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    Decomposition of process damping ratios and verification of process damping model for chatter vibration
    (ELSEVIER SCI LTD, 2012) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Yaldiz, Suleyman
    In the previous study, by the same authors, titled "A new process damping model (PDM) for chatter vibration (Measurement, 44 (8) (2011) 1342-1348)", a new approach has been presented for obtaining process damping ratios (PDRs). This PDM has been constituted on the basis of the shear angle (phi) oscillations of the cutting tool and the alteration of the penetration forces when they penetrate into the wavy surface. Variation and quantity of PDR are predicted by reverse running analytical calculation procedure of traditional Stability Lobe Diagrams (SLDs). In this study, firstly, how the PDM in previous study results with different materials such as AISI-1050 and Al-7075 are examined. Then, two problems are solved: how much of the total PDR of cutting system is caused by the tool penetration and how much is caused by (phi) oscillation? Finally, verification of PDR values and PDM are performed by energy equations. (C) 2012 Elsevier Ltd. All rights reserved.
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    Failure analysis of support during profile cutting process using horizontal milling machine
    (SPRINGER LONDON LTD, 2014) Gok, Kadir; Turkes, Erol; Neseli, Suleyman; Kisioglu, Yasin
    In this study, the effects of cutting forces on the support of horizontal woodworking milling machine are examined during profile cutting process using both experimental and analytical approaches. The support modeled in 3D using SolidWorks software is a crucial component of the horizontal milling machine used to locate and fix the wood workpiece during the cutting process on the workbench. The effects of cutting forces on the support specimens are measured experimentally considering vibration and failure analyses. Analytical stresses and modal analyses of the support were also calculated using finite element-based analysis approach. Chatter vibration forces of the cutting tool which resulted from cutting forces in x-, y-, and z-directions were calculated analytically during the profile cutting process. The results showed that both cutting and chatter forces are highly effective on the support component failure of the woodworking milling machines.
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    Linear analysis of chatter vibration and stability for orthogonal cutting in turning
    (ELSEVIER SCI LTD, 2011) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Yaldiz, Suleyman
    The productivity of high speed milling operations is limited by the onset of self-excited vibrations known as chatter. Unless avoided, chatter vibrations may cause large dynamic loads damaging the machine spindle, cutting tool, or workpiece and leave behind a poor surface finish. The cutting force magnitude is proportional to the thickness of the chip removed from the workpiece. Many researchers focused on the development of analytical and numerical methods for the prediction of chatter. However, the applicability of these methods in industrial conditions is limited, since they require accurate modelling of machining system dynamics and of cutting forces. In this study, chatter prediction was investigated for orthogonal cutting in turning operations. Therefore, the linear analysis of the single degree of freedom (SDOF) model was performed by applying oriented transfer function (OTF) and \tau decomposition form to Nyquist criteria. Machine chatter frequency predictions obtained from both forms were compared with modal analysis and cutting tests. (C) 2010 Elsevier Ltd. All rights reserved.
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    Modelling of dynamic cutting force coefficients and chatter stability dependent on shear angle oscillation
    (SPRINGER LONDON LTD, 2017) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Sahin, Mumin; Selvi, Selcuk
    Productivity of high-speed turning operations is limited by the onset of self-excited vibrations known as chatter. Unless avoided, chatter vibrations may cause large dynamic loads damaging the machine spindle, cutting tool or workpiece and leave a poor surface finish behind. Cutting force magnitude is proportional to the thickness of the chip removed from the workpiece. This paper presents a new procedure to determine dynamic cutting force coefficients (DCFC) required for process simulation by mechanistic modelling. In this study, a two degree of freedom complex dynamic model of turning with an orthogonal cutting system is considered. The complex dynamic system consists of a dynamic cutting system force model based on shear angle (phi) oscillations and penetration forces caused by the tool flank's contact with the wavy surface. The dynamic cutting force coefficients are identified by operating a series of cutting tests at the desired frequency, while changing phi oscillations and penetration forces. It is shown that the process damping coefficient increases as the tool is worn, which increases the chatter stability limit in cutting. The chatter stability of a dynamic cutting process is solved using the Nyquist law and time domain simulation (TDS) techniques and compared favourably against experimental results at low cutting speeds. Finally, comparisons among the proposed mechanistic model and experimental results show a good agreement with the analytically established SLD and, thus, validate the effectiveness of the proposed model.
