Dr. Emre Altaş currently works at the Department of Mechanical Engineering, Bartın University. Emre does research in Wear, Hard Coatings, Sustainable Manufacturing, NiTi shape memory alloy, Hard Machining and Design of Experiment. Their current project is "Machinability Of NiTi Shape Memory Alloy By Cryogenically Treated Tools" and "Investigation Of The Effect Of Different Cooling Conditions and Coating Materials On The Cutting Performance Of Carbide Cutting Tools In Milling Of Shape Memory Alloys"
Ti6Al4V titanyum alaşımı, sahip olduğu yüksek sıcaklık dayanımı ve biyolojik uyumluluğu nedeniyle... more Ti6Al4V titanyum alaşımı, sahip olduğu yüksek sıcaklık dayanımı ve biyolojik uyumluluğu nedeniyle havacılık ve sağlık alanında sıklıkla kullanılmaktadır. Ancak, bu malzemenin işlenmesi sırasında ortaya çıkan yüksek kesme sıcaklıkları ve malzemenin kesici takım yüzeyine adezyonu nedeniyle, karbür kesici takımlar kısa sürede aşınmakta ve ömürlerini tamamlamaktadırlar. Karbür kesici takımların aşınma direncinin ve ömürlerinin artırılması amacıyla, bu tez çalışmasında, bu takımlar üzerine nanotabakalı AlTiN/TiN kaplamalar biriktirilmiştir. Ayrıca kuru işleme yapılarak soğutma sıvısı kullanımının ortadan kaldırılması ve böylece işleme maliyetlerinin azaltılması çalışmanın hedefleri arasındadır. Nanotabakalı AlTiN/TiN kaplamaların aşınma davranışlarını ve kesme performanslarını karşılaştırmak amacıyla, tek tabakalı TiN ve tek tabakalı TiAlN kaplamalar da karbür takımlar üzerine biriktirilmiştir. Üretilecek nanotabakalı AlTiN/TiN kaplamaların mikrosertlik, altlık malzemeye adezyon ve sürtü...
Journal of Materials Engineering and Performance, 2021
In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was inv... more In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was investigated after face milling processes with cryogenically treated/untreated cemented carbide cutting tools at the conditions of dry cutting and minimum quantity lubrication (MQL) of cutting fluids depending on the changing cutting parameters. The integrity of surface layer of the workpiece material was evaluated according to the mean surface roughness, microstructure and hardness, as well as according to the resultant cutting force and flank wear of inserts. Cutting tests were carried out at three different cutting speeds (20, 35 and 50 m/min), feed rates (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The influence of these parameters on the surface integrity was extensively investigated. The face milling tests of NiTi SMA at optimal cutting parameters show that the surface integrity enhanced at a cutting speed of 50 m/min and feed rate of 0.03 mm/tooth using boron-added cutting fluid (EG + %5BX) with deep cryogenic heat treated (− 196 °C) CVD coated S40T grade cutting tool. Under MQL conditions, the minimum mean surface roughness (0.278 µm), resultant cutting force (268.2 N) and flank wear (0.18 mm) were obtained due to the high thermal conductivity and lubrication property of EG + %5BX cutting fluid. The highest hardness values (343 HV) were measured at the zone subjected to the highest deformation, while the lowest one (316 HV) was measured at the zone at the least deformation.
Titanium and its alloys are widely used in aerospace and aviation industries because of their hig... more Titanium and its alloys are widely used in aerospace and aviation industries because of their high strength-to-weight ratio, high fracture resistance and corrosion resistance at elevated temperatures. However, chemical reactivity and low thermal conductivity of these alloys lead to adhesion and diffusion wears on carbide tools, respectively. In addition, fluctuations in cutting forces occur during the cutting process due to chip shear band formation; and chipping wear is observed at the tool cutting edge as a result. Therefore, machining of these alloys is a challenge for researchers. A common method to increase the lifetime of carbide tools is to coat them with a thin hard coating. In this study, a nanolayer AlTiN/TiN coating was deposited on carbide cutting tools using an industrial magnetron sputtering system in order to enhance their wear resistance and lifetime in milling of Ti6Al4V. The cutting tests with the coated tools were performed at a cutting speed of 50 m/min, feed rat...
