Abstract

In this study, thermal evaluation of ABS polymer thin wall part fabricated by large scale additive manufacturing is presented. The cooling of single bead layers, the interface temperature and the effect of adjacent top layer on the temperature of the previous layer were investigated. The experimentally measured temperatures were one-dimensionalmensional heat transfer model of a single filament. The measured temperature values are in general agreement with the model until the adjacent top layer is going to be deposited. While the interface temperature was below the glass transition temperature at the beginning of the process, it was gradually increased with additional layers. The tension tests carried out using the specimens which were cut parallel and perpendicular to the building directions, showed mechanical anisotropy of the printed sample. The interlayer strength is about the half of the longitudinal strength of the printed sample, although interface temperature between adjacent layers was above the glass transition temperature and subsequent rolling was performed.

Authors: Ömer EYERCİOĞLU, Mehmet ALADAĞ, Samet SEVER
Journal: Sigma Journal of Engineering and Natural Sciences
Issue: Name: Regular, Year: 2018, Volume: 36, Issue: 3, (SEP 2018), pp:645-654
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Abstract

Prediction of the stresses of precision gear forging die is becoming increasingly essential and it also important to make the precision gear forging feasible. The usual way to design gear forging die is to use thick cylinder approach (Lame Equations). However, the finite element method (FEM) has been greatly successful to provide the understanding of die stresses for different forming process. The aim of this study is to evaluate the stresses on simple cylindrical, symmetric and asymmetric gear forging dies by applying internal pressure from 20% to 100% of inner surface of the dies. For this purpose, 3D FE analyses were carried out and the stresses encountered in partially pressurized forging dies were evaluated. The results show that partially loaded die has subjected to lower stresses than the fully loaded one and the maximum effective stresses are linearly increasing with increasing pressurized area. The value of maximum equivalent stresses is higher in gear shaped dies than the cylindrical one and asymmetric gear die is encountered to the highest stresses. The cylindrical approach (Lame Equations) is not adequate for gear forging die design.

Authors: Omer Eyercioglu, Necip Fazil Yilmaz, Gulaga Tas, Mehmet Aladag
Proceeding Book: VI. International GAP Engineering Congress 2018
Pages: 417-425
ISBN:9789757113683
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Abstract

Large Scale Additive Manufacturing (LSAM) defines a system that can be used for printing components on the order of several meters at high extrusion rates (up to 50 kg/hr). The feed stock material is in the form of thermoplastic or fiber reinforced thermoplastic pellets which are almost 20 times cheaper than the filament based feedstock. The system has the potential to significantly affect automobile, aerospace and energy industries. However, the design constraints of small-scale 3D printing may not be applied to the large-scale printing due to the nature of the process. New design rules and limitations should be taken into consideration. In this study, the maximum bridging distance in large scale direct extrusion 3D printing system is investigated experimentally. A specially designed V-shaped model is used for testing. The experiments were carried out for 2 mm, 4 mm and 6 mm nozzle diameters under free- and forced-air cooling conditions. The failure of bead is determined in terms of break off and sags down. The maximum bridge distance is dependent on the printer settings (nozzle diameter, extrusion rate, travel speed, etc.), material, surface area-to-volume ratio of the extruded bead and cooling rate (thermal effects). 

Keywords: Additive Manufacturing, Direct Extrusion, ABS, Large Scale, Bridging Authors: Omer Eyercioglua, Mehmet Aladag, Adem Aksoy , Kursad Gov
Proceeding Book: 4th International Congress on 3D Printing (Additive Manufacturing) Technologies and Digital Industry 2019
ISBN:978-975-96797-3-6
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Abstract

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 traditional manufacturing methods especially for complex featured and large scale solid parts manufacturing and it is particularly used for aerospace structural components, manufacturing and repairing of dies/molds. TIG welding-based SMD method is implemented by depositing continuous wire melted via heat. In this study, the overhang (self supporting) angle in TIG welding-based shape metal deposition process is investigated. The overhang angles are the angles at which a 3D printer can build tapered (overhang) surfaces without the need to supporting material below the printing layer. The material, bead height, TIG weld parameters and the environment temperature (cooling rate of printed layer) are the parameters which affect the overhang angle. The results show that the maximum overhang angle is also dependent on the temperature of the previous layer. For the selected set of process parameters, the maximum overhang angle is found as 28o, if the temperature of the previous layer is cooled to 150oC before the subsequent layer is deposited.  

