Makine Ve Metal Teknolojileri Bölümü
Bu koleksiyon için kalıcı URI
Güncel Gönderiler
Öğe Multi-Criteria optimization of surface roughness in wire EDM of Inconel 718 by Taguchi based gray relational analysis method(Pamukkale Univ, 2022) Karataş, Meltem AltınIn this study, the effect of machining parameters on Ra (average surface roughness), Rq (quadratic average roughness) and Rz (maximum roughness) values were measured on the material cut surface as a result of machining Inconel 718 (IN718) superalloy on a CNC wire erosion machine were investigated. As the processing parameters; voltage, wire feed rate and dielectric fluid pressure were determined. In the experiments, pure water was used as the dielectric fluid and 0.3 mm brass wire was used as the wire. The aim of the study is to determine the optimum values of the cutting parameters in order to obtain the lowest Ra, Rq and Rz values. Gray Relational Analysis (GRA), which is one of the multi-criteria decision-making methods, has been applied for the optimization of the machining parameters in the cutting process with the wire erosion machine. The experiments and the levels of the parameters used were designed and optimized according to the Taguchi L-9 (3(3)) orthogonal array. Analysis of Variance (ANOVA) was used to determine the effect percentages of the cut-off parameters. The parameter with the highest effect was determined as voltage with a ratio of 79.18% for Ra, 84.05% for Rq, and 89.25% for Rz. The lowest Ra, Rq and Rz values were obtained as 0.123 mu m, 0.178 mu m and 0.740 mu m, respectively.Öğe Statistical analysis of WEDM machining parameters of Ti-6Al-4V alloy using taguchi-based grey relational analysis and artificial neural network(Springer, 2023) Karataş, Meltem Altın; Biberci, Mehmet AliIn this present study, the effect of processing parameters on cutting width (kerf), material removal rate (MRR), Ra (arithmetic mean deviation), Rq (root mean square deviation) and Rz (maximum height) values as a result of wire electrical discharge machining (WEDM) of Ti-6Al-4V alloy was investigated. It is aimed to determine the optimum values of the cutting parameters to obtain the highest MRR value with the lowest kerf, Ra, Rq, Rz. Cutting experiments were carried out using three different voltages (46, 56, 66 V), three different dielectric fluid pressures (10, 12, 14 kg/cm(2)) and three different wire feed rates (8, 10, 12 m/min). The parameters used in the experiments were designed according to the Taguchi L-9 (3(3)) orthogonal array in order to reduce the experimental cost. Gray Relational Analysis (GRA), one of the multi-criteria decision-making methods, has been applied to optimize the machining parameters in the cutting process with the wire erosion machine. Analysis of variance (ANOVA) was used to determine the effect percentages of the processing parameters. By using the data obtained from the experiments, the prediction study of the experimental data was carried out with the Artificial Neural Networks (ANN) model. High correlation coefficients were obtained in the regression model created using the ANN technique, and it was observed that both models were suitable and usable to predict the answers. As a result of GRA, the most ideal sequence was determined as VG(1)LQ(1)WS(1). Ideal conditions were determined as 46 V voltage, 10 kg/cm(2) dielectric fluid pressure and 8 m/min wire feed rate. Using the optimum machining parameters, an improvement of 4.22%, 54.65%, 28.77%, 31.94% and 35.24% was obtained for kerf, MRR, Ra, Rq, and Rz, respectively. As for the results obtained from ANOVA the contribution rate of the voltage was 72.18%. However, the effect of wire feed rate and dielectric fluid pressure was not statistically significant.Öğe Evaluation of effect of machining parameters on surface roughness in drilling of glass fiber reinforced polymer (GFRP) composite material with different drill bits(Polish Society of Composite Materials, 2022) Karataş, Meltem AltınIn the present study, the arithmetical mean roughness (Ra) values obtained as a result of drilling glass fiber reinforced polymer (GFRP) composite material produced in fiber orientation angles (0 degrees/90 degrees) with different drill bits in a 5-axis CNC controlled vertical machining center, were analyzed. The experimental design was applied with the Taguchi method. The drilling experiments were performed using Minitab 19 software according to the Taguchi L-18 orthogonal array. The test results were evaluated based on the signal-to-noise (S/N) ratio. Two different drill bits (HSS and carbide), three different spindle speeds (750, 1000, 1500 rpm) and three different feed rates (0.05, 0.10, 0.15 mm/rev) were selected as the control factors. The effect levels of the control factors on Ra were found by applying analysis of variance (ANOVA). A confidence level of 95.62% was obtained with ANOVA analysis. The lowest Ra value was 1.279 mu m at the spindle speed of 1500 rpm and the feed rate of 0.05 mm/rev using a carbide drill bit. The drill bit type was obtained as the parameter with the highest effect with a rate of 61.33%.