Purpose This study aims to investigate the high-temperature wear behavior of the TiN- and AlTiN/T... more Purpose This study aims to investigate the high-temperature wear behavior of the TiN- and AlTiN/TiSiN-coated WC materials. Design/methodology/approach The coating process was carried out using the physical vapor deposition (PVD) method. Wear tests were performed by a ball-on-disc wear device with a high-temperature wear module. In microstructural investigation of the materials, it was benefited from traditional characterization methods such as, SEM, EDX analysis and microhardness measurement. Findings The best wear performance was obtained with AlTiN/TiSiN-coated WC materials at all loads and temperatures, followed by TiN-coated and uncoated WC samples. An important wear was not observed on the samples tested at room temperature tests. It was found that the temperature increase is an effective parameter on the decrease of the wear resistance of the samples. In addition, it was seen that the increasing load and temperature change the wear mechanism on the uncoated WC sample. The wear...
Machining of silicon is an expensive affair because its inherent brittleness leads to subsurface ... more Machining of silicon is an expensive affair because its inherent brittleness leads to subsurface crack generation. Research endeavours have therefore focused on ductile mode machining of silicon to obtain crack free machined surfaces with roughness as low as 0.22 µm or even below, hence eliminating the need for subsequent polishing/grinding operations. However, most of these research works utilized expensive ultraprecision machines and tools. This research aimed at determining the viability of using conventional milling machines with diamond coated tools, high speed attachments, and air blowing mechanisms in order to achieve ductile regime machining of silicon. Spindle speed, depth of cut, and feed rate, ranges: 60,000 to 80,000 rpm, 10 to 20 µm, and 5 to 15 mm/min respectively, were considered as the independent machining parameters. Compressed air at 0.35 MPa was also provided to prevent chip deposition on the finished surfaces. The resultant surfaces were analysed using Optical a...
The aim of this study was to optimize machining parameters to obtain the smallest average surface... more The aim of this study was to optimize machining parameters to obtain the smallest average surface roughness (Ra) and flank wear (Vb) values as a result of the surface milling of a nickel-titanium (NiTi) shape memory alloy (SMA) with uncoated cutting tools with different nose radius (rε) under dry cutting conditions. Tungsten carbide cutting tools with different rε (0.4 mm and 0.8 mm) were used in milling operations. The milling process was performed as lateral/surface cutting at three different cutting speeds (Vc) (20, 35 and 50 m/min), feed rates (fz) (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The effects of machining parameters in milling experiments were investigated based on the Taguchi L18 (21 × 32) orthogonal sequence, and the data obtained were analyzed using the Minitab 17 software. To determine the effects of processing parameters on Ra and Vb, analysis of variance (ANOVA) was used. The analysis results reveal that the dominant factor affect...
Shrink fit was analyzed according to the probability theory of maximum safety and compatibility o... more Shrink fit was analyzed according to the probability theory of maximum safety and compatibility of parts was compared with the results obtained from the analysis. Bearings and shafts were selected in sample hole system for the given connection type and stationary connection and thus moment transmission were investigated. To understand the behavior of materials against dynamic loads has great importance in terms of making safe designs at the present time.
In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated W... more In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated WC materials was investigated. The coating process was carried out using the Physical Vapor Deposition (PVD) method. All coatings have a dense and homogeneous microstructure without delamination or crack formation. Wear tests were performed by fixed ball micro abrasion wear device. Micro abrasion wear test were carried out at different loads, abrasive sizes and sliding distances. As a result of the experiments, the best wear performance was obtained with AlCrN coated WC materials at all loads and abrasive grit sizes, followed by TiAlN/TiSiN coated and TiAlN coated samples. Depending on the increase in load, volume losses were increased in all samples under all conditions. Higher wear losses were determined in the tests performed with larger SiC abrasive particles. In the tests performed with SiC F800, the wear mechanism was micro-grooving wear mechanism, while in SiC F1200 tests the wear mechanism was micro-rolling mechanism. The increased number of cycles increased the volume loss of the samples. In the tests conducted with the SiC F800, the micro-grooves were more pronounced in short-range tests, whereas the groove steps in the long-range tests were reduced.