Keywords: Shaped Metal Deposition. Wire Arc Additive Manufacturing. Overhang. 3D Printing Authors: Omer EYERCIOGLU, Yusuf ATALAY, Mehmet ALADAG, Oguzhan YILMAZ
Proceeding Book: 4th International Congress on 3D Printing (Additive Manufacturing) Technologies and Digital Industry 2019
ISBN:978-975-96797-3-6
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Özet

Bu çalışmada, bağlantı elemanları (cıvata, somun vb.) kalıplarının yüzey parlatma işlemlerinde aşındırıcı akış işleme yöntemi(AFM) kullanılmıştır. Tel elektro-erozyon ile kesilen kalıp bileşenlerinin, yüzey pürüzlülüğü, aşındırıcı akışkanla işleme öncesi ve sonrasında ölçülerek yüzey kalitesinin değişimi incelenmiştir. Bulgular, elektro-erozyon nedeniyle oluşan beyaz katman tabakasının tamamen ortadan kaldırıldığını ve son yüzey pürüzlülüğünün (Ra) 1,5 µm'den 0,4 µm'ye azaltıldığını göstermiştir. Yüzey kalitesinin artışı, kalıp malzemesinin sertliğiyle orantılıdır.  

Keywords: Aşındırıcı Akışkanla İşleme, Dövme Kalıbı, Yüzey İşlemleri
Authors: Omer EYERCIOGLU, Kürşad GÖV, Adem AKSOY, Mehmet ALADAG
Dergi: Makina Tasarım ve İmalat Dergisi
ISSN:1302-9487
Makaleyi İndir

Abstract

Asymmetric gears are those have two different pressure angles for drive and cost side of the gear. Because of this speciality of the asymmetric gears, they are superior to symmetric one in terms of load carrying capacity in one directional motion. Due to higher load carrying capacity in one directional motion, asymmetric gears have had great interest in turbine and aviation industry. Asymmetric spur gears can be produced by various manufacturing methods, such as hobbing, casting, precision forging. In this study, hot and warm precision forging of the asymmetric spur gears were investigated by using finite element method. In the simulations, workpiece temperature was selected as 1200 oC and 800 oC for hot and warm forging, respectively. Results of the simulations were compared in terms of required forging load, effective stresses, contact pressures and temperature distribution. 
 

Keywords: Asymmetric spur gear, precision forging, finite element method, warm forging, hot forging. Authors: Omer EYERCIOGLU, Mehmet ALADAG
Proceeding Book: 2. Uluslararası Türk Dünyası Mühendislik ve Fen Bilimleri Kongresi
ISBN:978-605-80038-4-2
Pages: 542-551
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Abstract

The measurement of the asymmetric gear tooth is difficult due to the asymmetricity of profile, so a method based on image processing to measure the error of the asymmetric spur gear is presented. Non-contact measurement for asymmetric spur gear was investigated using image processing technology. The digital image of the asymmetric spur gear is captured by the CMOS camera and the software is developd by using Python and as OpenCV image processing library. Some digital image processing techniques and algorithms are used, including distortion correction, frame resizing, color conversion, median filter, binarization, edge detection, and sub-pixel fitting arithmetic. According to the shape feature of the asymmetrical gear, some basic principles such as fit to least squares, Hough transformation and Bresenham drawing circle were applied synthetically and the measurement algorithm of the number of teeth, module, radius of center, radius of addendum, radius of dedendum, coefficient of variation, etc. was established. The experimental results show that this method satisfies the requirements of real-time inspection. 

Keywords: Digital image processing, asymmetric spur gear, non-contact measuring, Python, OpenCV
Authors: Omer EYERCIOGLU, Mehmet ALADAG
Proceeding Book: 2. Uluslararası Türk Dünyası Mühendislik ve Fen Bilimleri Kongresi
ISBN:978-605-80038-4-2
Pages: 524-531
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Abstract

Wire Arc Additive Manufacturing (WAAM) is a relatively new 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. WAAM process is preferable as an alternative to traditional manufacturing methods especially for complex featured and large scale solid parts manufacturing and it is particularly used for aerospace structural components, manufacturing and repairing of dies/molds. TIG weldingbased WAAM method is implemented by depositing continuous wire melted via heat. In this study, the overhang (self-supporting) angle in TIG welding-based wire arc additive manufacturing process is investigated. The overhang angles are the angles at which a 3D printer can build tapered (overhang) surfaces without the need to supporting material below the printing layer. The material, bead height, TIG weld parameters and the environment temperature (cooling rate of printed layer) are the parameters which affect the overhang angle. The results show that the maximum overhang angle is also dependent on the temperature of the previous layer. For the selected set of process parameters, the maximum overhang angle is found as 28o, if the temperature of the previous layer is cooled to 150oC before the subsequent layer is deposited. 

