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    Analysis of Drilling Behaviour in Jute Fibres Reinforced Natural Composites
    (Taylor & Francis Inc, 2023) Ozdemir, Burak; Yardimeden, Ahmet; Bahce, Erkan; Kilickap, Erol; Emir, Ender
    In the study, Natural jute composite materials, which have environmental advantages due to their easily degradable nature were drilled with different processing parameters and the effects of thrust force, vibration and temperature changes on hole quality were investigated. The effect of feed and spindle speed was statistically analyzed using ANOVA method. The thrust force, vibration and temperature factors that occur depending on the drilling parameters vary and affect the roughness and delamination values. The effect of feed and speed on thrust force was calculated as 97.87% and the feed effect (90.85%) is far greater than the speed (9.15%). The effect of drilling parameters on vibration is statistically insignificant due to the different spread behavior in the layers of the composite material (R2 = 0.2329). However, feed effect on vibration (94.6%) is greater than the speed effect (6.06%). The temperature is affected by 96.93% of the drilling parameters and the speed is 84.16% and the feed is 15.83%. The roughness effect depending on the drilling parameters is measured as 84.91%. The effect of speed on roughness (90.26%) is greater than the feed (9.73%). It has been determined that this situation is mostly related to vibration and temperature.
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    ANALYZING THE EFFECTS OF DIFFERENT TOOL PATHS ON FORM ERRORS IN THE MILLING OF FREEFORM SURFACES
    (Yildiz Technical Univ, 2020) Bahce, Erkan; Ozdemir, Burak
    Machining of free-form surfaces is an important place in terms of design and performance in transportation, electronics and aeronautical industry. Problems such as form error and surface roughness were frequently encountered in the manufacture of these surfaces. For the solution of the problems, reprocessing is done, which causes time and resource loss. To eliminate these losses, the parts must be produced in the desired quality at one time. In order to find out the causes of form errors and to remove the adverse effects, the distribution on the surface must be determined correctly. Form errors should be examined in a way to cover the point, region and the whole part. In this study, a surface created with B-Spline curve has been processed with different tool paths. Surfaces were scanned in 3D and form errors were determined. Point, regional and whole parts are examined and the tool path that creates minimum form error is determined.
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    Burr Measurement Method Based on Burr Surface Area
    (Korean Soc Precision Eng, 2021) Bahce, Erkan; Ozdemir, Burak
    One of the major issues of drilling operations pertains to the formation of burrs, which greatly influences the accuracy of the manufactured parts, and, thus, the capability to meet the desired performance of the part. To remove or prevent these burrs, their geometry must be measured accurately, even though they are sharp and irregular in shape. The accurate measurement of the geometry of a burr will lead to the development of a proper deburring method. In this work, the authors describe a simple and convenient new measurement technique for drilling burr profiles and a developed drilling burr measurement system based on surface area. The new method presented in this research aims at providing a comparative evaluation of the height, arc length and area of the burr, as well as its geometrical characteristics. When the average height and arc length measurement methods are compared with the area measurement method, large deviations in burr height are detected. In particular, these deviations increase more in non-uniform burrs. In the measurement of burr size, the new developed method is based on area measurement and is carried out using a computer. Therefore, there is no deviation between the measurements. In contrast, the average deviation ranges for the height and arc length measurement methods are found to be 9.94-48.14% and 6.07-18.82%, respectively.
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    Determination of tool deflection in drilling by image processing
    (Inst Engineering Technology-Iet, 2019) Bahce, Erkan; Ozdemir, Burak
    It is known that parameters such as the feed rate and the spindle speed affect the hole quality during the drilling of aluminium and its alloys. In particular, deflection occurs as a result of the increase or decrease of the reverse forces acting on the tool as a result of changing the parameter values. The tool deflection causes deviations in the hole geometry. This requires the initial detection of the deflection on the tool and then the most appropriate updating of the drilling parameters. At the present time, force-based estimation and inductive or laser sensor detection methods are used for the detection of tool deflection. These methods are useless because they require expensive measurement systems and continuous fine-tuning. This study aimed to calculate the tool deflection that occurs during the drilling of AL 7075 material using an image processing technique. In the experiments using different drilling parameters, the tool deflection was calculated and the effects of the parameters on tool deflection were investigated. As a result, it is shown that the tool deflection can be detected quickly and simply by image processing. In addition, the effects of the processing parameters on the tool deflection are discussed.
