Voltage Spark Research Articles

Evaluating the effectiveness of the TOPSIS approach for three-wire electrode machining of D2 steel using the wire EDM method

Due to the high demand for D2 steel as a tool material and the difficulty of the machine, optimization of process parameters in advanced manufacturing machines is needed. This study investigates three wire electrodes: brass, coated copper, and annealed copper, analyzing their impact on tool material. Employing 0.25 mm wires, 10 mm D2 steel cubes are cut for consistent comparison. An L27 orthogonal array tests six parameters at three levels, optimizing with analytic hierarchy process technique for order preference by similarity to the ideal solution (AHP-TOPSIS). The response parameters were the metal removal rate (MRR) and kerf width (KW). Pulse on/off time, wire tension, spark voltage, input current, and wire feed rate vary systematically for each wire. The tests validate the efficacy of the AHP-TOPSIS method in optimizing WEDM parameters and machining performance. ANOVA reveals pulse-on and pulse-off times as crucial factors for various wire electrodes. Under diverse conditions, pulse duration increases spark efficiency. Based on the AHP-TOPSIS method results, weights of outputs revealed that the annealed copper wire yields the highest MRR value (0.232 mm3/sec). The brass wire exhibited the lowest MRR value (0.127 mm3/sec) compared to the others.

Enhanced performance of cyclone separator through coupling of centrifugal force, electrostatic force and particle pre-charge

The electrostatic enhancement can effectively improve the performance of cyclone separator at low load or high-temperature, but its application is limited owing to the reduction of spark voltage in high-temperature. Aiming at this question, a new technology coupling centrifugal force, electrostatic force and particle pre-charge was proposed. The characteristics of particles charging and agglomeration were analyzed, and the influence of different factors on the change of particle partition number concentration and total removal efficiency of cyclone separator were studied. The results showed that, increasing the charge generator voltage and decreasing the main pipe gas velocity can increase the particles charge quantity and improve agglomeration, which is benefit for the efficiency improvement of either cyclone separator or electrostatic cyclone separator, especially at low inlet gas velocity. Higher charge generator voltage and lower inlet gas velocity, more obvious efficiency improvement. The total removal efficiency can be increased by up to 10 % and 9 % respectively for the cyclone separator and electrostatic cyclone separator because of particle pre-charge at 10 m/s of inlet gas velocity, and the removal efficiency of fine particles can also be effectively improved. Comparing with the electrostatic cyclone separator, achieving the same total removal efficiency, the internal voltage can be reduced 16 kV through particle pre-charge. The electrostatic force and centrifugal force were the main factor of the small particles and big particles removal, respectively.

Micro-feature fabrication on SS304 stainless steel using WEDM process

ABSTRACT Fabricating micro-pillars is a tough procedure as these features are highly debile. Wire Electro-Discharge Machining (WEDM) is a popular micromachining process to fabricate complex features on electrical conducting materials. SS304 stainless steel is commonly used in manufacturing of heating and cooling devices. A simple method of micro-pillars array fabrication on SS304 Stainless Steel material using WEDM was used through perpendicular crossed wire movement, keeping specified amount of step-over distance to form pillars. An analytical model for material removal rate prediction was developed using input parameters like spark duration, off time, voltage and current. Also, the influence of the process parameters was studied on depth and kerf width produced. Voltage and pulse-on time were found to be the major influencing parameters. Micro-featured surfaces fabricated for minimum kerf width and maximum feature depth were analysed using SEM and EDS along with the wettability study. The fabricated surfaces remained hydrophobic even after 100s.

Machine learning for multi-dimensional performance optimization and predictive modelling of nanopowder-mixed electric discharge machining (EDM)

