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Öğe An Experimental and Statistical Evaluation of The Cutting Parameters on The Machinability of Hadfield Steel(Gazi Univ, 2016) Kivak, Turgay; Uzun, Gultekin; Ekici, ErgunThe effects of cutting tool coatings and cutting parameters (cutting speed, feed rate) on the cutting forces and surface roughness during the turning of Hadfield steel were investigated in this study. Cutting experiments were made on a CNC lathe under dry cutting conditions by employing CVD TiCN/Al2O3/TiN-, PVD TiAlN- and PVD TiAlN/AlCrO-coated cementite carbide inserts. Four different cutting speeds (100, 140, 180, 220 m/min), two different feed rates (0.2, 0.3 mm/rev) and a constant cutting depth of 0.8 mm were used as the cutting parameters. At the end of the tests, cutting force and surface roughness results were subjected to variance (ANOVA) and multiple regression analyses. The experimental results showed that the PVD TiAlN coating was superior to the CVD TiCN/Al2O3/TiN and PVD TiAlN/AlCrO coatings with respect to cutting force and surface roughness. The correlation coefficients of the statistical model developed at the end of the analysis were R-2=0.994 and R-2=0.996 for the cutting forces and surface roughness, respectively. The feed rate was found to be the most effective parameter on the cutting forces and surface roughness, with contribution ratios of 91.31% and 94.79% respectively.Öğe An investigation of the effects of cutting parameters and graphite reinforcement on quality characteristics during the drilling of Al/10B4C composites(Elsevier Sci Ltd, 2017) Ekici, Ergun; Motorcu, Ali Rıza; Uzun, GultekinThis study investigated the effects of cutting parameters on the quality characteristics of thrust force (Ft), surface roughness (Ra), dimensional accuracy (Da) and burr height (Bh) during the drilling of Al/10B(4)C and Al/10B(4)C/5Gr composites. Machinability experiments were carried out with uncoated carbide twist drills at three different cutting speeds (18, 25 and 35 m/min) and three different feed rates (0.08, 0.112 and 0.16 mm/rev) under dry cutting conditions. The percent contribution of the cutting/drilling parameters/variables to the quality characteristics was determined using analysis of variance (ANOVA), and predictive linear equations were developed for the estimation of all the quality characteristics. As a result of the experimental study, it was determined that during the drilling of the composites, the 5% graphite reinforcement of Al/10B(4)C/5Gr decreased the thrust force and the burr height, improved the surface quality and brought the composite closer to its ideal diameter value. (C) 2016 Published by Elsevier Ltd.Öğe Delamination and thrust force analysis in GLARE: Influence of tool geometry and prediction with machine learning models(Sage Publications Ltd, 2024) Ekici, Ergun; Pazarkaya, Ibrahim; Uzun, GultekinThe multi-layered (fiber/metal) structure of glass fibre aluminium reinforced epoxy (GLARE) makes it difficult to obtain acceptable damage-free holes that meet aerospace standards. This paper investigated the effects of tool geometry and drilling parameters on reducing delamination damage and uncut fibers at the hole exit surface in drilling GLARE. The hole surfaces were examined by scanning electron microscope (SEM) at various magnifications. In addition, deep neural network (DNN) and long-short-term memory (LSTM) machine learning models were used to predict delamination (Fda), uncut fiber (UCF), and thrust forces using experimental data. No positive contribution of the special geometry tool was observed, while the standard geometry tool was found to be ideal for drilling conditions. Analysis of variance (ANOVA) revealed that feed rate contributed 57.83% to delamination damage, while tool geometry contributed 74.31% and 92.33% for uncut fiber and thrust force, respectively. SEM analysis revealed high deformation zones in the aluminum layers and fiber fracture and separation in the glass fibre reinforced polymer (GFRP) layers. DNN and LSTM models were found to provide accurate predictions with R2 values greater than 95% and 98%, respectively.Öğe Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel(Springer, 2015) Cicek, Adem; Kara, Fuat; Kivak, Turgay; Ekici, Ergun; Uygur, IlyasIn this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 degrees C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.