Öğe Investigation of the effect of AWJ drilling parameters for delamination factor and surface roughness on GFRP composite material(Emerald Group Publishing Ltd, 2022) Karataş, Meltem Altın; Gökkaya, Hasan; Akıncıoğlu, Sıtkı; Biberci, Mehmet AliPurpose The purpose of this study is to optimize processing parameters to get the smallest average surface roughness (Ra) and delamination damage (F-d) values during drilling via abrasive water jet (AWJ) of the glass fiber-reinforced polymer composite material produced at [0 degrees/90 degrees](s) fiber orientation angles. Design/methodology/approach Drilling experiments were done via AWJ with three-axis computer numerical control (CNC) control system. Machine processing parameters such as water pressure of 3,600, 4,300, 4,800 and 5,300 bar; stand-off distance of 1, 2, 3 and 4 mm; traverse rate of 750, 1,500, 2,000 and 3,000 mm/min; and hole diameters of 8, 10, 12 and 14 mm have been selected. The effects of processing parameters in drilling experiments were investigated in conformity with the Taguchi L-16 orthogonal array and the data obtained were analyzed using Minitab 17 software. The signal/noise (S/N) ratio was taken as a basis for evaluating the test results. Optimum processing conditions were determined by calculating the S/N ratio for both Ra and F-d in conformity with the smaller is better approximation. The effects of processing parameters on Ra and F-d were statistically investigated using analysis of variance, S/N ratio and Taguchi-based gray relational analysis. Ra and F-d were predicted by evaluating with the ANN model and were predicted with the least amount of error. Findings It has been determined that the most effective parameter for Ra and F-d is the water pressure and then the stand-off distance. Originality/value The novel approach is to reduce cost and the time spent by using Taguchi optimization as a result of AWJ drilling the material in this fiber orientation [0 degrees/90 degrees](s).Öğe Experimental investigation of the effects of aging and cryogenic treatments on the mechanical properties of superelastic nickel-titanium shape-memory alloys(SAGE Publications Ltd, 2022) Güven, Sedat; Karataş, Meltem Altın; Gökkaya, Hasan; Akınay, YükselIn this study, electropolishing and two different heat treatments were applied to wires made of superelastic nickel-titanium (NiTi) shape-memory alloy (SMA) and their mechanical properties and stress-induced deformations were investigated. In experimental studies, cryogenic and aging heat treatments were applied to NiTi SMA wire samples and tensile test experiments were carried out to determine the effect of the heat treatments on their mechanical properties. Following the tensile test experiments conducted at room temperature (23 degrees C), the study investigated changes in the elemental composition, fracture modes, micro cracks, and phase structures and in the mechanical properties formed in the fracture region. Intermetallic phase structures (Ti2Ni, Ni3Ti, and Ni4Ti3) were observed in the X-ray diffraction (XRD) analyses. It was concluded that the aging heat treatment had directly affected the reduction in hardness. In particular, in samples without the aging heat treatment, a stress-induced decrease in the Ni and Ti ratios and an increase in the carbon (C) ratio were observed in the chemical composition of the fracture surface of the superelastic NiTi SMA wires. It was determined that the changes in the chemical composition caused by stress had affected the mechanical properties negatively. In the fractography of the NiTi SMA wires, the samples exhibited mostly ductile fracture behavior with small dimples.