Namlu, Ramazan Hakkı
Loading...
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
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
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
13
Articles
8
Citation Count
37
Supervised Theses
2
13 results
Scholarly Output Search Results
Now showing 1 - 10 of 13
Article Citation Count: 6Cutting force prediction in ultrasonic-assisted milling of Ti-6Al-4V with different machining conditions using artificial neural network(Cambridge Univ Press, 2021) Namlu, Ramazan Hakkı; Turhan, Cihan; Turhan, Cihan; Kilic, S. Engin; Lotfısadıgh, Bahram; Kılıç, Sadık Engin; Energy Systems Engineering; Mechanical Engineering; Manufacturing EngineeringTi-6Al-4V alloy has superior material properties such as high strength-to-weight ratio, good corrosion resistance, and excellent fracture toughness. Therefore, it is widely used in aerospace, medical, and automotive industries where machining is an essential process for these industries. However, machining of Ti-6Al-4V is a material with extremely low machinability characteristics; thus, conventional machining methods are not appropriate to machine such materials. Ultrasonic-assisted machining (UAM) is a novel hybrid machining method which has numerous advantages over conventional machining processes. In addition, minimum quantity lubrication (MQL) is an alternative type of metal cutting fluid application that is being used instead of conventional lubrication in machining. One of the parameters which could be used to measure the performance of the machining process is the amount of cutting force. Nevertheless, there is a number of limited studies to compare the changes in cutting forces by using UAM and MQL together which are time-consuming and not cost-effective. Artificial neural network (ANN) is an alternative method that may eliminate the limitations mentioned above by estimating the outputs with the limited number of data. In this study, a model was developed and coded in Python programming environment in order to predict cutting forces using ANN. The results showed that experimental cutting forces were estimated with a successful prediction rate of 0.99 with mean absolute percentage error and mean squared error of 1.85% and 13.1, respectively. Moreover, considering too limited experimental data, ANN provided acceptable results in a cost- and time-effective way.Article Citation Count: 10An experimental investigation on the effects of combined application of ultrasonic assisted milling (UAM) and minimum quantity lubrication (MQL) on cutting forces and surface roughness of Ti-6AL-4V(Taylor & Francis inc, 2021) Namlu, Ramazan Hakkı; Kılıç, Sadık Engin; Kilic, Sadik Engin; Lotfısadıgh, Bahram; Mechanical Engineering; Manufacturing EngineeringTi-6Al-4V is widely used in aerospace, medical and defense industries where materials with superior characteristics are needed. However, Ti-6Al-4V is categorized as a difficult-to-cut material, and machining of this alloy is highly challenging. Ultrasonic Assisted Milling (UAM) is a quite recent method to facilitate the machining of difficult-to-cut materials. This method has numerous advantages over the Conventional Milling (CM) method, such as reduced cutting forces and increased surface quality. Besides, Minimum Quantity Lubrication (MQL) is an alternative cooling method to enhance the process efficiency with respect to conventional cooling methods. Cutting force and surface roughness are essential measures to evaluate the cutting performance of a machining process. However, the simultaneous effects of implementing MQL and ultrasonic vibrations in milling operations are not much researched yet. In this study, the combined effects of UAM and MQL on cutting forces and surface roughness during the machining of Ti-6AL-4V are investigated. Results show that the combination of MQL and UAM enhances the cutting forces in rough cutting operations and the surface roughness in both finish and rough cutting operations significantly compared to conventional processes. Consequently, it is concluded that simultaneous implementation of UAM and MQL enhances overall cutting performance in end-milling operation of Ti-6Al-4V.Master Thesis Ultrasonik destekli frezeleme işlemi kullanarak kesilmesi zor malzemelerin işlenebilirliğini artırmaya yönelik deneysel bir araştırma(2019) Namlu, Ramazan Hakkı; Lotfısadıgh, Bahram; Lotfısadıgh, Bahram; Kılıç, Sadık