Theoretical modeling of energy balance in electroerosion

Pérez, Rebeca; Rojas, H.; Wälder, Georg; Flükiger, R.

doi:10.1016/j.jmatprotec.2003.11.053

Cited by 30 publications

(5 citation statements)

References 8 publications

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“…Recent improvements in EDM machining speed, accuracy and roughness have been achieved mostly with improvements in robotics, automatization, process control, dielectric, flushing and generator design [2][3][4][5]. The other main research domains are the machining of non-conductive materials such as ceramics [6,7], micro-machining [8][9][10][11], characterization and improvement in the machined surface quality [12,13] and modelling of the EDM process [14][15][16]. But so far, few studies have been done on the discharge itself, which lies at the heart of the process.…”

Section: Introductionmentioning

confidence: 99%

Time- and spatially-resolved characterization of electrical discharge machining plasma

Descoeudres

Hollenstein

Wälder³

et al. 2008

Plasma Sources Sci. Technol.

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Plasma created during electrical discharge machining (EDM) is investigated with fast imaging and with time-and spatially-resolved optical emission spectroscopy. After the breakdown, the plasma develops very fast (< 50ns) and then remains stable. The plasma excites a broad volume around the electrode gap. Typical spectra show a strong H α and continuum radiation, with many lines emitted by impurities coming from electrodes materials. The plasma contamination from the electrodes is mostly concentrated in their vicinity. The electron density reaches 2·10 18 cm -3 at the beginning of the discharge. This extreme density causes merging of lines, strong Stark broadening and shift of the H α line. The density decreases afterwards rapidly with time. The electron temperature remains roughly constant around 0.7eV. The low temperature, the high density measured and other spectroscopic evidences prove that the EDM plasma is non-ideal (Γ ≅ 0.45).

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Section: Introductionmentioning

confidence: 99%

Time- and spatially-resolved characterization of electrical discharge machining plasma

Descoeudres

Hollenstein

Wälder³

et al. 2008

Plasma Sources Sci. Technol.

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show abstract

“…Recent EDM improvements in machining speed, accuracy and roughness have been achieved mostly with improvements in robotics, automatization, process control, dielectric, flushing and generator design [5,6]. The other main research domains are the machining of non-conductive materials such as ceramics [7,8], micro-machining [9][10][11], characterization and improvement in the machined surface quality [12,13] and modelling of the EDM process [14][15][16]. But so far, few studies have been done on the discharge itself, which lies at the heart of the process.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved imaging and spatially-resolved spectroscopy of electrical discharge machining plasma

Descoeudres¹,

Hollenstein²,

Wälder³

et al. 2005

J. Phys. D: Appl. Phys.

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The plasma created during electrical discharge machining is investigated with imaging and spatially-resolved optical emission spectroscopy. Analysis of the pre-breakdown duration shows that the breakdown is of stochastic nature. Due to the presence of gas bubbles created by electrolysis, the breakdown mechanism in water could be different from the one in oil. After the breakdown, the plasma develops very fast (<50 ns) and then remains stable. The plasma excites a broad volume around the electrode gap, between 50 and 400 µm in diameter depending on the discharge current. The Hα line is emitted from the whole plasma, since the hydrogen atoms originate from the dielectric. On the other hand, spatially-resolved spectroscopy shows that plasma contamination from the electrodes is concentrated in their vicinity. After the discharge, light is still emitted by incandescent metallic particles coming from erosion of the workpiece. Profiles between the electrodes of electron density and of electron temperature have been estimated from spatially-resolved emission spectra. The density is found to slightly increase towards the plasma centre, whereas the temperature is quite constant across the plasma (∼0.7 eV).

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“…The real effective fraction of discharge energy entering each electrode (tool or workpiece) depends on a number of factors, such as thermal properties, flushing conditions, gap distance, conductivity of dielectric, polarity, discharge current and pulse duration. 25–27 It is extremely difficult if not possible to define and identify a unique physical quantity fully reflecting the material properties and EDM conditions altogether to be used in assigning the energy share of each electrode.…”

Section: Methodsmentioning

confidence: 99%

Electro-thermal-based finite element simulation and experimental validation of material removal in static gap single-spark die-sinking electro-discharge machining process

Assarzadeh

Ghoreishi

2016

Proceedings of the Institution of Mechanical Engineers, Part B:

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Existing single spark models are subjected to too simplistic assumptions such as uniform or point heat source, constant plasma radius, invariable materials properties and constant surface temperature during discharge making them far from reality. In this study, more realistic assumptions including Gaussian type distribution of spark heat flux, temperature dependent materials properties, latent heat of melting and expanding plasma channel with pulse current and time have been made to establish a comprehensive modeling platform. The ABAQUS FEM software has been used to simulate the mechanism of crater formation due to a single discharge. The non-uniform thermal flux was programmed through the DFLUX subroutine. The simulation results show that the temperature of work piece decreases as the discharge time increases while the volume of melted and evaporated material increases. A specially designed single spark experimental set-up was developed in laboratory to carry out a few single spark tests for verification purposes. The obtained craters morphologies were examined by optical microscopy and scanning profilometer. It has been shown that the present approach outperforms other previously developed thermal models with respect to cavity outline and size possessing the maximum confirmation errors of 18.1% and 14.1% in predicting crater radius and depth, respectively. Parametric analysis reveals that the melting boundary moves onward by increasing discharge current, whereas it moves back prolonging discharge time. Finally, a closer proximity to experimental material removal rates than those predicted by analytical approach has been recognized which confirms its more precise generalization capabilities towards the real state EDM process.

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Theoretical modeling of energy balance in electroerosion

Cited by 30 publications

References 8 publications

Time- and spatially-resolved characterization of electrical discharge machining plasma

Time- and spatially-resolved characterization of electrical discharge machining plasma

Time-resolved imaging and spatially-resolved spectroscopy of electrical discharge machining plasma

Electro-thermal-based finite element simulation and experimental validation of material removal in static gap single-spark die-sinking electro-discharge machining process

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