Spark Test Research Articles

Numerical modelling and experimental investigations to predict the tool wear of copper electrodes during µ-EDM process

The micro electrical discharge machining (µ-EDM) process is one of the most widely used techniques to produce miniaturized components in micro-electro mechanical system (MEMS) applications due to its inherent advantages. This work investigates the wear phenomena and the morphology of the copper electrodes during the micro-die sinking process. A numerical model of a single spark is developed assuming the Gaussian distribution of heat flux to estimate the crater dimensions formed in the copper tool electrode (tool wear) used as a result of electric discharge. The crater dimension attained from the ABAQUS finite element model is validated with experimental results using a single spark test setup. Moreover, the effect of input parameters namely capacitance and voltage on the electrode wear rate and surface roughness is also studied. The crater dimensions from the single discharge study are used to formulate the wear model for different possibilities of crater distribution, such as non-overlapping craters, craters with less than 30 % overlap, and 50 % overlap. The electrode wear rate (EWR) also displayed a decline from 20.4 % to 11.6 % and further to 8 % when the overlap was permitted up to 30 % and up to 50 % for the wear model respectively. The developed model results are further compared with experimental results in terms of the electrode wear rate and depth of erosion and the deviations are found to be 20.33 % and 20.55 % respectively

Ensuring the reliability of automated pulse electric spark control of pipe coatings in in-line production

The issues of ensuring the reliability of automated electric spark testing of the continuity of dielectric coatings on metal pipes with diameters up to 1.5 meters in the context of in-line manufacturing are addressed. A simulation of the “high-voltage pulse source – electrode – dielectric coating – metal substrate” system has been conducted. Experimental studies have been conducted to evaluate the load capacity and voltage stability of the Corona 2.2 holiday detector using an improved generator at high capacitive loads.

Rapid Assessment of Steel Machinability through Spark Analysis and Data-Mining Techniques

The machinability of steel is a crucial factor in manufacturing, influencing tool life, cutting forces, surface finish, and production costs. Traditional machinability assessments are labor-intensive and costly. This study presents a novel methodology to rapidly determine steel machinability using spark testing and convolutional neural networks (CNNs). We evaluated 45 steel samples, including various low-alloy and high-alloy steels, with most samples being calcium steels known for their superior machinability. Grinding experiments were conducted using a CNC machine with a ceramic grinding wheel under controlled conditions to ensure a constant cutting force. Spark images captured during grinding were analyzed using CNN models with the ResNet18 architecture to predict V15 values, which were measured using the standard ISO 3685 test. Our results demonstrate that the created prediction models achieved a mean absolute percentage error (MAPE) of 12.88%. While some samples exhibited high MAPE values, the method overall provided accurate machinability predictions. Compared to the standard ISO test, which takes several hours to complete, our method is significantly faster, taking only a few minutes. This study highlights the potential for a cost-effective and time-efficient alternative testing method, thereby supporting improved manufacturing processes.

Fuel Effects on the Onset of Knock and the Intensity of Superknock at Stochastic Preignition-Relevant Engine Conditions

<div>To have a more complete understanding of the fuel effects on each subsequent stage of a stochastic preignition event in a spark-ignition engine and to build on the previous work of understanding the propensity of fuel to initiate and sustain a preignition flame, this work is focused on examining the role of fuel on the onset of knock and the intensity of superknock once the unburned mixture reaches certain conditions ahead of the preignition flame. Using a “skip advance” spark test method to simulate preignition flames initiated at different cylinder conditions, more than 20 single- and multicomponent fuels were ranked based on the condition required to reach the onset of knock (the start of end-gas autoignition) and the condition that leads to severe superknock intensities. It was found that average knock intensity can be mainly explained by the unburn mixture fraction and the thermodynamic condition of the unburned mixture and, not surprisingly, that the fuel ranking for the onset of knock and superknock based on average knock intensity is correlated to octane index. However, outlier cycles with extremely high knock intensities cannot be fully explained by the average cycle behavior. More interestingly, different fuels exhibit different superknock characteristics. Some fuels, such as toluene, have fewer extreme cycles once the same average knock intensity condition is reached, whereas other fuels, such as ethanol, have more extreme cycles that tend to break engine hardware in a single cycle event. A preliminary study based on the modes of reaction front propagation show that fuels with low-temperature heat release and negative temperature coefficient (NTC) behavior can lead to a higher propensity to produce extreme knock intensities when coupled with the right in-cylinder pressure wave.</div>

Delta Tecnic reportedly guarantees efficient insulation in the cable industry and impeccable spark test results

On September 28, Delta Tecnic reports that the masterbatch manufacturer reduces the granule size tenfold to achieve better dilution of the masterbatch in the cable compound; 25% of the company's sales are in the automotive industry, where satisfactory spark test results are reportedly more difficult to achieve.

