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    Design optimization of industrial robot arm to minimize redundant weight
    (Elsevier - Division Reed Elsevier India Pvt Ltd, 2019) Bugday, Mustafa; Karali, Mehmet
    In industrial robots, projected torque increases depending on the extending reach length and payload. This requires selection of powerful motors particularly on the second axis. Since arm rigidity becomes more important as the expected positioning precision increases, less flexible materials are used. Therefore, during operation conditions, 70% of motor's energy is used for redundant weight. In this study, analyses conducted on five different robotic arms belong to different brands. Arm's payload distribution in terms of region and amount is examined, alternative designs are analysed and compared with each other. Geometry and materials are changed in alternative designs. In this way, redundant weight is minimized (without increasing the share amount) at the same positioning precision. Results of this study demonstrated a 10% decrease in inert payloads. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.
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    Investigation on Characterization of GGG 60 Coated with WC/Co by ESD Technique
    (Maik Nauka/Interperiodica/Springer, 2023) Bugday, Mustafa; Karali, Mehmet; Talas, Suekrue
    Hard surface coatings are necessity when the surface of a metallic materials are required to perform better during the service and lower the cost of replacement and labour. In this study, WC/Co coatings were deposited on GGG60 ductile (spherical graphite) cast iron with Electro Spark Deposition technique. The ductile cast iron specimens were non heat treated, heat treated for hardening the surface and subsurface prior to coating. Optimum coating parameters were determined as 132 V and 1230 Hz. Coating characterization was investigated by SEM/EDS and XRD. The surface hardness value of the substrate sample increased from 270 +/- 5.6 HV0.2 to 1330 +/- 12.5 HV0.2. Surface hardness value increased 5 times. The presence of W2C, W and WC1 - x phases in the coatings increased the possibility of decarburization. WC ratio was calculated more in heat treated coated samples compared to other coatings. The mechanical properties of the coatings were tried to be determined by tensile and three-point bending tests. The tensile stress of the heat-treated coated samples was calculated as 780 MPa and the maximum bending stress was calculated as 1581 MPa. The decrease in the C ratio in the coating in the heat treated coated samples made the samples more resistant to thermal stresses.
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    Wear performance of GGG60 ductile iron rollers coated with WC-Co by electro spark deposition
    (Consejo Superior Investigaciones Cientificas-Csic, 2023) Bugday, Mustafa; Karali, Mehmet; Talas, Suekrue
    Nodular cast irons are used in many industrial applications such as machine frames and body, rollers and engine blocks due to their higher strengths and ductility with good machinability comparable to grey cast irons. In this study, the outer surface of nodular cast irons (GGG-60) was coated with WC/Co using electro spark deposition (ESD). The aim of the study is to improve both the surface quality and wear behaviour with the coatings formed on the surface of the plastic deformation rollers, whose wear resistance decreases over the time due to high stress working conditions. Heat treatment at 950 degrees C for 2 h was applied to the GGG60 specimen rollers and half of the rollers were uncoated and the other half was coated with WC-Co electrodes. The wear behaviour of the heat treated and coated surfaces was measured by ball-on-disc wear method using Al2O3 ball bearing with a diameter of 6 mm for a sliding distance of 250 m at a sliding rate of 6.5 m center dot s-1 under a dry condition, and using a load of 40 N. WC/Co coatings were successfully applied to rollers. In the SEM/EDS images, the presence of W, Fe, C, Co and Al elements in the coated part of the rollers and Fe, C and Al elements in the uncoated region were detected. It was concluded that Coating and heat treatment increased the wear resistance by nearly 5 times and decreased the friction coefficient by 2.13 times.