SEARCH RESULT

Investigations on cutting force, surface quality and dimension accuracy etc. are ongoing considering the feed rate and cutting speed despite the development of new drill qualities in terms of the material and geometry in drilling. In this study, the drillability of AISI 430 ferritic stainless steel used in many industrial environments such as automobile chassis parts, hot water tanks, kitchen utensils and decorative applications was investigated. The effects on thrust force, torque and surface quality of cutting speed and feed rate was evaluated in the drilling of workpiece prepared in sheet form. Experiments were performed with three different cutting speeds and feed rate with the uncoated carbide drill bit. Variance analysis was applied to determine the effect levels of the drilling parameters on the machining outputs. According to the experimental results, it was determined that as the feed rate increases, thrust force, torque and surface roughness increases. On the other hand, it has been observed that as the cutting speed increases, the machining outputs tends to decrease.

International Iron & Steel Symposium
UDCS

Tolga MERAL Mustafa GÜNAY

Hard turning is an alternative machining method instead of cylindrical grinding. In this method, more efficient results can be obtained for surface integrity (surface roughness, hardness, residual stress, etc.) of the machined parts when the cutting conditions are optimized. This study includes the optimization of cutting parameters for the minimum surface roughness (Ra) and the development of a mathematical model for estimation of Ra in turning of hardened X40CrMoV5-1 tool steel with ceramic cutting tools. In this context, hard turning tests were made at three different levels using the cutting speed (V), cutting depth (a) and feed rate (f). According to the Taguchi methodology, the optimum cutting parameters were determined as the a2V3f1 test sequence. According to the results of the analysis of interactive variance, the most important parameter was determined as the feed rate.

International Iron & Steel Symposium
UDCS

Mehmet Erdi KORKMAZ Mustafa GÜNAY

The residual stresses induced by any machining process affects fatigue life, corrosion crack resistance and part distortion. Therefore, residual stresses should be predicted better and the cutting parameters should be arranged for minimum value. This paper presents a 2D finite element analysis (FEA) on residual stresses during hard turning of AISI 4140 steel with HSS tools. The cutting parameters are chosen as feed rate and cutting speed with three levels and constant depth of cut. In simulation after the cutting process is finished, both the chip and tool are removed and the workpiece can thermo-mechanically relax. The average of three extraction points on eight different depths of machined surface for residual stresses is calculated for better results. FEA results showed that both tangential and axial residual stresses act as tensile in the depths near the surface until about 75 µm while they act as compressive stress after the depth of 75 µm until about 300 µm. Also, increasing cutting speed has decreasing effect on tensile residual stresses while increasing effect on compressive residual stresses.

International Iron & Steel Symposium
UDCS

Mehmet Erdi KORKMAZ Nafiz YAŞAR Mustafa GÜNAY

In this study, machinability experiments on hardened AISI H10A hot work tool steel with CBN inserts were performed in dry and minimum quantity lubrication (MQL) conditions. Hard turning experiments were conducted according to Taguchi L9 orthogonal array. The effects of cutting parameters (cutting speed, feed rate and depth of cut) and cutting conditions on surface roughness were analysed. The analysis of variance (ANOVA) in 95% confidence level was applied in order to effects of cutting parameters surface roughness. It was observed that average surface roughness (Ra) increased with increasing feed rate and depth of cut in dry cutting condition with CBN inserts. In dry and MQL cutting conditions, the most important parameter on surface roughness were determined as depth of cut with 51.79% PCR and 69.68% PCR, respectively.

International Iron & Steel Symposium
UDCS

Rıfat Akdere Halil DEMİR Gültekin Uzun Mustafa GÜNAY

Machining parameters for manufacturing methods can be optimized based on the finite element method using numerical simulation software. In this study, the simulation of the hot rolling process was performed for plain round bar producing. Rolling simulations were done in DEFORM-3D software and the hot rolling process was analyzed with three different rolling temperatures and rotation speed of rolls. In the results of numerical analysis, diameter and circularity tolerances have been measured for the product. The outputs of the finite element simulation were evaluated to determine the effects of rolling parameters on size quality of round bar product. The analysis of variance (ANOVA) with %95 confidence level was performed in order to determine the effect level of rolling parameters. It was determined that the rounded product geometry is out of diameter and circularity tolerances by increasing the rolling temperature and the rotational speed.