Optical Emission Spectroscopy of Cadmium Dominated Discharges Applied for Assessment of Explosion Protection

An assessment for the safe use of electrical equipment in explosive atmospheres can be performed with the aid of a spark test apparatus. Therefore, an anodic tungsten wire with 200 µm diameter is moved along the surface of a rotating cadmium disc (cathode). The explosion chamber enclosing the electrodes is filled with a highly explosive mixture of hydrogen and air. Depending on surface topology and relative movement of the contact pair, discharges occur randomly. A model contact device is used to investigate the plasma properties and the discharge characteristics near the thermo-chemical ignition threshold of the explosive atmosphere that typically occur at voltages around 30V and currents around 30mA.Spectroscopic investigations reveal that the emission of the discharges is dominated by atomic lines of cadmium, which allow the determination of distribution temperatures.

Identification of Type of Metals by Using Heat Transfer Rate

Abstract: Metals are advances in manufacturing processes which is the industrial revolution. It is very important to accurately identify types of metal when working with metal materials, and this is particularly important in maintenance welding. Metals with higher carbon content are sensitive to hot-cracking and hardening, which can result in poor ductility for welding projects. If it want to be simply identify a piece of scrap metal, it can be done by evaluating its colour, weight and composition. The common ways to identify metal is surface appearance, spark test, chip test, magnet test, hardness test. Project is to identifying metals based on their heat rate from one end to another end through a instrument automatically. This is because of electron arrangement in them.

Examination of the effects of reactive agility and planned change of direction skills on Self Defense techniques in private security and protection program students

The purpose of this study is investigate the impact of reactive agility, reaction-based planned change of direction training on the practice of self defence methods among students enrolled in the Private Security and Protection program of Vocational Schools. Twenty male volunteer students, 21.20±1.28 years, height 177.37±6.18 cm, weight 75.56±5.50 kg, voluntarily participated in the study. While the volunteer research group received reactive agility, response speed training for 2 hours 4 days a week for 8 weeks, the control group continued to receive self defence skills instruction as usual. Measurements of body composition Body analyzer Inbody 270 (Japan), reactive test Fitspeed (Turkey) gadget for measuring agility performance, as well as other agility planned change of direction tests Fusion Smart (Australia) with an integrated system of photocell doors, T Test digital integrated system stopwatch (Belgium), Reaction time Speed test was measured using a Performanz Spark test equipment (Turkey). The SPSS 22 software was utilized to analyze the data. First, the data distribution was evaluated using the Shapiro-Wilk test, it was discovered that it did not have a normal distribution. Mann Whitney U Tests were used in this manner to find the difference between the pre-test and post-test results of the nonparametric Wilcoxon Signed Rank Test across groups in order to determine the difference between the pre-post-test data within the group. The level of significance in the study was determined at p>0.05. According to the statistical analysis, the 8-week planned change of direction, reactive agility training improved the response speed, agility performance of the work group students (p>0.05).

Integrated Electric Spark Testing of Continuity and Unacceptable Thinning of Dielectric Coatings

At present, the main method for detecting continuity defects in dielectric coatings is the electrospark method of nondestructive testing (NDT). However, minimum coating thickness requirements are applied to most modern coatings. It seems promising to carry out tolerance control of the testing of dielectric coatings in one technological process with control of their continuity due to changes in the existing testing methods and the method of forming the test voltage. Theoretical and experimental analysis of the processes of sparking occurring upon detection of through and nonthrough defects in dielectric coatings on electrically conductive substrates has been carried out. The minimum control voltages have been measured and calculated for the studied dielectric coatings, taking into account the detection of both through defects and unacceptable thinning. The application of a probabilistic approach to the detection of the above defects is proposed. It is shown that with a known value of the electrical strength of the coating, it is possible to detect both through and nonthrough defects with a calculated probability in coatings with a given test voltage.

Steel type determination by spark test image processing with machine learning

The spark test method is a simple and low-cost method in which an operator with special skills observes the sparks emitted by a grinding wheel in contact with the steel in order to identify the material of the sample. However, the operator might classify erroneously two different steel materials with close spark characteristics. Therefore, we propose a method that extracts features from images captured from the spark test method and uses these features as input on machine learning models. The regression models predicted the carbon content of steel with 8% error while the classifiers had 82% of accuracy. The classifiers models had good results with few confusion points and regression models had low error. Regarding the confusion points, the regression algorithms could solve the misclassification by predicting the carbon content of the sample and increasing accuracy. The proposed method is suitable for real-time and shop floor applications.

