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Yayın Analysis of mechanical behavior of termoplastic composites(Necip Fazıl YILMAZ, 2022-03-04) Kuzu, Ali Taner; Kosemen, Elifnur; Yücel, Aysu Hande; Bakkal, MustafaThis paper presents the effect of fiber orientation on the tensile, compression, impact, and flexuralproperties of glass fiber reinforced acrylic-based thermoplastic composites. The mechanical behaviorof three different composite plates, produced by the resin transfer molding (RTM) method, with0°/90°/45°, 0°/90° and ±45° glass fiber orientations were investigated by carrying out tensile,compression, three-point bending and Charpy impact tests. A Weibull distribution model wasimplemented to explain the variation in mechanical properties of the acrylic-based composite.According to Weibull analysis results with 63.2% probability, the highest tensile strength (561 MPa),compressive strength (293 MPa) and impact values (19.44 J) were obtained when the plate with0°/90° glass fiber orientation was tested, whereas the highest flexural strength was obtained when theplate with 0°/90°/45° was tested.Yayın Dairesel testere makine parametrelerinin yüzey kalitesine etkisi incelenmesi(Motto, 2024-11-03) Çakır, Hasan; Yılmaz, Mahmut; Yeter, Alper; Karagüzel, Umut; Kuzu, Ali Taner; Bakkal, Mustafa; Saklakoğlu, İ. EtemDairesel testere ile yapılan kesimlerde gelişen teknolojiyle birlikte kesilen yüzeylerde yüksek yüzey kalitesi beklentisi artmıştır. Yüzey kalitesine kesme işleme sırasında kullanılan dairesel testere ve testere malzeme yapısı doğrudan etki etmektedir. Aynı zamanda makine çalışma parametreleri de yüzey kalitesine etki etmektedir. Yapılan bu çalışmada makine çalışma parametreleri içersinde yer alan ilerleme ve kesme hızlarında, farklı değerler kullanılarak kesme deneyleri yapılmıştır. Deneyler veri toplama cihazı ile makine gövdesi üzerine yerleştirilen ivmeölçer sensörlerden titreşim verileri toplanmıştır. Toplanan veriler, veri toplama cihazı arayüz programında işlenerek maksimum ivme değerleri ve ivmelerin ortalama karekök değerleri hesaplanmıştır. Hesaplanan veriler ile krest faktörünün farklı ilerleme ve kesim hızlarında değeri bulunmuştur. Yüzey pürüzlülük ölçüm cihazı kullanılarak kesim yapılan parçaların yüzey pürüzlülük değeri tespit edilmiştir. Deneyler sonucunda makinede meydana gelen titreşimlerin yüzey pürüzlülüğüne olan etkisi araştırılmıştır.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 Effect of cutting strategy on machining of thin walled polymer(UTIS Organizing Committee, 2017-11-02) Keklik, Burak Taha; Kuzu, Ali Taner; Başçı, Ümit Gencay; Karagüzel, Umut; Kayıhan, Mete; Bakkal, MustafaThis paper presents the effect of tool path on machining of thin walled thermoplastic polymer, ABS. The effects of cutting speed, feed rate and tool path are studied to evaluate surface quality on thin walled parts. Four different cutting pattern (“zig”, “zig-zag”, “follow periphery” and “trochoidal”) with uncoated WC tool were investigated in the cutting tests. The quality of grooves was examined by their surface roughness, dimensional accuracy and burr structure. Experiments show that the down-milling and “follow periphery” creates dimensionally more accurate grooves. Average 4 μm surface roughness and discontinuous chip formation is obtained in up-milling process. According to the study, the better surface quality and dimensional accuracy can be achieved by down milling in “zig-zag” pattern in terms of surface roughness.Yayın Effect of scanning strategies and laser parameters on metal-composite joining(Bellwether Publishing, 2021-07-27) Kuzu, Ali Taner; Karagüzel, Umut; Erbay, Batıray; Bakkal, MustafaThis study presents an investigation on the effectiveness, automation characteristics, and mechanics of joints between different material types namely glass ?ber reinforced plastics (GFRPs) and SS304 stainless steel using an industrial Nd: YAG continuous-wave laser welder and a 2-axis custom design jig. The custom design jig includes computer-controlled (CNC) step motors, which provide high accuracy position control of the selected laser patterns. Four different patterns (Linear Curve, Hilbert Curve, Triangle Weave, and Curlique Weave) are investigated under different process parameters (laser power, lap joint length, and traveling speed) to obtain more robust joints. The strength of the joint is examined by variance analysis and found that the laser power and the pattern are the most important factors. Tensile shear tests present that the best-resulted joint carried around 4000 N before fracture. Polymer vaporization resulted in sub-millimeter sized bubbles that are widely formed inside the molten zone of the GFRP specimen. Therefore, a strong joint between GFRP and SS304 stainless steel could be obtained by a direct laser joining process at low power, with load adaptable space-filling curve patterns and without needing surface pretreatment, sophisticated clamps or high clamping forces.Yayın Effects of different production parameters on mechanical properties in FDM-printed products(Eklemeli İmalat Derneği Yayınları, 2022-10-08) Kösemen, Elifnur; Kuzu, Ali Taner; Bakkal, MustafaFDM, which is a common additive manufacturing technology in producing plastic parts, allows for the comparison of many different production parameters. This article presents the variation of density, hardness, tensile and impact strength depending on the production parameters of the number of contours, infill pattern and orientation angle. 