Yazar "Sur, Gokhan" seçeneğine göre listele

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    CUTTING TOOL GEOMETRY IN THE DRILLING OF CFRP COMPOSITE PLATES AND TAGUCHI OPTIMISATION OF THE CUTTING PARAMETERS AFFECTING DELAMINATION
    (Yildiz Technical Univ, 2018) Sur, Gokhan; Erkan, Omer
    It is possible to improve the hole quality by reducing the delamination which occurs in the drilling of carbon fibre reinforced plastic (CFRP) composite plates. For this study, carried out under dry machining conditions, the parameters included three different cutting speeds, three different feed rates and drill geometry involving three different point angles. The Taguchi L-9 orthogonal array experimental design was selected and the optimum cutting parameters and drill geometry for reducing the damage factor to a minimum were determined. The optimum test conditions were achieved using the parameter combination of 118 degrees point angle, 30 m/min cutting speed and 0.06 mm/rev feed rate (A1B1C1). In addition, variance analysis (ANOVA) was conducted to determine the effect rate of the parameters on the damage factor. The variable having the greatest effect on the damage factor was found to be the point angle (47.66%), followed by the cutting speed (24.44%) and feed rate (19.82%). The conditions for minimising delamination damage in the drilling of the CFRP plates were optimised successfully by using the Taguchi test design.
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    Effect of Cementite Carbide Tool Coating Type and Tool Radius on Cutting Performance
    (Ieee, 2016) Yildiz, Tugce; Irez, Alaeddin Burak; Sur, Gokhan
    The present study represents an experimental investigation on machinability of Ti6Al4V titanium alloy by turning method. The effects of coating type (CVD and PVD coating) and cutting tool nose radius on dynamics of machining in particular the resultant cutting force and surface roughness were explored in dry cutting conditions and constant cutting depth. Cutting parameters were selected as two different cutting speed (75, 100 m/min), three different feed rate (0.15, 0.2, 0.25 mm/rev), three different nose radius (0.8, 1.2, 1.6 mm) and two different cementite carbide tool utilized (CVD and PVD coated tools) according to the literature survey and ISO 3685 standard. The components of cutting force (F-C, F-F, F-R) on cutting cementite carbide tool were measured by piezo-piezo-electric dynamometer and surface roughness measured by profilometer. It was seen that main cutting force (F-C) is the most prominent constituent of the resultant force. In addition, effects of feed rate and cutting speed to the machinability were verified experimentally. Experimental results showed that physical vapor deposition (PVD) coating causes more important resultant force values compared to chemical vapor deposition (CVD) coating for the cutting speeds 75 m/min, 100 m /min and CVD coated cutting tools causes rougher surfaces compared to PVD coated tools for the same cutting speeds. Furthermore, the resultant force decreases while the tool nose radius increases for CVD coated tools and surface roughness decreases while the tool radius increases for both CVD and PVD coated cutting tools.
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    Investigation of drilling properties of AA7075/Al2O3 functionally graded materials using gray relational analysis
    (Sage Publications Ltd, 2021) Yildiz, Tugce; Sur, Gokhan
    The present paper reports an experimental study on the fabrication and characterization of aluminum-oxide-reinforced functionally graded aluminum composites and optimization of drilling parameters on thrust force and average surface roughness using gray relational analysis. For this purpose, AA7075/Al2O3 functionally graded materials were produced with three layers that have different ratios of Al2O3 via high-temperature isostatic pressing and powder metallurgy method. Hardness behaviors of the layers were determined. Further, microstructural characterizations of the layers were carried out. Functionally graded materials were machined at dry cutting conditions with a 6 mm uncoated cemented carbide drill bit. The drilling experiments were carried out under different conditions such as point angles, helix angles, and feed rates, while the 25 m/min cutting speed was kept constant. The effects of factors on thrust force and surface roughness were evaluated using analysis of variance and gray relational analysis in full factorial experimental design. The minimum thrust force was measured at 221 N in a 140 degrees point angle, 15 degrees helix angle, and 0.075 mm/rev feed rate. Results of the gray relational analysis showed that feed rate was the dominant factor on thrust force and average surface roughness. Consequently, the highest and lowest gray relational grades were obtained at 0.899 and 0.374, respectively.
