Oguzhan YilmazGazi University · Department of Mechanical Engineering
Oguzhan Yilmaz
BSc, MSc, PhD (The University of Nottingham, Manufacturing Eng.)
About
48
Publications
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1,084
Citations
Citations since 2017
Introduction
Additive Manufacturing, Wire Arc Additive Manufacturing
Additional affiliations
June 2015 - present
June 2015 - present
Publications
Publications (48)
Wire Arc Additive Manufacturing method allows producing relatively large metal parts with minimum raw material. However, the high heat input used during production results in heat accumulation and temperature variance. Both of them can cause various problems, such as distortion, overflow, and residual stress. Heat accumulation is the rise in temper...
Powder bed fusion (PBF) systems are the most widely used metal additive manufacturing applications. Among these systems, selective electron beam melting (SEBM) is less common but is preferred for its fast-printing features and manufacturing high-density parts with lower residual stresses and distortion. As with other PBF systems, the predictions of...
In-situ decomposition in the laser powder bed fusion process enables the α’ martensite to transform into lamellar (α + β) microstructures to achieve superior mechanical properties, yet special conditions are required for the formation of decomposition, and these conditions are difficult to predict. In this context, an efficient model has been devel...
Porous structures have been used in many areas particularly in medical, transportation, space and defense applications. The building of porous structure is formed by the lattices which have many unusual and interesting features that make them candidates for innovative designs. Such designs include creating porosity variation in structures and the a...
Ti-6Al-4V is one of the most promising alloys for electron beam melting (EBM) of structural parts due to its outstanding properties and its extensive use in the aerospace, automotive, and energy industries. In this study, we report a detailed and systematic micromechanical characterization of additively manufactured Ti-6Al-4V parts produced via EBM...
Laser-based powder bed fusion (L-PBF) is one of the most widely used additive manufacturing methods. Its most striking feature is the melt pool in the powder bed, which is formed by a laser heat source. Many physical phenomena occur as a result of the interaction of the heat source with metal powders. Spattering, melting and sintering to each other...
![Specifications of the EC machine base [16].](profile/Hasan-Demirtas-5/publication/354867625/figure/tbl1/AS:1072719768592385@1632767731148/Specifications-of-the-EC-machine-base-16_Q320.jpg)
This study aims to improve the surface finish of γ-TiAl AM parts produced via Electron Beam Melting (EBM) process. The sample parts were machined by Electro Chemical Machining (ECM) by changing main variables such as electrolyte type, pulse and feed rate and their effects on the surface qualities are presented and discussed. ECM workshop trials hav...
Additive manufacturing (AM) offers high design flexibilities and challenging approaches to produce highly complicated and intricate parts, which could not be possible to produce with traditional manufacturing methods. However, one of the significant drawbacks of AM processes is of course poor surface qualities, which are not acceptable for end prod...
In this study, deviations for the porosity level of the Ti-6Al-4V functionally graded porous structures for three different cell structures were investigated. For this purpose, functionally graded porous structures are designed and produced by selective laser melting (SLM). It is also aimed to investigate the effects of unit cell structure, unit ce...
Sheet metal forming processes are very common manufacturing and leading processes in automotive and aerospace industries. Flexforming is one of the sheet metal forming processes which is preferable due to its flexible manufacturing capabilities and its ability to produce multiple parts simultaneously. Convex contoured shaped parts are very much use...
Additive Manufacturing (AM) is a new generation manufacturing method and AM is using digital CAD data directed to the machine to manufacture. AM is therefore regarded as a direct digital manufacturing method. This research work presents the methodology for designing critical aerospace parts used under fatigue conditions for AM. Selected fatigue cri...
Robots are used in industry as a machine tool for many years and are integrated into many areas. Materials can be machined without any contact in electrochemical machining (ECM). This paper presents, a new hybrid concept that combines ECM with a robotic arm which is called robotic electrochemical machining (RECM) and its components. RECM can be use...
Additive Manufacturing (AM) recently presents an increasing growth regarding the
production of mechanical parts, due to its outstanding characteristics in comparison
to conventional processes. AM methods facilitate the production of parts with unique
and complex geometries without requiring subsequent operations or processes [1].
Electron beam melt...
Porous structures are formed by the repetition of the lattice elements in regular and/or stochastic manner. These are commonly used in production of lighter and more durable structures which have great importance mainly in aerospace for lighter aircraft components and medical implants for creating biocompatible designs. In this study, the design an...
![Fig. 2. Photographic view of (a) the cathode and (b) the anode [19].](profile/Hasan-Demirtas-5/publication/333816236/figure/fig1/AS:897595635400705@1591014884317/Photographic-view-of-a-the-cathode-and-b-the-anode-19_Q320.jpg)
Electrochemical machining (ECM) is one of the most efficient non-traditional machining processes used to provide a bright surface finish, machine difficult-to-cut materials and manufacture complex shapes. However, due to some challenges, such as the lack of dimensional accuracy, process monitoring and control and environmental factors, implementati...