Öğe Wire EDM cutting of inconel 718 nickel-based superalloy: Kerf and MRR analysis(Emerald Group Publishing Ltd, 2022) Karataş, Meltem AltınPurpose Inconel 718 (IN718) is a high-performance nickel-based superalloy with high oxidation-corrosion-temperature resistance, high strength (tensile, fatigue, creep and rupture), durability, toughness, hardness and dimensional stability, which is difficult to machine with traditional fabrication methods. To overcome these difficulties, wire electrical discharge machining (WEDM), one of the modern manufacturing methods, is used. Design/methodology/approach Main performance criteria in WEDM; material removal rate (MRR), cutting speed, surface roughness, cutting width (kerf) and wire wear rate. In this study, the effect of processing parameters on kerf and MRR because of processing IN718 in WEDM was investigated. Machining parameters, voltage, wire feed rate and dielectric fluid pressure were determined. Deionized water was used as a dielectric fluid and 0.3 mm brass wire was used as wire in the experiments. Gray Relational Analysis (GRA), which is one of the multi-criteria decision-making methods, has been applied for the optimization of the machining parameters in the cutting process with the WEDM. Analysis of variance (ANOVA) was used to determine the effect percentages of the cut-off parameters. Findings The parameter with the highest effect was determined as tension with a rate of 76.95% for kerf and 91.21% for MRR. Originality/value The novel approach uses Taguchi-based GRA optimization as a result of cutting IN718 with WEDM, reducing cost and time consumption.Öğe Research on the manufacture and strength of the innovative joint of FRP machine parts(Elsevier Sci Ltd, 2021) Nekrasov, Serhii; Zhyhylii, Dmytro; Dovhopolov, Andrii; Karataş, Meltem AltınThis paper is devoted to a detachable fiber-reinforced plastic (FRP) machine parts joint of a new type along with its pull-through strength investigation. The relevance consists of a new mechanical processing technology proposition with the accompanying research into thread helical surfaces strength, which in turn benefits in a significant increase in strength compared to conventional thread joints. The paper presents a numerical experiment carried out with finite element method simulation using LS-DYNA. The helical surfaces contact problem of the rigid threaded insert pulled through the FRP thick cylindrical screw nut with constant velocity has been solved. Technology features of the mechanical processing form-generating method, which forms a threaded surface in one passage of the simple geometry tool are also revealed. The research is concluded with the physical experiment of the steel threaded insert pulled through internal thread made in the FRP thick plate with the pullthrough test machine, complete with results statistical assessment was obtained by simulation and testing. It is shown that the combination of the new processing technology with the new geometry of the threaded joint makes it possible to significantly surpass pull-through ultimate strength in comparison with modern analogues of metric threads made in parts directly and even with threaded inserts.Öğe Surface integrity of NiTi shape memory alloy in milling with cryogenic heat treated cutting tools under different cutting conditions(Springer, 2021) Altaş, Emre; Karataş, Meltem Altın; Gökkaya, Hasan; Akınay, YükselIn this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was investigated after face milling processes with cryogenically treated/untreated cemented carbide cutting tools at the conditions of dry cutting and minimum quantity lubrication (MQL) of cutting fluids depending on the changing cutting parameters. The integrity of surface layer of the workpiece material was evaluated according to the mean surface roughness, microstructure and hardness, as well as according to the resultant cutting force and flank wear of inserts. Cutting tests were carried out at three different cutting speeds (20, 35 and 50 m/min), feed rates (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The influence of these parameters on the surface integrity was extensively investigated. The face milling tests of NiTi SMA at optimal cutting parameters show that the surface integrity enhanced at a cutting speed of 50 m/min and feed rate of 0.03 mm/tooth using boron-added cutting fluid (EG + %5BX) with deep cryogenic heat treated (- 196 degrees C) CVD coated S40T grade cutting tool. Under MQL conditions, the minimum mean surface roughness (0.278 mu m), resultant cutting force (268.2 N) and flank wear (0.18 mm) were obtained due to the high thermal conductivity and lubrication property of EG + %5BX cutting fluid. The highest hardness values (343 HV) were measured at the zone subjected to the highest deformation, while the lowest one (316 HV) was measured at the zone at the least deformation.