AbstractAluminium 6061 (Al6061) is a widely used material for various industrial applications due to low density and high strength. Nevertheless, the conventional machining operations are not the best choice for the machining purposes. Therefore, amongst all the non-conventional machining operations, electric discharge machining (EDM) is opted to carry out the research due to its wide ability to cut the materials. But the high electrode wear rate (EWR) and high dimensional inaccuracy or overcut (OC) of EDM limit its usage. Consequently, nanopowder is added to the dielectric medium to address the abovementioned issues. Nanopowder mixed EDM (NPMEDM) process is a complex process in terms of performance predictability for different materials. Similarly, the interactions between the process parameters such as peak current (Ip), spark voltage (Sv), pulse on time (Pon) and powder concentration (Cp) in dielectric enhance the parametric sensitivity. In addition, the cryogenic treatment (CT) of electrodes makes the process complex limiting conventional simulation approaches for modelling inter-relationships. An alternative approach requires experimental exploration and systematic investigation to model EWR and overcutting problems of EDM. Thus, artificial neural networks (ANNs) are used for predictive modelling of the process which are integrated with multi-objective genetic algorithm (MOGA) for parametric optimization. The approach uses experimental data based on response surface methodology (RSM) design of experiments. Moreover, the process physics is thoroughly discussed with parametric effect analysis supported with evidence of microscopic images, scanning electron microscopy (SEM) and 3D surface topographic images. Based on multi-dimensional optimization results, the NT brass electrode showed an improvement of 65.02% in EWR and 59.73% in OC using deionized water. However, CT brass electrode showed 78.41% reduction in EWR and 67.79% improved dimensional accuracy in deionized water. In addition to that, CT brass electrode gave 27.69% less EWR and 81.40% improved OC in deionized water compared to kerosene oil.

Preferential Crystallographic Orientation and Optical Properties in (Ag,Zn)‐Based Oxide Nanoparticle Thin Film Depending on Spark Voltage

The effect of spark voltage on nanoparticle (NP) formation, crystal structure, and optical properties of Zn and Ag‐containing metal oxides produced using the spark‐discharge (SD) technique was investigated. Quasispherical‐shaped nanocrystals were observed in ZnO, Ag:ZnO, and AgO NP samples prepared at different spark voltages. The NP sizes in ZnO and Ag:ZnO samples were close and decreased as the spark voltage increased. It was observed that when AgO was prepared with only low‐spark voltage (4.3 kV), tetrahedron/octahedron‐shaped NPs were also formed. 4.3 kV spark voltage increased the crystal growth rate in the (100)‐plane and 7 kV spark voltage also increased the crystal growth in the (002)‐plane in hexagonal wurtzite ZnO and Ag:ZnO samples. Therefore, the a‐axial preferred orientation of these samples at low‐spark voltage had switched to the c‐axial preferred orientation at high‐spark voltage. For AgO, the increase in spark voltage revealed the monoclinic structure more strongly. The film thicknesses of AgO samples were close to each other with both spark voltages. Although, it was determined that the AgO prepared with 7 kV was optically more transparent and its optical band gap was significantly widened. This case may be due to the more presence of dodecahedral‐shaped particles in the morphology of the AgO sample prepared. Therefore, the wider optical band gap of metal oxides decorated with such nanoparticles could indicate facet dependency. In addition, the film thickness and optical band gap of both ZnO and Ag:ZnO samples increased significantly depending on the increase of spark voltage. The optical band gap narrowed (redshifted) due to the effect of Ag ions entering the ZnO structure. As the spark voltage increased, the difference between the optical band gaps of ZnO and Ag:ZnO also increased. With the spark‐voltage effect, the change in preferential crystallographic orientations of ZnO and Ag:ZnO samples and the change in optical band gap depending on the NP shape of the AgO sample can offer significant advantages in terms of optoelectronics.

Impact analysis of electrode materials and EDM variables on the surface characteristics of SS316L for biomedical applications

The biocompatibility of the SS316L makes it an alluring alternative for orthopaedic and other biomedical applications. In such applications, surface characteristics of the materials are key considerations for bacterial adhesion at the surface of the metallic implant. Therefore, the current study focuses on the investigation of surface roughness and microhardness of SS316L in the electric discharge machining process using adequate electrode/tool material. Machining is performed with brass, copper, and aluminum electrodes to limit the surface roughness and enhance the microhardness of machining surfaces. Besides this, process variables including peak current, pulse off time, pulse on time and spark voltage are also optimized to obtain superior surface characteristics. Results show that adequate surface roughness of 1.08 μm can be attained with the aluminum electrode while brass electrodes offered increased microhardness of 1270.6 HV of machined surfaces. Microstructural analysis shows that aluminum electrode yields shallow and small-sized craters and few micro-cavities while brass electrode generates high peaks and valleys on the machined surface due to the deep craters, micro cracks, and cavities. The composite desirability function approach suggests that aluminum electrode along with the optimal setting of process variables such as peak current = 25 A, pulse off time = 50 μs, pulse on time = 55 μs and spark voltage = 2 V offers reasonable values of surface roughness 4.09 μm and microhardness 1051.2 HV after trading off.

