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Yayın The development of a hybrid cutting model for workpiece temperature distribution via advection heat partition approach(Springer Science and Business Media Deutschland GmbH, 2023-04-15) Kara, Mehmet Emre; Kuzu, Ali Taner; Bakkal, MustafaThis paper presents a novel hybrid cutting model for the prediction of workpiece temperature distribution during the dry milling process of compacted graphite iron (CGI). The hybrid model consists of an analytical force model based on a mechanistic approach and finite element analysis (FEA) based on the thermal model. The heat generated during the milling process transferred to the workpiece is computed via the advection heat partition model. The workpiece temperature distribution obtained through the heat loads, using as boundary conditions in the FEA, was calculated by means of cutting forces. The developed force and thermal models have been experimentally validated, and good agreement between the measured and calculated results has been observed. The energy and active work calculations show that by doubling the feed during CGI milling, an energy saving of about 10% is achieved despite almost doubling the cutting forces.Yayın Enhancing mechanical performance of FDM-printed ABS parts through annealing optimization(John Wiley and Sons Inc, 2025-06-18) Kösemen, Elifnur; Bakkal, Mustafa; Kuzu, Ali TanerThis study examines the impact of annealing on the mechanical properties of acrylonitrile butadiene styrene (ABS) parts produced using fused deposition modeling (FDM). The research investigates how different annealing temperatures (90°C, 105°C, and 120°C), production orientations (upright, on edge, and flat), and infill patterns influence hardness, tensile strength, and impact resistance. Experiments were conducted using a Stratasys F370 printer, and samples were tested following ISO standards for mechanical performance. Results indicated that annealing at 90°C and 105°C generally improved hardness, tensile strength, and impact resistance, particularly for upright and on-edge orientations. However, annealing at 120°C led to a decrease in these properties, likely due to microstructural changes observed through scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analysis. The study highlights the importance of optimizing production parameters and annealing conditions to achieve desired mechanical properties in FDM-printed ABS parts. These findings may inform post-processing strategies for enhancing the reliability and performance of additive manufactured components, particularly for applications in industries utilizing ABS materials for customized and prototype parts.Yayın Investigation of residual stresses induced by turning of hot forged and heat treated AA7075(Springer Science and Business Media Deutschland GmbH, 2024-12) Tok, Görkem; Kuzu, Ali Taner; Bakkal, MustafaThis study investigates the impact of cutting parameters on residual stress in components made from AA7075 material, which were hot forged and subsequently subjected to T6 heat treatment. Using the Taguchi experimental design, two distinct cutting cases—face turning and circumferential turning—were devised to assess residual stress at different sections of the part. During the turning process, force measurements were conducted with a dynamometer, and residual stress was subsequently measured using the X-ray diffraction method. The results indicate that both mechanical and thermal loadings significantly influence residual stress. Notably, spindle speed has the most substantial effect on residual stress in both face turning and circumferential turning, with an observed increase of up to 30% and 20%, respectively, in tensile residual stress for Case 1 and Case 2. When thermal loads are predominant, residual stress tends to be tensile, with measurements reaching as high as 89 MPa.Yayın Effect of mechanically exfoliated graphite flakes on morphological, mechanical, and thermal properties of epoxy(Multidisciplinary Digital Publishing Institute (MDPI), 2024-11-11) Gül, Ayşenur; Kamali, Ali RezaCarbon-reinforced polymer composites form an important category of advanced materials, and there is an increasing demand to enhance their performance using more convenient and scalable processes at low costs. In the present study, graphitic flakes were prepared by the mechanical exfoliation of synthetic graphite electrodes and utilized as an abundant and potentially low-cost filler to fabricate epoxy-based composites with different additive ratios of 1–10 wt.%. The morphological, structural, thermal, and mechanical properties of these composites were investigated. It was found that the thermal conductivity of the composites increases by adding graphite, and this increase mainly depends on the ratio of the graphite additive. The addition of graphite was found to have a diverse effect on the mechanical properties of the composites: the tensile strength of the composites decreases with the addition of graphite, whilst their compressive strength and elastic modulus are enhanced. The results demonstrate that incorporating 5 wt% of commercially available graphite into epoxy not only raises the thermal conductivity of the material from 0.223 to 0.485 W/m·K, but also enhances its compressive strength from 66 MPa to 72 MPa. The diverse influence of graphite provides opportunities to prepare epoxy composites with desirable properties for different applications.Yayın Predictive modelling of surface roughness and residual stress induced by milling of hot forged and heat treated AA7075(Springer Nature, 2025-11-03) Tok, Görkem; Dinçer, Ammar Tarık; Kuzu, Ali Taner; Bakkal, MustafaThis study investigates the influence of cutting parameters on residual stress and surface roughness during the milling of hot-forged and T6 heat-treated AA7075 components. Using Taguchi L9 and full-factorial experimental designs and regression modelling, the research highlights important relationships between cutting parameters (cutting speed, feed rate, and depth of cut), residual stress and surface roughness. Higher cutting speeds (350 m/min) and lower feed rates (0.1 mm/tooth) significantly minimized residual stresses, with hoop stress values decreasing from 108.7 MPa at lower speeds (150 m/min) to approximately 73.4 MPa at higher speeds, and axial stress values ranging from 45.9 MPa to 88.5 MPa. Surface roughness (Ra) was most influenced by feed rate, with measurement values varying between 0.25 mu m and 0.92 mu m. Support Vector Regression (SVR) demonstrated better accuracy for predicting residual stress (MAPE: 11.5%) and surface roughness (MAPE: 7%), outperforming Lasso and Ridge regression models. These findings provide a consistent framework for optimizing cutting parameters and enhancing residual stress and surface roughness in AA7075 machining processes, offering practical implications for improving component performance and manufacturing efficiency.