![Figure 2. Main integrated units in SMD system [1].](profile/Mehmet-Aladag-6/publication/334599713/figure/fig2/AS:783190901927936@1563738670871/Main-integrated-units-in-SMD-system-1_Q320.jpg)
![Figure 4. Work cell structure in CAMDM hardware [1].](profile/Mehmet-Aladag-6/publication/334599713/figure/fig4/AS:783190901927937@1563738670978/Work-cell-structure-in-CAMDM-hardware-1_Q320.jpg)
Shaped metal deposition (SMD) is a relatively new additive layered manufacturing method. It is a novel technique to build net-shaped or near-net-shaped metal components in a layer-by-layer manner via applying metal wire and selection of a heat source such as laser beam, electron beam, or electric arc. SMD process is preferable as an alternative to...
Freeform surfaces are widely used in the design of complex parts to satisfy aesthetic and functional requirements, particularly in automotive, aeronautics, and die-mould industries. Traditional machining of freeform surfaces is gradual and involves significant manual interactions. Non-traditional machining processes such as electrochemical machinin...
ZET AlıĢılmamıĢ imalat yöntemlerinden biri olan Elektrokimyasal ĠĢleme (EKĠ) yöntemi ile iĢ parçasının mekanik özelliklerine bakılmaksızın iĢlenmesi sağlanabilmektedir. Bu yöntemde iĢ parçası ve takım birbiri ile temas etmediğinden dolayı iĢ parçası yüzeyinde artık gerilme, ısıdan etkilenmiĢ bölgeler gibi hatalar oluĢmamaktadır. Böylece iĢ parçasın...
ZET Elektrokimyasal ĠĢleme (EKĠ) yöntemi Faraday ve elektroliz kanunlarına dayanan bir alıĢılmamıĢ imalat yöntemidir. EKĠ yönteminde takım ve is parçası düĢük voltaj ve yüksek akım değerleri üretebilen bir doğru akım (DA) güç kaynağına bağlanmaktadır. EKĠ yönteminde takım negatif (-), iĢ parçası ise pozitif (+) kutuplara bağlanarak sırasıyla katot...
Electrochemical machining (ECM) is a non-traditional machining method that is the one of most effective to manufacture difficult to cut materials with bright surface finishing and high dimensional accuracy. Due to the lack of contact between the tool and workpiece, ECM has the following advantages: applicability to the machined materials with regar...
Freeform surfaces are widely used in the design of complex parts to satisfy aesthetic and functional requirements, particularly in automotive, aeronautics, and die-mould industries. Traditional machining of freeform surfaces is gradual and involves significant manual interactions. Non-traditional machining processes such as electrochemical machinin...
Wire plus arc-based shaped metal deposition is a metal rapid manufacturing technique whereby 3D complex parts are produced by building up metallic parts in layer by layer. In the present work, a type of shaped metal deposition using tungsten inert gas welding plus SS308LSi Wire technique was developed and integrated it with a new computer-aided met...
Shaped metal deposition (SMD) method would be an alternative way to traditional manufacturing methods, especially for complex featured and large scale solid parts and it is particularly used for aerospace structural components, manufacturing and repairing of die/molds and middle-sized dense parts. This method is implemented by depositing continuous...
Shaped metal deposition method using gas tungsten arc welding is a novel manufacturing technology that can be used for fabricating solid dense parts in layered manufacturing. This paper reports for the first time using the pulsed current shaped metal deposition technique for fabricating components using cold wire of AISI 308LSi stainless steel. The...
High-performance machining of free-form surfaces is highly critical in automotive, aerospace, and die–mold manufacturing industries. Therefore, electrochemical machining (ECM) process has been used in such cases in that sense. The most important challenges of using ECM process are the lack of accuracy and difficulty in designing proper machining to...
Tungsten inert gas arc welding–based shaped metal deposition is a novel additive manufacturing technology which can be used for fabricating solid dense parts by melting a cold wire on a substrate in a layer-by-layer manner via continuous DC arc heat. The shaped metal deposition method would be an alternative way to traditional manufacturing methods...
Electrochemical machining (ECM) is one of the non-traditional machining processes and it has been used for specific areas where they require high-performances. In this paper, development of a desktop size EC machine is presented for micro/macro manufacturing. In order to verify the capabilities of the developed machine, the process experiments were...
Shaped metal deposition is a relatively new additive layered manufacturing method. It is a novel technique to build net-shaped or near-net-shaped metal components in a layer-by-layer manner via applying metal wire and selection of a heat source such as laser beam, electron beam, or electric arc. It is a manufacturing method used for production of c...
Electrical discharge hole drilling is a variation of electrical discharge machining (EDM) process, which has been widely used for making starting holes for wire-EDM applications, opening ventilating holes on dies and diesel ejectors and turbine blade cooling holes, etc. In this research work, an automated and intelligent system was developed for ED...