Öğe Effects on machinability of cryogenic treatment applied to carbide tools in the milling of Ti6AI4V with optimization via the Taguchi method and grey relational analysis(Springer Heidelberg, 2022) Ekici, Ergun; Uzun, GultekinThe effects of processing parameters and cryogenic treatment on cutting force and surface roughness in the milling of Ti6AI4V alloy were investigated in this study. The effects of cutting speed, feed rate, and the treatments applied to the tools were evaluated through the Taguchi method and grey relational analysis. Control factors in the experiments performed under dry cutting conditions were based on two different cutting speeds and three different feed rates and tool properties. It was observed that the cutting force values decreased with increased cutting speed and significantly increased parallel to the feed rate. In terms of surface roughness, they were observed to change based on cutting parameters. Whereas the most effective parameter for cutting force was feed rate, with a 81.9% contribution, for surface roughness it was cutting speed, with a 48.8% contribution. Optimum machining conditions were determined as A(1)B(3)C(2) following the grey relational analysis performed for both responses.Öğe Evaluating the optimum abrasive water jet machinability for CARALL composites with various fiber orientations(Wiley, 2024) Karatas, Meltem Altin; Motorcu, Ali Rıza; Ekici, ErgunCarbon Fiber Reinforced Aluminum Laminated (CARALL) composites are widely used in aircraft structures due to their ability to be produced in different shapes with desired properties and their high impact resistance properties. As with other layered composite materials, processing of CARALL composites by conventional manufacturing methods results in many damage mechanisms such as fiber breakage, deformation in the hole region, stress concentration, resin-fiber separation and microcracks. One of the modern manufacturing methods, Abrasive Water Jet (AWJ), is a processing method in which the material is removed by abrasion and almost any material can be cut without thermal degradation. There are no experimental studies in the literature on the drilling of CARALL composites by modern manufacturing methods. The aim of this study is to investigate the impact of machining parameters on the output variables (kerf taper angle (K), roundness error (Re) and material removal rate (MRR)) as well as the effect of fiber orientation on the drilling of CARALL composites with different fiber orientations on an AWJ machine. PROMETHEE-GAIA weighted by Entropy Weighting Method were used to ascertain the optimum levels of control factors. CARALL composites with different fiber orientations were drilled with an 8 mm diameter AWJ with three different water pressures, three different nozzle feed rates. With PROMETHEE-GAIA multi-criteria optimization method, the optimum levels of the factors that provide both minimum Re and K values and maximum MRR value were obtained with twill woven material, 1680 mm/min feed rate and 1680 bar water pressure. Highlights center dot CARALL composite materials with two different fiber orientations (twill weave and UD) were used. center dot CARALL composite materials were drilled at different machining parameters. center dot Abrasive water jet was used in drilling experiments. center dot Optimum drilling parameters were determined to achieve minimum roundness error, minimum kerf angle and maximum material removal rate. center dot PROMETHEE-GAIA was used as a multi-criteria decision-making method.Öğe Evaluation and Multi-Criteria Optimization of Surface Roughness, Deviation From Dimensional Accuracy and Roundness Error in Drilling CFRP/Ti6Al4 Stacks(Univ Belgrade, Fac Mechanical Engineering, 2022) Motorcu, Ali Rıza; Ekici, ErgunIn this study, machinability tests were carried out to investigate the effects of control factors (cutting tool geometry, cutting speed, and feed rate) on the surface roughness (Ra), deviation from dimensional accuracy (Da_dev), roundness error (Re) in drilling CFRP/Ti6Al4V mixed metallic stack and to determine the optimum levels of drilling parameters. The effects of each control factor and their interactions on three quality characteristics were analyzed, and their levels were single-objectively