Ulutan, Durul
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Name Variants
Ulutan, Durul
D.,Ulutan
D. Ulutan
Durul, Ulutan
Ulutan, Durul
D.,Ulutan
D. Ulutan
Durul, Ulutan
D.,Ulutan
D. Ulutan
Durul, Ulutan
Ulutan, Durul
D.,Ulutan
D. Ulutan
Durul, Ulutan
Job Title
Dr. Öğr. Üyesi
Email Address
Durul.ulutan@khas.edu.tr
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Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
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Scholarly Output
5
Articles
3
Citation Count
0
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0
5 results
Scholarly Output Search Results
Now showing 1 - 5 of 5
Conference Object Citation Count: 2Optimum utilization of on-demand manufacturing and laser polishing in existence of supply disruption risk(Elsevier, 2022) Ulutan, Durul; Isler, Zulal; Kaya, Burak Erkan; Hekimoglu, Mustafa3D printing has moved from being a rapid prototyping tool to an additive manufacturing method within the last decade. Additive manufacturing can satisfy the need in dire situations where spare parts distribution is an issue but access to a 3D printer is much more likely and rapid than access to original parts. Managing inventories of spare parts can be tackled with more ease thanks to the reduced part types with additive manufacturing. While quality (in terms of reliability) of additively manufactured spare parts in terms of mechanical properties seem to be lower than original parts (particularly due to the inherent staircase appearance and the corresponding stress concentration zones that can lead to premature fatigue failure), use of post-processing subtractive techniques to correct such surface irregularities are found to improve reliability. While each process adds another layer of complexity to the cost minimization problem, demand uncertainty and risk of supply disruption represent the modern global problems faced recently. The problem tackled in this study is the joint optimization of the supply reliability considering the effect of laser polishing parameters and the demand uncertainty. In this problem, a condition of random breakdowns of identical products is considered. Also, the original supplier of machine components is subject to exogenous disruptions, such as strikes, raw material scarcity, or the COVID-19 pandemic. As a result, the optimum control policy with the right cost parameters was shown via numerical experiments originated from mathematical analyses. This optimality can be critical in managing the system in the best possible way, particularly during times of unforeseen circumstances such as pandemics. (C) 2022 Society of Manufacturing Engineers (SME). Published by Elsevier Ltd. All rights reserved. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the Scientific Committee of the NAMRI/SME.Conference Object Citation Count: 0True variable-depth milling(Elsevier B.V., 2020) Ulutan, DurulWhen tool wears during machining, cost of the process increases. Rapid tool wear leads to even further contributions to process cost and hence must be taken well care of. Among the many forms of tool wear, notch wear is one that has a big effect on the tool change decision. When the tool contacts the workpiece, a high amount of impact is created where depth of cut is. With continuous machining operations such as turning, the impact may not be as important; however, with interrupted machining operations such as milling, repetitive impact between tool and workpiece occurs at every rotation. Therefore, notch wear can propagate rapidly when milling at a constant depth. When that happens, machine operator would be required to discard the tool and replace it with a fresh one. However, this may not have to be the case, if the depth of cut is varied throughout the milling process (variable-depth milling). Although different patterns of varying the depth of cut can be determined, the easiest route of continuously varying the depth of cut in increasing or decreasing direction should be as effective as any other. While varying the depth of cut, the direction of the variation is also found to have an effect on the end results. In this work, first the theoretical difference between end milling and variable-depth milling is discussed. Afterwards, benefit of using "true variable-depth milling" is explained. Then, machining experiments to quantify such benefits is detailed and the results are presented. It was found that when the same machining conditions were used to end-mill, variable-depth mill, and true variable-depth mill a workpiece, impact of notch wear can be minimized by continuously varying depth of cut in the right direction.Article Citation Count: 0Yedek Parçaların Talebe Yönelik Eklemeli Üretiminde Lazer Cilalamanın Optimum Karar Verme Politikası Üzerinde Etkisi(2020) Hekimoğlu, Mustafa; Ulutan, DurulEklemeli imalatın yakınlarda bulunan bir 3D yazıcı kullanılarak sermaye ürünlerinin yedek parça ihtiyaçlarını karşılamak için kullanılması giderek yaygınlaşmaktadır. Böyle bir teknoloji, talebe-binaen parça üretimini mümkün kılarak arızaların rassallığı nedeniyle tutulan yedek parça envanterinin önemli bir kısmını ortadan kaldırma imkânı sunmaktadır. 3D yazıcı kullanımının en büyük sorunlarından biri olan basılı ve orijinal parçalar arasındaki kalite farkı, yüzey pürüzlülüğünü hafifleten ve ek maliyet terimi karşılığında parçaların güvenilirliğini artıran lazer parlatma kullanılarak azaltılabilir. Farklı parametreler kullanılarak, parçaların güvenilirliği, sermaye ürünlerinin ihtiyaçlarına ve sistemlerin durumuna göre değiştirilebilir. Bu çalışmada, basılı parçaların yüzey pürüzlülüğü ve güvenilirliğinin orijinal yedek parçaların envanter seviyeleri ile birlikte optimize edilmesi sorunu ele alınmıştır. Çalışmada, sınırlı bir planlama ufku üzerinde rastgele arızalara maruz kalan sabit sayıda özdeş makinadan oluşan bir üretim tesisi dikkate alınmıştır. Matematiksel analiz ve ayrıntılı sayısal deneyler kullanılarak, sistemin uygun maliyetli yönetimi için kritik olabilecek optimum kontrol politikası ve maliyet parametreleri arasındaki ilişki gösterilmiştir.Article Citation Count: 0True Variable-Depth Milling of Nickel-Based Alloy In-718(2020) Ulutan, Durulinvestigated deeply by researchers, notch wear has been somewhat overlooked, despite the fact that it hasan important role in the tool replacement decision. Notch wear happens due to impact forces at the depthof cut particularly during intermittent cutting. To avoid frequent tool change decisions, varying the depthof cut constantly during machining has been proposed as an alternative. In this study, milling experimentswere conducted on the nickel-based alloy IN-718 where the depth of cut was varied throughout the cut.Results show favorable findings towards eliminating notch wear without compromising from machiningefficiencyArticle Citation Count: 0Optimum Laser Polishing Decision-Making for On-Demand Additive Manufacturing of Spare Parts: an Exploratory Study(Süleyman Demirel Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 2020) Hekimoğlu, Mustafa; Ulutan, DurulAdditive manufacturing is increasingly being used for satisfying spare parts needs of capital products using a nearby 3D printer. Such a technology allows inventory managers to start manufacturing after the demand realization which eliminates significant portion of spare parts inventory being held due to random nature of component breakdowns. Quality difference between printed and original parts, which is one of the biggest problems of using 3D printers, can be decreased by the use of laser polishing which alleviates surface roughness and increases reliability of parts in exchange of an additional cost term. Using different parameters, reliability of parts can be altered depending on needs of capital products and systems’ status. In this study, the problem where surface roughness and reliability of printed parts are jointly optimized with inventory levels of original spare parts is considered. In the problem setting, a machine part consisting of a constant number of identical products which are subject to random breakdowns over a finite planning horizon is considered. Using mathematical analysis and exhaustive numerical experiments, the relationship between optimum control policy and cost parameters was shown, which might be critical for cost-effective management of the system.