Performance charateristics of a conventional spark ignition petrol engine powered by biogas

This research investigates the use of biogas to run a spark ignition petrol engine and test for the engine performance. Conventional spark ignition petrol engine was modified into a dual fuel engine by changing the engine single fuel carburettor to dual fuel carburettor. The air orifice was closed by 50% to enable cooled start with natural biogas as the low calorific value won't facilitate combustion. The speed, torque, and other engine parameters where measured using a TD200 small engine test set (hydraulic brake dynamometer) interface and emissions of SO2, CO were measured using an emissions analyser. The torque, brake power was higher for petrol by 39% than the biogas due to the lower calorific value of biogas. The exhaust temperature, SO2 and CO was 49% lower for the biogas than the petrol. The comparative analysis of the modified engine showed that petrol can be substituted partly with biogas and the engine used for varying applications because it offers window escape on the hydrocarbon reservoir depletion, green gasses emission from the use of these petrol and landfill emission as well.

High voltage testing of functional dielectric coatings with thickness from 25 μm and more

The high-voltage spark testing method for protective dielectric coatings is applied in almost all manufacturing areas and is governed by ISO, ASTM etc. However, they do not take into account high voltage generation (DC or AC) and its polarity, the impact of the environment and electric field inhomogeneity. A detailed analysis and modeling of the sparking process was carried out given the polarity of the applied control voltage and the design principles of creating a strongly inhomogeneous electric field in the interelectrode gap. The possibility of monitoring dielectric coatings with a thickness of 25 μm or more while reducing the control voltage without reducing the reliability of the results is shown, which is especially important when testing the continuity of paint coatings of large area objects.

THE HIGH VOLTAGE TESTING OF DIELECTRIC COATINGS THICKNESS

The technology of applying many coatings (including paints and varnishes) involves the layering of visually indistinguishable layers that make up the coating system. However, in case of application technology violation, the number of coating layers (thickness) may not correspond to the declared. Thus, in a number of cases, it is necessary to control the number of layers of the final coating system. One of the most common methods for monitoring the continuity of coatings is the high voltages spark method of non-destructive testing. The method involves the application of a high voltage U between the electrode installed on the surface of the coating and the conductive substrate. The revealing of defect coating area provide by registering the coating breakdown. The analysis shows that the development of methods for detecting not only discontinuities, but also unacceptable thinning of dielectric coatings due to their spark breakdown, seems to be a promising direction in the development of high voltages spark testing. In relation to pulsed high voltages spark testing, the electrical mechanism of the breakdown of dielectrics based on quantum-mechanical concepts, the conditions of its occurrence, and the main relations obtained for calculating the electric strength Es and breakdown voltage Us for protective dielectric coatings are considered in detail. Comparative results of an experimental study of the proposed algorithms for calculating Es and Us, as well as methods for identifying (tolerance control) sections of paint coatings with an unacceptable minimum thickness and coating bubbles, are presented. The application of the proposed algorithms and methods will allow one hundred percent control of the continuity and unacceptable thinning of paint and varnish and similar dielectric protective coatings of the external and internal surfaces of pipelines, as well as various large area facilities.

Study on the Mechanism of Carbon Steel Sparks

Abstract Spark testing is an effective and convenient method that can be used be identify general classification of the steel material by observing the sparks projected by the grinding wheel. In order to more accurately identify the type of spark, the spark streams of carbon steels are described and illustrated by a high-speed camera. The appearance and phase analysis of the residues collected from the spark streams are studied separately by scanning electron microscope and X-ray diffractometer. Results show that the spark streams are the trajectory of the movement of carbon steel wear debris. The luminescence of the debris is provided by the heat released by the iron oxidation reaction. The carbon burst is caused by the explosion of carbon monoxide (CO) on the surface of carbon steel wear debris, and CO is produced by the reduction reaction of carbon and iron oxides. The main shape of the residues is flaky and spherical. There are some holes caused by carbon burst on the surface of the spherical residues. For the qualitative phase analysis of the residues, the main phase is composed of iron, ferrous oxide (FeO), ferric oxide (Fe2O3), and ferroferric oxide (Fe3O4). As the increase of the carbon content of steel, the quantity of iron phase is greatly reduced, and the quantity of Fe2O3 and Fe3O4 phase is gradually increased. Moreover, the amount and density of carbon burst is increased, and the number of the holes in the spherical residues are also increased.