Keywords: TIG Welding, Wire Arc Additive Manufacturing, Overhang, 3D Printing.
Authors: Omer Eyercioglu; Yusuf Atalay; Mehmet Aladag
Journal: International Journal of Research -GRANTHAALAYAH
ISSN:2350-0530
Pages: 247-254
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Abstract

The mass production bevel gear is mainly realized by the precision forging process. The process can be carried out cold, warm, or hot conditions by using various forging presses (hydraulic or mechanical presses and HERF machines). The process cycle time is changing with the type of forging press (i.e. the speed of punch). During hot forging, the hot billet is in contact with the relatively colder die, and heat is transferred to the environment. Therefore, the billet temperature is changing during deformation and the processing time is an effective parameter of the temperature distribution of the billet. The flow stress of the material is dependent on both the temperature and strain rate (punch speed). In this study, the effects of punch speed on the forging load were investigated by the finite element method. To simulate different forging presses, various punch speeds were chosen as 0.001 m/s, 0.01 m/s, 0.1 m/s, 1 m/s. and 10 m/s. The temperature distributions of the billets and the forging loads were also determined for these punch speeds. The results show that the temperature drop of the billet and the forging load are decreasing with the increasing punch speed. So that forging with HERF machines is advantageous than the hydraulic and mechanical presses in the precision hot forging process of bevel gears.

Keywords: Bevel gear, precision forging, finite element method, forging temperature, punch speed.
Authors: Mehmet ALADAG, Omer EYERCIOGLU, Gulaga TAS
Proceeding Book: The International Conference of Materials and Engineering Technologies (TICMET'19)
ISBN:
Pages:
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Abstract

The compressive pre-stress due to the shrink fitting cause dimensional changes on the tooth profile of the precision gear forging dies. The accuracy of the gear die is directly affecting the accuracy of the final product. Therefore, the dimensional variations due to shrink fit must be pre-determined and the gear tooth profile on the die insert modified accordingly. In this study, the change of tooth profile of the symmetric and asymmetric precision spur gear forging dies because of shrink fitting are analyzed by finite element (FE) method and the results are compared with the experimental ones. Both the (CMM) measurements and the finite element results of gear dies predict much higher radial displacements than the results of the cylindrical approach (Lame Equations). The amount of radial displacements along the tooth profiles of both symmetric and asymmetric gear dies are not uniform and changing from root to tip of the tooth. The radial displacements of the asymmetric gear forging die are higher than the symmetric one.  

Keywords: Gear die, asymmetric gear, shrink fit, forging, involute profile
Authors: Omer EYERCIOGLU, Gulaga TAS, Mehmet ALADAG
Journal: Sigma Journal of Engineering and Natural Sciences
Issue: Name: Regular, Year: 2020, Volume: 38, Issue: 1, (MAR 2020), pp:71 - 81
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Abstract

This study presents an analysis of the mechanical behavior of different amounts of carbon fiber additive ABS composites produced by the large-scale additive manufacturing (LSAM) method. Additive manufacturing is distinguished from other manufacturing methods such as casting, molding, machining or etc. by its ability to obtain complex parts by this manufacturing method. Even it is desired to make rapid prototyping, due to the manufacturing time related to material deposition rate; it is not suitable for mass production. Also, the mechanical strength of produced parts is not adequate in terms of strength for the end-user. So, engineers made great efforts to overcome this problem, in particular, increasing the strength of produced parts with additive manufacturing technology. Adding some strengthen additives (carbon, fiberglass, etc.) into the material, therefore, significant having high strength materials would have been manufactured by this method. In order to validate enhanced material in terms of tensile and compression strength, flexural bending capacity, and non-supported bridging distance ability, many studies were carried out by researchers, however, these studies were generally carried out for small volume printers. Namely, there is a gap that must be filled in huge volume printing systems (LSAM) in view of these studies. Here, flexural capacity was investigated in a large-scale additive manufacturing system. Flexural tests were conducted following the ASTM standard of D790. In this study, In order to evaluate the flexural bending capacity of a single layer, four specimens are produced from the direct extrusion system of LSAM.

