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https://hdl.handle.net/20.500.12684/6794

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AISI 304 ve AISI 316 Östenitik Paslanmaz Çeliklerin İşlenebilirliğinin Değerlendirilmesi
(Gazi Univ, 2017) Özbek, Nursel Altan; Çiçek, Adem; Gülesin, Mahmut; Özbek, Onur
In this study, turning tests were performed to assess machinability of AISI 304 and AISI 316 austenitic stainless steels using uncoated tungsten carbide tools. The tests were conducted at four cutting speeds (100, 120, 140 and 160 m/min), three feed rates (0.15, 0.3 and 0.45 mm/rev), and a fixed depth of cut (2.4 mm) under dry cutting conditions. Machinability of AISI 304 and AISI 316 steels was evaluated in terms of tool wear, main cutting force and surface roughness. Experimental results showed that larger wear damages formed on the cutting inserts used for machining of AISI 316 steel. In addition, higher values of cutting forces and surface roughness were measured in machining of AISI 316 steel. In consequence of experimental study, it was found that AISI 316 steel had harder machinability characteristics than AISI 304 steel.
Experimental and Statistical Study on Machinability of the Composite Materials with Metal Matrix Al/B4C/Graphite
(Springer, 2017) Nas, Engin; Gökkaya, Hasan
In this study, four types of Al/B4C/Graphite metal matrix composites (MMCs) were produced by means of a hot-pressing technique with reinforcement elements, B4C 8 wt pct and graphite (nickel coated) 0, 3, 5, and 7 wt pct. Machinability tests of MMC materials thus produced were conducted using four different cutting speeds (100, 140, 180, and 220 m/min), three different feed rates (0.1, 0.15, and 0.20 mm/rev), and a fixed cutting depth (0.5 mm), and the effects of the cutting parameters on the average surface roughness were examined. After the machinability tests, the height of the built-up edge (BUE) formed on the cutting tools related to the cutting speed and feed rate was measured. The test results were examined by designing a matrix according to the full factorial design and the average surface roughness, and the most important factors leading to formation of the BUE were analyzed by the analysis of variance (ANOVA). As a result of analysis, it was found that the lowest surface roughness value was with 7 wt pct graphite MMC material, while the highest was without graphite powder. Based on the statistical analysis results, it was observed that the most important factor affecting average surface roughness was the type of MMC material, the second most effective factor was the feed rate, and the least effective factor was the cutting speed. Furthermore, it was found that the most important factor affecting the formation of the BUE was the type of MMC material, the second most effective factor was the cutting speed, and the least effective factor was the feed rate.
Experimental investigations of damage analysis in drilling of woven glass fiber-reinforced plastic composites
(Springer London Ltd, 2010) Işık, Birhan; Ekici, Ergün
This paper presented a new comprehensive approach to select cutting parameters for damage factor in drilling of glass fiber-reinforced polymer (GFRP) composite material. The influence of drilling on surface quality of woven GFRP plastic composite material was investigated experimentally. Drilling tests were carried out using carbide drills of 8 mm in diameter at 50, 70, and 90 m/min cutting speeds and at 0.06, 0.12, and 0.18 mm/rev feed rates. Damage factor was investigated based on hole entrance and exit. Analysis of variance (ANOVA) test was applied to the experimental results. The compared values were employed by Duncan test to identify which groups were significantly different from other groups.
Experimental Vibration Analysis of Cryogenic Treated Shafts Supported by Journal and Rolling Element Bearings
(Gazi Univ, 2019) Kam, Menderes; Saruhan, Hamit
In this study, the effects of cryogenic treatment and tempering on the vibration behaviors of rotating shafts mounted on the rolling element and journal bearings were investigated for the same loading conditions and operating speeds. In this experimental study, the data obtained with the help of proxy probes were analyzed and the results were compared. The results showed that the lowest amplitude values were obtained for the cryogenic treated shaft mounted on the journal bearing. The amplitude values of journal bearing are significantly superior to the rolling element bearings having stability in account.
Effect of cutting conditions on wear performance of cryogenically treated tungsten carbide inserts in dry turning of stainless steel
(Elsevier Sci Ltd, 2016) Özbek, Nurse Altan; Çiçek, Adem; Gülesin, Mahmut; Özbek, Onur
In this study, the effects of cryogenic treatment on tool wear of uncoated tungsten carbide inserts were investigated in the turning of AISI 316 stainless steel. It was found that notch wear appeared at low and medium cutting speeds, while flank wear and crater wear formed at all combinations of the process parameters selected for turning. In addition, treated inserts exhibited superior wear performance to untreated ones. This can be attributed to high wear resistance and low thermal conductivity of treated inserts. The results were verified by analyses of microstructure and hardness, image processing and Xray diffraction. (C) 2015 Elsevier Ltd. All rights reserved.