8 different production parameter combinations were created using 2 diff erent contour numbers as 1 and 2, 2 different infill patterns as sparse high density and hexagram, and two different orientation angles as 0o/45o degrees, and sample production was made with FDM technology and ABS material. In the experiments performed on the samples produced with the specified production combinations, no major change in density and hardness was detected, and it was determined that the production parameter combination that gave the best results in both tensile and impact strength was hexagram infill pattern, 45o orientation angle and 2 contour production parameters.Yayın Energy-based characterization of drilling-induced residual stresses in AA7075-T6(Multidisciplinary Digital Publishing Institute (MDPI), 2026-01) Tok, Görkem; Dinçer, Ammar Tarık; Bakkal, Mustafa; Kuzu, Ali TanerThis study examines the influence of drilling parameters on thrust force, torque, active work, and axial residual stress formation in hot-forged and T6-treated AA7075, a critical high-strength aluminum alloy. A full factorial design was applied using three spindle speeds (800, 1000, 1200 rpm) and three feed rates (0.05, 0.10, 0.15 mm/rev). Cutting force and torque signals were measured using a dynamometer, and axial residual stresses were determined by X-ray diffraction at two locations along the hole depth, namely, the hole entrance (Point A) and the hole exit (Point B). The results show that feed rate is the dominant factor influencing drilling mechanics and residual stress formation, whereas spindle speed mainly affects the thermal and frictional conditions governing stress relaxation. A consistent asymmetry was observed between the two measurement locations, with the exit side exhibiting stronger stress relaxation behavior associated with breakthrough mechanics. Finally, the relationship between active work and axial residual stress is discussed using a qualitative, energy-based interpretation, highlighting active work as a physically meaningful indicator for drilling-induced residual stress evolution.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 Experimental analysis on drilling of Al/Ti/CFRP hybrid composites(Bellwether Publishing, 2021-01-25) Kayihan, Mete; Karagüzel, Umut; Bakkal, MustafaCarbon fiber reinforced composites (CFRP) have superior mechanical properties such as high strength/density ratio, and good damping ability. CFRP which is frequently used in parts in the aviation industry can also be single or stacked together with titanium and aluminum alloys. However, delamination could occur on the CFRP surfaces after drilling which leads to deterioration in mechanical properties. Therefore, in this paper, the effect of process parameters and stack order on cutting force, torque are investigated. The tests were carried out at three different drilling speeds and feed rates on a CNC vertical machine tool by using a solid carbide cutting tool. The results of hole quality indicate that the process outputs are significantly affected by process parameters and stack order. The force and torque values obtained at high drilling speeds and low feed rates are independent of the stack order. However, the stacking order is determined to be the most effective parameter for the thrust force and torque values. The force generated during the Ti/CFRP/Al stack in which the highest force value is approximately 50% higher than the lowest force which occurs on Al/Ti/CFRP stack. The surface roughness value measured during the Al/Ti/CFRP stack is approximately half of the other stack order.Yayın Experimental and analytical investigation of drilling in high performance hybrid composites(2019-11-09) Kayıhan, Mete; Karagüzel, Umut; Bakkal, MustafaHybrid composites produced by the addition of metal alloys to carbon fiber reinforced composites (CFRP) have superior mechanical and physical properties, excellent specific strength and high resistance to corrosion. The most commonly used machining processes in the use of hybrid materials in industry is the drilling process. After the drilling processes, due to the anisotropic properties of the CFRP material, delamination, uncut fiber and fiber pullout are observed. For this reason, the performance of CFRP after drilling operation must be the main concern. Therefore, in this study, hybrid materials were tested