optimized for each component material by the Taguchi method. The material has components (CFRP and Ti6Al4V) with essentially different properties (mechanical, physical, machinability). Single-objective optimization has limited usability as the drilling must be performed in one through both layers. Therefore, in an additional step, the optimum levels of the control factors were determined by optimizing multi-objective with the Additive Ratio Assessment (ARAS) method. Higher Ra, Da_dev, and Re values were obtained on the CFRP component compared to the Ti6Al4V component. The CFRP/Ti6Al4V stack should be drilled with a nano fire coated carbide drill (T3) at medium cutting speed and high feed rate to achieve minimum Ra, Da_dev, and Re values in one go.Öğe Evaluation of drilling Al/B4C composites with carbide drills(Pamukkale Univ, 2016) Motorcu, Ali Rıza; Ekici, ErgunIn this study, cutting forces and torque was evaluated through Taguchi Method (TM) in the drilling of the high density B4C particle reinforced composites, which were produced through powder metallurgy-hot pressing method, with coated and uncoated carbide drills. Cutting speed (18, 25 and 35 m/min), feed rate (0.08, 0.112 and 0.16 mm/rev), coating properties (coated and uncoated) and the amounts of particle reinforcement (5%, 10% and 15% B4C) were used as the control factors. It was observed that the increased feed rate and particle reinforcement increased the axial force and torque, and decreased the cutting speed. The uncoated drills had a better performance than the coated drills. The amount of B4C reinforcement was observed to be the most effective parameter on the axial force and torque with the contribution ratios of 96.6% and 49.1%, respectively. Moreover, the correlation coefficients (R2) of the first order predictive equations developed for the axial force and torque were calculated as 0.895 and 0.854, respectively.Öğe Evaluation of drilling Al/SiC composites with cryogenically treated HSS drills(Springer London Ltd, 2014) Ekici, Ergun; Motorcu, Ali RızaThe purpose of this study was to evaluate the performance of cryogenically treated M35 high-speed steel (HSS) twist drills in the drilling of Al/SiC metal matrix composites (MMCs) produced with the hot-pressing method in terms of dimensional accuracy (Da), surface roughness (Ra) and tool life. The cutting tool (Ct), cutting speed (Vc) and feed rate (f) were taken as control factors. The Taguchi method L (18) (2(1) x 3(7)) was used for the determination of optimum control factors. Analysis of variance (ANOVA) was applied in order to determine the effects of the control factors on Da and Ra. The optimum combinations of the control factors for Da and Ra were determined as A(2)B(2)C(1) and A(2)B(1)C(1), respectively. First-order predictive models were developed with linear regression analysis, and the coefficients of correlation for Da and Ra were calculated as R (2) = 80.5 and R (2) = 79.0, respectively. The results of the conducted experiments showed that the cryogenically treated drills exhibited better performance than the untreated drills in terms of the dimensional accuracy and surface roughness of the MMCs. In the tool life experiments, when compared to the conventionally heat-treated (CHT) tools, the cryogenically treated (CT) tools gained increases in tool life of 256 and 161 % at the cutting speeds of 15 and 25 m/min, respectively. Moreover, on both cutting tools, built-up edge (BUE) on the chisel edges and flank wear on the cutting could be observed.Öğe Evaluation of machinability of hardened and cryo-treated AISI H13 hot work tool steel with ceramic inserts(Elsevier Sci Ltd, 2013) Cicek, Adem; Kara, Fuat; Kivak, Turgay; Ekici, ErgunThe positive effects of deep cryogenic treatment on the wear resistance of cutting tools and workpiece material are well known; however, no information has been reported about the effect on the machinability of cryo-treated tool steel in hard turning. In order to investigate the effects of cryogenic treatment on the machinability of hardened and cryo-treated tool steel, a number of investigations were performed on the hard turning of cryo-treated AISI H13 hot-work tool steel with two ceramic inserts under both dry and wet cutting conditions. Three categories of the hot-work tool steel were turned in the machinability studies: conventional heat treated (CHT), cryo-treated (CT) and cryo-treated and tempered (m). Experimental results showed that the lowest wear and surface roughness (Ra) values were obtained in the turning of the CTT samples. Additionally, in terms of main cutting force (Fc), surface roughness (Ra) and tool wear, Ti[C, N]-mixed alumina inserts (CC650) showed a better performance than SiC whisker-reinforced alumina inserts (CC670) under both dry and wet cutting conditions. The use of cutting fluid slightly improved the machinability of the tool steel. