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Abrasive Waterjet Machining (AWJM) is considered a viable alternative to conventional machining processes, due to its capability of rendering even complex features on parts with high productivity. However, it is currently also important for manufacturing processes to comply with the various aspects of sustainability, by putting emphasis on the environmental dimension apart from the economic. Although AWJM generally is considered an inherently environmentally friendly process, it is required that thorough experimental studies be carried out to evaluate the sustainability of AWJM under various conditions. In the present work, AWJM experiments under various conditions were conducted on a Ti-6Al-4V workpiece in order to determine the optimal conditions leading to a high degree of sustainability in this process based on several indicators. The experiments were carried out using glass beads, which act as an eco-friendly abrasive. After the basic outcome of the experiment was analyzed to determine the correlations between process parameters and depth of penetration, kerf width, and kerf taper angle, sustainability analysis with the aid of Grey Relational Analysis (GRA) was conducted. The optimum solution provided a sufficiently high score regarding both the economic and environmental dimensions of sustainability.
Nikolaos E. Karkalos; Panagiotis Karmiris-Obratański; Rafał Kudelski; Angelos P. Markopoulos. Experimental Study on the Sustainability Assessment of AWJ Machining of Ti-6Al-4V Using Glass Beads Abrasive Particles. Sustainability 2021, 13, 8917 .
AMA StyleNikolaos E. Karkalos, Panagiotis Karmiris-Obratański, Rafał Kudelski, Angelos P. Markopoulos. Experimental Study on the Sustainability Assessment of AWJ Machining of Ti-6Al-4V Using Glass Beads Abrasive Particles. Sustainability. 2021; 13 (16):8917.
Chicago/Turabian StyleNikolaos E. Karkalos; Panagiotis Karmiris-Obratański; Rafał Kudelski; Angelos P. Markopoulos. 2021. "Experimental Study on the Sustainability Assessment of AWJ Machining of Ti-6Al-4V Using Glass Beads Abrasive Particles." Sustainability 13, no. 16: 8917.
Electrical discharge machining is one of the most important non-conventional machining processes for removing material from electrically conductive materials by the use of controlled electric discharges. EDM is a non-contact machining process, therefore, is free from mechanical stresses. This paper investigates the machining Al7075-T6 alloy by EDM using a copper electrode. Al7075-T6 alloy was selected, because of its growing use in a lot of engineering applications. The effect of electrical parameters, peak current and pulse-on time, on the surface integrity, was studied. Area surface roughness parameters (arithmetical mean height, Sa, and maximum height, Sz) were measured on all samples and 3D surface characterization has been carried out with confocal laser scanning microscopy. The experimental results showed that the surface roughness is mainly affected by the pulse-on time.
Maria Balanou; Lazaros-Emmanouil Papazoglou; Angelos P. Markopoulos; Panagiotis Karmiris-Obratański. EXPERIMENTAL INVESTIGATION OF SURFACE TOPOGRAPHY OF AL7075-T6 ALLOY MACHINED BY EDM. Cutting & Tools in Technological System 2021, 3 -10.
AMA StyleMaria Balanou, Lazaros-Emmanouil Papazoglou, Angelos P. Markopoulos, Panagiotis Karmiris-Obratański. EXPERIMENTAL INVESTIGATION OF SURFACE TOPOGRAPHY OF AL7075-T6 ALLOY MACHINED BY EDM. Cutting & Tools in Technological System. 2021; (94):3-10.
Chicago/Turabian StyleMaria Balanou; Lazaros-Emmanouil Papazoglou; Angelos P. Markopoulos; Panagiotis Karmiris-Obratański. 2021. "EXPERIMENTAL INVESTIGATION OF SURFACE TOPOGRAPHY OF AL7075-T6 ALLOY MACHINED BY EDM." Cutting & Tools in Technological System , no. 94: 3-10.