Dual fluoroscopic evaluation of human tibiofemoral joint kinematics during a prolonged standing: A pilot study
(Elsevier - Division Reed Elsevier India Pvt Ltd, 2019) Uzuner, Sabri; Rodriguez, Marcel L.; Li, Leping; Küçük, Serdar
A complete knowledge of tibiofemoral joint kinematics is essential for understanding the function of the healthy and pathological joint. The objective of the present study was to establish a dual fluoroscopic measurement protocol and a data processing approach for the creep response of the knee joint in order to further evaluate the mechanical properties of articular cartilage and meniscus in vivo. A computational approach was developed for the determination of 3D translations and rotations of the joints of young participants with no history of injury using dual fluoroscopic images of loaded joints and joint geometry reconstructed from magnetic resonance imaging of the unloaded joints. High-resolution X-ray images were obtained for the distal femur and proximal tibia during 10-min standing when approximately 3/4 body weight was slowly applied to the right leg and then kept constant for the rest duration of the test. Anatomic coordinate systems were established for the 3D models of distal femur and proximal tibia. Translations and rotations of the joint as functions of time were then evaluated using the X-ray images and these coordinate systems with the JointTrack software. The displacements in the proximal-distal direction obtained from two participants were consistent, showing a substantial increase in the initial phase when joint loading increased from nil to 3/4 body weight and a continued small increase over time while the joint loading remained constant. The maximum anterior-posterior translations during 10-min standing were approximately 4 mm for both participants, although one showed better stability than the other. In conclusion, a creep loading protocol of the knee joint can be reasonably established for in vivo conditions and evaluated with the image-based computational approach. (C) 2019 Karabuk University. Publishing services by Elsevier B.V.
Trajectory Planning of a 5-DOF Serial Robot Manipulator in Joint-Space
(Gazi Univ, 2017) Uzuner, Sabri; Akkuş, Nihat; Toz, Metin
In this study, a five Degrees of Freedom (DOF) serial robot manipulator with revolute joints was designed and realized to be used for educational purposes. The robot has 150 gr payload and the motions of the joints were provided by using radio controlled R/C servo motors with smooth and vibration-free movement. In order to perform the trajectory planning in the joint space the inverse kinematics problem of the robot was solved and a third order polynomial was used for the trajectory planning. So as to present a simple and efficient way to the user for controlling the robot, a visual user interface was also designed by utilizing Visual Basic Programming Language. Finally, it was observed that the designed mechanism has been successfully used by the students for the projects involving robots.
Three-Point Bending Response of Corrugated Core Metallic Sandwich Panels Having Different Core Configurations - An Experimental Study
(Eos Assoc, 2019) Zurnacı, Erman; Gökkaya, Hasan; Nalbant, Muammer; Sur, Gökhan
Bending response of corrugated core metallic sandwich panels was studied experimentally under three-point bending loading. Two different core configurations were used: the corrugated monolithic core and the corrugated sliced core. The trapezoidal corrugated cores were manufactured from aluminum sheets via a sheet metal bending mould. After the sandwich panel samples were prepared, they were subjected to three-point bending tests. The load and displacement responses of the sandwich panels having different core configurations were obtained from the experimental testing. The influence of the core configuration on the three-point bending response and failure modes was then investigated. The experimental results revealed that the corrugated sliced core configuration exhibited an improved bending performance compared to the corrugated monolithic core configuration.
THE EFFECT OF CORE CONFIGURATION ON THE COMPRESSIVE PERFORMANCE OF METALLIC SANDWICH PANELS
(Inst Za Kovinske Materiale I In Tehnologie, 2019) Zurnacı, Erman; Gökkaya, Hasan
The compressive performance of metallic sandwich panels signifies a key mechanical behaviour under compression loading. This paper describes the compressive performance of metallic corrugated core sandwich panels having different core configurations under quasi-static compression loads. Two different sandwich panel core configurations were studied: the corrugated monolithic core and the corrugated sliced core. The corrugated cores were fabricated using a sheet-metal bending technique with trapezoidal geometry and then bonded to surface plates. Aluminium 1050 1114 sheets were used as the core and surface materials. Sandwich panel samples were prepared and tested experimentally under a quasi-static compression load (compression rate of 2 mm/min). The force-displacement curves of the sandwich panels with different core configurations were obtained from the experimental tests. The compressive performance parameters included the maximum compression load, the average compression load, the energy absorption and the specific energy absorption. It was found that the core configuration played a key role in the compressive performance. Finally, when the compressive performance of these two different core configurations was compared, the corrugated sliced-core configurations exhibited better performance.
