Spark Erosion Technique Research Articles

Artificial neural network-based prediction assessment of wire electric discharge machining parameters for smart manufacturing

Abstract Artificial intelligence (AI), robotics, cybersecurity, the Industrial Internet of Things, and blockchain are some of the technologies and solutions that are combined to produce “smart manufacturing,” which is used to optimize manufacturing processes by creating and/or accepting data. In manufacturing, spark erosion technique such as wire electric discharge machining (WEDM) is a process that machines different hard-to-cut alloys. It is regarded as the solution for cutting intricate parts and materials that are resistant to conventional machining techniques or are required by design. In the present study, holes of different radii, i.e. 1, 3, and 5 mm, have been cut on Nickelvac-HX. Tapering in WEDM is a delicate process to avoid disadvantages such as wire break, wire bend, wire friction, guide wear, and insufficient flushing. Taper angles viz. 0°, 15°, and 30° were obtained from a unique fixture to get holes at different angles. The study also shows the influence of taper angles on the part geometry and area of the holes. Next, the artificial neural network (ANN) technique is implemented for the parametric result prediction. The findings were in good agreement with the experimental data, supporting the viability of the ANN approach for the evaluation of the manufacturing process. The findings in this research provide as a reference to the potential of AI-based assessment in smart manufacturing processes and as a design tool in many manufacturing-related fields.

Особенности сферических электроэрозионных порошков сплавов Mo и Nb

Сharacteristics of spherical powders of (Mo,Nb) and (Nb,Mo) alloys prepared by spark erosion technique are described. Two regimes (U = 24 V, I = 10 A and U = 24 V, I = 20 A in distilled water) were chosen for powder preparation. The pyrolysis of dielectric liquid during spark erosion leads to the formation of stable oxides NbO and NbO2 as thin crusts and spherical inclusions from 10 nm to 10 µm in powder particles. The largest deviations from electrode compositions (from 3 to 7 wt.% Nb) are inherent to Mo alloys with 9 and 10 wt.% of Nb. The number of NbO and to a lesser extent NbO2 inclusions in spherical powder increase with increasing of Nb content in alloy, but only in series of (Mo,Nb) samples. Such regularity is not observed for (Nb,Mo) series. Decrease of current value results the change of granulometric compositions of spherical powders. The main fraction of powders at I = 20 A is 40-80 µm and I = 10 A is 20-50 µm.

A study on the influence of WEDM parameters on surface roughness, kerf width, and corrosion behavior of AZ31B Mg alloy

Wire electric discharge machining (WEDM) is a nontraditional machining process where the material is removed by the spark erosion technique. This technique is used to machine AZ31B, a biodegradable Magnesium alloy. In the present work impact of WEDM input parameters, namely pulse on time (Ton), pulse off time (Toff), servo voltage (SV), and wire feed (WF) on response characteristics is studied. The response characteristics considered are kerf width (KW), surface roughness (SR), and corrosion rate (CR). L9 orthogonal array by Taguchi’s is employed as the design of experimentation. Taguchi’s analysis implied that TON is the most influencing input parameter on the response characteristics. At a relatively lower TON setting (105 µs), comparatively lesser kerf width (335.894 µm), lower surface roughness (3.069 µm), and lower corrosion rate (0.95 mm/year) are exhibited by the machined specimens. From the main effects plots using signal-to-noise ratios, it is understood that the values of response characteristics increased with an increase in TON value. It is due to the increase in discharge at the more pulse on time duration. It is also understood that a surface with relatively better surface finish exhibited better corrosion resistance. With the help of regression equations, the relation between response characteristics and input parameters is built.

Experimental investigation of Machining of stellite alloy

In recent days, the applications of advanced alloys in manufacturing industries have been increased due its superior substance properties. Stellite alloy comes under the category of cobalt-chromium super alloys. In this paper the machinability performance of stellite using different unconventional machining process such as spark erosion (SE) and laser beam (LB) technique were discussed. The fine holes were produced on the surface of the stellite 1 alloy. The comparisons of rate of material removal (RMR) were analyzed using different input constrains. The interaction and contribution of process factor on material removal rate were determined. Finally, it was concluded that laser machining was provided high metal removal than spark erosion process. More than 25% of metal removal was achieved through laser machining process.