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    Mechanical characterization of lattice structure produced by additive manufacturing under torsion and compression
    (Sage Publications Ltd, 2024) Akbay, Ozgun Ceren; Ozdemir, Burak; Bahce, Erkan; Emir, Ender; Uysal, Mine Uslu
    In the present paper, the torsion and compression behaviors of lattice structures were studied. The PLA (Polylactic Acid) materials were used in assembly and produced by additive manufacturing method. The structure and lattice behaviors were investigated by Digital Image Correlation (DIC) system during experimental study. Models created using three different unit cell model as Trunch Octa Dense, Trunch Octa Light, Body Diagonals With Nodes and two different, 70 mm and 140 mm, total length size. The influence of the unit cell model, cell size on the strength of the structure were studied by compression and torsion experiments. The maximum compressive stress and maximum torsion were obtained and their deformations were presented. The highest maximum torque was determined in Body Diagonals With Nodes cell model and 140 mm due to the fact that the cell model structure compatible with torsion. The highest compressive stress was determined in Trunch Octa Light cell model and 140 mm cell length. Graphical Abstract
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    Monitoring chip color change in Ti6Al4V alloy milling and investigating the effects of cooling/lubrication on chip morphology
    (Elsevier Sci Ltd, 2024) Ozdemir, Burak; Bahce, Erkan; Aksungur, Serhat; Cakir, M. Cemal
    This study investigated how image processing technology and cooling/lubrication methods affect the change in chip color and chip shape when milling Ti6Al4V alloy. The focus was on solving the high temperature problem in the machining of titanium alloys, which are hard and have limited thermal conductivity. The experiment was carried out under the same standards as dry, coolant, MQL (minimum amount of lubrication), and cryogen. Experiment results showed that cooling and lubricating methods had an influence on chip morphology, with the chips morphing into tubular long spiral chips, conical short spirals, and short tubular chips. Dry machining produced distinctively adiabatic bands and saw-type chip formations. These structures were found to be at a lower level in the cryogenic cooling process than in other methods. Methods of cooling and lubrication were found to be effective on chip thickness, width, and radius. In addition, the color difference caused by burning in the chip depending on the machining temperature was investigated. The S (saturation ratio) of colors in the chip image processing rose in the order of cryogen, coolant, MQL, and dry machining (0.131623, 0.150836, 0.208414, 0.230374) technique. When the temperature change was evaluated according to the cooling and lubrication techniques, the lowest temperature was found in cryogenic processing; the temperature value rose by 25 % in fluid, 35 % in MQL, and 55 % in dry machining. As a result, the intention of this study is to improve machining performance by monitoring chip structures.
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    Optimization of parameters for drilling composite materials with freeform surfaces
    (Taylor & Francis Inc, 2024) Ozdemir, Burak; Kilickap, Erol; Bahce, Erkan; Yardimeden, Ahmet; Emir, Ender
    In the drilling process, the angle of surface is one of the parameters that affect hole quality. In study, the effects of feed rate, spindle speed and surface angle on the thrust force, roughness, and delamination, which are the factors affecting the quality of hole, were investigated in the drilling of GFRP (glass fiber reinforced polymer) and CFRP (carbon fiber reinforced polymer) with freeform surfaces. With ANOVA (Analysis of Variance) and regression analysis, the parameter effects were statistically compared, and descriptive mathematical models were derived. The mathematical models were subjected to the Genetic Algorithm approach according to the different surface angles determined and the optimum parameter values were calculated. Guiding data were obtained about the effects of machining on hole quality in drilling composite at different surface angles, which is the main motivation of the study. Optimization results will improve hole quality on curved surfaces, while saving cost and time.
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    Prediction of tool deflection using image processing in ball-end milling
    (Sage Publications Ltd, 2023) Ozdemir, Burak; Bahce, Erkan
    In milling, some of the factors that contribute to the poor quality of products are the cutting forces. Depending on the machining parameters, the cutting forces may significantly affect the tool being used in the machining process. Tool deflection can be modeled as bending deformation. Tool deflection causes poor surface quality, geometrical and dimensional errors. For this reason, it must be addressed during milling and reduced by changing the machining parameters. In the determination of tool deflection, force-based analytical and finite element methods (FEM) and sensor measurement methods are widely used. These technologies have drawbacks such as not being able to obtain fast data, being expensive, demanding precise control, and requiring continual calibration. This study aims to determine the deflection of the tool by image processing dependent on the tool/material pair and machining parameters in the milling process. For this purpose, the AL7075 material with a free-form surface was machined on a CNC milling machine. A mathematical equation is proposed to estimate the tool deflection based on the image processing results. The method has shown that tool deviation can be detected more quickly and simply by image processing.