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    Investigation of photochemical machining characteristics of stainless steel AISI 304 via novel PCM equipment design
    (Emerald Group Publishing Ltd, 2022) Tunc, Murat; Gokkaya, Hasan; Sur, Gokhan; Motorcu, Ali Riza
    Purpose The purpose of the paper is to investigate photochemical machining characteristics of stainless steel (AISI 304-SS304) parts with a novel design are investigated experimentally from the aspect of process parameters. The effects of phototool pattern geometry, ultraviole (UV) exposure time and etching time on of AISI 304 were evaluated. Design/methodology/approach The designed semi-automated photochemical manufacturing (PCM) equipment consists of 4 units, which include UV exposure, etching, developing and surface cleaning units. Experimental procedure has been designed via Taguchi method. Results were evaluated via Analysis of Variance (ANOVA) method. Findings Etching time is the most effective factor in PCM quality of AISI 304 stainless steel. Surface roughness is sensitive to geometrical pattern of the phototool for PCM of AISI 304 UV exposure time is less influential on the PCM quality for stainless steel. Research limitations/implications The designed PCM equipment prototype is not fully automated, which requires automation for part replacements into units. The effects of the temperature inside chemical processing units on process characteristics cannot be evaluated due to equipment limitations. The effects of surface cleaning time inside surface cleaning unit are not analyzed. Originality/value The utilized PCM equipment is semi-automated equipment, with which the process parameters such as etching time, surface cleaning time, UV exposure time and developing time can be controlled. Different from literature, the effects of phototool pattern geometries on the photochemical machining quality parameters are evaluated for the processing of AISI 304. The effects of processing parameters on dimensional accuracy, which is not common in the literature for AISI 304 stainless steel, are also evaluated.
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    INVESTIGATION OF SURFACE MORPHOLOGY OF DRILLED CFRP PLATES AND OPTIMIZATION OF CUTTING PARAMETERS
    (World Scientific Publ Co Pte Ltd, 2020) Erkan, Omer; Sur, Gokhan; Nas, Engin
    In this study, the carbon fiber reinforced polymer (CFRP) composite material was drilled using different parameters (118 degrees and 140 degrees Point Angle, 30, 60 and 90 m . min(-1) cutting speed and 0.06, 0.08 and 0.10 mm . rev(-1) feed rate). Experimental parameters were designed according to full factorial design method and the results were analyzed using Taguchi L18 experimental design. The results of the study show that the lowest surface roughness values are 0.1958 and 0.1945 mu m with the cutting speed of 90 m . min(-1) and feed rate of 0.06 m . rev(-1) in the Point angles of 118 degrees and 140 degrees, respectively. When the results of Anova analysis were evaluated, parameters (feed speed, cutting speed and end point angle) according to the effect ratios on surface roughness were formed at the rates of 41.06%, 33.13% and 5.07%, respectively. The most suitable parameters according to S/N ratios were determined using A2B3C1 factors for the average surface roughness.
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    Single and multi-objective optimization for cutting force and surface roughness in peripheral milling of Ti6Al4V using fixed and variable helix angle tools
    (Elsevier Sci Ltd, 2022) Sur, Gokhan; Motorcu, Ali Riza; Nohutcu, Samet
    Ti6Al4V titanium (Ti) alloy is a frequently used engineering material in industrial applications due to its superior properties. In this work, single-objective and multi-objective methods were used to optimize control factors (cutting speed, feed rate, and cutting tool helix angle) for minimal cutting force (Fc) and surface roughness (Ra) in peripheral milling of Ti6Al4V. Machinability experiments were performed using carbide end mill cutting tools with fixed and variable helix angles. Following the machinability tests performed using the L18 orthogonal array, the Taguchi technique was used as a single-objective optimization for each of the cutting forces and surface roughness. The Entropy-weighted TOPSIS approach was used in the second step to provide the optimum levels of the control factor, which minimizes both cutting force and surface roughness. The effects of control factors and interactions on thrust force and surface roughness were determined by Analysis of Variance (ANOVA) and contour plots. As a result of this study, it was determined that the helix angle of the cutting tool (84.91 % contribution) was the most effective parameter on the cutting force and the feed rate (22.71 % contribution) on the surface roughness. The cutting force and surface roughness values decreased in peripheral milling at high cutting speed, whereas the cutting forces increased, and the surface quality of the workpiece deteriorated in machining at high feed rates. The helix angle of the cutting tool has a favorable influence on the cutting force and surface roughness when milling with fixed helix tools. Cutting forces are minimized, and workpiece surface quality is improved using cutting tools with a larger helix angle. Variable helix tools with a large helix angle performed best in cutting force and surface roughness. Variable helix end mills with large helix angle (HA = 35 degrees/ 38 degrees), high cutting speed (Vc:108 m/min), and a low feed rate (f:0.04 mm/tooth) should be used in peripheral milling of Ti6Al4V Ti alloy to achieve both minimum cutting force and best surface quality. The mean cutting force and surface roughness values were obtained as 628.69 N and 0.363 mu m, respectively, in the peripheral milling process performed at different levels of control factors. The cutting force was reduced to 227.52 N (34.71 % improvement) and the surface roughness value to 0.237 mu m (276.32 % improvement) using the Entropyweighted TOPSIS multi-objective optimization approach.
