Papers by Ahmet Murat Pinar
Istanbul University - DergiPark, May 1, 2002
Engineering Sciences, 2009
In this study, the positioning accuracy of a two-axis hydraulic driven system controlled by CNC i... more In this study, the positioning accuracy of a two-axis hydraulic driven system controlled by CNC is statistically investigated. The effects of piston diameter, feed rate, direction and axis parameters on the positioning error and their optimum levels are determined via Taguchi method. The experiments conducted based on L16 orthogonal array are evaluated at 95% confidence level statistically. According to this, minimum positioning error is obtained with the piston diameter of 63 mm, feed rate of 10 mm/min, in q-q direction at Y-axis. Finally, the confirmation tests with optimum levels indicate that the method optimises the system successfully.
Bu calisma, CNC takim tezgâhlarin denetiminde kullanilan FM 357 fonksiyon modulu ile kontrol edil... more Bu calisma, CNC takim tezgâhlarin denetiminde kullanilan FM 357 fonksiyon modulu ile kontrol edilen hidroliksistemin pozisyonlama dogrulugunu incelemektedir. Sistem oransal yon denetim valflerinin yonlendirdigi ikiadet silindirin surdugu iki eksenden olusmaktadir. Ilerleme orani, hareket mesafesi, yon ve atalet yukuparametrelerinin pozisyonlama dogrulugu uzerindeki etkileri ve bunlara ait optimum seviyelerin tespiti Taguchimetodu ile gerceklestirilmistir. Buna gore minimum pozisyonlama hatasi 10 mm/dk’lik ilerleme oraninda, 5mm’lik hareket mesafesinde,“-” yonde ve 5 kg’lik atalet yukunde elde edilmistir. Son olarak, yapilan dogrulamadeneyleri, Taguchi metodunun, sistemin optimizasyonunu yeterli dogrulukta gerceklestirdigini gostermektedir.
Surface roughness is one of most significant quality characteristics in manufacturing industry an... more Surface roughness is one of most significant quality characteristics in manufacturing industry and is mostly evaluated with roughness average and maximum height of the profile parameters. In the study, the effects of cutting speed, feed rate, machining pattern and dept of cut process parameters in the milling of AA6013 aluminium alloy are determined by using Taguchi method. The experiments conducted based on Taguchi’s standard orthogonal array are evaluated with analysis of variance (ANOVA) and main effects plots for a confidence level of 95%.
Journal of the American Podiatric Medical Association, 2019
Background: We sought to investigate the different configurations of Kirschner wires used in dist... more Background: We sought to investigate the different configurations of Kirschner wires used in distal femur Salter-Harris (SH) type 2 epiphyseal fracture for stabilization after reduction under axial, rotational, and bending forces and to define the biomechanical effects on the epiphyseal plate and the fracture line and decide which was more advantageous. Methods: The SH type 2 fracture was modeled using design software for four different configurations: cross, cross-parallel, parallel medial, and parallel lateral with two Kirschner wires, and computer-aided numerical analyses of the different configurations after reduction were performed using the finite element method. For each configuration, the mesh process, loading condition (axial, bending, and rotational), boundary conditions, and material models were applied in finite element software, and growth cartilage and von Mises stress values occurring around the Kirschner wire groove were calculated. Results: In growth cartilage, the ...
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2016
In this study, the biomechanical effects of three different configurations (K-wire, stainless ste... more In this study, the biomechanical effects of three different configurations (K-wire, stainless steel screws, and titanium screws), which are used for stabilizing Salter–Harris (SH) type 3 epiphyseal fracture of distal femur after reduction process, on the epiphyseal plate and fracture line have been investigated under axial, rotational, and bending forces to determine the most advantageous configuration. Three different configurations have been modeled using SolidWorks, and computer-aided numerical analyses were performed by finite-element analysis software. For each configuration, mesh process, boundary conditions, and material model have been applied in finite-element analysis software. In addition, von Mises stress values on growth of epiphyseal plate and K-wire have been calculated. According to the results obtained, it has been found particularly advantageous to use the fixation shape of configuration with screw. In addition, the fixation shape of K-wire configuration was found to be disadvantageous in the SH type 3 epiphyseal fractures.