Investigation on the performance of wire electrical discharge machining (WEDM) using aluminium matrix composites (AMCs) micro-channel

This study focuses on microchannel fabrication of Al-10% SiC composite using Wire-EDM process with the applications of single variable and multi variable, optimization. This work was targeted keeping in considerations the wider scope of microchannel applications in the fields such as medical, aerospace, automobile, etc. In this research work, the experiment was conducted to achieve high precision and quality surface finish in terms of minimum surface roughness (SR), high material removal rate (MRR), low tool wear rate (TWR) and optimum spark gap (SG). The used experiments were design on the basis of Taguchi design of experiment approach. Four input process parameters were considered namely, pulse on time (Ton), sparking voltage (SV), wire tension (WT), and wire feed rate (WFR). For the experimentation task, the workpeice (Aluminum and silicon carbide (10% Wt SiCmicro)) material, in a desired shape was fabricated through stir casting process. The tool electrode applied for the experiment purpose had specification as, 0.25 mm diameter brass alloy wire (copper 63 percent and zinc 37 percent). For single variable optimization ANOVA (analysis of variance) was applied while as, for multi variables optimization, grey relational analysis (GRA) was applied. The results of the study indicated that, on the basis of single variable optimization, the highest contribution of Ton resulted in case of the performance measures, MRR and SR while as, for TWR and SG, the highest contribution of sparking voltage, observed. Furthermore, the findings of the study indicated that, on the basis of multi variables optimization, the optimal combination of input process parameters is, pulse on time 125 μs, sparking voltage 10 volt, wire tension 12 kgf, and wire feed rate 4 m min−1. These results also get support from the previous research works. The findings of this study be useful for microchannel manufacturing and other related industrial applications.

Determining the Sparking Voltage of Working Electrolytes

Sparking voltage is one of the vital parameters of the working electrolytes for aluminum electrolytic capacitors, which determines the operating voltage of the capacitors. However, the existing methods for measuring the sparking voltage suffer from low accuracy, bad reproducibility, high artificial error, etc. In this paper, we reported a versatile approach to determining the sparking voltage of the electrolytes. By a linear fitting procedure, the voltage-time data acquired from the test experiments were transformed into a correlation coefficient-time curve. Since the abrupt correlation coefficient change due to the occurrence of sparking could be more readily identified in the correlation coefficient-time curve, the limit voltage of the electrolyte was accurately determined. Thus, this voltage was subtracted from the IR drop in the solution to get the true sparking voltage of the electrolyte. This method prevented artificial errors arising from the direct observation or listening of sparking features, by which reliable and reproducible results can be gained by a computer program. This study provided active support for the development of high-performance working electrolytes.

Modeling of Dry EDM process parameters during machining of Inconel 718 using artificial neural network

Dry EDM is a modified technique with substituted gaseous medium instead of liquid dielectrics in the usual EDM phase. In this work, dry EDM attempt is made with copper electrode on Inconel 718 material using L27 orthogonal array with compressed air as a dielectric medium. This study takes into account process variables like gas dielectric pressure, pulse current, spark on time, and gap spark voltage. ANN models is developed using Feed-forward back propagation algorithms with trainlm, learngdm, MSE, transig as the training, learning, performance and transfer functions respectively for the Material Removal Rate (MRR), Tool Wear Rate (TWR) and Surface roughness (Ra) as a response characteristics. A good fitness is observed for the trained model. Experimental response values and the ANN predicted values is compared and found that the overall correlation coefficient was 0.94455 which shows good prediction accuracies and effectiveness of the model and ANN technique.