Journal of Materials Engineering and Performance, 2021
In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was inv... more In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was investigated after face milling processes with cryogenically treated/untreated cemented carbide cutting tools at the conditions of dry cutting and minimum quantity lubrication (MQL) of cutting fluids depending on the changing cutting parameters. The integrity of surface layer of the workpiece material was evaluated according to the mean surface roughness, microstructure and hardness, as well as according to the resultant cutting force and flank wear of inserts. Cutting tests were carried out at three different cutting speeds (20, 35 and 50 m/min), feed rates (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The influence of these parameters on the surface integrity was extensively investigated. The face milling tests of NiTi SMA at optimal cutting parameters show that the surface integrity enhanced at a cutting speed of 50 m/min and feed rate of 0.03 mm/tooth using boron-added cutting fluid (EG + %5BX) with deep cryogenic heat treated (2 196°C) CVD coated S40T grade cutting tool. Under MQL conditions, the minimum mean surface roughness (0.278 lm), resultant cutting force (268.2 N) and flank wear (0.18 mm) were obtained due to the high thermal conductivity and lubrication property of EG + %5BX cutting fluid. The highest hardness values (343 HV) were measured at the zone subjected to the highest deformation, while the lowest one (316 HV) was measured at the zone at the least deformation.
Ti6Al4V titanium alloy is widely used in aviation and medical industries due to its high temperat... more Ti6Al4V titanium alloy is widely used in aviation and medical industries due to its high temperature strength and biological compatibility, respectively. Since cutting forces obtained during machining of this material are directly related to cutting temperatures and tool life, determination of these forces has great importance for an economical and sustainable manufacturing. Therefore, in this study, the cutting forces occurring in face milling of Ti6Al4V alloy by carbide cutting tools were measured and the effect of cutting parameters on these forces was investigated. Single layer TiN and TiAlN coatings were deposited on the carbide tools by physical vapor deposition method. In cutting tests, three different cutting speed (50-150 m/min) and feed rate (0.05-0.15 mm/tooth) were used, keeping the depth of cut constant (0.5 mm). According to the results, the TiN coated tools have lower resultant cutting force than the TiAlN coated ones. The resultant cutting force increases with the feed rate at all cutting speeds, while at cutting speed of 50 m/min the maximum resultant cutting force was obtained at feed rate of 0.05 mm/tooth. When the effect of cutting speed was analyzed, it is seen that the resultant cutting force were affected differently for each feed rate values. The minimum resultant cutting force was obtained at cutting speed of 50 m/min and the feed rate of 0.10 mm/tooth with the TiN coated tools, while it was obtained at the feed rate of 0.05 mm/tooth and cutting speeds of 100 and 150 m/min. The influence of the coating material is more dominant at the hardest cutting conditions. Optimal cutting conditions in terms of resultant cutting force were determined as cutting speed of 100 m/min and feed rate of 0.05 mm/tooth using the TiN coated tools.
Titanium and its alloys are widely used in aerospace and aviation industries because of their hig... more Titanium and its alloys are widely used in aerospace and aviation industries because of their high strength-to-weight ratio, high fracture resistance and corrosion resistance at elevated temperatures. However, chemical reactivity and low thermal conductivity of these alloys lead to adhesion and diffusion wears on carbide tools, respectively. In addition, fluctuations in cutting forces occur during the cutting process due to chip shear band formation; and chipping wear is observed at the tool cutting edge as a result. Therefore, machining of these alloys is a challenge for researchers. A common method to increase the lifetime of carbide tools is to coat them with a thin hard coating. In this study, a nanolayer AlTiN/TiN coating was deposited on carbide cutting tools using an industrial magnetron sputtering system in order to enhance their wear resistance and lifetime in milling of Ti6Al4V. The cutting tests with the coated tools were performed at a cutting speed of 50 m/min, feed rate of 0.1 mm/tooth and depth of cut of 1 mm under dry conditions. Tool wear and surface roughness on the workpiece were measured and recorded as a function of cutting distance. Wear mechanisms and types were revealed using optical and scanning electron microscopy and energy dispersive spectroscopy. It was found that the nanolayer AlTiN/TiN coated tools provide higher wear resistance and 4 times longer lifetime when compared to uncoated ones. The main observed wear types are notch wear and build-up edge formation on the cutting edge. A slight improvement in surface roughness of the workpiece was observed with the nanolayered coating.