International Iron & Steel Symposium
UDCS

Emre EROL Mehmet Erdi KORKMAZ Mustafa GÜNAY

Teknoloji ve endüstrinin hızla gelişmesi ile yüksek mukavemetli, hafif ve mükemmel aşınma direncine sahip yapısal malzemelere olan talep sürekli artmaktadır [1,2]. Bu çalışmanın amacı, Al2014 alüminyum alaşımının kaplamasız sementit karbür takım ile delinmesi sonucunda itme kuvvetinin deneysel ve simülasyon sonuçlarını kıyaslamaktır. Bu sayede deneyler sonucunda elde edilecek verilen düşük sapmalar ile simülasyonla da elde edilebileceğini göstermektir. Deneyler ve delme simülasyonlarında ilerleme miktarı ve kesme hızının üç farklı seviyeleri kullanılmıştır. İşleme simülasyonları için yaygın olarak kullanılan [3] Johnson-Cook malzeme modeli Eşitlik 1'de verilmektedir. Malzeme modeli ağırlıklı olarak yüksek gerilme oranı metallerinde deformasyon davranışı için uygundur. Genellikle plastik deformasyon süreçlerinin adyabatik geçici dinamik analizinde kullanılmaktadır. Bu modele göre sertleşme, akma gerilmesinin σ0 olarak kabul edildiği belirli bir izotropik sertleşme türüdür [4]:

International Symposium on Light Alloys and Composite Materials
UHAKS

Mehmet Erdi KORKMAZ Ramazan Çakıroğlu Nafiz YAŞAR Ramazan Özmen Mustafa GÜNAY

The use of carbon fiber reinforced polymer (CFRP) composites in manufacturing of automotive, marine, sport, chemical and biological equipment is gradually increasing as well as aerospace industry. Especially, the need for drilling of these materials in tolerance of low roughness and suitable roundness because of requirement to high strength in assembly parts is an important safety problem for aerospace industry. The hole surface integrity and delamination occurred in drilling of the CFRP materials, which change depending on their characteristics properties which are anisotropy, heterogeneity and laminated structure, and so affect the hole quality. Also, the thermomechanical responses (e.g., cutting force, cutting temperature, chip formation) changing according to cutting conditions such as tool geometry, cutting speed and feed rate are negatively affect the machinability of the CFRP. For these reasons, the selection of drill geometry and drilling parameters has high importance due to in drilling of carbon fiber reinforced polymer which has anisotropy, heterogeneity and laminated structure. This study focused on the effects of drilling parameters on the hole quality in drilling of carbon fiber reinforced polymer composites by applying constant and varying feed rate with uncoated tungsten carbide.

International Symposium on Light Alloys and Composite Materials
UHAKS

Nafiz YAŞAR M.Erdi Korkmaz Mustafa GÜNAY

Metalik malzemelerin eklemeli imalatı, kalıp kullanmaksızın 3D kompleks parçaların üretilmesine imkan tanımakta ve yüksek verimlilikte hammadde faydalanma oranı sağlayan teknolojik bir üretim yöntemidir. Bu yöntemle, geleneksel yöntemlerle üretilmesi zor olan karmaşık geometrili parçalar ve pahalı metalik hammaddeleri kullanarak en az kayıpla üretim yapmak mümkündür. Metalik malzemelerin eklemeli imalatı uygulamalarında, temel olarak toz veya tel tabanlı besleme sistemleri kullanılmaktadır. Günümüzde, eklemeli imalat sistemlerinde paslanmaz çelik, titanyum, nikel, magnezyum ve alüminyum alaşımları kullanılmakta olup, sistemler geliştirilmeye devam etmektedir. Bu çalışmada, eklemeli imalatta metalik malzemelerin kullanım yöntemleri, eklemeli imalat teknolojilerinin avantaj ve dezavantajları, üretilen parçaların mekanik özellikleri ve maliyetleri hakkında bir değerlendirme yapılmıştır. Havacılık, medikal, enerji ve otomotiv endüstrilerinde yüksek performanslı parçaların üretimi için yeni bir teknoloji olarak kabul edilen eklemeli imalat sistemlerinde metalik malzemelerin kullanımı değerlendirilerek önerilerde bulunulmuştur. The additive manufacturing of metallic materials allows production of 3D complex parts without the use of molds and is a technological production method that provides high efficiency raw material utilization rate. With this method, it is possible to produce with minimum loss by using expensive metallic raw materials and parts with complex geometries which are difficult to produce by traditional methods. Powder or wire-based feeding systems are mainly used in additive manufacturing applications of metallic materials. Nowadays, stainless steel, titanium, nickel, magnesium and aluminum alloys are used in additive manufacturing systems and the systems continues to be developed. In this study, an evaluation on the usage of metallic materials in additive manufacturing, advantages and disadvantages of additive manufacturing technologies, mechanical properties and costs of produced parts were made. The use of metallic materials in additive manufacturing systems, which are considered as a new technology for the production of high performance components in the aerospace, medical, energy and automotive industries were evaluated and recommendations were given.