Additive Manufacturing concentrates the attention, not only of the research and academic community, but of the industry as well. Selective Laser Melting (SLM) and Selective Laser Sintering (SLS) are among the broadest employed methods in AM, since they can treat almost all types of materials. Along with the extensive experimental research that is carried out regarding SLS and SLM, modeling and simulation are powerful tools allowing better and more in depth understanding of the processes. Nevertheless, there is no general framework in modeling, but mainly studies and proposed modeling approaches. The current paper reviews modeling methods and techniques that in literature are presented for the simulation of SLM and SLS. Besides the Finite Element Method, which is the most common method used, other numerical methods like Discrete Element Method, Smoothed Particles Hydrodynamics and Molecular Dynamics have been overviewed as well. The heat transfer and fluid dynamics models consist the main core of every simulation, while other sub-models are integrated to estimate parameters like residual stresses, part deformation, material microstructure, or crystallization. The main scope of the current paper is to provide a comprehensive and detailed review on the modeling and simulation of SLS/SLM and to inform the reader concerning the different modeling strategies.
Emmanouil L. Papazoglou; Nikolaos E. Karkalos; Panagiotis Karmiris-Obratański; Angelos P. Markopoulos. On the Modeling and Simulation of SLM and SLS for Metal and Polymer Powders: A Review. Archives of Computational Methods in Engineering 2021, 1 -33.
AMA StyleEmmanouil L. Papazoglou, Nikolaos E. Karkalos, Panagiotis Karmiris-Obratański, Angelos P. Markopoulos. On the Modeling and Simulation of SLM and SLS for Metal and Polymer Powders: A Review. Archives of Computational Methods in Engineering. 2021; ():1-33.
Chicago/Turabian StyleEmmanouil L. Papazoglou; Nikolaos E. Karkalos; Panagiotis Karmiris-Obratański; Angelos P. Markopoulos. 2021. "On the Modeling and Simulation of SLM and SLS for Metal and Polymer Powders: A Review." Archives of Computational Methods in Engineering , no. : 1-33.
Electrical Discharge Machining (EDM) is a non-conventional machining process, widely utilized in the modern industrial environment, especially in applications that involve the manufacturing of complex shapes and geometries, along with high dimensional accuracy. Conceptually EDM is a simple process, which is based on the erosion that accompanies the spark occurrence between two electrically conductive materials, one that acts as working electrode and one as the workpiece. Nevertheless, in practice, and due to the technological advances in the relevant field, EDM has become a multi-parameter machining process. The current chapter aims to familiarize the reader with the process of EDM, while at the same time, to provide useful and practical information concerning more advanced topics. The chapter's first sections are an introduction to the EDM, where a brief historical review, and the basic working principles are presented. The basic physical mechanisms that take place during machining are analyzed, along with the major machining parameters and performance indexes. Moreover, a brief literature review concerning the machining of steel and aluminum alloys with EDM is quoted. Thereafter, the basic principles for modeling and simulation of the process are introduced, aiming to become a helpful reference in model development. Finally, in the last section, a comparative study regarding the machining of two different aluminum alloys (i.e., Al5052 and Al6063) with EDM is presented, indicating how different alloys of the same base may have different behavior during their machining with EDM.
Panagiotis Karmiris-Obratański; Emmanouil L. Papazoglou; Angelos P. Markopoulos. Modeling and Experimental Work on Electrical Discharge Machining. Introduction to Mechanical Engineering 2021, 19 -40.
AMA StylePanagiotis Karmiris-Obratański, Emmanouil L. Papazoglou, Angelos P. Markopoulos. Modeling and Experimental Work on Electrical Discharge Machining. Introduction to Mechanical Engineering. 2021; ():19-40.
Chicago/Turabian StylePanagiotis Karmiris-Obratański; Emmanouil L. Papazoglou; Angelos P. Markopoulos. 2021. "Modeling and Experimental Work on Electrical Discharge Machining." Introduction to Mechanical Engineering , no. : 19-40.
Titanium alloys, due to their unique properties, are utilized in numerous modern high-end applications. Electrical Discharge Machining (EDM) is a non-conventional machining process, commonly used in machining of hard-to-cut materials. The current paper, presents an experimental study regarding the machining of Titanium Grade2 with EDM, coupled with the development of a simulation model. The machining performance indexes of Material Removal Rate, Tool Wear Ratio, and Average White Layer Thickness were measured and calculated for different pulse-on currents and pulse-on times. Moreover, the developed model that integrates a heat transfer analysis with deformed geometry, allows to estimate the power distribution between the electrode and the workpiece, as well as the Plasma Flushing Efficiency, giving an insight view of the process. Finally, by employing the Response Surface Methodology, educed regression models that correlate the machining parameters with the corresponding results, while for all the aforementioned indexes, ANOVA was performed.