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Evaluation of Machining Characteristics and Tool Wear During Drilling of Carbon/Aluminium Laminated(Univ Belgrade, Fac Mechanical Engineering, 2024) Motorcu, Ali Rıza; Ekici, Ergun; Kesarwani, Shivi; Verma, Rajesh KumarIn the past few decades, fibre metal laminate (FML) machining has been facing critical challenges in quality control and tool wear monitoring due to the material's intrinsic heterogeneity and abrasiveness. Different drill tools have been used to investigate the effect of process parameters on machining performances. Composite holes and tool wear was studied for drilling forces and surface roughness. An emphasis was made on examining the tool morphologies and wear processes that influence the drilling of CARALL composites. The drilling responses obtained from both the drill bits were optimized using a decision-making approach viz; Combined Compromise Solution Analysis (CoCoSo). The SEM investigation of the machined samples was used to examine the hole quality and surface finish. A lower point angle drill with a longer chip flute length produced the best results for drilling CARALL composites up to a specific point with minimum flank wear and chip adhesion.Öğe Evaluation of surface roughness and material removal rate in the wire electrical discharge machining of Al/B4C composites via the Taguchi method(Sage Publications Ltd, 2016) Ekici, Ergun; Motorcu, Ali Rıza; Kus, AbdilThis study researched the effects of machining parameters on surface roughness and material removal rate in the wire electrical discharge cutting of high-density Al/B4C metal matrix composites produced via the hot pressing method. Wire tension, reinforcement percentage, wire speed, pulse-on time and pulse-off time were set as the control factors. The Taguchi L-18 (2(1)x3(4)) orthogonal array was used in the experiment design and determination of the optimum control factors. Variance analysis was applied to determine the effects of the control factors on the surface roughness and material removal rate. The results showed the most effective parameters to be pulse-on time (30.22%) for surface roughness and wire speed (83.20%) for material removal rate, and the optimum levels of the control factors to be A(2)B(1)C(2)D(1)E(1) and A(2)B(2)C(3)D(2)E(2), respectively. Predictive equations were then developed by applying linear regression analysis, and the adjusted correlation coefficients were calculated as 0.61 for surface roughness and 0.785 for material removal rate.Öğe Experimental and Statistical Investigation of the Machinability of Al-10% SiC MMC Produced by Hot Pressing Method(Springer Heidelberg, 2014) Ekici, Ergun; Samtas, Gurcan; Gulesin, MahmutIn this study, during the machining of metal matrix composites produced by a hot pressing method in CNC milling, the effects of cutting parameters and coating type on the surface roughness were experimentally and statistically investigated. The production of composite samples was accomplished by hot pressing, in which Al was used as the matrix element and 10 % SiC particles were chosen for the reinforcing phase. In the machining of samples, three different cutting tools (uncoated, multi-layered and Nano TiAlN coated), three different cutting speeds (60, 78, 101 m/min) and three different feed rates (0.04, 0.08 and 0.12 mm/rev) were employed. Full factorial (3(3)) experimental design was chosen for the statistical investigation of the cutting parameters and parameter interactions. The response surface method was used in the mathematical modelling of the surface roughness obtained from the experiments and in the optimisation of cutting parameters. At the end of the study, the cutting tool's wear was evaluated and the wear was discussed by comparison with similar studies.