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Öğe Experimental and Statistical Study on Machinability of the Composite Materials with Metal Matrix Al/B4C/Graphite(Springer, 2017) Nas, Engin; Gokkaya, HasanIn this study, four types of Al/B4C/Graphite metal matrix composites (MMCs) were produced by means of a hot-pressing technique with reinforcement elements, B4C 8 wt pct and graphite (nickel coated) 0, 3, 5, and 7 wt pct. Machinability tests of MMC materials thus produced were conducted using four different cutting speeds (100, 140, 180, and 220 m/min), three different feed rates (0.1, 0.15, and 0.20 mm/rev), and a fixed cutting depth (0.5 mm), and the effects of the cutting parameters on the average surface roughness were examined. After the machinability tests, the height of the built-up edge (BUE) formed on the cutting tools related to the cutting speed and feed rate was measured. The test results were examined by designing a matrix according to the full factorial design and the average surface roughness, and the most important factors leading to formation of the BUE were analyzed by the analysis of variance (ANOVA). As a result of analysis, it was found that the lowest surface roughness value was with 7 wt pct graphite MMC material, while the highest was without graphite powder. Based on the statistical analysis results, it was observed that the most important factor affecting average surface roughness was the type of MMC material, the second most effective factor was the feed rate, and the least effective factor was the cutting speed. Furthermore, it was found that the most important factor affecting the formation of the BUE was the type of MMC material, the second most effective factor was the cutting speed, and the least effective factor was the feed rate.Öğe Frezeleme işleminde kesici uç sayısının titreşim ve yüzey pürüzlülüğüne etkisinin incelenmesi(Karabük Üniversitesi, 2008) Nas, Engin; Demir, HalilBu çalışmada, AISI 1050 çelik malzeme kaplanmış sementit karbür kesici takımlar kullanılarak alın frezeleme işlemine tabi tutulmuştur. Alın frezeleme deneyleri beş farklı kesme hızında (V1=60 m/dak, V2=90 m/dak, V3=120 m/dak, V4=150 m/dak, V5=180 m/dak),üç farklı talaş derinliğinde (a=1 mm, a=2 mm, a=3 mm) ve üç farklı ilerlemede (s=0,5 mm/devir, s=0,1 mm/devir, s=0,15 mm/devir) soğutma sıvısı kullanılmadan yapılmıştır. Alın freze çakısındaki kesici takım sayısının titreşim ve yüzey pürüzlülüğüne etkisini incelemek amacıyla deneylerde farklı sayılarda (Z1=1, Z2=2, Z3=3, Z4=6) kesici takımlar kullanılmıştır.Frezeleme işlemi esnasında oluşan titreşim ve yüzey pürüzlülük değerleri ölçülmüştür. Bu parametrelerin yüzey pürüzlülüğü ve titreşim üzerindeki etkileri araştırılmıştır. Kesici uç sayısı arttığında yüzey pürüzlülük değerinin önemli miktarda arttığı gözlenmiştir. Ayrıca, titreşimin de yüzey pürüzlülüğü üzerinde önemli bir etkisi olduğu görülmüştür.Öğe INVESTIGATION OF ELECTROEROSION MACHINING PERFORMANCE OF METAL MATRIX COMPOSITE MATERIALS PRODUCED USING STIR AND INDIRECT SQUEEZE METHOD(World Scientific Publ Co Pte Ltd, 2023) Ugur, Abdullah; Nas, Engin; Gokkaya, HasanIn this study, metal matrix composite (MMC) materials were made with an aluminum matrix (AA7075 alloy) and reinforcement silicon carbide (SiC) elements using molten metal stir and indirect squeeze casting. SiC was used as a reinforcing element in the making of MMC material in different amounts (10%, 14%, and 18%) by mass. Electro Discharge Machining (EDM), cut depth (0.5 mm), three different pulse-on times, three different discharge current values, and a fixed pulse-off time (20 s) were used to machine MMC materials. The effects of machining parameters on machining time, average surface roughness, hole diameter, and material wear difference after machining were studied. As a result of the study, the composite material with 75 mu s pulse-on time, 6A current value, and 10% reinforcement element had the lowest machining time, the largest hole diameter, and the smoothest average surface. These machining parameters and materials also had the shortest machining time (5 min). Based on the signal-to-noise ratios, the best parameters for average surface roughness, hole diameter, Processing time, and material wear amount (MMC, discharge current value, and impact time) were found to be L2L1L1, L3L1L1, L1L3L3, and L1L1L2, respectively. Based on the ANOVA results, the R2 values for the average surface roughness, hole diameter, machining time, and material wear loss value were 99.3%, 98.7%, 77.8%, and 97.3%, respectively.