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    Effect of die inlet geometry on extrusion of clover sections through curved dies: Upper bound analysis and experimental verification
    (Elsevier Science Bv, 2013) Altinbalik, Tahir; Ayer, Onder
    The effect of die inlet and transition geometry on the extrusion loads and material flow for extrusion of clover sections were investigated and presented both theoretically and experimentally. For this purpose, four different die geometries including straight tapered and cosine transition profile and each of them having round and clover inlet geometries were chosen. In the experimental study, commercially pure lead was used because of its hot forming characteristic at room temperature. A newly kinematical admissible velocity field to analyze different profiles of extrusion dies of clover section from round bars was proposed by upper bound analysis. It is clear that the extrusion loads obtained from the theoretical analysis for various die inlet-die transition geometry combinations are in good agreement with the experimental results. Axis deviations of the parts which define the dimensional quality of the products were also investigated.
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    Effect of die parameters on the grain size, mechanical properties and fracture mechanism of extruded AZ31 magnesium alloys
    (Elsevier Science Sa, 2020) Ayer, Onder
    The study was carried out to evaluate the effect of extrusion ratio and extrusion die angle on the mechanical properties and microstructure of AZ31 magnesium alloy at 300 degrees C extrusion temperature with three different extrusion ratio of 1.77, 2.68, 3.55 and die angles of 10(0), 15(0), 20(0). It was identified that microstructure was significantly refined for all extrusion ratios. The average size was decreased to the range of 4.1 mu m-13.3 mu m from 22.4 mu m. By increasing extrusion ratio, it was observed that the tensile properties were considerably improved at room temperatures and tensile strength was reached to maximum 331 MPa after extrusion when initial measured value was 168.28 MPa. Significant grain refinement, enhanced mechanical strength and increase in microhardness values were observed with smaller die angles. It was observed that DRX mechanism is active and it supports the grain refinement. Dimples seen on the fractured surface were deeper that indicates the enhanced ductility of the material. Finally, among all the tests higher extrusion ratio with lower die angle gives better grain distribution in the microstructure and higher mechanical strength to the product.
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    Extrusion load prediction of gear-like profile for different die geometries using ANN and FEM with experimental verification
    (Springer London Ltd, 2015) Bingol, Sedat; Ayer, Onder; Altinbalik, Tahir
    This paper deals with the extrusion of gear-like profiles and uses of finite element method (FEM) and artificial neural network (ANN) to predict the extrusion load. In the study, gear-like components has been manufactured by forward extrusion for the AA1070 aluminum alloy and the process was simulated by using a DEFORM-3D software package to establish a database in order to provide the data for ANN modeling. Serious experiments were performed for only one die set and four teeth gear profile to obtain data for comparing with DEFORM-3D results. After verifying a highly appropriate FEM simulation with the experiment at the same conditions, Results were enhanced for different die lengths, extrusion ratios, and two extra teeth number as three and six using FEM simulations. Subsequently, the data from the performed FEM simulations were submitted for the best obtained ANN model. Finally, a good agreement between FE-simulated and ANN-predicted results was obtained. The proposed ANN model is found to be useful in predicting the forming load of the different die set variations based on the reliable test data.
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    Fatigue life modeling of gear like products using ANN
    (Natl Inst Science Communication-Niscair, 2016) Ayer, Onder; Bingol, Sedat; Altinbalik, Tahir; Kilicgedik, Hidir Yanki
    The expected life of a gear is important parameter especially for the gears to secure of the mechanics of it. Related to this importance, fatigue failure is one of the most seen failures occurred on gears working under cyclic loads. It is not possible to eliminate fatigue failure effects but it is possible to reduce by appropriate materials selection and design criteria. Due to demand for gears with higher load-carrying capacity and increased fatigue life, it is important to determine the fatigue strengths of the gears. hi this study, forward extrusion method with cosine and tapered profile dies is carried out to obtain gear-like products. The products are then tested under cyclic loads to determine the fatigue life. The results obtained from the experiments are used as inputs in developing the ANN models. Different ANN models are developed for cosine curved and straight tapered profiles to obtain the best models. A comparative analysis is performed in order to evaluate the accuracy of the developed models, in terms of statistical measurements (R-2, MSE, MAE). Results revealed that proposed ANN models for both cosine curved and tapered profiles are able to predict the fatigue life of the gear-like profiles.
