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    Energy consumption, mechanical and metallographic properties of cryogenically treated tool steels
    (De Gruyter Poland Sp Z O O, 2023) Savas, Ahmet Fevzi; Oktem, Hasan; Ozturk, Burak; Uygur, Ilyas; Kucuk, Ozkan
    This article examines energy consumption, microstructure, mechanical properties, and the change in the wear amount during the machining of GGG-42 cast iron material with two types of guide cutting tool produced by powder metallurgy and casting method The tap. tool samples used as cutting tool material were first subjected to the traditional hardening process and then to two different cryogenic treatments (24-16 h) at -90?. The internal structures of the guide samples obtained from conventional heat treatment and cryogenic treatment were examined with an optical microscope and Scanning Electron Microscope. The hardness changes were checked with Vickers measurement method. The wear amount forming after the threading process was measured with CLEMEX program in a light microscope. In addition, by measuring the current amount drawn during the machining of the cast iron with guide cutter tools, instantaneous power consumption during cutting and power consumption during chip removal were calculated. The application of heat treatment and cryogenic process increased the hardness of the guides. Moreover, the power consumption during the chip removal was also seen to increase. This can be commented that cutting tools produced with powder metallurgy perform better than the cutting tools produced via casting and 30% energy saving.
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    Friction-wear performance in environmentally friendly brake composites: A comparison of two different test methods
    (Wiley, 2021) Akincioglu, Gulsah; Uygur, Ilyas; Akincioglu, Sitki; Oktem, Hasan
    In this study, an eco-friendly brake composite sample (EFP) was produced with 3.5% hazelnut shell dust as a natural additive material. Friction tests were performed on the manufactured pad sample and on a commercial pad (CP) using both a Chase-type test machine and a specially designed device. A different approach is presented with the evaluation of the two different test device results. The experimental results were compared using the Taguchi method and it was concluded that the braking performance of the sample with hazelnut shell dust was in accordance with international standards. As a result of the study; the nominal friction coefficient value was found to be 0.505 mu. The shearing force of the EFP and CP samples was measured at 607.3 and 850.5 N, respectively. The friction coefficient values obtained from the EFP and CP samples were in accordance with the SAE J-661 standard and are in the F letter class.
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    The hybrid approach of genetic algorithm and particle swarm optimization on reduced weld line defect in plastic injection molding
    (Sage Publications Ltd, 2024) Oktem, Hasan; Uygur, Ilyas; Sari, Ece Simooglu; Shinde, Dinesh
    Weld lines are a serious defect observed in plastic injection molded parts, impacting both their cosmetic appearance and mechanical properties. Controlling the conditions of plastic injection is crucial to mitigate these weld lines. This study introduces a novel approach to identify polypropylene injection molding (PIM) conditions aimed at reducing weld lines in polypropylene parts. The PIM conditions considered in this study include melt temperature, injection pressure, packing pressure, packing time, and cooling time. An orthogonal array Taguchi L27 design was employed for the experimental setup, producing 27 polypropylene parts with varying combinations of process conditions. The width of weld lines generated on the parts' surfaces was measured using an optimum microscope for all trials. Parametric analysis was conducted using response surface plots and contour plots to estimate the process conditions yielding minimum weld lines. Analysis of variance and regression analysis were employed to interpret the experimental data, with the resulting regression equation used to predict weld lines for a set of PIM process conditions. Finally, two efficient optimization algorithms, genetic algorithm (GA), and particle swarm optimization (PSO), were implemented using MATLAB programming to estimate the optimum process conditions for minimizing weld lines. The GA and PSO predicted weld line widths of 6.12302 mu m and 6.123 mu m, respectively, representing an 18.51% improvement in results. These findings demonstrate that the novel approach presented in this study can be effectively and reliably applied to address plastic product defects in the industry.
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    A novel study of hybrid brake pad composites: new formulation, tribological behaviour and characterisation of microstructure
    (Taylor & Francis Ltd, 2021) Oktem, Hasan; Akincioglu, Sitki; Uygur, Ilyas; Akincioglu, Gulsah
    In the production of brake pad composites, a well-designed new composition formulation plays a key role in improving performance. The purpose of this study; was to investigate the effectiveness of a specifically developed formulation under brake-test conditions. The composition of the brake lining consists of 18 powder materials. As the friction adjuster, Petro-coke powder was used instead of Cashew, which is cheaper and more readily available. The wear tests were carried out in a special design test device simulated close to the real environment. The results obtained have been compared with commercial brake pads. The friction coefficient values decrease with increasing disc temperatures. Brake tests showed that as a friction modifier, petro-coke provided a more effective stabilizer for the friction coefficient and improved the specific wear rate. Also the study can be utilized effectively in determining the friction coefficient and the specific wear rate of designed brake composites.
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    Tribological and mechanical exploration of polymer-based hemp and colemanite composite as a friction material
    (Iop Publishing Ltd, 2024) Karakas, Hamdi; Oktem, Hasan; Uygur, Ilyas
    Natural and organic-based composite materials are widely used in many industrial applications due to their low cost, easy recyclability, economic feasibility, and ready availability. In this study, a polymer-based composite friction material consisting of Hemp-Colemanite composition (HCFCo) has been developed for the automotive sector to exhibit lower cost, environmentally friendly characteristics, and suitable friction-wear behaviors. For this purpose, three different ratios (%4, %8 and %12) of HCFCo composites were produced using a coating technique called impregnation process with a specially designed device. During the production stage, homogeneity of the composites was ensured, and then the final shape was given by the hot pressing method. Local based natural materilas frequently used for as anon-asbestos friction materails. For this reason, hemp and colomanited based composites were tested. Properties such as hardness, density, water and oil absorption, friction coefficient, and specific wear of HCFCo samples were examined. In addition, the microstructures of HCFCo composites were investigated to determine the bonding form between hemp fiber and colemanite. The results obtained revealed that the friction coefficient values decreased with an increase in temperature, while no significant change was observed in hardness and density values. Throughout the entire testing process, the friction coefficients varied between 0.14 and 0.29 on average. It was concluded that the developed fiber-reinforced composite can be reliably used in industrial applications and can contribute significantly to innovations in the literature.
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    Wear response of non-asbestos brake pad composites reinforced with walnut shell dust
    (Springer, 2020) Akincioglu, Gulsah; Akincioglu, Sitki; Oktem, Hasan; Uygur, Ilyas
    With automobile numbers continuing to increase, competition among manufacturers of brake pads is also increasing along with the search for additives to serve as alternatives to the materials presently being used. In addition to the cost of the additives used, another important consideration in choosing materials is that they should be safe for the environment and human health. This study investigated the effect on braking performance of brake pads produced using walnut shell powder as a natural additive material. Two different types of brake pad samples were produced using 3.5 (2A) and 7% (2B) walnut shell dust in the contents. A commercial Clio brake tip was used as the reference (CO). The produced brake pads were subjected to thermal conductivity, friction wear, density, hardness and water and oil absorption tests and microstructure analysis. A Chase type device was used for wear friction tests, and the results were obtained according to SAE-J661(Brake Lining Quality Test Procedure) standards. The experimental data were compared with those of the commercial brake pads, and the performances of the natural additive brake pads were evaluated. The addition of walnut shell was shown to be compatible within the composition and exhibited a positive effect on the friction coefficient.