 2024) Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, Sadik EnginInconel 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. (c) 2024 The Authors. Published by Elsevier B.V.Conference Object Effect of Tool Cavity Conditions on Damping, Chatter Mitigation, and Surface Quality in Internally Cooled Milling Tools(Elsevier B.V., 2025) Namlu, R.H.; Dogan, H.; Ozsoy, M.Chatter is a critical factor limiting productivity and efficiency in machining processes. Cutting tools significantly impact chatter stability, as they often serve as the most flexible component. The influence of cutting tools on chatter varies depending on their design and cooling mechanisms. Internally cooled cutting tools, commonly used in industrial applications, have the potential to exhibit distinct damping characteristics due to the presence of internal cavities, differentiating them from conventional solid tools. This study explores the effects of internally cooled milling cutting comparing an empty cavity cutting tool with a tool filled with viscous fluid. The primary objective is to evaluate how these conditions influence the damping of the machining system and their subsequent impact on surface quality, a key outcome sensitive to chatter. Surface topography and roughness measurements were taken after the experiments to assess changes in surface quality. The findings offer valuable insights into the role of internal cooling and fluid properties in not only chatter but also vibration suppressions in milling operations, highlighting their potential to enhance machining performance. © 2025 The Author(s).Article Citation - WoS: 41Citation - Scopus: 41Enhancing 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. EnginTi-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.Conference Object Citation - WoS: 20Citation - Scopus: 26An Experimental Study on Surface Quality of Al6061-T6 in Ultrasonic Vibration-Assisted Milling with Minimum Quantity Lubrication(Elsevier Science BV, 2022) Namlu, Ramazan Hakki; Yilmaz, Okan Deniz; Lotfisadigh, Bahram; Kilic, S. EnginAl6061-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. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)Article 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.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.Article Enhancing Machining Efficiency and Sustainability of Ti-6Al-4V Through Minimum Quantity Lubrication With Ester-Based Oils(Taylor & Francis Ltd, 2025) Namlu, Ramazan Hakki; Kavut, Kuebra; Tom, Hanife GulenTi-6Al-4 V is known as difficult-to-cut due to its low thermal conductivity and high chemical reactivity. While cutting fluids aid lubrication and reduce friction, Conventional Cutting Fluids (CCF) have high consumption, limited efficiency gains and negative environmental and health effects. Therefore, there is an ongoing search for more sustainable alternatives to CCF that do not adversely affect machining performance. Minimum Quantity Lubrication (MQL), which delivers compressed air - oil aerosol, has emerged as a promising solution by drastically reducing fluid use and associated risks. Selecting the right MQL fluid is key to optimising machining performance. This study evaluates MQL fluids based on polyol and polymeric esters for Ti-6Al-4 V machining and compares their performance with CCF. Cutting forces, surface roughness and topography are examined. Results show that MQL reduces cutting forces up to 21.7% and surface roughness up to 57.6% compared to CCF, with more uniform surface topography. Among MQL oils, polymeric esters perform better than polyol esters, with a reduction in cutting force up to 14.6% and surface roughness up to 47.7%. High viscosity indexed polymeric esters showed the best overall performance due to their thermal stability. Moreover, according to the sustainability assessment analysis polymeric esters were identified as the most sustainable option.Article Citation - WoS: 7Citation - Scopus: 10Combined 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, SametThe 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.
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