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    Finite Element Analysis of Gear Like Form by Using Lateral and Forward Extrusion
    (Assoc Information Communication Technology Education & Science, 2014) Altinbalik, Tahir; Ayer, Onder
    The aim of this research is the reduction in deformation load, improvement of the mechanical properties of the product by means of an optimum forming process and die profile. Forward extrusion and lateral extrusion were chosen as two different forming methods to manufacture a spur gear form. Four different die geometries were chosen for the forward extrusion; including straight tapered transition profile and cosine transition profile with having two different die lengths. Al 1070 was used as workpiece material in the experimental study. Experiments using five sets of dies with spur gear form were performed, and the measured forming load results were compared with the predictions of the finite element method for the same deformation situations by using DEFORM-3D. The state of stress and strain was also determined for two forming methods by means of DEFORM-3D. Finally, a series of fatigue tests were carried out for four teeth gear forms produced by both processes to evaluate influence of the forming processes.
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    A forming load analysis for extrusion process of AZ31 magnesium
    (Elsevier Science Bv, 2019) Ayer, Onder
    The effect of extrusion parameters on the extrusion load for AZ31 magnesium alloy was investigated with the support of numerical methods. With this regard, the process temperature, extrusion ratio, friction factor and punch velocity were selected as main parameters for the experiments. Besides, the experimental results were analyzed by using the finite element method (FEM) and artificial neural network (ANN) method to build a numerical model for predicting the forming load. All the experimental and numerical results were compared to each other and it was concluded from the results that the effect of friction factor on the extrusion load is more dominant at lower extrusion temperature for all given extrusion ratios and punch velocities. Besides this, higher extrusion ratios require higher process temperatures to obtain the lower extrusion load. Also, it was observed that the increase in the extrusion speed causes a significant increase in the forming load for all extrusion ratios and extrusion temperatures.
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    Influence of extrusion parameters on drilling machinability of AZ31 magnesium alloy
    (Sage Publications Ltd, 2022) Koklu, Ugur; Kocar, Oguz; Morkavuk, Sezer; Giasin, Khaled; Ayer, Onder
    AZ31 magnesium alloy is mainly used in aerospace applications due to its lightweight and good mechanical properties. The installation of AZ31 alloy in an aircraft usually requires machining operations such as drilling and milling for assembly purposes. The current study aims to investigate the effects of different extrusion ratios (1.77, 2.68, 3.55) on the drilling machinability of AZ31 alloys. The machinability was evaluated with thrust force, borehole surface quality, and chip characteristics. It was found that the thrust force and hole quality depend on the extrusion ratio and cutting parameters. The highest thrust force and surface roughness R-a occurred when drilling AZ31 alloy produced using the highest extrusion ratio of 3.55 in agreement with the improvement in the mechanical properties. The chip length decreased with the increase of the extrusion ratio depending on a decrease in the ductility, while SEM images showed that the AZ31 sample produced using intermediate extrusion ratio had the best hole edge quality and least burr formation.
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    Investigation of welding quality and internal elongation problem in aluminum extrusion
    (Elsevier Sci Ltd, 2023) Ayer, Onder; Karakaya, Ismail
    AA6082 aluminum alloys are particularly useful in heavy industry and machinery manufacturing given their mechanical properties, but when extruding complex profiles used in these sectors, one of the main problems is the welding problem. In order to prevent the welding defects by suitable die design, two different porthole extrusion die set were designed and manufactured using different design techniques in this study. Extrusion trials were conducted for each die. The analysis examined how die design affects profile exit temperature, stress and strain distribution, and billet interface. It also aimed to characterize the effect of die design on welding quality through tensile tests, hardness tests, and microstructural observations. The results show that tapering the mandrel and die plate parts at an angle causes compression of the material flow and reduces the volume of the weld chamber and helps to direct material to the critical regions. This design approach offers a solution for the welding problem of complicated profiles.