In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated W... more In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated WC materials was investigated. The coating process was carried out using the Physical Vapor Deposition (PVD) method. All coatings have a dense and homogeneous microstructure without delamination or crack formation. Wear tests were performed by fixed ball micro abrasion wear device. Micro abrasion wear test were carried out at different loads, abrasive sizes and sliding distances. As a result of the experiments, the best wear performance was obtained with AlCrN coated WC materials at all loads and abrasive grit sizes, followed by TiAlN/TiSiN coated and TiAlN coated samples. Depending on the increase in load, volume losses were increased in all samples under all conditions. Higher wear losses were determined in the tests performed with larger SiC abrasive particles. In the tests performed with SiC F800, the wear mechanism was micro-grooving wear mechanism, while in SiC F1200 tests the wear mechanism was micro-rolling mechanism. The increased number of cycles increased the volume loss of the samples. In the tests conducted with the SiC F800, the micro-grooves were more pronounced in short-range tests, whereas the groove steps in the long-range tests were reduced.
Shape memory alloys (SMAs) are increasingly used in the fields of aviation, automotive and biomed... more Shape memory alloys (SMAs) are increasingly used in the fields of aviation, automotive and biomedicine due to their unique properties. Nickel-Titanium (NiTi) alloy materials, which are one of the shape memory alloys, are among the most frequently used alloy materials. The shape memory and super elastic effects of NiTi alloys, high ductility and deformation hardening make it difficult to shape burr. An additional problem is the formation of a white layer during machining. In this study, surface milling operations were performed in dry cutting conditions with uncoated cutting tools with different nose radii. The processing parameters were determined based on the experience gained as a result of the preliminary tests. Tungsten carbide cutting tools with different nose radii (0.4mm and 0.8mm) were used for the milling operations. Milling was carried out at three different cutting speeds (20, 35, 50 m/min), feed rates (0.03, 0.07, 0.14 mm/tooth), and a constant axial cutting depth (0.7 mm). As a result of our experimental studies, the best tool life was found to be in 0.8 mm nose radius cutting tools at 20 m/min cutting speed and 0.03 mm/tooth feed rate (0.264 mm). The minimum average surface roughness was found after milling with 0.8 mm nose radius cutting tool at 20 m/min cutting speed and 0.03 mm/tooth feed rate (0.346 μm). It has been determined that increasing the cutting tool nose radius reduces both the flank wear over the cutting tool and the average surface roughness.
Purpose-This study aims to investigate the high-temperature wear behavior of the TiN-and AlTiN/Ti... more Purpose-This study aims to investigate the high-temperature wear behavior of the TiN-and AlTiN/TiSiN-coated WC materials. Design/methodology/approach-The coating process was carried out using the physical vapor deposition (PVD) method. Wear tests were performed by a ball-on-disc wear device with a high-temperature wear module. In microstructural investigation of the materials, it was benefited from traditional characterization methods such as, SEM, EDX analysis and microhardness measurement. Findings-The best wear performance was obtained with AlTiN/TiSiN-coated WC materials at all loads and temperatures, followed by TiN-coated and uncoated WC samples. An important wear was not observed on the samples tested at room temperature tests. It was found that the temperature increase is an effective parameter on the decrease of the wear resistance of the samples. In addition, it was seen that the increasing load and temperature change the wear mechanism on the uncoated WC sample. The wear mechanisms observed at high temperatures were delamination and oxidation for the WC, fatigue for AlTiN/TiSiN-coated WC and micro-scratch and micro-spalling for TiN-coated WC. Originality/value-The results of the experimental studies demonstrated that hard coatings improving wear resistance of WC.