Öğe Investigation of the WEDM of Al/B4C/Gr reinforced hybrid composites using the Taguchi method and response surface methodology(Walter De Gruyter Gmbh, 2016) Motorcu, Ali Rıza; Ekici, Ergun; Kus, AbdilIn this study, the effects of machining parameters on the material removal rate (MRR) and surface roughness (Ra) were investigated during the cutting of Al/B4C/Gr hybrid composites by wire electrical discharge machining (WEDM). Wire speed (W-S), pulse-on time (T-on) and pulse-off time (T-off) were chosen as the control factors. The L-27 (3(3)) orthogonal array in the Taguchi method was used in the experimental design and for the determination of optimum control factors. Response surface methodology was also used to determine interactions among the control factors. Variance analysis (ANOVA) was applied in the determination of the effects of control factors on the MRR and Ra. According to the ANOVA results, the most effective parameters on MRR and Ra were wire speed with a 85.94% contribution ratio, and pulse-on-time with a 47.7% contribution ratio. The optimum levels of the control factors for MRR and Ra were determined as A(3)B(3)C(3) and A(1)B(1)C(2). In addition, second-order predictive models were developed for MRR and Ra; correlation coefficients (R-2) were calculated as 0.992 and 0.63.Öğe Mechanical and fracture behavior of B4C reinforced Al composites produced by hot pressing(Carl Hanser Verlag, 2016) Ekici, Ergun; Ozcatalbas, Yusuf; Gulesin, MahmutIn this study, the effects of particle addition on the microstructure, mechanical properties and fracture behaviors of Al/B4C particle reinforced composite produced by hot pressing method were investigated. After the production of 5, 10 and 15 wt.-% of B4C reinforced composites, T6 heat treatment was applied. It was specified that a strong interface bond occurred between the matrix and particles, and during the fracturing of composites, this effect increased the particle fracture. It was observed that particles were fractured parallel to the fracture surface and to each other fracture surface of MMCp. In general, cavity of particle separated from the matrix was not seen. In the production of MMCp, it was also observed that hot pressing provided a density higher than 99 %. After the heat treatment the maximum hardness value of 173 HB was reached with 15 wt.-% B4C reinforced sample. The transverse rupture strength ( TRS) decreased with the increase of reinforcement ratio. The highest TRS was 510 MPa with the 5 wt.-% reinforced material, whereas the lowest value was obtained to be 387 MPa with the 15 wt.-% B4C reinforced material.Öğe Milling behavior of Hadfield steel with cryogenically treated tungsten carbide inserts(Carl Hanser Verlag, 2015) Ekici, ErgunIn this study, the performance of cryogenically treated tungsten carbide inserts in the milling of Hadfield steel (X120Mn12) was evaluated in terms of surface roughness (Ra) and tool wear (VB). Cutting tools were assessed under three conditions: untreated (U), cryogenic treated (CT) and cryo-tempered (CTT). For the cutting parameters, three different cutting speeds (70, 100 and 130 m.min(-1)) and feed rates (0.08, 0.14 and 0.2 mm.rev(-1)) were used. The experiments were carried out under a fixed depth of cut and dry cutting conditions. To determine the factorial effects, the procedure Taguchi L27 (33) was used. For the estimation of Ra and VB, the response surface method (RSM) was employed and mathematical models were developed. In terms of Ra, the effective parameter was feed rate (89.45 %) and in terms of VB, it was the cutting speed (60.42 %). For Ra and VB, the optimum levels of factors were determined as A3B3C1 and A3B1C1, respectively. The effects of the factors were also assessed by RSM.