Emmanouil L. Papazoglou; Panagiotis Karmiris-Obratański; Beata Leszczyńska-Madej; Angelos P. Markopoulos. A study on Electrical Discharge Machining of Titanium Grade2 with experimental and theoretical analysis. Scientific Reports 2021, 11, 1 -21.
AMA StyleEmmanouil L. Papazoglou, Panagiotis Karmiris-Obratański, Beata Leszczyńska-Madej, Angelos P. Markopoulos. A study on Electrical Discharge Machining of Titanium Grade2 with experimental and theoretical analysis. Scientific Reports. 2021; 11 (1):1-21.
Chicago/Turabian StyleEmmanouil L. Papazoglou; Panagiotis Karmiris-Obratański; Beata Leszczyńska-Madej; Angelos P. Markopoulos. 2021. "A study on Electrical Discharge Machining of Titanium Grade2 with experimental and theoretical analysis." Scientific Reports 11, no. 1: 1-21.
Surface quality has always been an important goal in the manufacturing industry, as it is not only related to the achievement of appropriate geometrical tolerances but also plays an important role in the tribological behavior of the surface as well as its resistance to fatigue and corrosion. Usually, in order to achieve sufficiently high surface quality, process parameters, such as cutting speed and feed, are regulated or special types of cutting tools are used. In the present work, an alternative strategy for slot milling is adopted, namely, trochoidal milling, which employs a more complex trajectory for the cutting tool. Two series of experiments were initially conducted with traditional and trochoidal milling under various feed and cutting speed values in order to evaluate the capabilities of trochoidal milling. The findings showed a clear difference between the two milling strategies, and it was shown that the trochoidal milling strategy is able to provide superior surface quality when the appropriate process parameters are also chosen. Finally, the effect of the depth of cut, coolant and trochoidal stepover on surface roughness during trochoidal milling was also investigated, and it was found that lower depths of cut, the use of coolant and low values of trochoidal stepover can lead to a considerable decrease in surface roughness.
Nikolaos Karkalos; Panagiotis Karmiris-Obratański; Szymon Kurpiel; Krzysztof Zagórski; Angelos Markopoulos. Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy. Machines 2021, 9, 75 .
AMA StyleNikolaos Karkalos, Panagiotis Karmiris-Obratański, Szymon Kurpiel, Krzysztof Zagórski, Angelos Markopoulos. Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy. Machines. 2021; 9 (4):75.
Chicago/Turabian StyleNikolaos Karkalos; Panagiotis Karmiris-Obratański; Szymon Kurpiel; Krzysztof Zagórski; Angelos Markopoulos. 2021. "Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy." Machines 9, no. 4: 75.
Electrical Discharge Machining (EDM) consists of a non-conventional machining process, which is widely used in modern industry, and especially in machining hard-to-cut materials. By employing EDM, complex shapes and geometries can be produced, with high dimensional accuracy. Titanium alloys, due to their unique inherent properties, are extensively utilized in high end applications. Nevertheless, they suffer from poor machinability, and thus, EDM is commonly employed for their machining. The current study presents an experimental investigation regarding the process of Ti–6Al–4V ELI with high power EDM, using a graphite electrode. Control parameters were the pulse-on current (Ip) and time (Ton), while Machining performances were estimated in terms of Material Removal Rate (MRR), Tool Material Removal Rate (TMRR), and Tool Wear Ratio (TWR). The machined Surface Roughness was calculated according to the Ra and the Rt values, by following the ISO 25178-2 standards. Furthermore, the EDMed surfaces were observed under optical and SEM microscopy, while their cross sections were also studied in order the Average White Layer Thickness (AWLT) and the Heat Affected Zone (HAZ) to be measured. Finally, for the aforementioned indexes, Analysis Of Variance was performed, whilst for the MRR and TMRR, based on the Response Surface Method (RSM), semi-empirical correlations were presented. The scope of the current paper is, through a series of experiments and by employing statistical tools, to present how two main machining parameters, i.e., pulse-on current and time, affect major machining performance indexes and the surface roughness.