Ti6Al4V titanyum alaşımı, sahip olduğu yüksek sıcaklık dayanımı ve biyolojik uyumluluğu nedeniyle... more Ti6Al4V titanyum alaşımı, sahip olduğu yüksek sıcaklık dayanımı ve biyolojik uyumluluğu nedeniyle havacılık ve sağlık alanında sıklıkla kullanılmaktadır. Ancak, bu malzemenin işlenmesi sırasında ortaya çıkan yüksek kesme sıcaklıkları ve malzemenin kesici takım yüzeyine adezyonu nedeniyle, karbür kesici takımlar kısa sürede aşınmakta ve ömürlerini tamamlamaktadırlar. Karbür kesici takımların aşınma direncinin ve ömürlerinin artırılması amacıyla, bu tez çalışmasında, bu takımlar üzerine nanotabakalı AlTiN/TiN kaplamalar biriktirilmiştir. Ayrıca kuru işleme yapılarak soğutma sıvısı kullanımının ortadan kaldırılması ve böylece işleme maliyetlerinin azaltılması çalışmanın hedefleri arasındadır. Nanotabakalı AlTiN/TiN kaplamaların aşınma davranışlarını ve kesme performanslarını karşılaştırmak amacıyla, tek tabakalı TiN ve tek tabakalı TiAlN kaplamalar da karbür takımlar üzerine biriktirilmiştir. Üretilecek nanotabakalı AlTiN/TiN kaplamaların mikrosertlik, altlık malzemeye adezyon ve sürtü...
Journal of Materials Engineering and Performance, 2021
In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was inv... more In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was investigated after face milling processes with cryogenically treated/untreated cemented carbide cutting tools at the conditions of dry cutting and minimum quantity lubrication (MQL) of cutting fluids depending on the changing cutting parameters. The integrity of surface layer of the workpiece material was evaluated according to the mean surface roughness, microstructure and hardness, as well as according to the resultant cutting force and flank wear of inserts. Cutting tests were carried out at three different cutting speeds (20, 35 and 50 m/min), feed rates (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The influence of these parameters on the surface integrity was extensively investigated. The face milling tests of NiTi SMA at optimal cutting parameters show that the surface integrity enhanced at a cutting speed of 50 m/min and feed rate of 0.03 mm/tooth using boron-added cutting fluid (EG + %5BX) with deep cryogenic heat treated (− 196 °C) CVD coated S40T grade cutting tool. Under MQL conditions, the minimum mean surface roughness (0.278 µm), resultant cutting force (268.2 N) and flank wear (0.18 mm) were obtained due to the high thermal conductivity and lubrication property of EG + %5BX cutting fluid. The highest hardness values (343 HV) were measured at the zone subjected to the highest deformation, while the lowest one (316 HV) was measured at the zone at the least deformation.
Titanium and its alloys are widely used in aerospace and aviation industries because of their hig... more Titanium and its alloys are widely used in aerospace and aviation industries because of their high strength-to-weight ratio, high fracture resistance and corrosion resistance at elevated temperatures. However, chemical reactivity and low thermal conductivity of these alloys lead to adhesion and diffusion wears on carbide tools, respectively. In addition, fluctuations in cutting forces occur during the cutting process due to chip shear band formation; and chipping wear is observed at the tool cutting edge as a result. Therefore, machining of these alloys is a challenge for researchers. A common method to increase the lifetime of carbide tools is to coat them with a thin hard coating. In this study, a nanolayer AlTiN/TiN coating was deposited on carbide cutting tools using an industrial magnetron sputtering system in order to enhance their wear resistance and lifetime in milling of Ti6Al4V. The cutting tests with the coated tools were performed at a cutting speed of 50 m/min, feed rat...