Öğe Investigation of friction performance and surface integrity of aramid fiber-reinforced polymer matrix composite(Wiley, 2021) Karataş, Meltem AltınBecause of its superior properties, aramid fiber-reinforced polymer (AFRP) composite material is used in many sectors including the aerospace, automotive, and defense industries and maintains a stable and reliable coefficient of friction under the various conditions required by these industries. In this study, the friction coefficient of AFRP composites was determined by tests carried out using a ball-on-disc friction tester under 8 and 12 N loads at 300, 450, and 550 rpm. The wear traces were investigated and according to the results, the high friction forces negatively affected the wear and led to more prominent wear traces. It was concluded that oxidation, fatigue (thermal), and delamination wear were effective because the increase in the load increased the forces on the samples. In sample A1, the value obtained under the 8 N load was 287.5% lower than that measured under the 12 N load.Öğe Study on delamination factor and surface roughness in abrasive water jet drilling of carbon fiber-reinforced polymer composites with different fiber orientation angles(Springer Heidelberg, 2021) Karataş, Meltem Altın; Motorcu, Ali Riza; Gökkaya, HasanCarbon fiber-reinforced polymer (CFRP) composites are used in aerospace applications because of their superior mechanical properties and light weight. Avoiding damage in the machining of CFRP composites is difficult using traditional methods. Abrasive water jet (AWJ) has recently become one of the preferred machining methods for CFRP composites. This study evaluated the AWJ machinability of CFRP composites having three different fiber orientation angles (M1: [0 degrees /90 degrees ]s, M2: [+45 degrees/- 45 degrees ]s, and M3: [0 degrees /45 degrees /90 degrees/- 45 degrees ]s) according to the delamination factor (D-f), and the average surface roughness (R-a) as quality characteristics of the drilled holes. The aim of the study was to investigate the effects of different levels of AWJ drilling parameters on the delamination factor and surface roughness and to determine the optimum drilling parameter levels that provide minimum delamination formation and surface roughness values. For this purpose, AWJ drilling experiments were carried out using the Taguchi L16 (4(4)) orthogonal array. Water pressure (WP), stand-off distance (L), traverse feed rate (F), and hole diameter (D) were chosen as process parameters. Analysis of variance was used to determine the percentage effects of the AWJ drilling process parameters. The microscopic surface roughness and delamination formation properties of the machined surfaces were revealed using a scanning electron microscope and an optical microscope, respectively. The most effective parameters on D-f and R-a in the AWJ drilling of M1, M2 and M3 CFRP materials were determined to be water pressure, and stand-off distance. Minimum D-f and R-a values were obtained when AWJ drilling the M3 CFRP composite with a fiber orientation angle of [0 degrees /45 degrees /90 degrees/- 45 degrees ]s. Minimum delamination formation and very good surface quality can be obtained when the optimum process parameters determined in this study are used in the planning process for the AWJ drilling of CFRP composites having different fiber orientation angles.Öğe Optimization of machining parameters for kerf angle and roundness error in abrasive water jet drilling of CFRP composites with different fiber orientation angles(Springer Heidelberg, 2020) Karataş, Meltem Altın; Motorcu, Ali Riza; Gökkaya, HasanIn this study, carbon fiber-reinforced polymer (CFRP) composites with three different fiber orientation angles (M1: [0 degrees/90 degrees](s), M2: [+ 45 degrees/- 45 degrees](s), and M3: [0 degrees/45 degrees/90 degrees/- 45 degrees](s)) were drilled (with and without pilot holes) on an abrasive water jet (AWJ) machine and the effect of the drilling parameters on the kerf angle (K) and roundness error (Re) of selected holes was investigated to determine quality characteristics. The first aim of the study was the single-objective optimization of drilling parameters for minimum K and Re individually. The second aim was the multi-objective optimization of drilling parameters for the simultaneous minimization of both K and Re. The Taguchi method was applied for single-objective optimization, while all steps of the Taguchi-based gray relational analysis were used for multi-objective optimization. Drilling experiments were performed using the L16 (4(4)) orthogonal array. Four levels each for water pressure, stand-off distance, traverse feed rate, and hole diameter were selected as control factors. Analysis of experimental findings revealed that pilot drilling improved the kerf angle of the hole by 12.4% and the roundness error by 22.87%. Minimum kerf angle and roundness error were realized in the AWJ drilling of the M3 CFRP. The most effective parameter on kerf angle and roundness error in AWJ drilling of M1, M2, and M3 CFRP materials was water pressure (80.6%, 76.9%, and 73.8%, respectively), followed by stand-off distance (11.7%, 12.0%, and 13.5%),while other drilling parameters remained below 10%. The statistical evaluation and optimization results in this study can contribute to the evaluation of the AWJ machinability of CFRP composites.