Panagiotis Karmiris-Obratański; Emmanouil L. Papazoglou; Beata Leszczyńska-Madej; Krzysztof Zagórski; Angelos P. Markopoulos. A Comprehensive Study on Processing Ti–6Al–4V ELI with High Power EDM. Materials 2021, 14, 303 .
AMA StylePanagiotis Karmiris-Obratański, Emmanouil L. Papazoglou, Beata Leszczyńska-Madej, Krzysztof Zagórski, Angelos P. Markopoulos. A Comprehensive Study on Processing Ti–6Al–4V ELI with High Power EDM. Materials. 2021; 14 (2):303.
Chicago/Turabian StylePanagiotis Karmiris-Obratański; Emmanouil L. Papazoglou; Beata Leszczyńska-Madej; Krzysztof Zagórski; Angelos P. Markopoulos. 2021. "A Comprehensive Study on Processing Ti–6Al–4V ELI with High Power EDM." Materials 14, no. 2: 303.
Abrasive waterjet cutting is a well-established non-conventional technique for the processing of difficult-to-cut material and rendering of various complex geometries with high accuracy. However, as in every machining process, it is also required that high efficiency and productivity are achieved. For that reason, in the present study, the effect of performing the machining process by multiple passes is investigated, and the evaluation of this approach is performed in terms of total depth of penetration, kerf width, kerf taper angle, mean material removal rate, and cutting efficiency. In the case of multiple passes, the passes are performed in the same direction with the traverse speed adjusted accordingly in order to maintain the total machining time constant in each case. From the experimental results, it was found that the effect of multiple passes on the kerf characteristics, mean material removal rate, and cutting efficiency depends on the process conditions, especially regarding the depth of penetration, and it is possible to achieve significantly higher efficiency by the multi-pass cutting technique when the appropriate process conditions are selected.
Panagiotis Karmiris-Obratański; Nikolaos E. Karkalos; Rafał Kudelski; Emmanouil L. Papazoglou; Angelos P. Markopoulos. On the Effect of Multiple Passes on Kerf Characteristics and Efficiency of Abrasive Waterjet Cutting. Metals 2021, 11, 74 .
AMA StylePanagiotis Karmiris-Obratański, Nikolaos E. Karkalos, Rafał Kudelski, Emmanouil L. Papazoglou, Angelos P. Markopoulos. On the Effect of Multiple Passes on Kerf Characteristics and Efficiency of Abrasive Waterjet Cutting. Metals. 2021; 11 (1):74.
Chicago/Turabian StylePanagiotis Karmiris-Obratański; Nikolaos E. Karkalos; Rafał Kudelski; Emmanouil L. Papazoglou; Angelos P. Markopoulos. 2021. "On the Effect of Multiple Passes on Kerf Characteristics and Efficiency of Abrasive Waterjet Cutting." Metals 11, no. 1: 74.
Electrical Discharge Machining (EDM) is a non-conventional machining process, which allows the machining of any electrical conductive material, regardless its mechanical properties, with high dimensional accuracy, and in complex shapes and geometries. EDM widely utilized by modern industry, taking advantage of its unique inherent capabilities. Aluminum alloys find extensive use in numerous applications, and their machining consist an interesting topic, with tangible industrial interest. The current study presents an experimental investigation of machining Al6063 alloy with EDM. A full scale experiment was conducted, with control parameters the pulse-on current and time. The productivity of the process calculated based on the Material Removal Rate (MRR), while the Surface Roughness of the machined surfaces was estimated in terms of Ra and Rt. For these performance indexes Analysis Of Variance was performed and semi-empirical relations that correlate machining parameters with obtained results were proposed. Finally, the cross sections of the specimens were observed in optical microscopy, in order the formation of the White Layer to be studied.
Emmanouil L. Papazoglou; Nikolaos E. Karkalos; Angelos P. Markopoulos; Panagiotis Karmiris-Obratański. ON THE MACHINING OF ALUMINUM ALLOY AL6063 WITH EDM. Cutting & Tools in Technological System 2020, 76 -87.