Purpose This study aims to investigate the high-temperature wear behavior of the TiN- and AlTiN/T... more Purpose This study aims to investigate the high-temperature wear behavior of the TiN- and AlTiN/TiSiN-coated WC materials. Design/methodology/approach The coating process was carried out using the physical vapor deposition (PVD) method. Wear tests were performed by a ball-on-disc wear device with a high-temperature wear module. In microstructural investigation of the materials, it was benefited from traditional characterization methods such as, SEM, EDX analysis and microhardness measurement. Findings The best wear performance was obtained with AlTiN/TiSiN-coated WC materials at all loads and temperatures, followed by TiN-coated and uncoated WC samples. An important wear was not observed on the samples tested at room temperature tests. It was found that the temperature increase is an effective parameter on the decrease of the wear resistance of the samples. In addition, it was seen that the increasing load and temperature change the wear mechanism on the uncoated WC sample. The wear...
Machining of silicon is an expensive affair because its inherent brittleness leads to subsurface ... more Machining of silicon is an expensive affair because its inherent brittleness leads to subsurface crack generation. Research endeavours have therefore focused on ductile mode machining of silicon to obtain crack free machined surfaces with roughness as low as 0.22 µm or even below, hence eliminating the need for subsequent polishing/grinding operations. However, most of these research works utilized expensive ultraprecision machines and tools. This research aimed at determining the viability of using conventional milling machines with diamond coated tools, high speed attachments, and air blowing mechanisms in order to achieve ductile regime machining of silicon. Spindle speed, depth of cut, and feed rate, ranges: 60,000 to 80,000 rpm, 10 to 20 µm, and 5 to 15 mm/min respectively, were considered as the independent machining parameters. Compressed air at 0.35 MPa was also provided to prevent chip deposition on the finished surfaces. The resultant surfaces were analysed using Optical a...
The aim of this study was to optimize machining parameters to obtain the smallest average surface... more The aim of this study was to optimize machining parameters to obtain the smallest average surface roughness (Ra) and flank wear (Vb) values as a result of the surface milling of a nickel-titanium (NiTi) shape memory alloy (SMA) with uncoated cutting tools with different nose radius (rε) under dry cutting conditions. Tungsten carbide cutting tools with different rε (0.4 mm and 0.8 mm) were used in milling operations. The milling process was performed as lateral/surface cutting at three different cutting speeds (Vc) (20, 35 and 50 m/min), feed rates (fz) (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The effects of machining parameters in milling experiments were investigated based on the Taguchi L18 (21 × 32) orthogonal sequence, and the data obtained were analyzed using the Minitab 17 software. To determine the effects of processing parameters on Ra and Vb, analysis of variance (ANOVA) was used. The analysis results reveal that the dominant factor affect...
Shrink fit was analyzed according to the probability theory of maximum safety and compatibility o... more Shrink fit was analyzed according to the probability theory of maximum safety and compatibility of parts was compared with the results obtained from the analysis. Bearings and shafts were selected in sample hole system for the given connection type and stationary connection and thus moment transmission were investigated. To understand the behavior of materials against dynamic loads has great importance in terms of making safe designs at the present time.
In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated W... more In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated WC materials was investigated. The coating process was carried out using the Physical Vapor Deposition (PVD) method. All coatings have a dense and homogeneous microstructure without delamination or crack formation. Wear tests were performed by fixed ball micro abrasion wear device. Micro abrasion wear test were carried out at different loads, abrasive sizes and sliding distances. As a result of the experiments, the best wear performance was obtained with AlCrN coated WC materials at all loads and abrasive grit sizes, followed by TiAlN/TiSiN coated and TiAlN coated samples. Depending on the increase in load, volume losses were increased in all samples under all conditions. Higher wear losses were determined in the tests performed with larger SiC abrasive particles. In the tests performed with SiC F800, the wear mechanism was micro-grooving wear mechanism, while in SiC F1200 tests the wear mechanism was micro-rolling mechanism. The increased number of cycles increased the volume loss of the samples. In the tests conducted with the SiC F800, the micro-grooves were more pronounced in short-range tests, whereas the groove steps in the long-range tests were reduced.
