Yazar "Kulekci, Mustafa Kemal" seçeneğine göre listele

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    Aluminum Forming by Vaporizing Foil Actuator Welding
    (2023) Önder, Ganime Tuğba; Kulekci, Mustafa Kemal
    Aluminum, has a wide range of uses, from industry to medical industrial products such as automotive, defense-aviation, and space. Aluminium has become a preferred material in applications where weight needs to be reduced. It is also used as a material in metal cladding and shaping applications. However, the high thermal conductivity coefficient of aluminum may cause some difficulties in the production process. These difficulties due to thermal conductivity may not allow to manufacture of desired products. In this study formability of aluminum with vaporizing foil actuator welding (VFAW) has been investigated as an alternative process to the traditional and solid state welding processes. By using different voltage values and separation distance parameters, the effects of these parameters on the formability of aluminum and copper sheet metal pairs with VFAW were examined experimentally. Experimental data show that voltage value is an important parameter in the VFAW process where a DC capacitor is used. In the VFAW process, where a 375 V voltage value is used, it has been determined that welding occurs in processes performed with three different separation distances (0.4 mm- 0.9 mm -1.5 mm). It was determined that 0.4 mm and 0.9 mm separation distances were effective in joining Al/Cu metal sheets with 0.1 mm thickness.
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    Corrosion behavior of a dissimilar Inconel 625 superalloy and AISI 316L stainless steel weld
    (Walter De Gruyter Gmbh, 2025) Dokme, Fatih; Kulekci, Mustafa Kemal; Engin, Kaan Emre; Esme, Ugur
    Corrosion significantly impacts the welding of dissimilar components, leading to a decrease in the lifespan of products. The primary aim of this research is to examine the corrosion behavior of the weld region in dissimilar welding of Inconel 625 and AISI 316L plates with a thickness of 20 mm. The plates are weld together by using continuous current gas tungsten arc welding (CCGTA) and pulsed current gas tungsten arc welding (PCGTAW) methods. The process employs ERNiCr-3, TIG 316L, and a twisted combination of both filler metals (ERNiCr-3+TIG 316L). Specimens with dimensions of 12 mm x 20 mm x 42 mm are obtained by cutting the weld samples for corrosion tests. The divided parts are each submerged in a 100 ml pool of sulfuric acid and are maintained for a combined duration of 240 h. A weight loss investigation is undertaken, in addition to metallurgical characterizations of the specimens. Energy Dispersive Spectroscopy (EDS) in conjunction with Scanning Electron Microscopy (SEM) are utilized to conduct metallurgical investigations. It is observed that twisted filler metal and CCGTA welding method results in the highest amount of mass loss. The least corroded sample is obtained by using twisted filler metal combined with PCGTA welding method.
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    Effect of ultrasonic vibration on the process of wire drawing
    (Pamukkale Univ, 2019) Duman, Onur; Kulekci, Mustafa Kemal
    In this study, the effects of ultrasonic vibrations on the lubrication between die and wire and wire drawing force in wire drawing process were investigated. In the work done, the lubrication effect and the drawing force in the wire drawing process are compared comparatively by using the conventional wire drawing method and the ultrasonic effect Drawing force is measured with a dynamometer. In wire drawing process, evaluations were made by comparing macro images of wire surface in determining the effect of ultrasonic vibration on lubrication. The time-dependent force change graph obtained from the experimental studies was used to reveal the force differences between conventional wire drawing and ultrasonic vibrating wire drawing. At the end of the experiment a sample with reduced diameter was taken and the surface quality of the sample was examined under a microscope. According to the results of the tests ultrasonic vibratory wire drawing showed a reduction of force between 9% and 15% in drawing force according to tradition. According to the studies made on the microscope, the lubrication ability of the wire surface was increased by the ultrasonic effect. For this reason, it has been found that the wire surfaces drawn by ultrasonic vibration are smoother.
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    Experimental Investigation of Stretchability and Bendability Characterization of AISI 1020 Steel
    (2019) Kahraman, Funda; Kulekci, Mustafa Kemal; Küçük, Mehmet
    In this study formability of AISI 1020 steel sheet with different thicknesses was investigated by limitingdome height test at room temperature. The influence of thickness on the stretchability, bendabilitycharacteristics and dome height for AISI 1020 steel sheets had been identified from experimental data.Increase in the thickness enhanced stretchability, bendability characteristics and dome height values.Results of experiments indicate that AISI 1020 steel sheets can be used to product components withmanufacturing processes based on bending and stretching.
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    Increasing Surface Coating Quality Using New Generation Current Waveforms
    (Ieee-Inst Electrical Electronics Engineers Inc, 2020) Muhurcu, Gulcin; Kulekci, Mustafa Kemal
    In this study, a novel current generator system was designed that can convert the basic signals used in engineering field into electrical current waves. The current generator system was realized by using Buck Converter and H-Bridge, which are Power Electronics circuit topologies. In order to produce the predicted current waveforms, the Artificial Neural Network (ANN), as a nonlinear control algorithm, has been adapted to the hybrid Power Electronics system. Then, Electrodeposition based coating experiments were carried out using the new generation current generator system. Copper (Cu) was used as a cathode and Nickel (Ni) as an anode in the coating process. Coating experiments were carried out for constant maximum current (Imax) conditions. The experiments were repeated with 3 different frequencies for each coating current wave. After coating, the surface morphology and sharp edge coating success of the covered areas were examined and the results were discussed by comparing to the DC's, PC's and PRC's.