AMA StyleEmmanouil L. Papazoglou, Nikolaos E. Karkalos, Angelos P. Markopoulos, Panagiotis Karmiris-Obratański. ON THE MACHINING OF ALUMINUM ALLOY AL6063 WITH EDM. Cutting & Tools in Technological System. 2020; (93):76-87.
Chicago/Turabian StyleEmmanouil L. Papazoglou; Nikolaos E. Karkalos; Angelos P. Markopoulos; Panagiotis Karmiris-Obratański. 2020. "ON THE MACHINING OF ALUMINUM ALLOY AL6063 WITH EDM." Cutting & Tools in Technological System , no. 93: 76-87.
Non-conventional manufacturing processes are often advantageous compared to conventional ones, as they can achieve high productivity in demanding cases. Abrasive waterjet (AWJ) machining is one of the most established non-conventional machining processes, which can achieve high material removal rates without leading to undesired workpiece material alterations and can render a large variety of shapes. In the present work, experiments regarding the AWJ milling of high strength 7075-T6 aluminum alloy are conducted with a view to correlate the process parameters, such as waterjet pressure, jet standoff distance, jet traverse speed and abrasive mass flow rate with depth of penetration, width and taper angle of the produced kerf. After the correlation between input and output parameters of the process is established, statistical analysis enables the determination of the influence of input parameters on output quantities and finally, appropriate process conditions for the regulation of depth of cut and kerf characteristics are derived.
Panagiotis Karmiris-Obratański; Rafał Kudelski; Nikolaos E. Karkalos; Angelos P. Markopoulos. Determination of the Correlation between Process Parameters and Kerf Characteristics in Abrasive Waterjet Milling of High Strength 7075-T6 Aluminum Alloy. Procedia Manufacturing 2020, 51, 812 -817.
AMA StylePanagiotis Karmiris-Obratański, Rafał Kudelski, Nikolaos E. Karkalos, Angelos P. Markopoulos. Determination of the Correlation between Process Parameters and Kerf Characteristics in Abrasive Waterjet Milling of High Strength 7075-T6 Aluminum Alloy. Procedia Manufacturing. 2020; 51 ():812-817.
Chicago/Turabian StylePanagiotis Karmiris-Obratański; Rafał Kudelski; Nikolaos E. Karkalos; Angelos P. Markopoulos. 2020. "Determination of the Correlation between Process Parameters and Kerf Characteristics in Abrasive Waterjet Milling of High Strength 7075-T6 Aluminum Alloy." Procedia Manufacturing 51, no. : 812-817.
Conventional machining processes such as turning, milling and drilling have long been prominent in the metalworking industry but alternative processes which do not require the use of a cutting tool in order to conduct material removal have also been proven to be sufficiently capable of achieving high efficiency in various cases. In particular, Abrasive Waterjet (AWJ) machining can be regarded as a rather appropriate choice for cutting operations, taking into consideration that it involves no heat affected zones, is able to process all material types and create a variety of complex features with success. In the present work, a comprehensive study on the effect of four process parameters, namely jet traverse speed, stand-off distance, abrasive mass flow rate and jet pressure on the width and depth of machined slots on a steel workpiece is conducted. The results are first analyzed with statistical methods in order to determine the effect and the relative importance of each parameter on the produced width and depth of the slots. Finally, these results are used to develop soft computing predictive models based on Artificial Neural Networks (ANN), which can efficiently relate the process parameters with its outcome.
Panagiotis Karmiris-Obratański; Nikolaos E. Karkalos; Anastasios Tzotzis; Panagiotis Kyratsis; Angelos P. Markopoulos. Experimental Analysis and Soft Computing Modeling of Abrasive Waterjet Milling of Steel Workpieces. MATEC Web of Conferences 2020, 318, 01031 .
AMA StylePanagiotis Karmiris-Obratański, Nikolaos E. Karkalos, Anastasios Tzotzis, Panagiotis Kyratsis, Angelos P. Markopoulos. Experimental Analysis and Soft Computing Modeling of Abrasive Waterjet Milling of Steel Workpieces. MATEC Web of Conferences. 2020; 318 ():01031.