Taguchi method based optimisation of drilling parameters in drilling of AISI 316 steel with PVD monolayer and multilayer coated HSS drills
(Elsevier Sci Ltd, 2012) Kıvak, Turgay; Samtaş, Gürcan; Çiçek, Adem
This paper focuses on the optimisation of drilling parameters using the Taguchi technique to obtain minimum surface roughness (Ra) and thrust force (Ff). A number of drilling experiments were conducted using the L16 orthogonal array on a CNC vertical machining centre. The experiments were performed on AISI 316 stainless steel blocks using uncoated and coated M35 HSS twist drills under dry cutting conditions. Analysis of variance (ANOVA) was employed to determine the most significant control factors affecting the surface roughness and thrust force. The cutting tool, cutting speed and feed rate were selected as control factors. After the sixteen experimental trials, it was found that the cutting tool was the most significant factor on the surface roughness and that the feed rate was the most significant factor on the thrust force. The results of the confirmation experiments showed that the Taguchi method was notably successful in the optimisation of drilling parameters for better surface roughness and thrust force. (C) 2012 Elsevier Ltd. All rights reserved.
Performance of cryogenically treated Cu and CuCrZr electrodes in an EDM process
(Redakcia Kovove Materialy, 2017) Çetin, A.; Çakır, Gültekin; Aslantaş, Kubilay; Uçak, Necati; Çiçek, Adem
In this study, the effects of cryogenic treatment (CT) on the performance of CuCrZr alloy and Cu electrodes in electro discharge machining (EDM) of AISI P20 tool steel were investigated experimentally. For this purpose, a group of electrodes were cryogenically treated at 140 degrees C for 30 min and then tempered at 175 degrees C for 1 h. The tool performance was evaluated in terms of electrode wear rate (EWR), material removal rate (MRR), and average surface roughness (Ra) of machined surfaces. The EDM tests were conducted at pulse currents of 4, 8, 12, and 16 A and pulse durations of 25 and 50 is. Experimental results showed that treated electrodes were less worn than the untreated ones and the Ra values of machined surfaces decreased when cryo-treated electrodes were used. Also, it was observed that pulse current is the most effective parameter in the EDM process.
Optimization of surface roughness via the Taguchi method and investigation of energy consumption when milling spheroidal graphite cast iron materials
(Carl Hanser Verlag, 2018) Nas, Engin; Öztürk, Burak
Due to its excellent casting ability, spheroidal graphite cast iron is widely used in the production of complex automotive and machine products. In this study, the milling of spheroidal cast iron was carried out at different parameters. First, using the Taguchi statistical method, the parameters affecting surface roughness values were determined to b e cutting tool (65.54 %), then feed rate (19.65%), and finally, with a minimum effect, cutting speed (7.31%). Second, the amount of power consumed during chip removal was observed as being larger than the amount consumed when the machine was operating without a cutting load. Increases in the power index (PI) were measured by an amperemeter and it was determined that, as cutting speed was augmented, the amount of total power (P-total) consumed decreased, while, as feed rate was augmented, total power consumption increased. Total cutting energy (Pcutting) was increased by stepping up cutting speed. The PI was increased as a result of stepping up cutting speed and feed rate. On the basis of the cutting parameters, the Pcutting, P(total )spindle torque (%) and specific energy consumption (SEC) value changes were calculated.
Modelling of Thrust Forces in Drilling of AISI 316 Stainless Steel Using Artificial Neural Network and Multiple Regression Analysis
(Assoc Mechanical Engineers Technicians Slovenia, 2012) Çiçek, Adem; Kıvak, Turgay; Samtaş, Gürcan; Çay, Yusuf
In this study, the effects of cutting parameters (i.e., cutting speed, feed rate) and deep cryogenic treatment on thrust force (Ff) have been investigated in the drilling of AISI 316 stainless steel. To observe the effects of deep cryogenic treatment on thrust forces, M35 HSS twist drills were cryogenically treated at -196 degrees C for 24 h and tempered at 200 degrees C for 2 h after conventional heat treatment. The experimental results showed that the lowest thrust forces were measured with the cryogenically treated and tempered drills. In addition, artificial neural networks (ANNs) and multiple regression analysis were used to model the thrust force. The scaled conjugate gradient (SCG) learning algorithm with the logistic sigmoid transfer function was used to train and test the ANNs. The ANN results showed that the SCG learning algorithm with five neurons in the hidden layer produced the coefficient of determinations (R-2) of 0.999907 and 0.999871 for the training and testing data, respectively. In addition, the root mean square error (RMSE) was 0.00769 and 0.009066, and the mean error percentage (MEP) was 0.725947 and 0.930127 for the training and testing data, respectively.