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    A NUMERICAL STUDY FOR PREDICTION OF FORMING LOAD AND EXPERIMENTAL VERIFICATION OF BIMETALLIC DISC UPSETTING
    (Univ Osijek, Tech Fac, 2017) Ayer, Onder
    Forming of disc samples composed from aluminium and copper in performed study was examined with upsetting procedure. An approach for prediction deformation load of upsetting processes is developed. This study combines the finite element method model, neural network model and upper bound method to simulate and predict the deformation load in upsetting of bimetallic materials. The Finite Element Method (FEM) results were obtained from DEFORM-3D software and they were compared and validated with experiments by taking forming load into consideration. Also, Artificial Neural Network (ANN) model was used to analyze and predict the forming load for different process parameters. The Upper Bound (UB) model was also proposed to estimate the forming load and the results were compared with experiments. It was understood that calculated results were in concordance with experimental results in upsetting of bimetallic hollow discs. Thus, proposed ANN, FEM and UB models provide a valuable insight into the parameters affecting forming load and can be named as useful tools to predict the forming load without the need of any experiments.
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    An Optimization Study for Bridge Design of a Porthole Extrusion Die
    (Lublin Univ Technology, Poland, 2019) Ayer, Onder; Ozmen, Burcu Gizem; Karakaya, Ismail
    In this study, a porthole die extrusion simulation was carried out for a box profile by using HyperXtrude Inspire Extrude Metal 2019 which is a FEM based software. Aluminum AA6063 material was the billet material, temperature of the billet was 450 degrees C and ram speed was selected as 5 mm/sec. The die design was obtained according to the shape of the bridges of the porthole die. Finally, the design optimization was achieved by analyzing FEM results. It was obtained that the dies which have curved bridges offer optimum process conditions.
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    SIMULATION OF HELICAL GEAR FORMING OF AZ31 MAGNESIUM MATERIAL
    (Lublin Univ Technology, Poland, 2017) Ayer, Onder
    The simulation of helical gear forming is investigated in this study. AZ31 type magnesium material was selected for workpiece material because of its high specific strength. The finite element method was used to simulate the closed die upsetting method for magnesium material of helical gear upsetting. Three dimensional finite element analyses were carried out to obtain the forming load, effective stress, effective strain and temperature change with DEFORM-3D software.
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    A theoretical and experimental study for forward extrusion of clover sections
    (Elsevier Sci Ltd, 2008) Altinbalik, Tahir; Ayer, Onder
    Forward extrusion of clover section from different billet diameters has been investigated. The die profile is given by radius function to construct the new kinematically admissible velocity fields for three dimensional extrusion and then by using the upper bound method total extrusion loads are obtained. In the experimental studies, lead billets which having same initial heights but three different diameters have been extruded with the same strokes in order to verify the analysis. Die land length/billet diameter ratio was taken equal or greater than 0.6 as recommended in literature. A good agreement was found between the measured and the predicted load and so it is suggested that present analysis could be used the other commercial materials. (C) 2007 Elsevier Ltd. All rights reserved.
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    A THEORETICAL AND EXPERIMENTAL STUDY FOR THE LOAD OPTIMIZATION OF GEAR-LIKE PROFILES BY USING FORWARD AND LATERAL EXTRUSION
    (Canadian Science Publishing, 2015) Altinbalik, Tahir; Ayer, Onder
    The main purpose of this research is to investigate the minimum deformation load by selecting a suitable forming method for manufacturing of gear-like sections and to compare the load estimation methods between Upper Bound Analysis and DEFORM-3D. Forward and lateral extrusion were chosen as two different forming methods. The effect of die transition geometry on deformation load was also investigated by straight tapered and cosine profiles. A newly kinematical admissible velocity field to analyze different profiles of extrusion dies was proposed by upper bound analysis. Al 1070 was used as working material. Experiments using five sets of dies with gear-like form were performed, and the measured forming load results were compared with the predictions of the theoretical solutions. Experiments were carried out on the 150 metric ton hydraulic press.