Çoğun, Can
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Prof. Dr.
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cogun@cankaya.edu.tr
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Mekatronik Mühendisliği
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24
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36
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234
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24 results
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Now showing 1 - 10 of 24
Article Citation - Scopus: 6The comparison of performance of electrolytic cu and cube tool electrodes in electric discharge machining of ti6al4v alloy(TUBITAK, 2021) Urtekin, L.; Çoğun, Can; Bozkurt, F.; Özerkan, H.B.; Çoğun, C.; Uslan, İ.; 3837; Mekatronik MühendisliğiThe most crucial cost element of Electric Discharge Machining (EDM) is the production of tool electrode (shortly electrode). Copper, its alloys, and graphite are the most commonly used electrode materials. Selecting the proper electrode material with low production and material cost, high workpiece material removal rate (MRR) and low tool electrode wear rate (TWR) is key to reducing machining costs with EDM. In this study, the EDM performance of CuBe tool electrodes in the machining of Ti6Al4V alloy was experimentally investigated in comparison to electrolytic Cu (E-Cu) electrodes for different pulse time (ts) and discharge current (I) settings. An increase in MRR and a decrease in TWR and relative wear (RW=TWR/MRR) were observed in machining with CuBe electrodes. However, the high raw material cost of CuBe alloy is an essential drawback in widely using these electrodes in industrial applications. A new performance index formulation is introduced for EDM applications that factor in the production cost of the electrode and its life (i.e., RW). According to our results, the CuBe could be used advantageously as the electrode material at medium current settings. However, at low and high current settings, the low raw material cost of E-Cu makes it more favorable. © 2021, TUBITAK. All rights reserved.Article Citation - WoS: 17Citation - Scopus: 22Experimental Investigation on Wire Electric Discharge Machining of Biodegradable AZ91 Mg Alloy(Springer, 2021) Çoğun, Can; Urtekin, Levent; Ozerkan, Haci Bekir; Esen, Ziya; Cogun, Can; Genc, Asim; Esen, Ziya; Bozkurt, Fatih; 3837; 52373; Mekatronik Mühendisliği; Ortak Dersler BölümüThe AZ91 magnesium alloy, used commonly as a biodegradable material in biomedical applications, is generally formed by conventional casting method (CCM) and high-pressure die casting method (HPDCM). The AZ91 alloys exhibit poor machinability with conventional chip removal methods since they degrade at elevated temperatures. In this study, the wire electric discharge machining (WEDM) was presented as a candidate process to machine the AZ91 alloy since no cutting stresses and plastic deformations were applied by the cutting tool to the part causing elevated temperatures. In this context, the WEDM machinability of the AZ91 alloy samples produced by cold chamber HPDCM and CCM at different process parameters, was experimentally investigated. The machining performance outputs (the machining current (I), the machining rate (MR), the average surface roughness (R-a), and surface topography) were found for the varying process parameters [pulse time (t(s)), pulse-off time (t(off)), dielectric flushing pressure (P-d), and wire speed (V-w)]. The present study revealed that the I and the MR were significantly dependent on the density, the porosity, and the micro structure of the samples, and the HPDCM samples gave the higher MR and the smoother surface than that of the CCM.Article Citation - WoS: 12Citation - Scopus: 12ELECTROCHEMICAL SMALL DIAMETER DEEP HOLE DRILLING OF POWDER METAL STEEL(Univ Zagreb Fac Mechanical Engineering & Naval Architecture, 2020) Ozerkan, Haci Bekir; Çoğun, Can; Cogun, Can; 3837; Mekatronik MühendisliğiIn this study, a new hybrid electrochemical drilling (ECD) method is proposed. The method makes use of a tubular tool capable of rotating and an electrolyte flushing through the inner hole at the same time. The designed and manufactured small size ECD machine's most important features are the regulation of the tool feed rate via current feedback control and the use of a rotating tubular tool with internal electrolyte flushing. The powder metal (PM) FLN2 4405 steel was drilled by using a brass tubular tool with various combinations of machining parameters such as machining voltage, electrolyte concentration and flushing pressure, and tool rotation speed. The machining performance outputs, namely, material