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    A new process damping model for chatter vibration
    (ELSEVIER SCI LTD, 2011) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Yaldiz, Suleyman
    This paper presents a new analytical process damping model (PDM) and calculation of Process Damping Ratios (PDR) for chatter vibration for low cutting speeds in turning operations. In this study a two degree of freedom complex dynamic model of turning with orthogonal cutting system is considered. The complex dynamic system consists of dynamic cutting system force model which is based on the shear angle (phi) oscillations and the penetration forces which are caused by the tool flank contact with the wavy surface. Depending on PDR, the dynamic equations of the cutting system are described by a new mathematical model. Variation and quantity of PDR are predicted by reverse running analytical calculation procedure of traditional Stability Lobe Diagrams (SLD). Developed mathematical model is performed theoretically for turning operations in this study and simulation results are verified experimentally by cutting tests. (C) 2011 Elsevier Ltd. All rights reserved.
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    Optimization of tool geometry parameters for turning operations based on the response surface methodology
    (ELSEVIER SCI LTD, 2011) Neseli, Suleyman; Yaldiz, Suleyman; Turkes, Erol
    This investigation focuses on the influence of tool geometry on the surface finish obtained in turning of AISI 1040 steel. In order to find out the effect of tool geometry parameters on the surface roughness during turning, response surface methodology (RSM) was used and a prediction model was developed related to average surface roughness (Ra) using experimental data. The results indicated that the tool nose radius was the dominant factor on the surface roughness. In addition, a good agreement between the predicted and measured surface roughness was observed. Therefore, the developed model can be effectively used to predict the surface roughness on the machining of AISI 1040 steel with in 95% confidence intervals ranges of parameters studied. (C) 2010 Elsevier Ltd. All rights reserved.
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    A simple approach to analyze process damping in chatter vibration
    (SPRINGER LONDON LTD, 2014) Turkes, Erol; Neseli, Suleyman
    This paper investigates how changes in chatter amplitude and frequency depend on process damping effect in dynamic turning process. For this purpose, the two degrees of freedom (TDOF) cutting system was modeled, and for an orthogonal turning system, the process damping model with a new simple approach was developed. To further explore the nature of the TDOF cutting model, a numerical simulation of the process was developed by this model. This simulation was able to overcome some of the weaknesses of the analytical model. The equations of motion for this cutting system were written as linear and nonlinear in the tau-decomposition form. The variation in the process damping ratios for different work materials was simply obtained by solving the nonlinear differential equations. A series of orthogonal chatter stability tests were performed for the identification of dynamic cutting force coefficients, using AISI-1040, Al-7075, and Al-6061 work materials, at a constant spindle speed. Finally, the experimental results were analyzed and compared with the simulation model, and it was observed that the results obtained through the experiments comply with the simulation model results.
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    Three-dimensional finite element modeling of effect on the cutting forces of rake angle and approach angle in milling
    (SAGE PUBLICATIONS LTD, 2017) Gok, Kadir; Sari, Huseyin; Gok, Arif; Neseli, Suleyman; Turkes, Erol; Yaldiz, Suleyman
    In this study, milling operations were carried out using AISI 1040 specimens steel in dry cutting conditions. The cutting tools used in the experiment include P20 tool steel and they also have three different approach angles (45 degrees, 60 degrees, 75 degrees) and rake angles (0 degrees, -6 degrees, -12 degrees). In milling experiments, cutting parameters with a depth of cut of 1.5mm, cutting speed of 193m/min, and feed rate of 313mm/min were selected. A comparison was presented between the force values which were obtained by measured value and predicted with numerical simulations, and then a good agreement was found between measured and predicted force values. As result of, it was observed that the rake and approach angles were effective in milling operations.