Öğe Taguchi optimization of surface roughness in the turning of Hastelloy C22 super alloy using cryogenically treated ceramic inserts(Sage Publications Ltd, 2020) Akıncıoğlu, Sıtkı; Gökkaya, Hasan; Akıncıoğlu, Gülşah; Karataş, Meltem AltınCryogenic treatment has been used in recent years to improve the performance of cutting tools. This study evaluated the machinability of a nickel-molybdenum-based super alloy using cryogenically treated (-80 celcius and -145 celcius) ceramic inserts under dry turning conditions. Three cutting speeds (350, 400, and 450 m/min), three feed rates (0.1, 0.2, and 0.3 mm/rev), and a 1-mm fixed cutting depth were used in the turning tests. Experiments were conducted using the Taguchi orthogonal array L(27)design. The factors affecting the surface roughness (Ra) were determined via analysis of variance. The effect of cryogenic treatment type (shallow and deep), cutting speed, and feed rate on surface roughness was investigated. Results of the analysis determined that the feed rate was the major parameter that affected surface roughness and that the deep cryogenic treatment was more effective. The regression analysis confirmed that the experimental results and the predicted values were within the 95% confidence interval. The most effective parameter affecting the surface roughness was feed rate at a contribution of 57.9%. The contribution of the cutting tool type to the surface roughness was 28.5%. The results obtained showed that the surface roughness can be optimized for turning the Hastelloy c22 super alloy with the Taguchi method.Öğe Analysis of surface roughness and flank wear using the taguchi method in milling of niti shape memory alloy with uncoated tools(Mdpi, 2020) Altaş, Emre; Gökkaya, Hasan; Karataş, Meltem Altın; Özkan, DervişThe aim of this study was to optimize machining parameters to obtain the smallest average surface roughness (Ra) and flank wear (Vb) values as a result of the surface milling of a nickel-titanium (NiTi) shape memory alloy (SMA) with uncoated cutting tools with different nose radius (r(epsilon)) under dry cutting conditions. Tungsten carbide cutting tools with different r(epsilon) (0.4 mm and 0.8 mm) were used in milling operations. The milling process was performed as lateral/surface cutting at three different cutting speeds (V-c) (20, 35 and 50 m/min), feed rates (f(z)) (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The effects of machining parameters in milling experiments were investigated based on the Taguchi L18 (2(1) x 3(2)) orthogonal sequence, and the data obtained were analyzed using the Minitab 17 software. To determine the effects of processing parameters on Ra and Vb, analysis of variance (ANOVA) was used. The analysis results reveal that the dominant factor affecting the Ra is the cutting tool r(epsilon), while the main factor affecting Vb is the f(z). Since the predicted values and measured values are very close to each other, it can be said that optimization is correct according to the validation test results.Öğe Optimization of machining parameters for abrasive water jet drilling of carbon fiber-reinforced polymer composite material using Taguchi method(Emerald Group Publishing Ltd, 2019) Karataş, Meltem Altın; Gökkaya, Hasan; Nalbant, MuammerPurpose The aim of this paper is to optimize the machining parameters to obtain the smallest average surface roughness values during drilling of the carbon fiber-reinforced polymer (CFRP) composite material with abrasive water jet (AWJ) and analyze the damage of the delamination. Design/methodology/approach CFRP composite material had been fabricated having fiber orientations frequently used in the aerospace industry (0 degrees/45 degrees/90 degrees/-45 degrees). Three different stand-off distances (1, 2 and 3 mm), three different water pressures (1,800, 2,800 and 3,800 bar) and three different hole diameters (4, 8 and 12 mm) were selected as processing parameters. The average surface roughness values were obtained, and delamination damage was then analyzed using Taguchi optimization. Drilling experiments were performed using the Taguchi L-27 orthogonal array via Minitab 17 software. The signal/noise ratio was taken into account in the evaluation of the test results. Using the Taguchi method, the control factors giving the mean surface roughness values were determined. Analysis of variance was performed using the experimental results, and the effect levels of the control factors on the average surface roughness were found. Findings It was found that water pressure and hole diameter had a higher effect on average surface roughness, while water pressure and stand-off distance were effective on delamination. Originality/value The novel approach is to reduce cost and spent time using Taguchi optimization as a result of AWJ drilling the material in this fiber orientation ([0 degrees/45 degrees/90 degrees/-45 degrees](s), which is often used in the aerospace industry).