Öğe Optimization and alternative image processing approach for the comprehensive assessment of delamination and uncut fiber in drilling fiber metal laminate(Springer Heidelberg, 2022) Ekici, Ergun; Motorcu, Ali Rıza; Polat, AdemIn this study, hole exit delamination and uncut fiber (UCF) formation in the drilling of carbon fiber-reinforced aluminum laminates (CARALL) were investigated. The adjusted delamination factor (F-da) was used to assess delamination. The experiments were carried out using a brad spur drill (Tool 1), a twist drill (Tool 2), and a dagger drill (Tool 3) tool. A multi-mapped image processing model (MMIPM) was developed for an advanced and comprehensive delamination assessment in images by evaluating F-da and UCF parameters. In order to provide more information about the preferential orientation of delamination, in addition to F-da, conventional delamination factor (F-d) and minimum delamination factor (F-dmin) were calculated and a comparison of all delamination approaches was performed. Furthermore, the PROMETHEE-GAIA method was used to perform multi-objective optimization of F-da and UCF. The minimum F-da and UCF values were achieved with the twist drill (Tool 2). Vc = 118 m/min and f = 0.156 mm/rev were optimal conditions for minimum F-da and UCF.Öğe Optimization of low-velocity impact behavior of FML structures at different environmental temperatures using taguchi method and grey relational analysis(Sage Publications Ltd, 2024) Dundar, Mustafa; Uygur, Ilyas; Ekici, ErgunCarbon fiber-reinforced Aluminum Laminate (CARALL) is a new generation of Fibre Metal Laminate (FML) material. This study investigates the low-velocity impact behavior of CARALL structures at different environmental temperatures (-40 degrees C, 23 degrees C, and 80 degrees C). Two different groups of CARALL composite structures with varying fiber orientations were produced by hot pressing in a 3/2 arrangement: C1 (Al/0 degrees 90 degrees/Al/90 degrees 0 degrees/Al) and C2 (Al/0 degrees 0 degrees/Al/0 degrees 0 degrees/Al). Low-velocity impact tests were conducted at 23 J, 33 J, and 48 J energy levels using a & Oslash;20 mm spherical impactor tip. The area of damage was detected by ultrasonic C-Scan. In addition, analysis of variance (ANOVA) was applied to reveal the influential parameters and their effect levels. After conducting experiments using the Taguchi L18 test set, it was observed that the C2-coded specimen yielded better results in terms of maximum peak load, maximum displacement, and damage area. While the decrease in temperature increased the damage and maximum peak load, the increase in temperature did not cause a significant change in the maximum peak load. The primary damage mechanisms observed in damage investigations were matrix cracks and delamination between composite layers. Although delamination is present between the Al/CFRP layer, it is not significant. According to ANOVA results, impact energy was the most effective parameter for maximum impact force, maximum displacement, and damage area, with contribution rates of 81%, 74%, and 76%, respectively. The optimal experimental conditions (23 degrees C temperature and 23 J impact energy with the C1-coded sample) were determined using grey relational analysis based on principal component analysis.Öğe The machinability of Al/B4C composites produced by hot pressing based on reinforcing the element ratio(Walter De Gruyter Gmbh, 2016) Ekici, Ergun; Gulesin, MahmutIn this study, the effects of the particle reinforcement ratio on cutting forces and surface roughness were investigated when milling particle-reinforced metal matrix composite (MMCp) produced by hot pressing with different cutting tools. Alumix 123 alloy as the matrix material and B4C particles with an average size of 27 mu m and 5%, 10% and 15% ratio as reinforcing elements were used for the manufacture of composite materials. The experiments were carried out in dry cutting conditions with four different cutting speeds, constant feed rate and depth of cut. Changes depending on the increased reinforcement ratio in cutting forces and surface roughness values were investigated; the effects of 10% B4C reinforced composite on tool wear were also examined. It was observed that cutting forces increased with the increase in cutting speed and particle ratio with carbide cutting tools, and it was seen that the cutting forces on the cutting tools decreased when cutting speed decreased and the cutting forces increased as the reinforcement ratios increased. In addition, with increasing the cutting speed, the surface roughness of the machined surfaces of composite samples increased with the carbide tools, while the cubic boron nitride (CBN) tools have the opposite effect. While it was seen that flank and crater wear occurred on the cemented carbide cutting tools, abrasive, adhesive and other wear mechanism tools in addition to the main wear mechanism, no remarkable flank and crater wear occurred on CBN cutting tools.