Effect of Chloride Ions on the Sparking Voltage of Working Electrolytes and Its Restraint Method

Effect of Chloride Ions on the Sparking Voltage of Working Electrolytes and Its Restraint Method

Wedm Process Optimization for Machining Characteristcis of AISI 52100 Grade Alloy Steel

The present study deals with one of such investigations, which focuses on optimization of the different machining parameters of WEDM for AISI 52100 grade steel. For this work, a standard design of experimentation (DOE) based on Taguchi L27 orthogonal array (OA) has been used by selecting 6 different input parameters of the WEDM for optimization of two output characteristics (surface roughness (Ra) and dimensional deviation (DD). The results suggest that Pulse on Time (Ton): 1µs, Pulse off time: 18µs; Wire Feed (WF): 12mm/min, Spark Gap Set Voltage (SV): 20V, Wire Tension (WT): 1650, and Servo Feed (SF): 8units) are the best condition for the machining AISI 52100 grade steel as the roughness value (Roughness value: 1.02Ra) and dimensional deviation (Dimensional deviation: 0.02) obtained for these settings came to be least. From the result analysis of the current study, the pulse on time (Ton) was ranked at 1st, spark gap voltage came to be as 2nd rank parameter and pulse off (Toff) time was ranked 3rd, and wire tension was ranked at 4th position which significantly contributed towards the wire-EDM machining of AISI 52100 grade steel. Morphological analysis such as semi electron microscopic (SEM) analysis and 3D surface rendering also supported the observed surface and dimensional behaviour.

Variasi Nilai Tegangan Percik Arrester Akibat Pengaruh Kapasitas Trafo Daya dan Jarak Arrester

The ability of each substation to withstand lightning and overvoltage affects the power distribution of the power system. In order to make the best operation of the substations, it is necessary to install Arresters which are used to protect the transformers in each substation from overvoltage caused by lightning surges. In this study, the effect of capacity on the placement distance of the arrester is discussed with 30 MVA and 60 MVA transformers. The purpose of this study was to determine the effect of the power transformer capacity of the four substations on the value of the arrester spark voltage and to obtain the optimal arrester installation technique at each substation using the Lagrange optimization method. Lagrange optimization method is used to determine the optimal distance between the arrester and the power transformer. The calculation results show that in a transformer with a capacity of 60 MVA, the Arrester spark voltage occurs at t = 20 microseconds with a voltage drop of 390.49 kV. Meanwhile, in a transformer with a capacity of 30 MVA, the Arrester spark time is at t = 13.9 microseconds with a voltage drop of 266.3 kV. This shows the capacity of the transformer that affects the magnitude of the Arrester's spark voltage and the spark time. Thus, the smaller the transformer capacity, the smaller the arrester spark time with the large voltage drop

INFLUENCE OF CURRENT DENSITY ON THE PROCESS OF FORMATION OF OXIDE COATING ON ZIRCONIUM ALLOY E110

Today, binary, triple and quadruple zirconium alloys containing iron, chromium and copper are known for corrosion protection, which have a clear advantage over circal and niobium binary alloys in terms of corrosion resistance. However, insufficient attention is paid to studies aimed at studying the process of formation and morphology of oxide films on the zirconium alloy E110. This area of research has a high scientific and technical interest in the development of oxide coatings on metal surfaces, given the widespread use of zirconium alloys in nuclear energy as a structural material in the construction of nuclear reactors. The paper considers the advantages of the method of microarc oxidation in comparison with other methods of protection of zirconium alloys from different types of corrosion damage. The main task of the work is to study the influence of current density on the formation and morphology of oxide films on zirconium alloy. It was found that the obtained dependences of the formation stress on the time of microarc oxidation of zirconium alloy in 1 mol/l potassium pyrophosphate at different current densities have a characteristic classical appearance, characterized by three sections, such as spark, spark and microarc. The dependence of the rate of change of the voltage dU / dt on the molding voltage is constructed for a more detailed study of the process of formation of oxide films and determination of the moment of the beginning of sparking and microarcs. It was found that when the current density increases to 6 A/m2, the spark voltage increases by 5 V, and when it increases to 10 A/m2 - by 15 V, but the voltage of the microarcs remains unchanged. Mostly solid, well-bonded to the base oxide films of light gray colour on a zirconium alloy are obtained. The morphology of oxide coatings obtained on the surface of the zirconium alloy E110 by the method of microarc oxidation in potassium pyrophosphate at different current densities was studied. It is shown that oxide films without cracks and surfaces have irregularities with a cellular texture.

