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Öğe The contribution of a state-owned enterprise to regional, industrial and agricultural production in Turkey: An example of ülfet stock company of food and soap industry(Mediterranean Center of Social and Educational Research, 2014) Oguz, A.; Karatas, A.R.; Olcay, T.; Günay, M.In the mixed economy which private and public enterprises are active in economic life, have their primary goal which is to maximize social prosperity. Public enterprises in Turkey were used to function as a means of economic improvement in parallel with the role of government in the 20th century. Public enterprises out of the aimed social prosperity, they have certain political aims of accomplishing resource allocation, fair income distribution and sustainable growth. These lead to some problems of public enterprises which have strengthened the privatization arguments especially through the end of 20th century. The aim of this study has to investigated (stay away from the controversial issue of privatization and the focus on) the activities of a public enterprise and its contribution to local and national economy. So we will focus on Ülfet Stock Company of Food and Soap Industry which was established in Gaziantep, in 1955 to produce olive oil, soap and glycerin and privatized in 2001. The establishing a public enterprise in this region has to increases a culture of industrialization and regional, agricultural production as well as added value. The result of this study has significant implications for public enterprise. Local governments and policy makers in their search of strategies for improving the roles of public and private enterprises in economy.Öğe An evaluation on machining processes for sustainable manufacturing(Gazi Universitesi, 2013) Günay, M.; Yücel, E.Sustainable manufacturing consists of environmental protection, profitability and societal benefit for all industrial areas. Manufacturing practices are investigated for optimize production efficiency while minimizing environmental impact and maintaining social equity. It can be achieved through changes in products, processes and systems related to the sustainability issues. In sustainable manufacturing process, the natural resources which are key elements of sustainability must be used prudently by academic, scientific, cultural and human organizations. In this context, sustainable machining can be defined as a process which has been performed of sustainable manufacturing by using alternative machining technologies such as cryogenic machining, high pressure jet assisted machining. Sustainable machining investigates the conflict and synergy between economical and environmental considerations as well as the effect of system boundaries in determining optimum machining conditions. This paper presents a general evaluation on the importance of sustainable machining technologies in obtaining sustainable manufacturing objectives.Öğe An experimental investigation of effect of cutting parameters on cutting zone temperature in drilling(2013) Yagmur, S.; Acir, A.; Seker, U.; Günay, M.Drilling is one of the most important machining processes in manufacturing industry. Recently, the work dealing with the problems encountered during drilling and their solution has been increased. Modelling of thermal and mechanical loads developed during drilling has also been increased. In this study, the drillability of AISI 1050 steel widely used in industrial applications will be investigated under various drilling types (hole type) cutting parameters (60, 75, 90 and 108 m/min cutting speed and 0.15, 0.20 and 0.25 mm/rev feed) and cutting tool type (uncoated and TiN/TiAl/TiCN coated solid carbide). Cutting temperatures developed along the drill rake face when drilling with coated and uncoated drill bits will be measured with the help of K type thermocouples inserted in the cooling channels of the drills. When the results of the experiments are evaluated, cutting temperature decreased with increasing feed and coating application significantly reduced cutting temperatures in the cutting zone. Coating application has provided significant benefits in the all parameters.Öğe Finite Element Analysis of Thrust Force in Drilling of Al2014 Aluminum Alloy(TUBITAK, 2019) Korkmaz, M.E.; Çakiroglu, R.; Yagar, N.; Özmen, R.; Günay, M.The purpose of this work is to compare the experimental and simulational results of the thrust force in drilling of the Al2014 aluminum alloy with the uncoated cemented carbide tool. In the experimental study, drilling was performed using cutting parameters (cutting speed and feed rate) at different levels. Numerical analyzes for thrust force were performed using the ThirdWave Advantages simulation program, which is based on the finite element method. With constant feed rates of 0,1, 0,2 and 0,3 mm / rev, the thrust force decreased by 9,1%, 12,8% and 18,6%, respectively, with the cutting speed increased by 35%. At constant cutting speeds of 170, 200 and 230, the thrust force increased by 23,9%, 16,1% and 11%, respectively, by increasing the feed rate from 0,1 to 0,3 mm / rev. It has been determined that the thrust force decreases with increasing the cutting speed and increases with the increasing feed rate. The results of drilling simulation performed by finite element method were similar to experimental results. As a result of the study, it was determined that there was an average difference of 7% between the experimentally measured thrust force and the force values obtained as a result of the simulation. Finally, the applicability of the finite element model was proved. © 2019, TUBITAK. All rights reserved.