1TEMPERATURE EVALUATION AND BONDING QUALITY OF LARGE SCALE ADDITIVE MANUFACTURING THIN WALL PARTS

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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2STRESS EVALUATION OF ASYMMETRIC AND SYMMETRIC SPUR GEAR FORGING DIES USING FINITE ELEMENT METHOD

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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3DETERMINATION OF THE MAXIMUM BRIDGING DISTANCE IN LARGE SCALE ADDITIVE MANUFACTURING

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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4EXPERIMENTAL INVESTIGATION OF OVERHANG ANGLE IN TIG WELDING-BASED SHAPE METAL DEPOSITION PROCESS

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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5BAĞLANTI ELEMANLARI ŞEKİLLENDİRME KALIPLARININ AŞINDIRICI AKIŞKAN YÖNTEMİYLE PARLATILMASI

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
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