Optimization and Prediction of Machining Responses Using Response Surface Methodology and Adaptive Neural Network by Wire Electric Discharge Machining of Alloy-X

Wire electric discharge machining non-contact machining process based on spark erosion technique. It can machine difficult-to-cut materials with excellent precision. In this paper Alloy-X, a nickel-based superalloy was machined at different machining parameters. Input parameters like pulse on time, pulse off time, servo voltage and wire feed were employed for the machining. Response parameters like cutting speed and surface roughness were analyzed from the L25 orthogonal experiments. It was noted that the pulse on time and servo voltage were the most influential parameters. Both cutting speed and surface roughness increased on increase in pulse on time and decrease in servo voltage. Grey relation analysis was performed to get the optimal parametric setting. Response surface method and artificial neural network predictors were used in the prediction of cutting speed and surface roughness. It was found that among the two predictors artificial neural network was accurate than response surface method.

Electrochemical behavior of machined Ni55Ti45 alloy by Wire Electro Spark Erosion (WESE) technique

This study aims to understand the electrochemical behavior of the Wire Electro Spark Eroded Ni55Ti45 alloy. The WESE machining process had been performed by considering the spark on time, spark off time and applied voltage as process parameters. The response chosen for the valuation of the machining process is surface quality. The surface properties of machined specimen were studied through the Scanning Electron Microscopy (SEM) and surface roughness meter. Then the maximum and minimum surface roughness samples were exposed to the electrochemical corrosion studies considering NaCl as the electrolyte medium. The outcomes of the corrosion result are projected in form of corrosion rate found from the TAFEL plot. Further, the surface of corroded specimens was studied using the imaging techniques.

Development of a capacitive sensing technology for the measurement of perpendicularity in the narrow, deep slot-walls of micromolds

This paper presents a novel approach to narrow, deep slot-wall measurement in micromolds. A tabletop hybrid measurement-center combining micro spark erosion and automatic optical inspection technique (AOI) with Capacitive Sensing (CS) technology is developed for measuring the perpendicularity of slot-walls in the very narrow and deep slots of precision molds. A microprobe is machined in-situ using micro wire spark erosion while the AOI system acquires images to help fast position the completed microprobe precisely over the narrow slot to be measured. Capacitive sensing with a high-frequency, low-voltage electric signal is employed between the probe and slot-wall to precisely sense the perpendicularity of the wall. A four-step probe feed approach is utilized to improve measurement accuracy. The technical feasibility of capacitive sensing technology is experimentally confirmed.

Implant-supported titanium framework: photoelastic analysis before and after spark erosion procedure

Aim: This study used a photoelastic analysis to evaluate the passive fit of titanium cast laser welding frameworks before and after spark erosion procedure. Methods: A stainless steel cast was used in order to reproduce a human mandible. Five Multi-Unit abutment analogs were attached to this cast and 6 frameworks were produced in commercial pure titanium. The cast was molded and a photoelastic matrix was produced incorporating 5 dental implants with Multi-Unit abutments. All samples were subjected to a laser welding. The precision of adjustments within a range of 0.5 μm was evaluated under microscope observation. The best fitted framework was selected and subjected to a photoelastic analysis (Group I). The tightening of the screws was in 3 predetermined sequences (1,2,3,4,5/ 5,4,3,2,1/ 3,2,4,1,5). Then the same framework was subjected to a refinement by spark erosion technique (Group II) and evaluated by photoelastic analysis. Results: The sequence (3,2,4,1,5) achieved better results in both groups. A larger number of fringes were observed around the median implants in all sequences in both groups. Conclusions : The titanium cast laser welded frameworks processes associated with spark erosion procedure improves significantly the marginal framework adaptation and is effective for its passive fit.