removal rate (MRR), average radial overcut (RADOC), conicity (CO) and hole geometries were calculated and compared in different machining conditions. The results have shown that the aforementioned variables had a direct impact on the machining performance outputs in ECD. In all experiments, MRR increased with an in increase in machining voltage, tool rotational speed, electrolyte concentration and flushing pressure. RADOC values decreased with the rotational speed of the tool. The present study shows that deep holes with precise geometries and dimensions can be drilled successfully by employing the proposed hybrid ECD method. The method is economical and environmentally friendly since it requires low machining current values (0.1 to 0.7A) and a small amount of non-hazardous halide salt solutions instead of acidic solutions throughout the drilling process.Conference Object Elektrolitik ve alaşım bakır elektrotların elektro-erozyon ile işleme performansına etkisi(2014) Çoğun, Can; Şimşek, Ülke; 3837; Mekatronik MühendisliğiElektro erozyon ile işlemenin (EEİ) en önemli maliyet unsuru elektrotun üretilmesidir. EEİ’de en yaygın kullanılan elektrot malzemeleri bakır ve alaşımlarıdır. Maliyeti arttırmadan EEİ yapmanın yolu, hammadde maliyeti düşük, işlemesi kolay ve elektriksel aşınma direnci yüksek bakır alaşımlarını tespit etmektir. Bu çalışmada, EEİ’de elektrot olarak kullanılan elektrolitik bakır, CuCr1Zr ve CuCo2Be bakır alaşımları için işleme hızı, elektrot aşınma hızı, bağıl aşınma ve işparçası yüzey pürüzlülüğü gibi performans çıktıları deneysel olarak incelenmiştir. Ayrıca, CuCr1Zr alaşımına uygulanan yaşlandırma işlemi sonrası artan elektriksel iletkenliğin EEİ performans çıktılarına etkileri incelenmiştir. Performans çıktılarının alaşım türünden ve uygulanan yaşlandırma işleminden etkilendiği görülmüştür.Conference Object Citation - WoS: 20Citation - Scopus: 21Effect of electrical discharge machining on dental Y-TZP ceramic-resin bonding(Elsevier Ireland Ltd, 2017) Çoğun, Can; Rona, Nergiz; Yenisey, Murat; Esen, Ziya; Kucukturk, Gokhan; Gurun, Hakan; Cogun, Can; Esen, Ziya; 3837; 52373; Mekatronik Mühendisliği; Ortak Dersler BölümüPurpose: The study determined (i) the effects of electrical discharge machining (EDM) on the shear-bond strength (SBS) of the bond between luting resin and zirconia ceramic and (ii) zirconia ceramic's flexural strength with the three-point bending (TPB) test. Methods: Sixty 4.8 mm x 4.8 mm x 3.2 mm zirconia specimens were fabricated and divided into four groups (n = 15): SBG: sandblasted + silane, TSCG: tribochemical silica coated + silane, LTG: Er:YAG laser treated + silane, EDMG: EDM + silane. The specimens were then bonded to a composite block with a dual-cure resin cement and thermal cycled (6000 times) prior to SBS testing. The SBS tests were performed in a universal testing machine. The SBS values were statistically analyzed using ANOVA and Tukey's test. To determine flexural strength, sixty zirconia specimens were prepared and assigned to the same groups (n = 15) mentioned earlier. After surface treatment TPB tests were performed in a universal testing machine (ISO 6872). The flexural strength values were statistically analyzed using ANOVA and Tukey's test (a = 0.05). Results: The bond strengths for the four test groups (mean SD; MPa) were as follows: SBG (Control), 12.73 +/- 3.41, TSCG, 14.99 +/- 3.14, LTG, 7.93 +/- 2.07, EDMG, 17.05 +/- 2.71. The bond strength of the EDMG was significantly higher than those of the SBG and LTG (p < 0.01). The average flexural strength values for the groups SBG (Control), TSCG, LTG and EDMG were 809.47, 800.47, 679.19 and 695.71 MPa, respectively (p > 0.05). Conclusions: The EDM process improved the SBS. In addition, there was no significant adverse effect of EDM on the flexural strength of zirconia. (C) 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 6Design and implementation of an electrode feed rate control system in the electrochemical drilling process(Springer Heidelberg, 2022) Ozerkan, Haci Bekir; Çoğun, Can; Cogun, Can; 3837; Mekatronik MühendisliğiThe interelectrode gap distance control is essential for preventing short circuit and spark discharge occurrences in the machining gap and ensuring a constant distance between the tool electrode (shortly electrode) and the workpiece throughout the electrochemical drilling (ECD) process. In this study, a gap distance control system was designed and implemented in the constructed ECD machine tool. The gap distance control strategy was based on the machining current's discrete measurement (in microsecond intervals) and changing the gap distance according to a set current value by