![Figure 1 [Poursaeidi et al., 2013].](profile/Oezguer-Poyraz/publication/325264246/figure/fig1/AS:642387449757696@1530168511135/Poursaeidi-et-al-2013_Q320.jpg)
Harsh working conditions of gas turbine blades lead to various types of unexpected failures which result in a worn-out or broken blade. Besides replacement by a new blade, the repair of worn-out blades may be preferred as a low-cost solution. The adaptive repair of worn-out blades needs reverse engineering of the actual blade shape since the nomina...
Electro-Chemical Machining (ECM) is a non-traditional machining process that has been effectively used in aerospace manufacturing industry especially in recent years. Anode (work piece) surface is machined via chemical reactions that are occurred during the process with the help of cathode (electrode) and electrolyte liquid. ECM method is generally...
This paper presents a comparative experimental investigation of electrical discharge machining fast hole drilling of aerospace
alloys, namely Inconel 718 and Ti–6Al–4V. A series of experiments was carried out using electrical discharge machining process
in order to explore the influence of electrode type and material, i.e., single and multi-channel...
Repair and maintenance of aeroengine components have been one of the main tasks to be overwhelmed by aerospace industries due to continual increase in raw material and manufacturing costs. In this paper, an advanced methodology for the repair of complex geometry and expensive components via reverse engineering, free-form surface modeling and machin...
This paper proposes a novel method of collision-free fixture and tool space design for five-axis grinding, considering tool movement, machine degrees of freedom, the machine envelope, inspection, and related features. The fixture space is designed in three steps. First, the fixture space is generated as the remaining space after cutting out the too...
This paper introduces an intelligent and automated system proposed for EDM hole drilling of super-alloys in manufacturing and re-manufacturing stages of products used in aerospace, die/mold and medical surgery. The system is a user-friendly computer-based program, which guides the end-user in order to perform sustainable and effective process. To a...
This paper reports an experimental investigation of EDM drilling of Ø2 mm holes on Inconel 718 using brass electrode. The effect of process parameters (discharge current, pulse on and off times, and capacitance) on process outputs (material removal rate and electrode wear rate) was determined based on minimum number of experiments. The mathematical...
The repair of worn parts is of great interest for aerospace industries to extend the life cycle of aerospace parts. Due to
the distortion and defects of a worn part, the nominal CAD model from the design stage is no longer suitable for the use of
the repairing process, which causes the main problem for precisely repairing complex components. In thi...
After a certain number of hours of running, no two mechanical components are completely the same due to normal wear or foreign object damage. A nominal CAD model from a component designer is different from its corresponding worn one and therefore cannot be directly used for tool path generation for build up and machining repair processes. This is t...
We describe our experience using magnetic resonance imaging (MRI) to evaluate the unossified dislocated cartilaginous patella in a 6-year-old male patient with restricted extension and flexion deformity of both knees. MRI is used widely in the visualization of cartilage since it can show cartilage directly. In addition, FS FLASH 3D sequence has rec...
This paper introduces a user-friendly intelligent system for the selection of electro discharge machining (EDM) parameters. In this system, a compact selection method based on expert rules, which were obtained from experimental results and extracted from the knowledge of skilled operators, is presented. Expert rules are evaluated by the fuzzy set t...
Purpose
This paper discusses research on machining and repairing of turbomachinery components which are generally complex geometries and made up of difficult to machine materials (nickel super alloys or titanium alloys).
Design/methodology/approach
The approaches, methods and methodologies used for machining and repairing of blades are reviewed as...
Purpose
The aim of the paper is to provide an economically viable solution for the blade repair process. There is a continual increase in the repair market, which requires an increased level of specialised technology to reduce the repair cost and to increase productivity of the process. Design/methodology/approach – This paper introduces the aerosp...
This paper introduces a system that has been developed for the selection of cutting parameters of turning operations from
the machinability data handbook by using Fuzzy Logic (FL) approach. Main objective of the system is to get rid of the manually
input-output oriented handbook, so selection of cutting parameters is made by a user-friendly intelli...
Projects
Projects (3)
This project proposes, a new hybrid machining process that combines the ECM with the high flexibility of the robot arm, which is called Robotic Electrochemical machining (RECM). The material can be machined in a non-contact way with the RECM, and the chatter formation by forces during the RM is prevented. Additionally, it is aimed at machine hard-to-cut materials (Ti6Al4V, etc.) with low investment costs by avoiding problems such as trial error or cathode design for ECM freeform surfaces.
High-performance machining of freeform surfaces is highly critical in the automotive, aerospace and die-mold manufacturing industries. In such machining operations, tight dimensional and geometrical tolerances must be maintained while controlling thermal and residual stresses; therefore, the electrochemical machining (ECM) process is a key process in that sense. In this project a mathematical model is developed to machine freeform surfaces with high dimensional accuracy