Öğe A review on machinability of carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) composite materials(Elsevier Science Bv, 2018) Karataş, Meltem Altın; Gökkaya, HasanFiber reinforced polymer (FRP) composite materials are heterogeneous and anisotropic materials that do not exhibit plastic deformation. They have been used in a wide range of contemporary applications particularly in space and aviation, automotive, maritime and manufacturing of sports equipment. Carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) composite materials, among other fiber reinforced materials, have been increasingly replacing conventional materials with their excellent strength and low specific weight properties. Their manufacturability in varying combinations with customized strength properties, also their high fatigue, toughness and high temperature wear and oxidation resistance capabilities render these materials an excellent choice in engineering applications. In the present review study, a literature survey was conducted on the machinability properties and related approaches for CFRP and GFRP composite materials. As in the machining of all anisotropic and heterogeneous materials, failure mechanisms were also reported in the machining of CFRP and GFRP materials with both conventional and modern manufacturing methods and the results of these studies were obtained by use of variance analysis (ANOVA), artificial neural networks (ANN) model, fuzzy inference system (FIS), harmony search (HS) algorithm, genetic algorithm (GA), Taguchi's optimization technique, multi-criteria optimization, analytical modeling, stress analysis, finite elements method (FEM), data analysis, and linear regression technique. Failure mechanisms and surface quality is discussed with the help of optical and scanning electron microscopy, and profilometry. ANOVA, GA, FEM, etc. are used to analyze and generate predictive models. (c) 2018 The Authors. Published by Elsevier Ltd.Öğe Optimization of MQL parameters using the Taguchi method in milling of nickel based Waspaloy(Gazi Univ, 2017) Yıldırım, Çağrı Vakkas; Kıvak, Turgay; Erzincanlı, Fehmi; Uygur, İlyas; Sarıkaya, MuratThis study aimed to investigate the effect of the minimum quantity lubrication (MQL) parameters such as cutting oil type, flow rate, milling method, pulverization distance and nozzle type on average surface roughness (Ra) in milling of nickel based Waspaloy super alloy. During milling experiments, constant cutting speed (45 m/min), feed rate (0.1 mm/rev) and depth of cut (0.5 mm) were selected as machining parameters. Four different types of oil (vegetable, synthetic, mineral and mineral-synthetic), four different flow rates (25, 50, 75 and 100 ml/h), two different milling methods (down milling and up milling) two pulverization distances (25 and 50 mm) and two different nozzle types were chosen as MQL parameters. The results were analyzed using 3D surface graphs, signal-to-noise ratio (S/N) and main effect graphs of means. Optimal MQL parameters were determined using the S/N ratio. Mathematical models have been created for surface roughness. The analysis results indicated that the dominant factors were oil type and flow ratio on surface roughness. In addition, confirmation test results showed that the Taguchi method was very successful in the optimization of MQL parameters in order to obtain minimum surface roughness in milling of Waspaloy super alloy.Öğe Determination of MQL parameters contributing to sustainable machining in the milling of nickel-base superalloy Waspaloy(Springer Heidelberg, 2017) Yıldırım, Çağrı Vakkas; Kıvak, Turgay; Sarıkaya, Murat; Erzincanlı, FehmiIn addition to reducing production costs, minimum quantity lubrication (MQL) aims to minimize the adverse effects of conventional cutting fluid usage on the environment and human health. Because of the positive effect of the MQL system on both health and production efficiency, sustainable production is increasing daily. Therefore, optimum MQL parameters must be determined in order to obtain maximum efficiency in the manufacturing process. In this study, unlike similar studies in which MQL parameters were evaluated, the scope was widened and the main parameters affecting the efficiency of the system were tested at the same time. For this aim, nickel-base