International Congress on 3D Printing (Additive Manufacturing) Technologies and Digital Industry
3D-PTC2019

Mustafa GÜNAY İskender YEŞİLDAĞ

In this study, the effects of raster angle on the behavior under the static load of PA12 base materials which were manufactured by Multi Jet Fusion Technology (MJF) in 3D printer, was investigated. For this purpose, standard tensile and three-point bending test samples were produced by 3D printer at a constant deposit thickness (80 µm), constant infill rate (%100) and different printing orientations (0, o 45 and 90 ). Tensile and three-point bending tests were applied for the samples and the findings was evaluated. Consequently, it was determined that the tensile and bending strength of PA12 base sample o has the highest value in 90-90-90 printing orientation.

International Congress on 3D Printing (Additive Manufacturing) Technologies and Digital Industry
3D-PTC2019

Mehmet Erdi KORKMAZ Mustafa GÜNAY

The improvements which need in railway vehicles made neccessary also brake systems developing. The main factors affecting the performance and functioning of the brake system are brake force, mass and speed of the train, stopping distance and road curvature. With the operating speed exceeding 120 km/h, very different braking systems and equipment have been developed. In this work, the brake systems such as air brakes, dynamic brakes, parking brakes, vacuum brakes, electro-pneumatic brakes have been considered. Especially, evaluations have been made on brake disc-pad systems, which represent the most important components in terms of safe navigation for high-speed trains operating at speeds of 200 km/h and above. For this purpose, experimental and numerical analysis studies on braking system interactions based on brake disk-pad geometry and material properties were investigated. As a result of this study, important information will be gained on the basis of the detailed analysis of the scientific and applied researches which will contribute to the productivity to the institutions and organizations that are in the design and manufacturing activities on the braking systems of our country railway vehicles.

International Symposium on Railway System Engineering
ISERSE

Erhan Selçuk Mehmet Erdi KORKMAZ Mustafa GÜNAY

Günümüzde raylı sistemlerde tam otomatik veya sürücüsüz metro sistemlerine doğru bir geçiş süreci yaşanmakta olup, geçmişten bu yana kullanılan metro hatları da bu sisteme göre yenilenmektedir. Diğer yandan, metro araçlarının konumları, istikametleri ve hareketleri sinyalizasyon sistemleri tarafından sağlanmaktadır. Bu çalışmada, tam otomatik metro sistemleri, avantajları, dezavantajları, güvenlik, bakım maliyetleri, enerji tüketimi ve hizmet kalitesi açısından diğer raylı sistemlerle karşılaştırılmıştır. Sürücüsüz metro sistemleri; maksimum güvenilirlik, duraklar arasında geçiş sürelerinin daha az olması ve yolcu bekleme süresinin azalması, yüksek işletme hızı, işletme maliyetlerinin düşük olması, tahrik ve fren sistemlerinde daha az aşınma gibi birçok avantajlara sahiptir. Ayrıca, bütün kontrollerin trafik kontrol merkezinden yapılarak herhangi bir acil durumda merkezden müdahale edilmesi, sürücüsüz metro sistemlerinin diğer sistemlere göre daha kaliteli ve güvenli bir hizmet verdiğini göstermektedir. Bu çalışma ile geleceğin Türkiye’sinde sürücüsüz metro sistemlerinin istihdam ve ekonomiye katkısı, kazanılacak otonom tecrübesi, alt yüklenici kurum ve kuruluşlara inovasyon katkısı ve otonom raylı sistemlerdeki güvenlik önlemleri hakkında ilgili sektörlere detaylı bilgiler kazandırılacaktır. Nowadays, there is a transition process to full automatic or driverless metro systems in railway systems and subway lines that have been used since the past are being renewed according to this system. On the other hand, the locations, directions and movements of subway cars are provided by signaling systems. In this study, firstly, based on driver/driverless automation systems in railway systems are examined in detail. Fully automatic metro systems are compared with other systems in terms of advantages, disadvantages, safety, maintenance costs, energy consumption and service quality. Driverless subway systems; maximum reliability, reduced transit times between stops and reduced passenger waiting time, high operating speed, low operating costs, and less wear on the drive and braking systems. Moreover, the fact that all the controls are made from the traffic control center and intervened in the center in any emergency show that the driverless subway systems provide a better and more reliable service than the other systems. Through this study, the contribute to the employment and economy of driverless metro systems in future Turkey, autonomic experience to be gained, detailed information about the contribution of innovation to sub-contracting institutions and organizations and security measures in the autonomous rail systems will be provided to the relevant sectors.

International Symposium on Railway System Engineering
ISERSE

Ali Öztürk Mustafa GÜNAY