Keywords: Large scale additive manufacturing, direct extrusion system, flexural bending test, carbon fiber abs.
Authors: Omer EYERCIOGLU, Engin TEK, Mehmet ALADAG
Proceeding Book: The International Conference of Materials and Engineering Technologies (TICMET'20)
ISBN:
Pages:
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Abstract

Sheet metal bending is one of the important metal forming processes at ambient temperature. The usage of high-strength steel is one of the stronger materials for the construction of components in the automotive industries. However, for complex shapes, cold forming is not always sufficient, and heating the workpiece plays a major role in manufacturing these shapes. Bendability may increase with increasing forming temperature and currently, hot forming of advanced high strength steels (AHSS) is becoming more attractive. While hot forming of AHSS is beneficial for high formability, subsequent quenching is required to maintain final strength. This procedure extends the production time. In this study, temperature gradients, bending loads, and spring back after V-bending were investigated. The experimental study was carried out on a 2 mm thick Docol 1500M steel at various temperatures by using a speed-controlled servo press machine. The bending regions of the specimens were locally heated to 200, 300, 400, 500, and 600oC by using a high-frequency induction heating device. The results show that; punch loads were significantly lowered with increasing the local heating temperature during bending. There were no cracks observed on the specimens. The amount of spring back is decreasing with the bending temperature and around 500oC almost no spring-back was measured. Negative spring back was observed for the bending temperatures higher than 500oC

Keywords: Springback, V-Bending, Local Heating, AHSS, Docol 1500M
Authors: Omer EYERCIOGLU, Sevket ALACACI, Mehmet ALADAG
Journal: International Journal of Research -GRANTHAALAYAH
ISSN:2350-0530
Pages: 269-277
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Abstract

EN:
In this study, an analysis is presented for the determination of the forging load and material flow by using the upper bound energy method (UBEM) in the precision forging process of asymmetric spur gears. In this analysis, the driver and driven sides of the asymmetrical tooth are divided into 12 deformation zones. Calculation of regional material flow rates and solution of energy equations were realized with software developed in Python programming language and an interactive user interface is presented. An experimental study was carried out and the results of material flow pattern and forging load were compared with the results of upper limit energy analysis (UBEA).<br />

TR:
Asimetrik dişliler özellikle tek yönlü güç ve hareket iletiminin olduğu uygulamalarda simetrik dişlilere göre daha üstün performansları nedeniyle tercih edilmektedirler. Asimetrik dişlilerin imalatında, hassas dövmecilik teknolojisinin kullanılması ile profilden kaynaklanan imalat sınırlandırmaların ortadan kaldırılması ve yüksek mukavemete sahip dişlilerin verimli bir şekilde üretilmesi mümkün olacaktır. Bu çalışmada, asimetrik düz dişlilerin hassas dövme işleminde, üst sınır enerji metodu (ÜSEM) kullanılarak dövme yükü ve malzeme akışının belirlenmesi için bir analiz sunulmuştur. Bu analizde, asimetrik dişin süren ve sürülen tarafları 12 şekil değiştirme bölgesine ayrılmıştır. Yapılan analizde, iş parçası malzemesinin isotropik ve homojen olduğu, dövme sırasında pekleşmediği, simetri ekseni boyunca malzeme geçişi olmadığı ve simetri ekseni üzerinde malzeme akış hızlarının eşit olduğunu varsayılmıştır. Bölgesel malzeme akış hızlarının hesaplanması ve enerji denklemlerinin çözümü, Python programlama dilinde geliştirilen bir yazılımla gerçekleştirilmiş ve interaktif bir kullanıcı arayüzü sunulmuştur. Prototip bir asimetrik dişli için dövme deneyleri yapılarak elde edilen sonuçlar üst sınır enerji analizi (ÜSEA ) sonuçlarıyla karşılaştırılmıştır. ÜSEA ile elde edilen dövme yükü değişimi ve malzeme akışı, deneysel sonuçlarla benzer olup maksimum dövme yükü göre %10’un altında bir sapma göstermiştir. Geliştirilen yazılım ile dövme yükü kısa bir süre içerisinde hesaplanabilmektedir. Hesaplanan maksimum dövme yükünün deneysel olarak belirlenenden daha yüksek olması, üst sınır enerji metodunun özelliğinden kaynaklanmakta olup, kalıp tasarımı ve pres kapasitesinin belirlenmesinde emniyetli bölgede kalmak için uygundur.

Authors: Omer Eyercioglu, Gulaga Tas, Mehmet Aladag
Proceeding Book: Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi
Pages: 333-346
DOI:https://doi.org/10.17341/gazimmfd.718534
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