Engin; Mechanical Engineering; Manufacturing EngineeringTi-6Al-4V, yüksek mukavemet/ağırlık oranı, iyi korozyon direnci ve mükemmel kırılma tokluğu gibi eşsiz malzeme özelliklerine sahiptir. Bu nedenle, işlemenin önemli bir süreç olduğu havacılık, tıp ve otomotiv endüstrilerinde yaygın olarak. Bununla birlikte, Ti-6Al-4V'nin işlenmesi aşınma direnci ve düşük ısı iletkenliği nedeniyle oldukça zordur. Ultrasonik destekli işleme, talaşlı imalat uygulamalarında oldukça yeni bir methoddur ve azaltılmış kesme kuvvetleri, arttırılmış yüzey kalitesi ve azaltılmış takım aşınması gibi geleneksel işleme proseslerine göre sayısız avantaja sahiptir. Ek olarak, minimum miktar yağlama (MMY) işlem verimliliğindeki birçok iyileştirme nedeniyle, geleneksel soğutma sistemlerinin yerine kullanılan alternatif bir soğutma türüdür. Kesme kuvvetleri, bir işleme prosesinin kesme performansını ölçen en önemli çıktılardan biridir. İşleme için bir başka önemli çıktı, iş parçasının kalitesi üzerindeki doğrudan etkisi nedeniyle yüzey pürüzlülüğüdür Bununla birlikte, ultrasonik destekli işlemede kesme kuvvetleri ve yüzey pürüzlülüğündeki değişiklikleri minimum miktarda yağlama kullanımı ile karşılaştırmak için çok fazla çalışma yoktur.. Bu çalışmada, Ti-6AL-4V malzemesinin işlenmesi sırasında kesme kuvvetleri ve yüzey pürüzlülüğündeki değişiklikler, MMY kullanılarak Z ekseninde kesici takıma uygulanan ultrasonik titreşimler ile ultrasonik destekli frezeleme kullanılarak araştırılmıştır. Bunun literatürde ilk kez yapıldığı düşünülmektedir. Tezde yapılan deneysel çalışma, MMY soğutmalı ultrasonik destekli frezelemenin, kesme koşulları uygun şekilde seçilirse kesme kuvvetleri ve yüzey kalitesi açısından kesme performansını önemli ölçüde artırabildiğini göstermiştir.Conference Object Citation Count: 0Multi-axial ultrasonic vibration-assisted machining of Inconel 718 using Al2O3-CuO hybrid nanofluid MQL(Elsevier B.V., 2024) Namlu, Ramazan Hakkı; Lotfi,B.; Lotfi, Bahram; Mechanical Engineering; Department of Mechanical EngineeringInconel 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.Article Citation Count: 2Machining performance and sustainability analysis of Al2O3-CuO hybrid nanofluid MQL application for milling of Ti-6Al-4V(Taylor & Francis inc, 2024) Namlu, Ramazan Hakkı; Namlu, Ramazan Hakki; Lotfi, Bahram; Kılıç, Sadık Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing EngineeringMachining 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.Article Citation Count: 0Investigation of the Combined Effects of Ultrasonic Vibration-Assisted Machining and Minimum Quantity Lubrication on Al7075-T6(Hindawi Ltd, 2024) Namlu, Ramazan Hakkı; Cetin, Baris; Lotfi, Bahram; Kilic, S. Engin; Kılıç, Sadık Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing EngineeringThe 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.Conference Object Citation Count: 4Investigation of the effects of axial ultrasonic vibrations on chatter stability in milling with bull nose cutters(Elsevier B.V., 2023) Namlu, Ramazan Hakkı; Kiliç,Z.M.; Lorain,R.; Kiliç,S.E.; Mechanical EngineeringUltrasonic 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.Article Citation Count: 1Combined use of ultrasonic-assisted drilling and minimum quantity lubrication for drilling of NiTi shape memory alloy(Taylor & Francis inc, 2023) Namlu, Ramazan Hakkı; Lotfi, Bahram; Lotfi, Bahram; Yılmaz, Okan Deniz; Akar, Samet; Kılıç, Sadık Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing EngineeringThe 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.Article Citation Count: 2An experimental study on ultrasonic-assisted drilling of Inconel 718 under different cooling/lubrication conditions(Springer London Ltd, 2024) Namlu, Ramazan Hakkı; Tekaut, Hasan; Lotfi, Bahram; Ucak, Necati; Kılıç, Sadık Engin; Lotfi, Bahram; Kilic, S. Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing EngineeringUltrasonic-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.Article Citation Count: 1Enhancing machining efficiency of Ti-6Al-4V through multi-axial ultrasonic vibration-assisted machining and hybrid nanofluid minimum quantity lubrication(Elsevier Sci Ltd, 2024) Namlu, Ramazan Hakkı; Lotfi, Bahram; Lotfi, Bahram; Kılıç, Sadık Engin; Mechanical Engineering; Department of Mechanical Engineering; Manufacturing EngineeringTi-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.