Öğe INVESTIGATION OF SURFACE MORPHOLOGY OF DRILLED CFRP PLATES AND OPTIMIZATION OF CUTTING PARAMETERS(World Scientific Publ Co Pte Ltd, 2020) Erkan, Omer; Sur, Gokhan; Nas, EnginIn this study, the carbon fiber reinforced polymer (CFRP) composite material was drilled using different parameters (118 degrees and 140 degrees Point Angle, 30, 60 and 90 m . min(-1) cutting speed and 0.06, 0.08 and 0.10 mm . rev(-1) feed rate). Experimental parameters were designed according to full factorial design method and the results were analyzed using Taguchi L18 experimental design. The results of the study show that the lowest surface roughness values are 0.1958 and 0.1945 mu m with the cutting speed of 90 m . min(-1) and feed rate of 0.06 m . rev(-1) in the Point angles of 118 degrees and 140 degrees, respectively. When the results of Anova analysis were evaluated, parameters (feed speed, cutting speed and end point angle) according to the effect ratios on surface roughness were formed at the rates of 41.06%, 33.13% and 5.07%, respectively. The most suitable parameters according to S/N ratios were determined using A2B3C1 factors for the average surface roughness.Öğe Investigation of the machinability of SiC reinforced MMC materials produced by molten metal stirring and conventional casting technique in die-sinking electrical discharge machine(Pergamon-Elsevier Science Ltd, 2020) Ugur, Abdullah; Nas, Engin; Gokkaya, HasanIn this study, MMC materials were produced by stir casting method using AA7075 alloy matrix and silicon carbide (SiC) as reinforcement elements in order to investigate the effect of die-sinking electric discharge machining (EDM) process parameters for various weight percentage reinforcement (10% 14% and 18%) used MMC. EDM with three different pulse-on time (Time on) (25, 50 &75 mu s) and discharge current value (2, 4 & 6 Amperes) and at constant dwell time (20 mu s) and depth of cut (0.5 mm). After machining process, the effects of process parameters on processing time, average surface roughness, hole diameter and the weight loss were investigated. As a result of the study, highest values, the lowest values of processing time, hole diameter and average surface roughness were obtained for various weight percentage reinforcement MMC respectively. Ideal MMC, discharge current value and time-on duration for average surface roughness, hole diameter, processing time and material wear loss according to signal to noise ratio were determined. According to ANOVA results, R-2 values for the average surface roughness, hole diameter, processing time and material wear loss were calculated as 89.55%, 98.46%, 89.85% and 24.06% respectively.Öğe Karma takviyeli (Al/B4C–Ni(K)GR) alüminyum matrisli kompozitlerin sıcak presleme yöntemi ile üretimi mekanik özellikleri ve işlenebilirliği(Karabük Üniversitesi, 2015) Nas, Engin; Gökkaya, HasanBu çalışmada, endüstriyel alanda gittikçe yaygınlaşan karma takviyeli metal matrisli kompozit (MMK) malzemelerin üretilmesinde karşılaşılan sorunları enaza indirmek, üretimi gerçekleştirilen karma takviyeli MMK malzemelerin içerisinde ağırlıkça farklı oranlarda bulunan nikel kaplı grafitin mekanik özellikleri (sertlik, üç nokta eğme ve aşınma) ve işlenebilirlik üzerine etkileri araştırılmıştır. Deneysel çalışmada, matris elemanı olarak ikincil metalurji işlemler (yaşlandırma) ile dayanım özellikleri geliştirilen alüminyum alaşımı Alumix 13, takviye elemanları olarak ise bor karbür (B4C) ve üzeri nikel kaplı grafit (Ni(K)Gr) kullanılmıştır. Takviye elemanı olan B4C ağırlıkça % 8 oranda sabit tutulup yapı içerisine ağırlıkça % 0, % 3, % 5 ve % 7 oranında ilave edilen diğer bir takviye elemanı üzeri Ni(K)Gr kullanılarak dört farklı karma takviyeli