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    Effects of Cutting Parameters and Point Angle on Thrust Force and Delamination in Drilling of CFRP
    (Carl Hanser Verlag, 2014) Yardimeden, Ahmet; Kilickap, Erol; Celik, Yahya Hisman
    Parts made of composite materials are generally produced by near-net-shape technology. However, additional machining operations such as drilling are often required to facilitate components assembling. Drilling of composite materials is also a common process in the assembly of aerospace and automotive composite structures. During drilling, unlike the conventional materials, a few damage forms may take place. Among these damage forms, the delamination is the most important one. Therefore, the experimental studies carried out on drilling of CFRP composite materials for determining optimum processing parameters are of great importance. In this particular study, delamination in CFRP composites caused by drilling was investigated. The composite material was drilled under various spindle speeds, feed rates and drill point angles. The results showed that delamination and thrust forces were affected by cutting parameters. It was demonstrated that feed rate and drill point angle make the largest contribution to the overall performance.
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    Estimate of cutting forces and surface roughness in end milling of glass fiber reinforced plastic composites using fuzzy logic system
    (Walter De Gruyter Gmbh, 2014) Celik, Yahya Hisman; Kilickap, Erol; Yardimeden, Ahmet
    Milling glass fiber reinforced plastic (GFRP) composite materials are problematic, owing to, e. g., nonhomogeneous and anisotropic properties and effects of plastic deformation. To reduce these problems, the effects of cutting speed, feed rate, and the number of flutes on surface roughness and of thrust forces occurring during the milling of GFRP composite materials were investigated by both experimental and fuzzy logic models. Experiments were performed at 30 m/min, 60 m/min, and 90 m/min cutting speeds, at 0.1 mm/rev, 0.15 mm/rev, and 0.2 mm/rev feed rates and 10 mm diameters in a cemented carbide end mill, which has two, three, and four flutes without cutting fluids. The values obtained from experiments were defined by a fuzzy logic model. A fuzzy logic model was employed to estimate the surface roughness and thrust forces for different cutting parameters. As a result of both the experimental study and the fuzzy logic model, while the minimum thrust force was obtained at low cutting speeds, and feed rates and a high number of flutes end mill, the best surface quality was obtained at low feed rates, high cutting speed, and number of flutes end mill.
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    Investigation of experimental study of end milling of CFRP composite
    (Walter De Gruyter Gmbh, 2015) Kilickap, Erol; Yardimeden, Ahmet; Celik, Yahya Hisman
    Carbon fiber-reinforced plastic (CFRP) composites are materials that are difficult to machine due to the anisotropic and heterogeneous properties of the material and poor surface quality, which can be seen during the machining process. The machining of these materials causes delamination and surface roughness owing to excessive cutting forces. This causes the material not to be used. The reduction of damage and surface roughness is an important aspect for product quality. Therefore, the experimental study carried out on milling of CFRP composite material is of great importance. End milling tests were performed at CNC milling vertical machining center. In the experiments, parameters considered for the end milling of CFRP were cutting speed, feed rate, and flute number of end mill. The results showed that damage, surface roughness, and cutting forces were affected by cutting parameters and flute number of end mill. The best machining conditions were achieved at low feed rate and four-flute end mill.
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    Investigation of optimum cutting parameters and tool radius in turning glass-fiber-reinforced composite material
    (Walter De Gruyter Gmbh, 2016) Yardimeden, Ahmet
    Glass-fiber-reinforced composite materials (GFRPs) are used widely in various fields of engineering. Turning is the principal process conducted on these materials for obtaining minimum surface roughness. Machining of GFRP materials is different from traditional style due to their inhomogeneous and anisotropic structures. Optimum machining parameters for specific GFRP materials need to be ascertained for perfect machining. In this study, the influence of cutting parameters and insert radius on the cutting force and surface roughness of GFRP material during machining was investigated. For measuring main cutting force, a three-component piezoelectric crystal type of dynamometer was used. Cutting force and surface roughness were experimentally measured through longitudinal axes of the GFRP material. Through this study, it was observed that high cutting speeds and low feed rates provide the best surface quality in the turning process of GFRP composite materials.
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    Optimization of drilling parameters on surface roughness in drilling of AISI 1045 using response surface methodology and genetic algorithm
    (Springer London Ltd, 2011) Kilickap, Erol; Huseyinoglu, Mesut; Yardimeden, Ahmet
    Modeling and optimization of cutting parameters are one of the most important elements in machining processes. The present study focused on the influence machining parameters on the surface roughness obtained in drilling of AISI 1045. The matrices of test conditions consisted of cutting speed, feed rate, and cutting environment. A mathematical prediction model of the surface roughness was developed using response surface methodology (RSM). The effects of drilling parameters on the surface roughness were evaluated and optimum machining conditions for minimizing the surface roughness were determined using RSM and genetic algorithm. As a result, the predicted and measured values were quite close, which indicates that the developed model can be effectively used to predict the surface roughness. The given model could be utilized to select the level of drilling parameters. A noticeable saving in machining time and product cost can be obtained by using this model.
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    Three-Dimensional Modeling and Quantitative Assessment of Mandibular Volume in Ectodermal Dysplasia: A Case Series
    (Mdpi, 2024) Akleyin, Ebru; Yavuz, Yasemin; Yardimeden, Ahmet
    Background and Objectives: Ectodermal dysplasia (ED)-a genetic disorder-is characterized by severe tooth deficiency. We compared the mandibular volume and the sagittal and horizontal mandibular widths between patients with ED (ED group) and individuals without tooth deficiency (control group) using three-dimensional modeling. We hypothesized that the mandibular volume differs in ED cases owing to congenital tooth deficiency. Materials and Methods: We used previously obtained cone-beam computed tomography (CBCT) images of 13 patients with ED. The control group data comprised retrospective CBCT images of patients of similar age and sex with a skeletal relationship of class 1. Further, using the three-dimensional image analysis software, the tooth crowns were separated from the mandible, the mandible was reconstructed and the gonion-to-gonion distance in the mandible was marked, the distance to the menton point was measured, and the distance between the two condyles was measured and compared with the control group. Results: Overall, 46.2% and 53.8% of the participants were men and women, respectively. In the ED group, the mean age of the participants was 15.46 (range, 6-24) years, and the mean number of mandibular teeth was 4.62. Notably, the edentulous mandible volume of the ED group (27.020 mm(3)) was statistically significantly smaller than that of the control group (49.213 mm(3)) (p < 0.001). There was no difference between the two groups in terms of the marked points. For data analysis, the Shapiro-Wilk test, independent samples t-test, and Mann-Whitney U test were used. Conclusions: It has been considered that mandible volume does not develop in ED cases because of missing teeth. Modern practices, such as the CBCT technique and three-dimensional software, may be effective in identifying the true morphologic features, especially in patients with genetic syndromes affecting the maxillofacial structure.