on factors such as stack order, drilling speed and feed rate which should be applied in hole drilling process and analysis were made on various results. The tests were performed with three-factor and three-level L9 Taguchi orthogonal experiment design due to minimize the cost and material. As a result of this study, the best stack order and drilling parameters of the hybrid composite materials was determined with many variables such as force and torque values, the required energy, surface roughness values and delamination factors.Yayın Frezeyle tornalamada takımda ortaya çıkan termal deformasyonların modellenmesi(Gazi Universitesi Muhendislik-Mimarlik, 2017) Karagüzel, Umut; Bakkal, Mustafa; Budak, ErhanFrezeyle tornalama işleminde işlemiş parça doğruluğu ve üretkenliği arttırarak işlem performansını iyileştirmek kesme kuvvetlerini ve takım ucundaki ısı kaynaklı deformasyonları kontrol etmekle mümkündür. Bu çalışmanın amacı frezeyle tornalama sırasında ortaya çıkan ısı kaynaklı deformasyonları belirlemek ve bunları basınçlandırılmış soğuk hava kullanarak azaltmaktır. Kesme kuvvetleri, takım sıcaklıkları ve deformasyonlar sonlu elemanlarla modellenmiş ve deneylerle doğrulanmıştır. Kuru kesme koşullarında bu deformasyonların paso derinliğinin %40’ı kadar olabileceği ve bunun sonlu elemanlarla tahmin edilecebileceği gösterilmiştir. Ayrıca bu deformasyonlar soğuk hava ile %65’e kadar azaltılabilir. Termal deformasyonlara ek olarak çalışmada takım aşınması ve işlenen parçada yüzey pürüzlülüğü değerleri de ölçülmüştür ve özellikle frezeyle tornalamada yüzey pürüzlülüğü değerlerinin taşlamadaki kadar iyi olabileceği gösterilmiştir.Yayın Investigation and prediction of surface integrity induced by milling of hot forged and heat treated AA7075(Motto, 2024-11-03) Tok, Görkem; Dinçer, Ammar Tarık; Kuzu, Ali Taner; Bakkal, Mustafa; Saklakoğlu, İ. EtemThis study examines the influence of cutting parameters on surface integrity, focusing on residual stress and surface roughness, in hot-forged and T6 heat-treated AA7075 components post-milling. Using the Taguchi L9 DOE method, orthogonal cutting milling experiments were performed, with residual stress measured via nondestructive X-ray diffraction (XRD). The analysis indicated that lower cutting speeds reduce residual stress, with down milling causing compressive and up milling causing tensile stresses. A proposed model showed a significant correlation between cutting force and residual stress—higher cutting forces increased residual stress. Surface roughness assessment revealed that feed rate greatly impacts residual stress, with lower feed rates reducing roughness. These insights will aid in developing a regression model for predicting outcomes in future experiments, enhancing the understanding and control of surface integrity in milling AA7075 components.Yayın Investigation of process parameters in rotary swaging(TICMET, 2023-11-16) Bakkal, Mustafa; Karagüzel, Umut; Kuzu, Ali Taner; Kurt, Hasan Aytuğ; Çakır, HasanRotary swaging is a metalworking process used to reduce the diameter of a cylindrical workpiece or to shape it into a desired form. It is a cold-forming process, meaning it is carried out at room temperature or slightly elevated temperatures without the need for additional heat. Rotary swaging is particularly useful for creating components with a taper or complex geometries. In this study, focusing on an effects of die angle and feeding rate upon specified tubular geometry which have 2 mm thickness. An identified load was applied to the tubular geometry in Simufact finite element software for 3 different die angles and feed rates. As a result, optimum die angle and feed rate were determined.Yayın Investigation of residual stresses induced by milling of compacted graphite iron by x-ray diffraction technique(Springer, 2024-04) Kara, Mehmet Emre; Kuzu, Ali Taner; Bakkal, MustafaThis study investigates the relationship between residual stresses, cutting parameters, and machining performance in the milling process of compacted graphite iron (CGI). X-ray diffraction (XRD) analysis is employed to measure residual stresses on the cast and milled surfaces, while cutting force modeling is utilized to calculate the tangential force, power, and active work. The results demonstrate that tensile residual stresses are predominant on the milled surfaces, attributed to the both mechanical and thermal loads generated during milling. By analyzing various cutting conditions, it is observed that lower feeds contribute to reduced plastic deformation, resulting in lower residual stress levels. Additionally, higher cutting speeds lead to higher temperatures, but due to the shorter machining time, heat accumulation is limited, resulting in higher residual stresses, especially at low feeds. At high feeds, residual stresses decreased as the cutting speed increased. The interplay between cutting parameters and residual stresses highlights the need for optimizing cutting conditions to enhance fatigue strength in CGI components. These findings provide valuable insights for process optimization and quality control in the milling of CGI materials.