Journal of Materials Engineering and Performance, 2021
In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was inv... more In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was investigated after face milling processes with cryogenically treated/untreated cemented carbide cutting tools at the conditions of dry cutting and minimum quantity lubrication (MQL) of cutting fluids depending on the changing cutting parameters. The integrity of surface layer of the workpiece material was evaluated according to the mean surface roughness, microstructure and hardness, as well as according to the resultant cutting force and flank wear of inserts. Cutting tests were carried out at three different cutting speeds (20, 35 and 50 m/min), feed rates (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The influence of these parameters on the surface integrity was extensively investigated. The face milling tests of NiTi SMA at optimal cutting parameters show that the surface integrity enhanced at a cutting speed of 50 m/min and feed rate of 0.03 mm/tooth using boron-added cutting fluid (EG + %5BX) with deep cryogenic heat treated (2 196°C) CVD coated S40T grade cutting tool. Under MQL conditions, the minimum mean surface roughness (0.278 lm), resultant cutting force (268.2 N) and flank wear (0.18 mm) were obtained due to the high thermal conductivity and lubrication property of EG + %5BX cutting fluid. The highest hardness values (343 HV) were measured at the zone subjected to the highest deformation, while the lowest one (316 HV) was measured at the zone at the least deformation.
Ti6Al4V titanium alloy is widely used in aviation and medical industries due to its high temperat... more Ti6Al4V titanium alloy is widely used in aviation and medical industries due to its high temperature strength and biological compatibility, respectively. Since cutting forces obtained during machining of this material are directly related to cutting temperatures and tool life, determination of these forces has great importance for an economical and sustainable manufacturing. Therefore, in this study, the cutting forces occurring in face milling of Ti6Al4V alloy by carbide cutting tools were measured and the effect of cutting parameters on these forces was investigated. Single layer TiN and TiAlN coatings were deposited on the carbide tools by physical vapor deposition method. In cutting tests, three different cutting speed (50-150 m/min) and feed rate (0.05-0.15 mm/tooth) were used, keeping the depth of cut constant (0.5 mm). According to the results, the TiN coated tools have lower resultant cutting force than the TiAlN coated ones. The resultant cutting force increases with the feed rate at all cutting speeds, while at cutting speed of 50 m/min the maximum resultant cutting force was obtained at feed rate of 0.05 mm/tooth. When the effect of cutting speed was analyzed, it is seen that the resultant cutting force were affected differently for each feed rate values. The minimum resultant cutting force was obtained at cutting speed of 50 m/min and the feed rate of 0.10 mm/tooth with the TiN coated tools, while it was obtained at the feed rate of 0.05 mm/tooth and cutting speeds of 100 and 150 m/min. The influence of the coating material is more dominant at the hardest cutting conditions. Optimal cutting conditions in terms of resultant cutting force were determined as cutting speed of 100 m/min and feed rate of 0.05 mm/tooth using the TiN coated tools.
Titanium and its alloys are widely used in aerospace and aviation industries because of their hig... more Titanium and its alloys are widely used in aerospace and aviation industries because of their high strength-to-weight ratio, high fracture resistance and corrosion resistance at elevated temperatures. However, chemical reactivity and low thermal conductivity of these alloys lead to adhesion and diffusion wears on carbide tools, respectively. In addition, fluctuations in cutting forces occur during the cutting process due to chip shear band formation; and chipping wear is observed at the tool cutting edge as a result. Therefore, machining of these alloys is a challenge for researchers. A common method to increase the lifetime of carbide tools is to coat them with a thin hard coating. In this study, a nanolayer AlTiN/TiN coating was deposited on carbide cutting tools using an industrial magnetron sputtering system in order to enhance their wear resistance and lifetime in milling of Ti6Al4V. The cutting tests with the coated tools were performed at a cutting speed of 50 m/min, feed rate of 0.1 mm/tooth and depth of cut of 1 mm under dry conditions. Tool wear and surface roughness on the workpiece were measured and recorded as a function of cutting distance. Wear mechanisms and types were revealed using optical and scanning electron microscopy and energy dispersive spectroscopy. It was found that the nanolayer AlTiN/TiN coated tools provide higher wear resistance and 4 times longer lifetime when compared to uncoated ones. The main observed wear types are notch wear and build-up edge formation on the cutting edge. A slight improvement in surface roughness of the workpiece was observed with the nanolayered coating.