Parametric Optimization for Quality of Electric Discharge Machined Profile by Using Multi-Shape Electrode.

The electrical discharge machining (EDM) process is one of the most efficient non-conventional precise material removal processes. It is a smart process used to intricately shape hard metals by creating spark erosion in electroconductive materials. Sparking occurs in the gap between the tool and workpiece. This erosion removes the material from the workpiece by melting and vaporizing the metal in the presence of dielectric fluid. In recent years, EDM has evolved widely on the basis of its electrical and non-electrical parameters. Recent research has sought to investigate the optimal machining parameters for EDM in order to make intricate shapes with greater accuracy and better finishes. Every method employed in the EDM process has intended to enhance the capability of machining performance by adopting better working conditions and developing techniques to machine new materials with more refinement. This new research aims to optimize EDM’s electrical parameters on the basis of multi-shaped electrodes in order to obtain a good surface finish and high dimensional accuracy and to improve the post-machining hardness in order to improve the overall quality of the machined profile. The optimization of electrical parameters, i.e., spark voltage, current, pulse-on time and depth of cut, has been achieved by conducting the experimentation on die steel D2 with a specifically designed multi-shaped copper electrode. An experimental design is generated using a statistical tool, and actual machining is performed to observe the surface roughness, variations on the surface hardness and dimensional stability. A full factorial design of experiment (DOE) approach has been followed (as there are more than two process parameters) to prepare the samples via EDM. Regression analysis and analysis of variance (ANOVA) for the interpretation and optimization of results has been carried out using Minitab as a statistical tool. The validation of experimental findings with statistical ones confirms the significance of each operating parameter on the output parameters. Hence, the most optimized relationships were found and presented in the current study.

Effect of different wire materials on WEDM performance of Bio-compatible material

Abstract The present experimental investigation aims to analyse the effect of various machining parameters, such as pulse peak current (Ion), pulse on time (Ton), pulse off time (Toff) and spark voltage (SV) on the surface roughness (SR) and material removal rate(MRR) by using continuous traveling of both wire electrode (i.e. brass wire and zinc-coated brass wire). The present work also analyses the effect of types of wires, such as brass wire and zinc-coated brass wire used during machining of Titanium alloy (Ti-6Al-4V) on Surface roughness (SR) and material removal rate (MRR). This work studies the correlation between various response parameter such SR and MRR by using same machining parameter by for both wires.

EDM of Ti-6Al-4V under Nano-Graphene Mixed Dielectric: A Detailed Investigation on Axial and Radial Dimensional Overcuts.

Ti-6Al-4V is considered a challenging material in terms of accurate machining. Therefore, electric discharge machining (EDM) is commonly engaged, but its low cutting rate depreciates its use. This issue is resolved if graphene nanoparticles are mixed in the dielectric. However, the control over the sparking phenomenon reduces because of the dispersion of graphene particles. Subsequently, the machined profile’s geometric accuracy is compromised. Furthermore, the presence of nanographene induces different sparks along axial and radial cutting orientations. This aspect has not been comprehensively examined yet and dedicatedly targeted in this study to improve the quality of EDM process for Ti-6Al-4V. A total of 18 experiments were conducted under Taguchi’s L18 design considering six parameters namely, electrode type, polarity, flushing time, spark voltage, pulse time ratio, and discharge current. The aluminum electrode proved to be the best choice to reduce the errors in both the cutting orientations. Despite the other parametric settings, negative tool polarity yields lower values of axial (ADE) and radial errors (RDE). The developed optimal settings ensure 4.4- and 6.3-times reduction in RDE and ADE, respectively. In comparison to kerosene, graphene-based dielectric yields 10.2% and 19.4% reduction in RDE and ADE, respectively.