Mechanical and physical properties of hybrid reinforced (Al/B4C/Ni(K)Gr) composite materials produced by hot pressing
(Carl Hanser Verlag, 2015) Nas, Engin; Gökkaya, Hasan
In this study, the mechanical and physical properties of hybrid reinforced (Al/B4C/Ni(K)Gr) metal matrix composite (MMC) materials were investigated. The MMC materials were produced using the powder metallurgy (PM) production method of hot pressing (HP). The aluminum alloy Alumix 13 was used as matrix material and boron carbide (B4C) and nickel-coated graphite (Ni(K) Gr) as reinforcement elements. The microstructural characteristics, hardness, 3-point bending strength and density values of the produced hybrid reinforced MMC materials were determined. The reinforcement element B4C was kept at constant concentration of 8 wt.-%. Four different MMC materials were produced with the addition of 0, 3, 5 and 7 wt.-% Ni(K) Gr in the B4C. From the SEM images of the MMC materials produced by the HP technique, it was observed that the reinforcement element exhibited a uniform distribution. Moreover, the particles showed an approach to each other depending on the particle size and the amount (wt.-%) of the reinforcement element. With increasing graphite content in the structure density, hardness and 3-point bending test values decreased.
INVESTIGATION THE EFFECTS OF 3D PRINTER SYSTEM VIBRATIONS ON MECHANICAL PROPERTIES OF THE PRINTED PRODUCTS
(Yildiz Technical Univ, 2018) Kam, Menderes; Saruhan, Hamit; İpekçi, Ahmet
In recent years, three-dimensional (3D) printing is attracting widespread interest due to functional rapid prototyping and products by reducing the time and material involved in process. Most of 3D printer users focus on mechanical properties of products neglecting vibration characteristics of printer system effects on products. The aim of this study is to investigate the effects of 3D printer system vibrations on mechanical properties of printed products. Fused Deposition Modeling (FDM) technology which is one of most used additive manufacturing process was used to print test samples and Polyethyletherphthalate Glycol (PET-G) was used as material for printing. Vibration measurements were taking for eighteen printed test samples. Vibrations data were measured from 3D printer movement in three axes (x, y, and z) by accelerometers. The processing parameters were selected as occupancy rate, filling structures orientation, and processing speed. The samples in rectilinear filling structure with occupancy rate of 50 % having different orientations (45 degrees by 45 degrees and 60 degrees by 30 degrees) and processing speeds (3600, 3900, and 4200 mm/min). Tensile test was used to test mechanical properties of test samples. The findings have shown that induced vibration has significant impact on mechanical properties which can be used to control the mechanical properties in terms of tensile stress and elongation of printed products during mass printing. Results showed that vibration amplitude values for orientations of 60 degrees by 30 degrees and processing speed 3600 mm/min are much lower compared to the other test samples. While tensile strength increases about % 5 when orientation is 45 degrees by 45 degrees with 3600 mm/min processing speed. From result obtained, it can be said that orientation of the product has a significant effect on the response of the printer system in terms of vibrations.
INVESTIGATION OF THE EFFECT OF CUTTING PARAMETERS ON SURFACE ROUGHNESS AND CHIP FORMATION IN DRILLING OF INCONEL 718 SUPER ALLOY
(Gazi Univ, Fac Engineering Architecture, 2010) Kıvak, Turgay; Habalı, Kasım; Şeker, Ulvi
In this study, the effects of cutting parameters on surface roughness and chip formation obtained during the drilling of Inconel 718 super alloy with coated and uncoated carbide drills were investigated. Drilling tests were performed using TiN and TiAlN coated carbide drills on a vertical CNC machining center with four different cutting speeds (10, 12,5, 15, 17,5 m/min) and three different feed rates (0,05, 0,075, 0,1 mm/rev). Blind holes with 8 mm depth were drilled with 5 mm diameter drills. Surface roughnesses evaluation of holes based on the cutting tools was made with respect to the roughness measurements. According to this evaluation, the best results for surface roughness on the holes were obtained with the ones drilled by uncoated carbide tools. When the chip formations were examinated, for all tests the chip formations for the first drilled holes were a discontinuous chip form or tight helical chip form.