feeding the electrode towards the workpiece or retracting it during the ECD process. The small diameter deep hole ECD experiments were conducted using 0.5 mm diameter side insulated tubular rotational electrodes with through-hole electrolyte flushing to drill Hadfield and AISI 1040 steels. The experimental results demonstrated the success of the developed control system in ECD operations yielding uniform hole geometries and smooth hole surfaces. The use of the control system eliminated the undesirable formations of spark discharges and short circuit pulses.Article Citation - WoS: 7Citation - Scopus: 9An experimental work on using conductive powder-filled polymer composite cast material as tool electrode in EDM(Springer London Ltd, 2014) Yaman, Kemal; Çoğun, Can; Cogun, Can; 3837; Mekatronik MühendisliğiThis paper introduces the composite tool electrodes made of electrical conductive powder-filled polyester resin matrix material, providing promise for the electrical discharge machining (EDM) process. The dendrite-shaped copper powder, graphite powder, and their mixture were used as conductive fillers. Six different types of composite electrodes, namely, plain copper-polyester, pressed copper-polyester, furnaced copper-polyester, plain copper-graphite-polyester, pressed copper-graphite-polyester, and furnaced copper-graphite-polyester were prepared. It is found experimentally that increasing v (f) improved workpiece material removal rate, tool wear rate, relative wear, and electrical conductivity of electrodes. The pressed copper-polyester electrodes were found to be promising in the ED finishing of workpieces at low machining current settings. The practical applicability of the proposed composite electrodes in the industry was also illustrated.Conference Object Elektro Erozyon İle İşlemede Döner Elektrot İle Delik Delmede Dielektrik Sıvısına Karıştırılan Tozların Ve Isıtmanın İşleme Performansına Etkisi(2013) Çoğun, Can; Çoğun, Can; Uslan, İbrahim; Urtekin, Levent; Özerkan, Hacı Bekir; 3837; Mekatronik MühendisliğiArticle Citation - WoS: 6Citation - Scopus: 6Thermo-fluid multi-physics modeling and experimental verification of volumetric workpiece material removal by a discharge pulse in electric discharge machining process(Iop Publishing Ltd, 2020) Erdem, Oguz; Çoğun, Can; Cogun, Can; Uslan, Ibrahim; Erbas, Murat; 3837; Mekatronik MühendisliğiThe volume of material removed from the workpiece by a pulse (V-v) in the electric discharge machining was quantitatively determined using a multi-physics simulation model in ANSYS CFX software. Electrical heating is used in the model to simulate the plasma channel formation by defining the boundary and time-controlled current density initial conditions. Time-dependent physical properties at plasma temperature were used to reflect the actual processing environment. The heat was transferred from the plasma channel to the workpiece by electrical heating from the electrode, and V(v)was calculated by means of the amount of heat transfer. The calculated V(v)values for AISI4140, Ti6Al4V and Inconel 718 workpieces were lower than the experimental results and the difference was observed to change between 38.3% and 46.9%.Article Citation - WoS: 7Citation - Scopus: 7Development and experimental investigation of electrochemical drilling method using rotary tube tool(Gazi Univ, Fac Engineering Architecture, 2013) Ozerkan, H. Bekir; Çoğun, Can; Cogun, Can; 132262; 3837; Mekatronik MühendisliğiIn this study, a new hybrid electrochemical drilling (ECD) method, based on electrochemical machining in nonconventional machining processes, was developed. In the developed method, tube tool makes rotary motion together with inner through hole flushing. A small scale prototype ECD machine has been designed and manufactured to test the developed method. One of the important features of the new system is the regulation of tool feed rate using current feedback control. The Hadfield (manganese) steel, whose strain hardening behavior makes it very difficult to machine with conventional methods, and AISI 1040 steel, whose machinability is fairly good, were drilled using the prototype machine and results were compared. Workpiece material removal rate increased with the increasing machining voltage, tool rotational speed, electrolyte concentration and flushing pressure in both types of steels. Average radial overcut values increased with the rotational speed of the tool. The AISI 1040 steel hole geometries were regular than that of Hadfield steel. Experimental results showed that deep holes can be drilled successfully with the proposed hybrid ECD method.
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