Celal Bayar Üniversitesi Fen Bilimleri Dergisi, 2016
Alüminyum alaşımları iyi korozyon/yorulma direnci, yüksek dayanım/ağırlık oranları, ısı ve elektr... more Alüminyum alaşımları iyi korozyon/yorulma direnci, yüksek dayanım/ağırlık oranları, ısı ve elektrik iletkenlikleri, arttırılabilen mukavemet karakteristikleri ve kolay şekillendirme özellikleri nedeniyle havacılık, denizcilik, otomotiv ve kalıpçılık alanlarında sıklıkla kullanılmaktadır. Bu çalışmada AA 5083-H36 malzemesinin cep frezelenmesinde vorteks tüplü ve klasik soğutma şartlarında çapak yüksekliği istatististiksel olarak değerlendirilmektedir. Taguchi L16 ortogonal diziye (OD) göre kesme hızı (100 ve 250m/dk), ilerleme oranı (150 ve 1000mm/dk), eksenel talaş derinliği (1 ve 2,5mm), radyal talaş derinliği (4 ve 8mm) ve uç yarıçapı (0,4 ve 0,8mm) işlem parametrelerinin farklı seviyelerinde deneyler gerçekleştirilmiştir. Deneysel Sonuçlar %95 güven seviyesinde varyans analizi (ANOVA) ve ana etkiler grafikleri ile değerlendirilmiştir. Sonuç olarak, iki soğutma tipinde de çapak yüksekliğinin kesme hızı ile ters, ilerleme ve eksenel/radyal talaş derinliği ile doğru orantılı olarak değiştiği ancak uç yarıçapının etkili olmadığı gözlemlenmiştir. Varyans analizine göre eksenel talaş derinliğinin en anlamlı faktör olduğu ve bunu ilerleme oranı ve kesme hızı işlem parametrelerinin izlediği görülmüştür. Vorteks tüp ve klasik soğutma şartlarında optimum çapak yükseklikleri sırasıyla 0,056 ve 0.009mm olarak elde edilmiştir. Yapılan doğrulama testleri sonucunda önerilen metodun optimizasyonu yeterli doğrulukta gerçekleştirdiği gözlemlenmiştir.
Gazi University Journal of Science, 2011
The objective of the presented study is to model the effects of cutting speed, feed rate and dept... more The objective of the presented study is to model the effects of cutting speed, feed rate and depth of cut on the surface roughness (roughness average, Ra) in the turning process carried out by the grooving cutting tool by using Artificial Neural Network (ANN). To realize this aim, twenty seven specimens are machined at the cutting speeds of 100, 140 and 180m/min, feed rates of 0.05, 0.15 and 0.25mm/rev, and cutting depth of 0.6, 1.3 and 2mm in wet conditions. Data from these experiments are used in the training of ANN. When we compare the experimental results with the ANN ones, it is observed that proposed method is applied with an error rate of 8.14% successfully.
Materials Science, 2015
High-performance engineering polymers that ensure the desired properties of journal bearings and ... more High-performance engineering polymers that ensure the desired properties of journal bearings and give good wear results are investigated. We determine the microstructural properties of polymer-based particle-reinforced polytetrafluoroethylene composite bearings by analyzing the optical and SEM surface wear images.
Materials Testing, 2012
Tin and lead based alloys are widely used as journal bearing materials in tribological applicatio... more Tin and lead based alloys are widely used as journal bearing materials in tribological applications. If Al or Zn with their sliding property will be added to such materials the tribological properties of journal bearings can be improved once more. In this study, wear properties of these journal bearings manufactured from SnPbAlZn, pure Sn, pure Pb, pure Al, and pure Zn bearings were investigated. Experiments were carried out in every 30 min for the total of 150 min by using radial journal bearing wear test rig. As a result wear properties can be improved by variation of SnPbAlZn material.
Materials & Design (1980-2015), 2015
ABSTRACT In this work, 20 different iron based powder metal (PM) compositions were pressed at 600... more ABSTRACT In this work, 20 different iron based powder metal (PM) compositions were pressed at 600 MPa and sintered at 1120 °C for 30 min using a conventional sintering furnace, and then boronizing, steaming and carbo-nitriding heat treatments were applied. The results of all the heat treated compacts for the effects of bending test, microstructure images and HV microhardness results were investigated. Microstructure and SEM images were compared for all heat treated PM compacts. Micro structure image of the carbo-nitrided iron based PM compact is given as follows: The thickness of carbo-nitride layer is measured from the microstructure images of the compacts. All results were calculated from the average of the three recorded measurements. The average thickness of the boronizing, carbo-nitriding, and steaming layers were observed; 162 μm, 124 μm, and 5 μm respectively. As a results this paper illustrated that what are the advantages and disadvantages of the boronizing, carbo-nitriding, and steaming heat treatments for the iron based PM samples.