Chicago/Turabian StylePanagiotis Karmiris-Obratański; Nikolaos E. Karkalos; Anastasios Tzotzis; Panagiotis Kyratsis; Angelos P. Markopoulos. 2020. "Experimental Analysis and Soft Computing Modeling of Abrasive Waterjet Milling of Steel Workpieces." MATEC Web of Conferences 318, no. : 01031.
E.L. Papazoglou; Panagiotis Karmiris-Obratański; N.E. Karkalos; A.P. Markopoulos. On the Use of Deformed Geometry in EDM Modelling: Comparative Study. Acta Physica Polonica A 2020, 138, 268 -271.
AMA StyleE.L. Papazoglou, Panagiotis Karmiris-Obratański, N.E. Karkalos, A.P. Markopoulos. On the Use of Deformed Geometry in EDM Modelling: Comparative Study. Acta Physica Polonica A. 2020; 138 (2):268-271.
Chicago/Turabian StyleE.L. Papazoglou; Panagiotis Karmiris-Obratański; N.E. Karkalos; A.P. Markopoulos. 2020. "On the Use of Deformed Geometry in EDM Modelling: Comparative Study." Acta Physica Polonica A 138, no. 2: 268-271.
This research work focuses on the investigation of the correlation between hydrogen cathodic charging conditions and toughness properties of a welded X65 pipeline steels. The experimental technique which was applied to determine the characteristic parameters associated with toughness was the crack tip open displacement after hydrogen cathodic charging process. The hydrogen cathodic charging process was carried out in an electrolytic cell with applied current densities of 10, 20, 30 mA/cm2 and hydrogen cathodic charging duration 48 h. Through this study, interesting results were provided concerning the diffusion depth and the diffusion coefficient of atomic hydrogen as far as toughness properties. The maximum diffusion depth value is assigned for each current density field in the region of heat-affected zone and the minimum in the area of fusion zone. In addition, the highest diffusion coefficients are attributed to heat-affected zone and the lowest to fusion zone, for all applied current densities. Finally, the fusion zone is considered to be more prone to the occurrence of embrittlement phenomena compared to base metal. The rate of toughness parameters drop is higher for current densities between 0-10 and 20-30 mA/cm2, where the cathodic current promotes the electrochemical reduction in hydrogen cations to atomic hydrogen.
H. P. Kyriakopoulou; I. D. Belntekos; A. S. Tazedakis; N. M. Daniolos; Panagiotis Karmiris-Obratański; D. I. Pantelis. Investigation of the Correlation between Hydrogen Cathodic Charging Conditions and Toughness Properties of Longitudinal Submerged Arc Welded X65 Pipeline Steels. Journal of Materials Engineering and Performance 2020, 29, 3205 -3219.
AMA StyleH. P. Kyriakopoulou, I. D. Belntekos, A. S. Tazedakis, N. M. Daniolos, Panagiotis Karmiris-Obratański, D. I. Pantelis. Investigation of the Correlation between Hydrogen Cathodic Charging Conditions and Toughness Properties of Longitudinal Submerged Arc Welded X65 Pipeline Steels. Journal of Materials Engineering and Performance. 2020; 29 (5):3205-3219.
Chicago/Turabian StyleH. P. Kyriakopoulou; I. D. Belntekos; A. S. Tazedakis; N. M. Daniolos; Panagiotis Karmiris-Obratański; D. I. Pantelis. 2020. "Investigation of the Correlation between Hydrogen Cathodic Charging Conditions and Toughness Properties of Longitudinal Submerged Arc Welded X65 Pipeline Steels." Journal of Materials Engineering and Performance 29, no. 5: 3205-3219.
