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Öğe Effects of cutting parameters and point angle on thrust force and delamination in drilling of CFRP(De Gruyter, 2014-11-14) Çelik, Yahya Hışman; Kılıçkap, Erol; Yardımeden, AhmetParts made of composite materials are generally produced by near-net-shape technology. However, additional machining operations such as drilling are often required to facilitate components assembling. Drilling of composite materials is also a common process in the assembly of aerospace and automotive composite structures. During drilling, unlike the conventional materials, a few damage forms may take place. Among these damage forms, the delamination is the most important one. Therefore, the experimental studies carried out on drilling of CFRP composite materials for determining optimum processing parameters are of great importance. In this particular study, delamination in CFRP composites caused by drilling was investigated. The composite material was drilled under various spindle speeds, feed rates and drill point angles. The results showed that delamination and thrust forces were affected by cutting parameters. It was demonstrated that feed rate and drill point angle make the largest contribution to the overall performance.Öğe Investigation of cutting parameters affecting on tool wear and surface roughness in dry turning of Ti-6Al-4V using CVD and PVD coated tools(Springer Nature, 2017-06-01) Çelik, Yahya Hışman; Kılıçkap, Erol; Güney, MusaThere are some problems in the machining of titanium alloys with excellent properties such as high strength, good corrosion resistance, long service life and low weight. The leading problem appears to be the fast tool wear and the bad machining surface. Therefore, in this study, it was investigated whether cutting parameters have effect on tool wear and surface roughness by turning under dry cutting condition of Ti-6Al-4V alloy with excellent properties. CVD (TiCN + Al2O3 + TiN) and PVD (TiAlN) coated WC tools were used in the experiments. Then the Ti-6Al-4V alloy turned with the combinations of the different cutting speed, feed rate, cutting long and depth of cut. We observed that the tools wear in both CVD and PVD coated WC tools increased with increasing the cutting speed, feed rate, depth of cut and cutting length. However, while tools wear increased with increasing cutting speed, the surface roughness reduced to an optimum level. Especially, the surface roughness was worsened above the optimum level changing with increasing the feed rate, cutting length and depth of cut. The tool wear with PVD coated WC tools was observed to be less than the CVD coated WC tools. However, the values of the surface roughness obtained with PVD coated WC tools with increase in depth of cut, feed rate and cutting length has given us higher values when compared to CVD coated WC tools.Öğe Mathematical modelling and optimization of cutting force, tool wear and surface roughness by using artificial neural network and response surface methodology in milling of Ti-6242S(Applied Sciences-Basel, 2017-10-15) Çelik, Yahya Hışman; Kılıçkap, Erol; Yardımeden, AhmetIn this paper, an experimental study was conducted to determine the effect of different cutting parameters such as cutting speed, feed rate, and depth of cut on cutting force, surface roughness, and tool wear in the milling of Ti-6242S alloy using the cemented carbide (WC) end mills with a 10 mm diameter. Data obtained from experiments were defined both Artificial Neural Network (ANN) and Response Surface Methodology (RSM). ANN trained network using Levenberg-Marquardt (LM) and weights were trained. On the other hand, the mathematical models in RSM were created applying Box Behnken design. Values obtained from the ANN and the RSM was found to be very close to the data obtained from experimental studies. The lowest cutting force and surface roughness were obtained at high cutting speeds and low feed rate and depth of cut. The minimum tool wear was obtained at low cutting speed, feed rate, and depth of cut.Öğe Effect of matrix material and orientation angle on tensile and tribological behavior of jute reinforced composites(De Gruyter, 2019-07-27) Çelik, Yahya Hışman; Demir, Mehmet Emin; Kılıçkap, ErolEnvironmental friendly natural fibers have been used instead of petroleum-based synthetic fibers as reinforcements because of the depletion of oil resources, plastic waste disposal problems and the emissions generated during combustion. In these natural fibers, thermoplastic or thermoset materials are used as matrix material because of their low cost, light weight and durability. In this study, the effects of ply number (2 and 3 layer) and orientation angle of reinforcement (0/90° and ± 45°) and matrix type (thermoset and thermoplastic) on the tensile strength of jute reinforced composites were investigated. Also, the effect of the reinforcement orientation angle, sliding time (600, 1200 and 1800 s) and applied load (5, 10 and 15 N) on tribological characteristics were determined. Adhesive and abrasion wear tests were carried out at 0.15 m × s−1 sliding speed. It was observed that the matrix material and the reinforcement are very important in tensile and wear tests, while the ply number and the orientation angle only exert an influence in the tensile strength of composites. It was determined that an increase in load and sliding time is the most effective parameter on wear experiments.Öğe Evaluation of drilling performances of nanocomposites reinforced with graphene and graphene oxide(Springer Nature, 2018-09-16) Çelik, Yahya Hışman; Kılıçkap, Erol; Koçyiğit, NihayetThe use of graphene (G) and graphene oxide (GO) reinforced nanocomposites have a great importance since G and GO improve the interface conditions of composite materials. However, the effects of G and GO on some mechanical properties and machinability in nanocomposites are still a research topic. In this study, G was converted to GO by Hummers’ method. G and GO nanoparticles were added to epoxy at different ratios and the tensile strengths of nanocomposites were determined. By taking into account, the reinforcement ratio of nanocomposites having the highest tensile strength, epoxy with G and GO, and unreinforced epoxy were added to carbon fiber (CF) fabric by hand lay-up. Thus, fabrication of the carbon fiber-reinforced plastic (CFRP) composite, and the G/CFRP and GO/CFRP nanocomposites was carried out. The effects of the G and GO on the fabricated nanocomposites, and the effect of different drilling parameters (cutting speed and feed rate) on the cutting force, cutting torque, temperature, and delamination factor were investigated. In the drilling of these composites, drills with the different bit point angles and the diameter of 5 mm were used. As a result, it was observed that GO was successfully synthesized, and G and GO positively affected the tensile strength, and GO exhibited a more effective feature than G on the tensile strength. It was also seen that the increase of the cutting speed, feed rate, bit point angle caused the increase in the cutting forces, cutting torque, and delaminations.Öğe Evaluation of drilling performances of nanocomposites reinforced with graphene and graphene oxide(Springer Nature, 2019-02-25) Çelik, Yahya Hışman; Kılıçkap, Erol; Koçyiğit, NihayetThe use of graphene (G) and graphene oxide (GO) reinforced nanocomposites have a great importance since G and GO improve the interface conditions of composite materials. However, the effects of G and GO on some mechanical properties and machinability in nanocomposites are still a research topic. In this study, G was converted to GO by Hummers’ method. G and GO nanoparticles were added to epoxy at different ratios and the tensile strengths of nanocomposites were determined. By taking into account, the reinforcement ratio of nanocomposites having the highest tensile strength, epoxy with G and GO, and unreinforced epoxy were added to carbon fiber (CF) fabric by hand lay-up. Thus, fabrication of the carbon fiber-reinforced plastic (CFRP) composite, and the G/CFRP and GO/CFRP nanocomposites was carried out. The effects of the G and GO on the fabricated nanocomposites, and the effect of different drilling parameters (cutting speed and feed rate) on the cutting force, cutting torque, temperature, and delamination factor were investigated. In the drilling of these composites, drills with the different bit point angles and the diameter of 5 mm were used. As a result, it was observed that GO was successfully synthesized, and G and GO positively affected the tensile strength, and GO exhibited a more effective feature than G on the tensile strength. It was also seen that the increase of the cutting speed, feed rate, bit point angle caused the increase in the cutting forces, cutting torque, and delaminations.