superalloy Waspaloy was machined under MQL using a CNC milling machine with uncoated carbide inserts. In the machining process, the MQL parameters selected were cutting oil type (mineral-, synthetic-, mineral-synthetic-and vegetable-based oils), fluid flow rate (25, 50, 75 and 100 ml/h), milling method (up milling and down milling), spray distance (25 and 50 mm) and nozzle type (Type 1 and Type 2). In order to analyze the effect of MQL parameters on the quality characteristics of tool life and cutting force, the cutting parameters, including cutting speed, feed rate and depth of cut, were kept constant for all experiments. Taguchi's L16 (4(2) x 2(3)) orthogonal array was employed to minimize the number of experiments. As a result, both maximum tool life and minimum cutting force were attained via a combination of vegetable-based cutting oil, 100 ml/h flow rate, opposite-direction (up) milling, Type 1 nozzle and a 25-mm spray distance.Öğe Drilling of a hybrid Al/SiC/Gr metal matrix composites(Springer London Ltd, 2012) Altunpak, Yahya; Ay, Mustafa; Aslan, SerdarThe present study investigates the influence of cutting parameters on cutting force and surface roughness in drilling of Al/20%SiC/5%Gr and Al/20%SiC/10%Gr hybrid composites fabricated by vortex method. The drilling tests are conducted with diamond-like carbon-coated cutting tools. This paper is an attempt to understand the machining characteristics of the new hybrid metal matrix composites. The results indicate that inclusion of graphite as an additional reinforcement in Al/SiCp reinforced composite reduces the cutting force. The cutting speed and its interactions with feed rate are minimum. Feed rate is the main factor influencing the cutting force in both composites. The surface roughness value is proportional with the increase in feed rate while inversely proportional with cutting speed in both composites. For all cutting conditions, Al/20%SiC/10%Gr composite has lower surface roughness values than Al/20%SiC/5%Gr composite. The surface is analyzed using scanning electron microscope.Öğe The effect of plasma spraying on the microstructure and aging kinetics of the Al-Si matrix alloy and Al-Si/SiC composites(Springer, 2010) Altunpak, Yahya; Akbulut, Hatem; Üstel, FatihThe Al-Si (LM 13)-based matrix alloy reinforced with SiC particles containing 10, 20, and 30 vol.% SiC particles were spray-formed onto Al-Si substrates. The sprayed samples were directly subjected to a standard aging treatment (T551). From the experiments, it was observed that the high rate of solidification resulted in very fine silicon particles which were observed as continuous islands in the matrix and each island exhibited several very fine silicon crystals. Analysis showed that plasma-spraying caused an increased solid solubility of the silicon in the aluminum matrix. DSC measurements in the permanent mold-cast Al-Si matrix alloy and plasma-sprayed Al-Si matrix alloy showed that plasma-spraying causes an increase in the amount of GP-zone formation owing to the very high rate solidification after plasma-spraying. In the plasma-sprayed Al-Si/SiC composites GP zones were suppressed, since particle-matrix interfaces act as a sink for vacancies during quenching from high plasma process temperature. Introduction of SiC particles to the Al-Si age-hardenable alloy resulted in a decrease in the time required to reach plateau matrix hardness owing to acceleration of aging kinetics by ceramic SiC particles.Öğe Wear behaviour of aged Cu-Be alloy under electrical sliding(Academic Journals, 2010) Altunpak, YahyaThe sliding friction and wear behaviors of aged Cu-Be alloy was studied in the presence of electrical current. Electrical sliding was performed between a Cu-Be pin and a flat surface of a hardened steel disk in ambient atmosphere. The effects of aging heat treatment, electrical current density on the friction and wear behavior were investigated. The microstructure and the worn surfaces of the aged Cu-Be alloy were also investigated by optical microscope, scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). The results indicated that the aging treatment has affected the microstructure, hardness and wear resistance of Cu-Be alloy. The values of hardness for the alloy reached the peak hardness after an aging treatment at 330 degrees C for 3 h and over-aging occurred at higher temperature. Both the coefficient of friction and wear loss increased when small electrical current was applied and decreased as the electrical current density increased. Adhesive wear and abrasive wear were the dominant mechanisms during the electrical sliding processes. The alloy treated at 330 degrees C for 3 h exhibited much better wear resistance.