Titanium alloys find extensive applications in the modern aerospace and offshore industry, as well in the field of biomedical implants. Nevertheless, the titanium inherent thermo-physical properties (low thermal conductivity and high chemical reactivity) make it a hard to machine material. For the efficient machining of titanium alloys, non-conventional machining processes are employed. Electrical Discharge Machining (EDM) is a non-contact machining process, in which the material removal occurs through repetitive electrical sparks. The capabilities of machining any electrically conductive material, regardless of its thermo-physical and other properties, render it as one of the most widely used non-conventional machining processes. As titanium alloys are used in high-quality parts and products, the integrity and texture of the machined surface constitute an essential parameter. The current study presents an experimental investigation of the surface texture and integrity of Ti6Al4V ELI after its machining with high power EDM. Namely, a full-scale experiment has been carried out, for pulse currents up to 65A and pulse-on time up to 200 μs, using graphite electrode. The surface texture (ST) and integrity has been estimated in terms of arithmetic mean height (Sa), the maximum height of scale-limited surface (Sz), maximum peak height (Sp), maximum pit height (Sv) and skewness of the scale-limited surface (Ssk). Additionally, through microscopy observation, the surface topography and integrity have been estimated, distinguishing and characterizing the surface cracks and micro-cracks. For all the above mentioned ST parameters, an Analysis of Variance (ANOVA) test has been performed.
Panagiotis Karmiris-Obratański; Krzysztof Zagórski; Jacek Cieślik; Emmanouil Lazaros Papazoglou; Angelos Markopoulos. Surface Topography of Ti 6Al 4V ELI after High Power EDM. Procedia Manufacturing 2020, 47, 788 -794.
AMA StylePanagiotis Karmiris-Obratański, Krzysztof Zagórski, Jacek Cieślik, Emmanouil Lazaros Papazoglou, Angelos Markopoulos. Surface Topography of Ti 6Al 4V ELI after High Power EDM. Procedia Manufacturing. 2020; 47 ():788-794.
Chicago/Turabian StylePanagiotis Karmiris-Obratański; Krzysztof Zagórski; Jacek Cieślik; Emmanouil Lazaros Papazoglou; Angelos Markopoulos. 2020. "Surface Topography of Ti 6Al 4V ELI after High Power EDM." Procedia Manufacturing 47, no. : 788-794.
The present research focuses on the investigation of an in situ hydrogen charging effect during Crack Tip Opening Displacement testing (CTOD) on the fracture toughness properties of X65 pipeline steel. This grade of steel belongs to the broader category of High Strength Low Alloy Steels (HSLA), and its microstructure consists of equiaxed ferritic and bainitic grains with a low volume fraction of degenerated pearlite islands. The studied X65 steel specimens were extracted from pipes with 19.15 mm wall thickness. The fracture toughness parameters were determined after imposing the fatigue pre-cracked specimens on air, on a specific electrolytic cell under a slow strain rate bending loading (according to ASTM G147-98, BS7448, and ISO12135 standards). Concerning the results of this study, in the first phase the hydrogen cations’ penetration depth, the diffusion coefficient of molecular and atomic hydrogen, and the surficial density of blisters were determined. Next, the characteristic parameters related to fracture toughness (such as J, KQ, CTODel, CTODpl) were calculated by the aid of the Force-Crack Mouth Open Displacement curves and the relevant analytical equations.
Helen P. Kyriakopoulou; Panagiotis Karmiris-Obratański; Athanasios S. Tazedakis; Nikoalos M. Daniolos; Efthymios C. Dourdounis; Dimitrios E. Manolakos; Dimitrios Pantelis. Investigation of Hydrogen Embrittlement Susceptibility and Fracture Toughness Drop after in situ Hydrogen Cathodic Charging for an X65 Pipeline Steel. Micromachines 2020, 11, 430 .
AMA StyleHelen P. Kyriakopoulou, Panagiotis Karmiris-Obratański, Athanasios S. Tazedakis, Nikoalos M. Daniolos, Efthymios C. Dourdounis, Dimitrios E. Manolakos, Dimitrios Pantelis. Investigation of Hydrogen Embrittlement Susceptibility and Fracture Toughness Drop after in situ Hydrogen Cathodic Charging for an X65 Pipeline Steel. Micromachines. 2020; 11 (4):430.
Chicago/Turabian StyleHelen P. Kyriakopoulou; Panagiotis Karmiris-Obratański; Athanasios S. Tazedakis; Nikoalos M. Daniolos; Efthymios C. Dourdounis; Dimitrios E. Manolakos; Dimitrios Pantelis. 2020. "Investigation of Hydrogen Embrittlement Susceptibility and Fracture Toughness Drop after in situ Hydrogen Cathodic Charging for an X65 Pipeline Steel." Micromachines 11, no. 4: 430.