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    INVESTIGATION OF MECHANICAL AND METALLOGRAPHIC PROPERTIES OF TWO DIFFERENT ALUMINUM ALLOYS JOINED WITH FRICTION STIR WELDING METHOD USING DIFFERENT WELDING PARAMETERS
    (Yildiz Technical Univ, 2020) Ocalir, Seref; Esme, Ugur; Boga, Cem; Kulekci, Mustafa Kemal
    In this study two aluminum alloy materials of EN AW-5083-H111 and EN AW-6082-T651 were joined with Friction Stir Welding considering the parameters as the tool shoulder diameter, spindle speed and feed rate. The mechanical properties of the weld joints such as yield strength, tensile strength and micro-hardness and metallographic properties were investigated comparatively with the use of these welding parameters. The yield strength of the weld joints were determined to be between 136-217 MPa while the tensile strengths were between 159-230 MPa and the percent elongations were between 2.28-5.44 %. The hardness values measured in weld areas were higher in the EN AW-6082 base metal side compared with EN AW-5083 base metal side.
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    Investigation of Milling Process Parameters for the Optimization of Surface Roughness of EN AW 5754 (AlMg3) Aluminum Alloy
    (Çukurova Üniversitesi, 2017) Kulekci, Mustafa Kemal; Eşme, Uğur; Ekşi, Abdul Kadir; Koçoğlu, Zülfü; Yılmaz, Necip Fazıl
    In this study, the effects of milling process parameters; such as feed rate, revolution per minute, chip thickness and radius of cutting tool on surface roughness experimentally investigated. Experiments performed using the parameters in the range of 1330-1500 rpm rotating speed, 97-196 mm/min feed rate, 1-2mm radius cutting tool tip, 1-1,5mm chip thickness. Diesel fuel was used as a lubricant oprevent adhesion of the chip to the machined surface. Optimum surface roughness results were obtained with increasing the radius of cutting tool. The results of the study reveal that cutting parameter optimization is needed to obtain required surface roughness.
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    Microstructural and Mechanical Characterization of Dissimilar Metal Welding of Inconel 625 and AISI 316L
    (Mdpi, 2018) Dokme, Fatih; Kulekci, Mustafa Kemal; Esme, Ugur
    This study investigated the microstructure of the dissimilar metal welding of Inconel 625 and AISI 316L using Continuous Current Gas Tungsten Arc Welding (CCGTAW) and Pulsed Current Gas Tungsten Arc Welding (PCGTAW) processes with ERNiCr-3, TIG 316L and twisted (ERNiCr-3 and TIG 316L) fillers. Microstructure examinations were carried out using an optical microscope and Scanning Electron Microscopy (SEM)/Energy Dispersive X-Ray (EDAX). The results of the study showed the existence of a partially melted zone (PMZ) on the AISI 316L side. Weld zone (WZ) analysis showed the existence of a multi-directional grain growth on the 316L side in all specimens, although less growth was found on the Inconel 625 side. Grain growth almost disappeared using PCGTAW with twisted fillers. SEM/EDAX investigations indicated that secondary deleterious secondary phases were tiny and white in five experiments. However, a meager amount of precipitates occurred in PCGTA welding with twisted fillers. Moreover, these were particularly innocent precipitates, represented by black dots in images, whereas other tiny white secondary phases are known to be brittle. As a result, PCGTA welding with twisted fillers exhibited the best metallurgical properties.
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    Multi Response Optimization of Friction Stir Spot Welding Process
    (2021) Er, Onur; Kulekci, Mustafa Kemal; Esme, Ugur; Boğa, Cem
    Friction stir spot welding (FSSW) is a solid state welding method mainly used to join non-ferrous metalsand their alloys. When opposed to other welding processes, FSSW has the benefits of being pollution-freeand having no filler material. In this study an attempt was made for multi response optimization offriction stir spot welded EN AW 5005 aluminum alloy using Taguchi method and Grey relational analysis(GRA). Pin height (h, mm), tool rotation (S, rpm), and welding time (t, s) were used as input parameterswhile tensile shear strength (TSS, MPa) and joint efficiency (JE, %) were used as multi responseparameters. Therefore, Taguchi’s L8 orthogonal design matrix was used in order to plan the experiments.GRA was then applied to determine the optimum condition which gives the higher grey relational degree.Analysis of Variance method (ANOVA) was also carried out in order to show the most significantparameter. Finally, confirmation test was applied to confirm the results and determine the improvement ingrey relational grade throughout this method. The best results were obtained with parameters such as2.6 mm pin height, 1500 rpm tool rotation and 10 s welding time with 122.16 MPa TSS and 111.05 JE. Asignificant improvement of 0.310 was obtained in the optimal parameter in grey relation grade.