Low-loss terahertz transmission through curved metallic slit waveguides fabricated by spark erosion

Propagation characteristics of broadband terahertz pulses in straight and curved metallic slit (MS) waveguides fabricated using spark erosion technique are investigated in the 0.1–1.0THz frequency range. As the straight MS waveguides, the curved MS waveguides, having radii of curvature as small as 5mm, exhibit comparably undistorted terahertz pulse transmission. The observed bending loss is unexpectedly low, giving rise to the assumption that surface oxidization and roughness generated by the fabrication process are responsible for the improved signal routing behavior. Experimental results are compared with theoretical data from numerical field simulations incorporating the influence of a thin dielectric cover layer.

A novel spark erosion technique for the fabrication of high aspect ratio micro-grooves

Micro groove is an important geometrical feature of components used in microsystem technology (MST). Straight micro grooves are the predominant features in microsystem components such as micro heat exchangers and diffraction gratings. Micro Electrical Discharge Machining (micro EDM) is a complementary microfabrication technique adopted from the conventional EDM machining process for the purpose of micro machining. Using micro EDM it is possible to machine all electrically conductive materials irrespective of their hardness. High aspect ratio microgroove machining for length as high as 20 mm is a formidable task for the conventional micro EDM. In the present work, a novel spark erosion technique has been described wherein a graphite foil has been used instead of the traditional pin shaped tool electrode, for the purpose of making straight grooves. In a single setup microgroove of 20 mm length and an aspect ratio of about 2.3 has been achieved on hardened tool steel by this technique. This process is further refined by using the gravitational effect for the effective debris removal, which has improved the aspect ratio to about 8.

Hollow and solid spherical magnetostrictive particulate composites

Nickel microspheres were produced by the spark erosion technique under both liquid nitrogen and water conditions. Density measurements and Scanning electron microscope analysis revealed that a significant portion of the Ni particles produced under the liquid nitrogen conditions are hollow spheres with a density of 6.67(4)g∕cm3 while the particles produced in water are primarily solid spheres with a density of 8.40(1)g∕cm3, close to the bulk nickel value of 8.90g∕cm3. Nickel∕polymer composites incorporating the hollow and solid nickel microspheres were manufactured with volume fractions of 25% and 36%, respectively. The hollow and solid nickel composites exhibited saturation magnetostrictions of −24 and −28ppm, respectively. In addition, small quantities of Terfenol-D (Tb0.3Dy0.7Fe2) were spark eroded under liquid argon conditions with ∼10% by volume of the spark eroded particles being solid microspheres. Calculations indicate that aligned composites that incorporate these Terfenol-D microspheres could reach a strain value of 2000ppm.

Growth and characterization of La 2−xSr xCuO 4-δ bulk single crystals

Single crystals of La 2-xSr xCuO 4-δ ( x=0, x=0.10, x= 0.15 and x=0.20) were grown in oxygen atmosphere using the Travelling Solvent Floating Zone (TSFZ) method. The as grown rods were analyzed by Electron Probe Micro Analysis (EPMA), x-ray diffraction and neutron diffraction techniques. EPMA results showed the correct phase with homogeneous strontium distribution. Neutron diffraction revealed single crystalline grains with sizes up to 200 mm 3. The onset of the superconducting transition temperatures of crystals with composition La 1.90Sr 0.10CuO 4-δ and La 1.85Sr 0.15CuO 4-δ determined from ac susceptibility were 25K and 35K with 90% of the transition within 3K. A full report is given on preparation method of the starting materials and growth parameters. Additionally, single crystals of La 2NiO 4, Nd 2CuO 4 and Sm 2CuO 4 were grown. Diamond saw and spark-erosion were used to separate the crystals from as grown boules. Experience with spark-erosion technique to shape samples for physical measurements is reported.

Methanol synthesis by amorphous copper-based catalysts prepared by spark-erosion

Amorphous metallic powders, with compositions: Cu70Zr30, Cu70Zn30 and Cu70Zn15Al15, were prepared by a spark-erosion technique, using kerosene as the dielectric. Two of them, viz. Cu70Zr30 and Cu70Zn15Al15, were obtained in a fully amorphous state, whereas some crystalline copper was detected in the Cu70Zn30 sample. Specific surface areas were measured for these spark-eroded powders and were several orders of magnitude higher than those of traditional amorphous ribbons prepared by melt-spinning. SEM analysis indicated that the powders were in fact very small, spherical, metallic particles ( < 1.5 μ diameter), highly dispersed in a carbon matrix of large surface area. These powders were found to be active for the synthesis of methanol from both CO + H2 and CO2 + H2. The steady-state rate of methanol production from CO2 + H2 was greater than that measured from CO + H2. This indicates that methanol is produced preferentially from carbon dioxide. Steady-state selectivities to methanol of over 99 mol-% were observed for CO2 + H2 , whereas only 75–90 mol-% of methanol was formed from CO + H2 as reactants.