Although electrical discharge machining (EDM) is one of the first established non-conventional machining processes, it still finds many applications in the modern industry, due to its capability of machining any electrical conductive material in complex geometries with high dimensional accuracy. The current study presents an experimental investigation of ED machining aluminum alloy Al5052. A full-scale experimental work was carried out, with the pulse current and pulse-on time being the varying machining parameters. The polishing and etching of the perpendicular plane of the machined surfaces was followed by observations and measurements in optical microscope. The material removal rate (MRR), the surface roughness (SR), the average white layer thickness (AWLT), and the heat affected zone (HAZ) micro-hardness were calculated. Through znalysis of variance (ANOVA), conclusions were drawn about the influence of machining conditions on the EDM performances. Finally, semi empirical correlations of MRR and AWLT with the machining parameters were calculated and proposed.
Angelos P. Markopoulos; Emmanouil-Lazaros Papazoglou; Panagiotis Karmiris-Obratański. Experimental Study on the Influence of Machining Conditions on the Quality of Electrical Discharge Machined Surfaces of aluminum alloy Al5052. Machines 2020, 8, 12 .
AMA StyleAngelos P. Markopoulos, Emmanouil-Lazaros Papazoglou, Panagiotis Karmiris-Obratański. Experimental Study on the Influence of Machining Conditions on the Quality of Electrical Discharge Machined Surfaces of aluminum alloy Al5052. Machines. 2020; 8 (1):12.
Chicago/Turabian StyleAngelos P. Markopoulos; Emmanouil-Lazaros Papazoglou; Panagiotis Karmiris-Obratański. 2020. "Experimental Study on the Influence of Machining Conditions on the Quality of Electrical Discharge Machined Surfaces of aluminum alloy Al5052." Machines 8, no. 1: 12.
Electrical Discharge Machining (EDM) is a non-conventional machining process, with a wide range of applicability and capabilities in modern industry. As a non-contact machining process, it has no limitations regarding the workpiece material mechanical properties, i.e. toughness and strength, with most important factors being the electrical conductivity and the thermal properties of the material. The material removal mechanism is relatively simple, including a spark occurrence between the electrode and the workpiece, which are immerged in a dielectric fluid. An amount of material, from both the electrode and the workpiece, melts or evaporates due to spark’s thermal energy. Machining parameters, namely the pulse current Ip and the pulse-on time Ton, highly affect the process’ performances, and so have to be carefully chosen, according the workpiece material and the desired machining results. The current study is an experimental investigation of machining aluminum alloy Al5052, with EDM for different machining parameters (Ip and Ton) setups. The material removal rate (MRR), the Surface Roughness (SR), the White Layer (WL) formation and the micro-hardness of the Heat Affected Zone (HAZ), were measured or calculated. Finally, using statistical tools, mathematical expressions of correlation between machining parameters and results are proposed. The current experimental study concluded that the MRR strongly depends on the pulse-on current, while the Surface Roughness mainly depends on the pulse-on time. Furthermore, the interaction and the combination of the machining parameters, namely the pulse-on current and the pulse-on time, have a major impact on the process efficiency. Lastly, the existence of a HAZ with decreased microhardness was verified.
A.P. Markopoulos; E.L. Papazoglou; P. Svarnias; Panagiotis Karmiris-Obratański. An Experimental Investigation of Machining Aluminum Alloy Al5052 with EDM. Procedia Manufacturing 2019, 41, 787 -794.
AMA StyleA.P. Markopoulos, E.L. Papazoglou, P. Svarnias, Panagiotis Karmiris-Obratański. An Experimental Investigation of Machining Aluminum Alloy Al5052 with EDM. Procedia Manufacturing. 2019; 41 ():787-794.
Chicago/Turabian StyleA.P. Markopoulos; E.L. Papazoglou; P. Svarnias; Panagiotis Karmiris-Obratański. 2019. "An Experimental Investigation of Machining Aluminum Alloy Al5052 with EDM." Procedia Manufacturing 41, no. : 787-794.