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    Optimization of Friction Stir Welded Dissimilar Aluminum Alloys EN AW-5083-H111 and EN AW-6082-T651 using Hybrid Taguchi-Based Grey Relation Analysis
    (2022) Esme, Ugur; Öcalır, Şeref; Kulekci, Mustafa Kemal
    Friction Stir Welding (FSW) which is a kind of solid state welding process used essentially for joining nonferrous metals and their alloys. Involving pollution free and no filler material are the advantages of FSW when compared to other welding methods. The present work was focused on the multi objective optimization of friction stir welded EN AW-6082-T651 and EN AW-5083-H111 aluminum alloys using Taguchi based Grey relational analysis (GRA) method under different parameters of shoulder diameter (SD, mm), tool rotation (TR, rpm) and welding speed (WS, mm/min) on tensile strength (TS, MPa), percent elongation (E, %) and joint efficiency (JE). Taguchi related experiments were performed using L27 Orthogonal Array. The grey relational analysis which relates between the FSW parameters and the responses applied to find the optimum condition. Additionally, the Analysis of Variance (ANOVA) approach was used to identify the most important factor and its impact on the multiple response. The results of the obtained tests were then verified using the confirmation test.
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    The Mediating Role of Mushroom Management Within the Impact of Job Stress on Intention to Leave
    (2020) Kulekci, Mustafa Kemal; Ozbozkurt, Onur Başar; Bahar, Emel
    Purpose – Mushroom management style which refers to being kept of the employees in the dark likemushroom cultivation and given them inadequate information to increase their performance, hasbeen considerably drawn attention as a rising metaphor in the few years for management science.Since there are limited mushroom management studies and none of them quantitatively beinginvestigated, the present study aims at being fulfilled the research gap via exploring the mediatingrole played by mushroom management style within the impact of job stress on intention to leavewhich have a great impact on the management of organizations.Design/methodology/approach – Based on the purpose, the focus of this paper is on the privatehealthcare sector due to the centralized and hierarchical structure, and being intensely exposed tojob stress. From this point of view, the questionnaire has been applied to 221 employees working atthe four private hospitals and the data obtained from the questionnaire has been analyzed via “SPSS22.0”.Findings – As a result of the analysis, it has been indicated that the job stress has a significant effecton intention to leave; the mushroom management has a statistically significant effect on both jobstress and intention to leave, and the mushroom management has a mediating role on within theimpact of job stress on intention to leave.Discussion – It has been recommended that managers should pay more attention to encouragingeffective and operative communication throughout the organization and regularly share moreinformation with the employee since they have a significant role in achieving organizational goals;namely, effectiveness.
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    Vaporizing Foil Actuator Welding Arc Problems and Precautions
    (2024) Önder, Ganime Tuğba; Kulekci, Mustafa Kemal
    The management of the \"arc\" has an important place in welding methods made with electric discharge and in cases where the arc is not managed correctly, important technical and environmental problems may occur. Vaporizing foil actuator welding (VFAW) is a novel welding method developed particularly for joining metals and operates on the principle of electrical discharge. This study describes the welding prototype of vaporized foil actuator welding and outlines technical changes made during the increase in energy levels. The locations, causes, preventive interventions, and solution proposals for arc problems occurring during the welding process are addressed. Welding operations must be carried out safely and comprehensively. Alongside the welding method, potential safety issues should be identified. Necessary precautions must be taken before, during, and after welding. The safety of the welding method can be ensured by eliminating specific risks.
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    Vaporizing foil actuator welding prototype manufacturing
    (Gazi Univ, Fac Engineering Architecture, 2025) Onder, Ganime Tugba; Kulekci, Mustafa Kemal
    Providing new materials with superior properties and discovering usable industrial techniques for thesematerials has always been a noteworthy issue for manufacturing technologies. In addition, design andmanufacturing conditions of existing materials need to be constantly improved. Vaporizing foil actuatorwelding (VFAW) is a welding method developed for joining dissimilar metals, which is an important issue,especially in industrial and academic fields. In this study, a welding prototype was created and tested in orderto improve the applicability of VFAW, which has been introduced to the manufacturing field as a newwelding technique, under laboratory conditions. The process of making VFAW using direct current (DC)capacitors has been explained. The study has shown that making VFAW using DC capacitors is possible.
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    Vaporizing foil actuator welding prototype manufacturing and applications risk analysis
    (2023) Önder, Ganime Tuğba; Kulekci, Mustafa Kemal
    This study was conducted to examine risk levels for Vaporizing Foil Actuator Welding (VFAW) prototype manufacturing and applications. A risk analysis was carried out by using the L-type matrix method to detect hazards and risks in newly developing VFAW applications. 60 risks were identified for VFAW, 37 of which were high and 23 were moderate. To reduce the risk and occupational accidents to the lowest possible level; a measuring instrument that can continuously monitor current and voltage values, a remote detonation system and a discharge mechanism have been added to the prototype system. Thanks to the measures taken the situations that may result in serious accidents, fire, explosion, loss of limb, and even death that may occur during the experiment have been brought under control and VFAW applications have been made safer.