In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated W... more In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated WC materials was investigated. The coating process was carried out using the Physical Vapor Deposition (PVD) method. All coatings have a dense and homogeneous microstructure without delamination or crack formation. Wear tests were performed by fixed ball micro abrasion wear device. Micro abrasion wear test were carried out at different loads, abrasive sizes and sliding distances. As a result of the experiments, the best wear performance was obtained with AlCrN coated WC materials at all loads and abrasive grit sizes, followed by TiAlN/TiSiN coated and TiAlN coated samples. Depending on the increase in load, volume losses were increased in all samples under all conditions. Higher wear losses were determined in the tests performed with larger SiC abrasive particles. In the tests performed with SiC F800, the wear mechanism was micro-grooving wear mechanism, while in SiC F1200 tests the wear mechanism was micro-rolling mechanism. The increased number of cycles increased the volume loss of the samples. In the tests conducted with the SiC F800, the micro-grooves were more pronounced in short-range tests, whereas the groove steps in the long-range tests were reduced.
Shape memory alloys (SMAs) are increasingly used in the fields of aviation, automotive and biomed... more Shape memory alloys (SMAs) are increasingly used in the fields of aviation, automotive and biomedicine due to their unique properties. Nickel-Titanium (NiTi) alloy materials, which are one of the shape memory alloys, are among the most frequently used alloy materials. The shape memory and super elastic effects of NiTi alloys, high ductility and deformation hardening make it difficult to shape burr. An additional problem is the formation of a white layer during machining. In this study, surface milling operations were performed in dry cutting conditions with uncoated cutting tools with different nose radii. The processing parameters were determined based on the experience gained as a result of the preliminary tests. Tungsten carbide cutting tools with different nose radii (0.4mm and 0.8mm) were used for the milling operations. Milling was carried out at three different cutting speeds (20, 35, 50 m/min), feed rates (0.03, 0.07, 0.14 mm/tooth), and a constant axial cutting depth (0.7 mm). As a result of our experimental studies, the best tool life was found to be in 0.8 mm nose radius cutting tools at 20 m/min cutting speed and 0.03 mm/tooth feed rate (0.264 mm). The minimum average surface roughness was found after milling with 0.8 mm nose radius cutting tool at 20 m/min cutting speed and 0.03 mm/tooth feed rate (0.346 μm). It has been determined that increasing the cutting tool nose radius reduces both the flank wear over the cutting tool and the average surface roughness.
Purpose-This study aims to investigate the high-temperature wear behavior of the TiN-and AlTiN/Ti... more Purpose-This study aims to investigate the high-temperature wear behavior of the TiN-and AlTiN/TiSiN-coated WC materials. Design/methodology/approach-The coating process was carried out using the physical vapor deposition (PVD) method. Wear tests were performed by a ball-on-disc wear device with a high-temperature wear module. In microstructural investigation of the materials, it was benefited from traditional characterization methods such as, SEM, EDX analysis and microhardness measurement. Findings-The best wear performance was obtained with AlTiN/TiSiN-coated WC materials at all loads and temperatures, followed by TiN-coated and uncoated WC samples. An important wear was not observed on the samples tested at room temperature tests. It was found that the temperature increase is an effective parameter on the decrease of the wear resistance of the samples. In addition, it was seen that the increasing load and temperature change the wear mechanism on the uncoated WC sample. The wear mechanisms observed at high temperatures were delamination and oxidation for the WC, fatigue for AlTiN/TiSiN-coated WC and micro-scratch and micro-spalling for TiN-coated WC. Originality/value-The results of the experimental studies demonstrated that hard coatings improving wear resistance of WC.
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