MMK malzeme üretimi gerçekleştirilmiştir. Tornalama deneyleri dört farklı kesme hızı (100, 140, 180 ve 220 m/dak), üç farklı ilerleme miktarında (0,1, 0,15 ve 0,20 mm/dev), sabit kesme derinliği (0,5 mm) ve kuru işleme şartlarında gerçekleştirilmiştir. Üretilen karma takviyeli MMK malzemelerin aşınma deneyleri ASTM: G99'a göre kuru kayma şartları altında, sabit kayma hızında (0,8 m/s), dört farklı yük ile (10, 20, 30 ve 40 N) ve dört farklı yol (300, 600, 900 ve 1200 m) kat edilerek Pin–on disk aşınma cihazında gerçekleştirilmiştir. Elde edilen ortalama yüzey pürüzlülüğü ve yığıntı talaş oluşumlarına göre bütün karma takviyeli MMK malzemelerde kesme hızı arttıkça ortalama yüzey pürüzlülük değerinin ve yığıntı talaş oluşumunun azaldığı, ilerleme miktarının artması ile ortalama yüzey pürüzlülük değerinin ve yığıntı talaş oluşumunun arttığı tespit edilmiştir. En iyi ortalama yüzey pürüzlülük değeri olan 1,03 µm 0,1 mm/dev ilerleme miktarında ve 220 m/dak kesme hızında K4 kodlu karma takviyeli MMK malzemede, en yüksek ortalama yüzey pürüzlülük değeri olan 2,67 µm ise 0,2 mm/ dev ilerleme miktarında 100 m/dak kesme hızında K1 kodlu karma takviyeli MMK malzemede elde edilmiştir. En düşük yığıntı talaş değeri 0,1 mm/dev ilerleme miktarında ve 220 m/dak kesme hızında K4 kodlu karma takviyeli MMK malzemede 0,065 mm, en yüksek yığıntı talaş değeri 100 m/dak kesme hızında K1 kodlu karma takviyeli MMK malzemede 0,279 mm olarak elde edilmiştir. Aşınma deneylerinde en düşük aşınma değeri K1 kodlu karma takviyeli MMK malzemede 10 N yük altında 300 m kayma mesafesinde 0,0010 g, en yüksek aşınma kaybı ise 40 N yük altında 1200 m kayma mesafesinde 0,0152 g elde edilmiştir.Öğe Mathematically Modeling Parameters Influencing Surface Roughness in CNC Milling(Pamukkale Univ, 2012) Nas, Engin; Samtas, Gurcan; Demir, HalilIn this study, steel AISI 1050 is subjected to process of face milling in CNC milling machine and such parameters as cutting speed. feed rate. cutting tip, depth of cut influencing the surface roughness are investigated experimentally. Four different experiments are conducted by creating different combinations for parameters. In conducted experiments. cutting tools, which are coated by PVD method used in forcing steel and spheroidal graphite cast iron are used. Surface roughness values. which are obtained by using specified parameters with cutting tools, are measured and correlation between measured surface roughness values and parameters is modeled mathematically by using curve fitting algorithm. Mathematical models are evaluated according to coefficients of determination (R-2) and the most ideal one is suggested for theoretical works. Mathematical models. which are proposed for each experiment, are estipulated.Öğe Optimization of surface roughness via the Taguchi method and investigation of energy consumption when milling spheroidal graphite cast iron materials(Carl Hanser Verlag, 2018) Nas, Engin; Ozturk, BurakDue to its excellent casting ability, spheroidal graphite cast iron is widely used in the production of complex automotive and machine products. In this study, the milling of spheroidal cast iron was carried out at different parameters. First, using the Taguchi statistical method, the parameters affecting surface roughness values were determined to b e cutting tool (65.54 %), then feed rate (19.65%), and finally, with a minimum effect, cutting speed (7.31%). Second, the amount of power consumed during chip removal was observed as being larger than the amount consumed when the machine was operating without a cutting load. Increases in the power index (PI) were measured by an amperemeter and it was determined that, as cutting speed was augmented, the amount of total power (P-total) consumed decreased, while, as feed rate was augmented, total power consumption increased. Total cutting energy (Pcutting) was increased by stepping up cutting speed. The PI was increased as a result of stepping up cutting speed and feed rate. On the basis of the cutting parameters, the Pcutting, P(total )spindle torque (%) and specific energy consumption (SEC) value changes were calculated.