Experimental investigations on wire cut electric discharge machining on Monel 400 alloys

In this present work, the machinability effect of Monel alloy is studied by varying the parameters of Wire Electrical Discharge Machine (WEDM). Pulse on time (T on), Pulse off time (T off), Spark voltage (SV), Servo feed (SF) and Cutting Speed (CS) were the input parameters considered for the study. Material Removal rate (MRR) and Surface roughness were the responses that were measured and analysed. The experiments were conducted by using Taguchi’s L9 orthogonal array. Each experiment was conducted thrice under different conditions of input parameters. The influences of each independent parameter on the output measures were analyzed using Grey Relational Analysis (GRA) with the intension of improving the machinability. From the experiments, the best combination of input parameters was found that can increase the machinability. The experimental results confirm that the machining performance of WEDM process can be improved effectively through this approach.

Steady states of gas ionization with secondary emission

We consider the steady states of a gas between two parallel plates that is ionized by a strong electric field so as to create a plasma. There can be a cascade of electrons due both to the electrons colliding with the gas molecules and to the ions colliding with the cathode (secondary emission). We use global bifurcation theory to prove that there is a one-parameter family $\mathscr{K}$ of such steady states with the following property. The curve $\mathscr{K}$ begins at the sparking voltage and either the particle density becomes unbounded or $\mathscr{K}$ ends at an anti-sparking voltage. These critical voltages are characterized explicitly.

Comparative electrical characterization of spark-erosion of silicon and steel as a base and its implications on equivalent circuit

This study uses electrical characterization of sparks to advance the understanding of complex mechanism involved in wire electrical discharge machining (WEDM) of photovoltaic grade silicon. Specifically, WED machining of silicon is compared with that of steel as a base, with two approaches of experimentation — (a) one factor at a time (OFAT) and (b) design of experiments (DoE). The responses are measured in terms of four pulse parameters — maximum current Imax, maximum voltage Vmax, average voltage Vavg, pulse energy Ep; and three summary statistics. It was evident that the current required for steel workpiece is more by ≈ 10–15 A than that for silicon, whereas the spark voltage is more by ≈ 10 V for silicon than that for steel. Analysis of variance (ANOVA) showed that, current setting primarily affects the mean of Imax, Vavg, Ep and the effect is >60% for both silicon and steel. Moreover, quantitative effect of input factors on the pulse-to-pulse variation was also obtained for the first time. The pulse-to-pulse variation in Vavg for silicon is influenced by several parameters: current, pulse period, ON-time, and wire speed (cumulative effect ≈55%), whereas that for steel only current setting influences and the effect is >51%. The role of workpiece thickness (height of cut) has not been studied in detail in the available literature and is important for slicing cylindrical ingots as the length of cut changes continuously while slicing the cylindrical ingots. Therefore, the effect of workpiece thickness was studied, especially from perspective of the current and voltage pulse parameters during slicing. For silicon, an increase in workpiece thickness results in an increase in Vavg, and a decrease in Imax, whereas for steel, such effect was not seen. The equivalent circuit of spark as observed from the pulse generator showed that besides electrical conductivity of the materials, the junction between spark plasma and silicon plays a dominant role in deciding the current drawn by the spark-erosion process.

ANALISA PENEMPATAN LIGHTNING ARRESTER SESUDAH CUT OUT UNTUK MENGURANGI GANGGUAN TEGANGAN LEBIH PADA TRAFO KL 0074 DI PT. PLN (Persero) ULP KLUNGKUNG

Where it was recorded that according to BMKG data in 2019 in East Bali there were 15,000-30,000 lightning strikes. This gives the potential for, lightning strike on a 20 kV distribution linewhich is quite high. This connection will cause interference to the feeder if the lightning arresteris placed on the distribution transformer incorrectly. The equepment used to protect equipmentfrom lightning surge distrubances, one of which is a lightning arrester. The lightning arresterused in the KL 0074 substation is in place after the cut out. The Losan medium-voltage aerialfeeder is conncected by an A3CS cable for 8.5 km and an MVTIC cable for a distance of 2.02km which is connected to the KL 0074 substation. The distance between the KL 0074transformer and the lightning arrester is 3.75 meters, so it needs to be examined further to findout whether the protection generated by the lightning arrester is optimal or not. Theeresulttofftheanalysissshowwthatttheelightning arrester with an instalation distance of 0.34 meters from thetransformer is still able to cut the lightning surge, with the resulting splash voltage of 124.977.4Volts but the spark voltage is within the tolerance limit of the 125 kV lightning arrester splashvoltage.,