THE IMPROVEMENT OF THE HIGH VOLTAGE TESTING METHOD

The high voltage spark testing method of protective dielectric coatings is applied in almost all manufacture areas and is governed by ISO, ASTM etc. However, all of it doesn’t pay proper attention to high voltage forming (DC or AC) and its polarity relative to electrode, influence of environment and electric field inhomogeneity. In that paper a detailed analysis of air gap breakdown forming processes was given. A dependence of electric field strength on an interelectrode gap length was given for homogeneous and highly inhomogeneous electric fields. It was shown a breakdown voltage of air gaps in highly inhomogeneous field is greatly less than in homogeneous field. Also, it is described the breakdown voltage of air gaps with positive polarity is less then with negative polarity. The possibility coatings testing with a minimum thickness up to 50 m while reducing the testing voltage without reducing the reliability of the results is shown.

A System Architecture for the Detection of Insider Attacks in Big Data Systems

In big data systems, the infrastructure is such that large amounts of data are hosted away from the users. In such a system information security is considered as a major challenge. From a customer perspective, one of the big risks in adopting big data systems is in trusting the provider who designs and owns the infrastructure from accessing user data. Yet there does not exist much in the literature on detection of insider attacks. In this work, we propose a new system architecture in which insider attacks can be detected by utilizing the replication of data on various nodes in the system. The proposed system uses a two-step attack detection algorithm and a secure communication protocol to analyze processes executing in the system. The first step involves the construction of control instruction sequences for each process in the system. The second step involves the matching of these instruction sequences among the replica nodes. Initial experiments on real-world hadoop and spark tests show that the proposed system needs to consider only 20 percent of the code to analyze a program and incurs 3.28 percent time overhead. The proposed security system can be implemented and built for any big data system due to its extrinsic workflow.

Spark testing to measure carbon content in carbon steels based on fractal box counting

Spark testing is an effective and inexpensive way to classify the steel materials in industrial practice. Especially, it could determine carbon content in a moment. However, this method has reliance upon the skill and experience of operator. Therefore, computer recognition of spark has been developed to determine carbon content for increasing reliability and efficiency. The numerable high-resolution images of sparks emitting at high speed are taken pictures by camera or mobile phone, then input the images into computer, and calculated the fractal dimension of spark based on fractal box counting method. Result shows that the fractal dimension has a good correlation with carbon content, and the similar natural logarithm function is obtained by a least squares fit through plots of carbon content against fractal dimension. Carbon content measurement error is about 0.06%. It means a convenient and accurate way to identify an unknown carbon steel may be achieved.

Электроискровой контроль сплошности защитных лакокрасочных покрытий

Электроискровой контроль сплошности защитных лакокрасочных покрытий

The in-process control of PVC sheath of a double core cable

In this work the possibility of the sheath hermiticity testing by measuring of the cable capacity per unit length variation during spark testing is considered. The research object is 2×0.75 HO3VVH2-F cable. According to the physical modelling it is proved that such defect of sheath as pinhole through the whole thickness of sheath can be registered for the test length 10 cm with test voltage frequencies 1kHz and 10kHz.

Methoden der Temperaturbestimmung von elektrischen Entladungen bei Öffnungs-Kontaktvorgängen in zündfähigen Gasen

Zusammenfassung Für elektrische Entladungen, die bei niedrigen Spannungen von 20–40 V und Strömen von 40–100 mA nach der Öffnung eines elektrischen Kontaktes in explosiven Atmosphären auftreten, wurden erste spektroskopische Untersuchungen hinsichtlich der dabei entstehenden Temperatur durchgeführt. Diese Metalldampf-Entladungen, die ähnlich dem „kurzen Bogen“ (short arc) sind, werden im international standardisierten Funkenprüfgerät gemäß IEC 60079-11 erzeugt, um die Eignung elektrischer Komponenten in explosionsgeschützten Bereichen zu beurteilen. Die Temperatur ist bei diesen komplexen Zündvorgängen, die im Funkenprüfgerät auftreten, ein Schlüsselparameter. Einerseits ist die Temperatur der Kontaktmaterialien für die Beurteilung der zwingend erforderlichen Vorprozesse vor der Hauptentladung relevant, andererseits kann die Wirkung der Entladung durch die Elektronen-, Ionen und Gastemperatur charakterisiert werden. Dieser Artikel beschreibt den aktuellen Stand zur Temperaturmessung dieser elektrischen Entladungen, einschließlich der Herausforderungen, die dem genaueren Verständnis dieser Entladungsvorgänge und des thermochemischen Zündprozesses dienen sollen. Für Entladungen mit 30 V und 100 mA unter den genannten Rahmenbedingungen wurden Anregungstemperaturen im Bereich von 3500–5000 K gemessen und berechnet.