Öğe Investigation of the effects on screw thread of infeed angle during external threading(Gazi Universitesi, 2011) Günay, M.This paper presents the effects of the infeed angles in terms of the surface analysis and cutting force components on thread quality in the external threading operations. Threading operations were carried out on a CNC lathe by single-point cutting tools for 0°, 14.5°, 15°, 27.5° and 30° infeed angles at the constant cutting speed of 100 m/min. The main cutting force and the radial force were determined as significant force components in terms of energy consumption in threading processes. It was also determined that the microhardness increased toward the thread root from the thread crest throughout the flanks. According to experimental results and the surface analysis, it was found that the optimum infeed angle was 30° in external threading.Öğe An investigation on deformation behaviors of energy absorbers for passenger coaches(International University of Sarajevo, 2017) Özmen, R.; Günay, M.Thin-walled structures is used commonly as energy absorbers at the front and back of the coaches. These parts should be designed to minimize the damage to the vehicle and prevent the passengers from fatality and/or injury by absorbing the collision energy in railway transportation. In this paper, deformation behaviors of tube like structures with truncated cone under the axial impact load were investigated by means of finite element analysis (FEA). The energy absorbers having tube like structures were modelled at the same weight and have three different wall thickness and taper angle. As a result of FEA, the performances of straight and truncated cone type energy absorbers were compared in terms of energy absorption capacities and an optimization study was done to determine the effects of thickness and taper angle on energy absorbing performances of the members. The analysis of variance in 95% confidence level was applied in order to determine the effects of design parameters on total efficiency (TE). Besides, optimum design parameters for TE were determined by using Taguchi optimization methodology. Thickness was found as the most significant parameter on total efficiency with 60.52% percentage contribution ratio according to ANOVA results.Öğe Modelling and optimization of the surface roughness in high speed hard turning with coated and uncoated CBN insert(Gazi Universitesi, 2016) Yurtkuran, H.; Korkmaz, M.E.; Günay, M.This study focuses on predictive model for Ra and optimization of cutting conditions in high speed hard turning of X40CrMoV5-1 steel by CBN insert. Cutting speed, feed rate, depth of cut and coating condition have been considered as cutting parameters. The experiments have been performed in CNC lathe according to Taguchi L32 orthogonal array. The first order mathematical model for the Ra has been developed with multiple regression analysis. Optimization study with analysis of signal-to-noise (S/N) ratios has indicated that feed rate is the negatively most significant factor for Ra under dry cutting conditions. The best surface roughness has been achieved by the lower feed rate and uncoated CBN insert. © 2016, Gazi University Eti Mahallesi. All rights reserved.Öğe Optimization of honing parameters for renewal of cylinder liners(Gazi Universitesi, 2017) Günay, M.; Korkmaz, M.E.This study presented the optimization of honing parameters for surface roughness in plateau honing process used for renewal of engine cylinders. The honing experiments were performed based on Taguchi L9 orthogonal array. The honing parameters directly affected on surface roughness (Ra) were determined as linear speed (m/min), grain size and number of stroke with three different levels. These levels were adjusted by considering honing industry and investigations on honing process. The results of variance analysis showed that the most important factor on surface roughness is the grain size while number of stroke has insignificant effect. Finally, an optimization study has been performed with “the smaller the better” method and then confirmation experiment has been conducted. The results have shown that the optimum conditions for better surface roughness were determined as feed rate of 10 m/min, grain size of 220 and stroke number of 6 according to analysis of signal-to-noise (S/N) ratios under these cutting conditions. According to confirmation experiment, the difference between experiment and the calculated value was determined as 2.5%. Thus, the optimum levels of honing parameters for Ra were confirmed as confident in renewal of engine cylinders. © 2017, Gazi University Eti Mahallesi. All rights reserved.Öğe Optimization with taguchi method of cutting parameters and tool nose radius in machining of aisi 316l steel(2013) Günay, M.Surface quality and dimensional precision significantly affect to strength and performance of working machine parts that are contacted one another. Additionally, cutting tool geometry and cutting parameters are the most important factor affecting to cutting force, surface roughness and productivity in machining. In this paper, optimization of cutting parameters and tool nose radius (variables) was performed for which Fc and Ra are occurred in machining of AISI 316L austenitic stainless steel. For this purpose, the machinability experiments were carried out using Taguchi's L9 orthogonal array. An analysis of variance (ANOVA) was employed to determine the level of contribution and effects of variables on Fc and R a values measured during the machining experiments. Optimal values of variables which were obtained using the S/N ratios were found at different levels for Fc and Ra. According to the ANOVA results, the most significant variable affecting to cutting force and surface roughness values was determined as feed rate.