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 Manufacturing techniques of bulk metallic glasses(Wiley, 2019-08-16) Bakkal, Mustafa; Karagüzel, Umut; Kuzu, Ali Taner; Koç, Muammer; Özel, TuğrulThis chapter discusses some of the most common metallic glass sheets, ribbons, and bulk metallic glasses (BMGs) rod, bar, and plate manufacturing methods. The discussed methods include: rapid quenching methods, water-quenching method, arc melting drop/suction casting method, high-pressure die casting method, copper mold casting method, cap casting method, centrifugal casting method, and metal foaming method. Water quenching method is one of the easiest methods to obtain amorphous microstructure for some BMG alloys. Method includes a sequence of heating and quenching processes. Another BMG manufacturing method is arc melting method with a special combination of different casting methods. Arc melting and drop casting methods are well established and known processes for BMG alloys. Drop casting is typically used to process materials with diameters larger than 6mm, while suction casting is used for casting of materials with diameters under 6mm.Yayın Material replacement and topology optimization study on a PVC cutting machine component(TICMET Organizing Committee, 2011-11-03) Hançerkıran, Zeynep; Ahlatcı, Umut Can; Topuzoğlu, Ertan; Kasapcopur, Taylan; Alkan, Erkan; Ertürk, Fikret; Karagüzel, Umut; Bakkal, MustafaIn this study, it is aimed to lighten the aluminum body of the PVC cutting machine, reduce the production cost and shorten the production time. With this purpose, firstly, literature researches of composite materials were made and the PVC machine was introduced. Then, alternative designs of this body were made in Fusion360, and material selection was discussed in line with the analyzes made on the designs in ANSYS. Designs of this body were reexamined by topology optimization of designs created with selected materials. Test and analyzes are shown step-by-step in order to achieve the final result with the necessary changes to mitigate. As a result the body part has lightened up to %70 with the choice of different materials and design.Yayın Mechanical and thermal modeling of orthogonal turn-milling operation(Elsevier Science BV, 2017) Karagüzel, Umut; Bakkal, Mustafa; Budak, ErhanTurn-milling is a relatively new machining technology which is performed for cutting of symmetrical or non-symmetrical rotational parts. To improve productivity, determination of cutting parameters in turn-milling is crucial. However, experimental approach is costly, hence it is important to develop predictive models, especially analytical models, for improved process outputs such as cutting force, MRR, cutting temperature etc. In this study, cutting forces, part quality, MRR, cutting temperatures are modeled for orthogonal turn-milling operation. The developed models are verified by experiments. The results show that the eccentricity parameter in turn-milling has a significant effect on process outputs.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.Yayın Sıcak dövme kalıplarına infrared (kızılötesi) yöntemi ile ön ısıtma uygulanmasına yönelik deneysel ve teorik analiz(Makina Tasarım ve İmalat Derneği, 2020-09-19) Karagüzel, Umut; Kuzu, Ali Taner; Korap, Vedat; Çilingir, Hasan; Bakkal, MustafaSıcak dövme işlemi, üretim teknolojisinin önemli bir parçasınıoluşturur. Sıcak dövmede uygulanan ısı enerjisi ile parçanın akmadayanımı azalır böylelikle şekil verme kabiliyeti artarak daha karmaşıkgeometrili parçaların üretilmesine imkân tanır. Ancak artan sıcaklıklabirlikte kalıp dayanımında da düşüş yaşanması kalıp ömrünün azalmasınave üretim maliyetlerinin artmasına neden olur. Kalıp ömrünü azaltanetkenlerden biri de kalıbın dövme işlemi süresince karşılaştığı yükseksıcaklık farklarıdır, bunun önüne geçebilmek için dövme işlemi öncesindekalıba ön ısıtma işlemi uygulanır. Bu çalışmada sıcak dövme sırasındadengeli ve homojen bir ön ısıtma için infrared ısıtıcı geliştirilmiş veüretime uygulanmıştır. İnfrared ısıtıcının verimi ısıtılıcak kalıbın yüzeydurumuna da bağlı olduğundan, çalışmada kalıp yüzeyi için çeşitlikaplamalar ve yüzey uygulamaları denenmiş ve bunların verimlerikarşılaştırılmıştır. Çalışmada ısıtma prosesinin sonlu elemanlar modelide geliştirilmiş ve sıcaklık sonuçları deneysel sonuçlarlakarşılaştırılmıştır. Geliştirilen model ile sıcaklıkların en fazla % 9’luk birfark ile tahmin edilebileceği ortaya konulmuştur. Bu modelle ayrıca farklıkalıp geometri ve kalıp derinliğinde, istenilen sıcaklığa ulaşabilmek içingereken ısıtma süresi kolaylıkla belirlenebilir. Çalışma sonucundainfrared ısıtıcı ile kalıbın ön ısıtıma işleminin homojen ve verimli birşekilde yapılabiliceği gösterilmiştir.