Politeknik …, 2007
CNC işleme merkezlerindeki eğrisel hareketler dairesel interpolasyon hareketleri ile gerçekleştir... more CNC işleme merkezlerindeki eğrisel hareketler dairesel interpolasyon hareketleri ile gerçekleştirilmektedir. Bu hareketlerdeki hatalar dairesellik hatası olarak adlandırılmaktadır. Bu çalışmada, dairesellik hatası ölçüm sistemi tanıtılmıştır. Dairesellik hatası tarif edilerek, bu hatanın değerlendirildiği algoritmalar tanıtılmıştır. Ayrıca bu sistemdeki ölçüm cihazları, ayrıntılı yayın taraması ile analiz edilerek tartışılmıştır.
International Journal of Refrigeration, 2009
The purpose of this study is to analyze the parameters of cold temperature and coefficient of per... more The purpose of this study is to analyze the parameters of cold temperature and coefficient of performance refrigeration (COPref) of the vortex tube cooling machine and how much the contribution of each parameter to the performance. This analysis also aims to predict the optimal value of cold temperature and COPref of the vortex tube as well as to predict the condition of how the optimal value is obtained. To find out whether the analysis is suitable for optimizing the performance, then the confirmation data verification is done to know the error level. The parameters considered in the experiment were the tube type consisting of natural cooling and forced cooling, the pressures are 0.5bar, 1.0bar, and 1.5bar, and fractions are 30 %, 40 %, 50 %, 60 %, and 70 %. The results of the experimental test optimized using the Taguchi method where data is reduced by selecting the three optimal fractions in each response. Obtained that tube type, pressure, and fraction are factors that influence performance with the level of error for predicting the optimal value at cold temperatures is <5 %. This study provides an analysis of the contribution of improved design of vortex tube performance parameters that are efficient experimental and reliable statistics.
Experimental Heat Transfer, 2009
In this article, the effect and optimization of process parameters in a counter-flow vortex tube ... more In this article, the effect and optimization of process parameters in a counter-flow vortex tube on temperature difference were investigated through the Taguchi method. The experiments were planned as per Taguchi's L27 orthogonal array with each experiment performed under different conditions of inlet pressure, nozzle number, and cold mass fraction. By means of analysis of variance and regression analysis, the effects of factors and their interactions on temperature difference were determined and modeled with a correlation coefficient of 93.5%. Accordingly, it was observed that temperature difference goes up with the increase in inlet pressure, and the cold mass fraction and decreases with the increase in nozzle number. In addition, the optimum settings of process parameters maximizing the temperature difference are an inlet pressure of 650 kPa, a nozzle number of 2, and a cold mass fraction of 0.7. Finally, confirmation tests verified that the Taguchi method was successful in the assessment of vortex tube parameters for temperature difference.
Corrosion Science, 2005
ABSTRACT The corrosion resistance and mechanical strength of four newly developed low-alloy steel... more ABSTRACT The corrosion resistance and mechanical strength of four newly developed low-alloy steels (LAS) were compared with a carbon steel (SS400) and a weathering steel (Acr-Ten A) using a laboratory-accelerated test that involved cyclic wet/dry conditions in a chloride environment (5 wt.% NaCl). The new LAS were designated 1605A, 1605B, 1604A, and 1604B. After 72 cycles of cyclic corrosion tests, the susceptibility of the steels to corrosion could be listed in the following order based on their weight loss (from high to low): SS400 &gt; Acr-Ten A &gt; 1604B ⩾ 1604A &gt; 1605B ⩾ 1605A. The change in mechanical properties by corrosion was the least for SS400, Acr-Ten A was second, and effects of corrosion on the mechanical properties of the other four low-alloy steels were similar. Finally, the characteristics of the rust layers on each LAS sample were observed by SEM, and analyzed by FTIR and EPMA. The results indicated that most of the rust layers on the test steels were composed of a loose outer rust layer and a dense inner rust layer. The outer rust layer of each steel was composed of α-FeOOH, γ-FeOOH, magnetite (Fe3O4), H2O, and amorphous ferric oxyhydroxide (FeOx(OH)3−2x, x=0–1), while the inner rust layer was composed mainly of Fe3O4 with a little α-FeOOH. In addition, it was apparent that the copper and chromium alloying additions were enriched, respectively, at the rust-layer/substrate interface and in the rust layers. Finally, combining the results of the accelerated tests and the rust layer analysis showed that low-alloy steels, such as 1605A and 1605B, have better weathering steel properties than Acr-Ten A for use in the humid and salty weather.