Investigation of the effects of cryogenic treatment applied at different holding times to cemented carbide inserts on tool wear
(Elsevier Sci Ltd, 2014) Özbek, Nurse Altan; Çiçek, Adem; Gülesin, Mahmut; Özbek, Onur
Cutting tool costs is one of the most important components of machining costs. For this reason, tool life should be improved using some methods such as cutting fluid, optimal cutting parameters, hard coatings and heat treatment. Recently, another one of the methods commonly used to improve tool life is cryogenic treatment. This study was designed to evaluate the effects of different holding times of deep cryogenic treatment on tool wear in turning of AISI 316 austenitic stainless steel. The cemented carbide inserts were cryogenically treated at -145 degrees C for 12, 24, 36, 48 and 60 h. Wear tests were conducted at four cutting speeds (100, 120, 140 and 160 m/min), a feed rate of 0.3 mm/rev and a 2.4 mm depth of cut under dry cutting conditions. The wear test results showed that flank wear and crater wear were present in all combinations of the cutting parameters. However, notch wear appeared only at lower cutting speeds (100 and 120 m/min). In general, the best wear resistance was obtained with cutting inserts cryogenically treated for 24 h. This case was attributed to the increased hardness and improved microstructure of cemented carbide inserts. These improvements were confirmed through hardness, image processing, and XRD analyses. (C) 2014 Elsevier Ltd. All rights reserved.
Application of Taguchi Method for Surface Roughness and Roundness Error in Drilling of AISI 316 Stainless Steel
(Assoc Mechanical Engineers Technicians Slovenia, 2012) Çiçek, Adem; Kıvak, Turgay; Samtaş, Gürcan
In this study, the effects of deep cryogenic treatment and drilling parameters on surface roughness and roundness error were investigated in drilling of AISI 316 austenitic stainless steel with M35 HSS twist drills. In addition, optimal control factors for the hole quality were determined by using Taguchi technique. Two cutting tools, cutting speeds and feed rates were considered as control factors, and L-8(2(3)) orthogonal array was determined for experimental trials. Multiple regression analysis was employed to derive the predictive equations of the surface roughness and roundness error achieved via experimental design. Minimum surface roughness and roundness error were obtained with treated drills at 14 m/min cutting speed and 0.08 mm/rev feed rate. Confirmation experiments showed that Taguchi method precisely optimized the drilling parameters in drilling of stainless steel.
Application of Deep Cryogenic Treatment to Uncoated Tungsten Carbide Inserts in the Turning of AISI 304 Stainless Steel
(Springer, 2016) Özbek, Nurse Altan; Çiçek, Adem; Gülesin, Mahmut; Özbek, Onur
This study investigated the effects of deep cryogenic treatment (DCT) on the wear performance of uncoated tungsten carbide inserts. AISI 304 austenitic stainless steel, widely used in industry, was selected as the workpiece material. Cutting experiments showed that the amount of wear significantly increased with increasing cutting speed. In addition, it was found that DCT contributed to the wear resistance of the turning inserts. The treated turning inserts were less worn by 48 and 38 pct in terms of crater wear and notch wear, respectively, whereas they exhibited up to 18 pct superior wear performance in terms of flank wear. This was attributed to the precipitation of new and finer eta-carbides and their homogeneous distribution in the microstructure of the tungsten carbide material after deep cryogenic treatment. Analyses via image processing, hardness measurements, and SEM observations confirmed these findings.
An approach for handling individual customer preferences and emotional needs - Yielding 3D product assembly generation
(Sage Publications Ltd, 2016) Göloğlu, Cevdet; Zurnacı, Erman
The development of fully personalised product design solutions for customers is hindered by lack of a satisfactory means of interaction. Mass production techniques used by manufacturing firms cannot be applied for user-centred design. A stronger interaction between customer and product can only be achieved when the customer guides the product generation via individual preferences and emotional needs. The aim of this article is to introduce a Kansei engineering (KE)-based methodology that involves customers in the product generation process by taking their preferences and emotional needs into account. The methodology is integrated by a CAD environment to provide a 3D dynamic product representation which is generated by individual customer preferences via fuzzy logic (FL) reasoning. For validation, the methodology was demonstrated by using the case study of an ironing board. Both functional and emotional needs were handled by KE implementation. By combining KE and FL, the methodology enabled the multiple quantitative demands of the customer to be addressed in order to generate a more personalised product in a responsive manner. Located in shopping venues, fixed and mobile stations for the customer decision-making process could facilitate increased customer satisfaction without need of a customer assistance desk.

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