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    Surface quality optimization of CFRP plates drilled with standard and step drill bits using TAGUCHI, TOPSIS and AHP method
    (Emerald Group Publishing Ltd, 2021) Sur, Gokhan; Erkan, Omer
    Purpose Drilling of carbon fiber reinforced plastic (CFRP) composite plates with high surface quality are of great importance for assembly operations. The article aims to optimize the drill geometry and cutting parameters to improve the surface quality of CFRP composite material. In this study, CFRP plates were drilled with uncoated carbide drill bits with standard and step geometry. Thus, the effects of standard and step drill bits on surface quality have been examined comparatively. In addition, optimum output parameters were determined by Taguchi, ANOVA and multiple decision-making methods. Design/methodology/approach Drill bit point angles were selected as 90 degrees, 110 degrees and 130 degrees. In cutting parameters, three different cutting speeds (25, 50 and 75 m/min) and three different feeds (0.1, 0.15 and 0.2 mm/rev) were determined. L18 orthogonal sequence was used with Taguchi experimental design. Three important output parameters affecting the surface quality are determined as thrust force, surface roughness and delamination factor. For each output parameter, the effects of drill geometry and cutting parameters were evaluated. Input parameters affecting output parameters were analyzed using the ANOVA method. Output parameters were estimated by creating regression equations. Weights were determined using the analytic hierarchy process (AHP) method, and multiple output parameters were optimized using technique for order preference by Similarity to An ideal solution (TOPSIS). Findings It has been determined from the experimental results that step drills generate smaller thrust forces than standard drills. However, it has been determined that it creates greater surface roughness and delamination factor. From the Taguchi analysis, the optimum input parameters for Fz step tool geometry, 90 degrees point angle, 75 m/min cutting speed and 0.1 mm/rev feed. For Fd, are standard tool geometry, 90 degrees point angle, 25 m/min cutting speed and 0.1 mm/rev feed and for Ra, are standard tool geometry, 130 degrees point angle, 25 m/min cutting speed and 0.1 mm/rev feed. ANOVA analysis determined that the most important parameter on Fd is the tip angle, with 56.33%. The most important parameter on Ra and Fz was found to be 40.53% and 77.06% tool geometry, respectively. As a result of the optimization with multiple criteria decision-making methods, the test order that gave the best surface quality was found as 4-1-9-5-8-17-2-13-6-16-18-15-11-10-3-12-14. The results of the test number 4, which gives the best surface quality, namely, the thrust force is 91.86 N, the surface roughness is 0.75 mu m and the delamination factor is 1.043. As a result of experiment number 14, which gave the worst surface quality, the thrust force was 149.88 N, the surface roughness was 3.03 mu m and the delamination factor was 1.163. Practical implications Surface quality is an essential parameter in the drilling of CFRP plates. Cutting tool geometry comes first among the parameters affecting this. Therefore, different cutting tool geometries are preferred. A comparison of these cutting tools is discussed in detail. On the other hand, thrust force, delamination factor and surface roughness, which are the output parameters that determine the surface quality, have been optimized using the TOPSIS and AHP method. In this way, this situation, which seems complicated, is presented in a plain and understandable form. Originality/value In the experiments, cutting tools with different geometries are included. Comparatively, its effects on surface quality were examined. The hole damage mechanism affecting the surface quality is discussed in detail. The results were optimized by evaluating Taguchi, ANOVA, TOPSIS and AHP methods together.
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    Three-Point Bending Response of Corrugated Core Metallic Sandwich Panels Having Different Core Configurations - An Experimental Study
    (Eos Assoc, 2019) Zurnaci, Erman; Gokkaya, Hasan; Nalbant, Muammer; Sur, Gokhan
    Bending response of corrugated core metallic sandwich panels was studied experimentally under three-point bending loading. Two different core configurations were used: the corrugated monolithic core and the corrugated sliced core. The trapezoidal corrugated cores were manufactured from aluminum sheets via a sheet metal bending mould. After the sandwich panel samples were prepared, they were subjected to three-point bending tests. The load and displacement responses of the sandwich panels having different core configurations were obtained from the experimental testing. The influence of the core configuration on the three-point bending response and failure modes was then investigated. The experimental results revealed that the corrugated sliced core configuration exhibited an improved bending performance compared to the corrugated monolithic core configuration.