Spark erosion of high accuracy metal spheres (d>or approximately=6 mm)

The spark erosion technique developed by Muirhead et al and capable of producing metal spheres of diameter 4000 mu m accurate to +or-0.5 mu m (0.013%), has been extended to the preparation of a larger sphere of the more reactive rare earth metal Dy with increased relative accuracy: diameter d=6965.8+or-0.7 mu m (0.010%). A test brass sample of diameter d=5966.9+or-0.5 mu m (0.009%) was also produced.

Preparation and properties of noninteracting spherical magnetic particles

A method is described for preparing samples of noninteracting spherical magnetic particles with a narrow size distribution. The particles are produced using the spark erosion technique. Any conductive material, including alloys, can easily be used to produce particles with this method; electrodes of nickel are used in this study. The particles are filtered through Nuclepore filters which are suspended in an ultrasonic bath. Particles which have diameters the same as the filter pore size become trapped in the pores, forming a sample of narrowly distributed, isolated spherical particles. SEM micrographs show the distribution of particle diameters is quite narrow, with a typical standard deviation of less than 10%. Magnetization curves of nickel particles trapped in 3 μm filters have been studied. Fits of log-normal distributions of anisotropy fields to the magnetization curves in the approach to saturation have determined the mean magnetocrystalline anisotropy fields to be of the order of 2 kOe. These values are much higher than what is expected for magnetically soft spherical particles, and indicate the particles may be under some form of stress as a result of the production method.

Fracture toughness of WC-Co alloys precracked by spark erosion technique.

Fracture toughness of WC-Co alloys precracked by spark erosion technique.

Vaporization of atherosclerotic plaques by spark erosion

An alternative to the laser irradiation of atherosclerotic lesions has been developed. A pulsed electrocardiogram R wave-triggered electrical spark erosion technique is described. Controlled vaporization of fibrous and lipid plaques with minimal thermal side effects was achieved and documented histologically in vitro from 30 atherosclerotic segments of six human aortic autopsy specimens. Craters with a constant area and a depth that varied according to the duration of application were produced. The method was confirmed to be electrically safe during preliminary in vivo trials in the coronary arteries of seven anesthetized pigs. The main advantages of this technique are that it is simpler to execute than laser irradiation and potentially more controllable.

Magnetothermal Characteristics of Rapidly-Quenched Fe–Si Magnetic Powder

For this investigation, the Si–Fe powder containing 1% to 6.5% silicon was prepared by the spark erosion technique, which has a higher quenching rate than splat-cooling. The roughly spherical powder particles of 6.5% Si–Fe ranged from 0.1 µm to 30 µm in diameter, and the rapidly quenched magnetic powder was composed of both noncrystalline and crystalline portions. The fractional volume of the noncrystalline portion increased as the particle size decreased. The procedure for preparing the powder, its magnetothermal characteristics and its crystallization behaviour are discussed.

Amorphous Fe72Cr8P13C7 Powder with High Corrosion Resistance

Abstract Amorphous Fe72Cr8P13C7 powder has been prepared by the spark erosion technique and its corrosion behavior investigated potentiodynamically. It is concluded that the powder prepared this way possesses a relatively high corrosion resistance, as does amorphous Fe72Cr8P13C7 ribbon prepared by rapid quenching.

Spark erosion of single-crystal metal spheres

A spark erosion technique capable of producing accurate metal spheres, and described by Muirhead et al. (see ibid., vol.9, p.872 (1976)) is applied to a single-crystal specimen of gadolinium-yttrium alloy. X-ray back-reflection Laue photography is used to show that the method does not damage the crystallographic structure.