Politeknik Dergisi, 2006
... Bu çalışma, hatanın or-27 Page 2. Ahmet Murat PİNAR, Abdulkadir GÜLLÜ/ POLİTEKNİK DERGİSİ, Cİ... more ... Bu çalışma, hatanın or-27 Page 2. Ahmet Murat PİNAR, Abdulkadir GÜLLÜ/ POLİTEKNİK DERGİSİ, CİLT 9, SAYI 1, 2006 talamasını 0 yapan klasik en küçük kareler özelliğine sadık kalmaktadır. Metot ayrıca hataların toplam varyansını minimize etmektedir (6). ...
uvt.ulakbim.gov.tr
Bu çalışmada; Dyna Myte 2900 Dik İşleme Merkezinin kontrol ünitesinde Bilgisayarlı Sayısal Deneti... more Bu çalışmada; Dyna Myte 2900 Dik İşleme Merkezinin kontrol ünitesinde Bilgisayarlı Sayısal Denetim (BSD) programlarını inceleyen, işleme süresi ve kesicilerin hızlı hareket (boşta ilerleme) sürelerini hesaplayan bir program yapılmıştır. İncelenecek parça programı kullanıcı tarafından klavyeden elle, bir bilgisayar dosyası olarak disketten ya da hard diskten veya tezgahtan BSD (CNC) kod editörüne aktarılır. Kesicilerin tüm hareketleri incelenerek, ayrıntılı olarak işleme ve boşta ilerleme süresi ve toplam süre kullanıcıya sunulur. Böylelikle iş parçası maliyet analizi için önemli bir veri elde edilmiş olur.
Turkish J. Eng. Env. Sci, 2005
An algorithm was prepared for minimizing the machining time of CNC part programs used in a vertic... more An algorithm was prepared for minimizing the machining time of CNC part programs used in a vertical machining center. The CNC program is transferred from the machine to the CNC code editor with a serial cable (RS-232). The time calculator examines all the codes in the code editor and calculates the time of all the moves in minutes. The other processor, which does the code formation, analyzes each individual movement of machining. As a result, it orders all the operations formed with the same cutting tool on the x and y axes. It also generates the G codes by minimizing the rapid movements of the tool in terms of the shortest tool path. With the cutting parameters module, machine table feed and spindle speed are modified using the machine power and tool life as limiting factors for each machining operation. In this way, the CNC program is modified. By reanalyzing the new CNC program with the time calculation processor, the time saved can be seen.
Arabian Journal for Science and Engineering, 2012
This paper aims at determining the effects of process parameters (cutting speed, feed rate, tool ... more This paper aims at determining the effects of process parameters (cutting speed, feed rate, tool path pattern and depth of cut) on surface roughness and the factor levels with minimum surface roughness in pocket machining. The experiments conducted based on Taguchi's L27 orthogonal array are assessed with analysis of variance and signalto-noise ratio. According to this, it is observed that surface roughness correlates negatively with cutting speed and positively with feed rate and cutting depth. Minimum surface roughness is predicted as 0.5413 µm with the cutting speed of 300 m/min, feed rate of 150 mm/min, spiral tool path pattern and 1 mm depth of cut. Finally, confirmation tests verify that Taguchi method achieves the optimization of the system with sufficient accuracy at 95 % confidence level.
Sunulan calisma, AISI 4140 malzemenin kaba isleme sartlarinda, (yuksek ilerleme ve talas derinlig... more Sunulan calisma, AISI 4140 malzemenin kaba isleme sartlarinda, (yuksek ilerleme ve talas derinligi) kanal takimiyla tornalanmasini istatistiksel olarak tartismaktadir. Taguchi’nin L8 ortogonal dizisi esas alinarak, kesme hizi, talas kirici tipi ve uc yaricapi faktorlerinin farkli seviyelerinde deneyler gerceklestirilmistir. %95 guven seviyesinde yapilan analizler sonucunda, uc yaricapinin puruzluluk uzerinde en anlamli etkiye sahip oldugu, bunu talas kirici tipi ve uc yaricapi etkilesiminin izledigi ve optimum puruzlulugun 0,572 µm oldugu gozlemlenmistir. Ayrica her bir deney sarti icin takim asinma performanslari arastirilmistir.
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Papers by Ahmet Murat Pinar