Pulsed ultrasonic assisted electrical discharge machining for finishing operations

Goiogana, M.; Sarasua, Jon Ander; Ramos, J.M.; Echavarri, L.; Cascón, Itxaso

doi:10.1016/j.ijmachtools.2016.07.005

Cited by 27 publications

(10 citation statements)

References 25 publications

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“…Figure 12 shows the resultant MRR for the eight different electrode geometries. In these EDM trials, as previously explained, a shaped electrode simultaneously rotates and retracts, which promotes self-pumping of the dielectric fluid [26,31]. This evacuates debris along the helical paths generated between the moving shaped electrode and the machined hole (see Figure 3b) and, thus, induces self-flushing of the debris through the gap at the top surface.…”

Section: Resultsmentioning

confidence: 89%

“…Ultrasonic vibrations have been suggested as a way to improve the flushing of the EDM process, especially for difficult-to-cut materials [23] and high aspect ratio blind holes [24]. This technique has shown promising increases in MRR [13], a higher process efficiency [25] and significant improvements in the obtainable surface quality in EDM finishing operations [26]. Although ultrasonic assisted EDM processes are widely used in industry, further investigation is still needed to help understand the ultrasonic vibration-assisted EDM process, dominant variables, process modelling and optimization, especially its application to deep micro/conventional drilling [27].…”

Section: State-of-the-art Flushing Approachesmentioning

confidence: 99%

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Self-Flushing in EDM Drilling of Ti6Al4V Using Rotating Shaped Electrodes

Goiogana

Elkaseer

2019

Materials

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This article reports an experimental investigation of the efficacy of self-flushing in the Electrical Discharge Machining (EDM) process in terms of tool wear rate (TWR), hole taper angle and material removal rate (MRR). In addition to a plain cylindrical shape, electrodes of different cross sections (slotted cylindrical, sharp-cornered triangular, round-cornered triangular, sharp-cornered square, round-cornered square, sharp-cornered hexagonal and round-cornered hexagonal) were designed as a means of inducing debris egress and then fabricated in graphite. EDM drilling trials using the rotating shaped electrodes were carried out on a Ti6Al4V workpiece. The results revealed that, although a low TWR and minimum hole taper angle were achieved using a plain cylindrical electrode, the usage of rotating shaped electrodes provided self-flushing of the dielectric fluid during the EDM process, which led to an improvement in MRR compared to that achieved with a plain cylindrical electrode. Besides, in general, the electrodes with rounded corners are associated with a lower TWR, a lower hole taper angle and a higher MRR when compared to the electrodes with sharp corners. Considering these results, it was concluded that different process attributes, i.e., TWR, hole taper angle and MRR, are all greatly affected by the electrode shape, and thus, the proper selection of the electrode shape is a precondition to attain a specific response from the EDM process.

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Section: Resultsmentioning

confidence: 89%

Section: State-of-the-art Flushing Approachesmentioning

confidence: 99%

Self-Flushing in EDM Drilling of Ti6Al4V Using Rotating Shaped Electrodes

Goiogana

Elkaseer

2019

Materials

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“…2 The formation process of the discharge channel under the bubble breakdown mechanism The current density due to cathode electron emission can be expressed by the Fowler and Nordheim equation [7]. 2 exp…”

Section: Electric Field Strength Under Bubble Breakdown Mechanismmentioning

confidence: 99%

Analysis of Discharge Channel Characteristics Based on Three-Phase Flow Dielectric Characteristics in USV-MF Assisted WEDM-LS

Wang

Yang

Xiong

et al. 2021

Preprint

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In this paper, considering the effects of the characteristics of the three-phase flow dielectric in the discharge gap flow field on the discharge channels in the ultrasonic vibration and magnetic field assisted low speed WEDM, the model of discharge channel including discharge position and size of discharge channel is established and analyzed. Firstly, given working conditions of cutting workpiece with large thickness, a mechanism of bubble-particle bridging breakdown was proposed. Then a prediction model of the discharge point position in USV-MF assisted WEDM-LS under three-phase flow dielectric characteristics based on the breakdown mechanism was performed, and FEM software COMSOL was used to simulate and analyze this model. By comparing with the experimental results of discharge point position captured by high speed camera, the accuracy of the prediction results of discharge point position in USV-MF assisted WEDM-LS was verified, showing that this model can more accurately explain the dielectric breakdown in cutting workpiece with large thickness. Next, the model of radius of discharge channel including magnetic field intensity, electric field intensity, medium pressure and surface tension of discharge channel was established, and the influence of ultrasound and magnetic field on the size of discharge channel was analyzed theoretically. The radius of discharge channel in USV-MF assisted WEDM-LS was obtained by solving the partial differential equation in MATLAB. According to discharge point position and radius of the plasma discharge channel, surface morphology of workpiece was simulated by COMSOL. Finally, the experiment of photographing the discharge channel in USV-MF assisted WEDM-LS was carried out to verify the above model. It shows that the trend of the simulated results of discharge channel position is the same as that of the experimental results, and the error between the peak height value of the simulated surface morphology of workpiece and that of the experimental surface morphology of workpiece is within 6%.

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“…Surface roughness and mean depth of irregularity increase proportionally with supply current Cu Tool steel Li et al [9] concluded that the additive-mixed fluids possess better surface finishing for a specific value of spark gap and other physical conditions, but on the same side, it causes high concentric precipitation inside the spark gap. This comparative microscopic study was performed for both electrode materials in terms of carbonaceous layer formations Kerosene Cu and graphite Alloy steel Goiogana et al [21] concluded that pulse ultrasonic-assisted machining of tool steel with copper electrode improved the surface characteristics by reducing the roughness by 14-20%. Vibration was applied to mix the additives uniformly throughout the entire volume of dielectrics.…”

Section: Graphite Powder-mixed Dielectricsmentioning

confidence: 99%

Feasibility assessment of some alternative dielectric mediums for sustainable electrical discharge machining: a review work

Das

Paul

Doloi

2020

J Braz. Soc. Mech. Sci. Eng.

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Low removal rate, high power consumption, and dependency on conventional fuels (kerosene as a dielectric) are some premier issues that keep the sustainability index of EDM low, though it has huge acceptability and popularity mostly in aviation sectors and biomedical instrumentation to machine some extensively hard ferrous and nonferrous metal/metal alloys. Besides these, the thermal agitation inside the fusion/machining zone partially burns the dielectrics and tool-workpiece-metal, which evolve some oxides/monoxides. These evolved gases promote an unhygienic breathing atmosphere, which is very much harmful to the operator's health. Sometimes because of inadequate flushing pressure and velocity, carbon particles deposited inside the crater makes the spark unstable and releases carbon monoxide when the temperature exceeds its melting point. According to ISO 14000, every manufacturing process must be comprised of the sustainability criteria, which maintains a compromised balance between the economic, environmental, and social aspects, including the issue of the operator's health. But in real practices, it is very tough to maintain a stoichiometric balance between all these constraints. The article intensely focuses on the issue of emergence of gases during machining and tries to promote the utility of some alternative vegetable oil-based dielectrics, which are experimentally justified as a potent alternative of conventional kerosene. Apart from these, it includes some comparative talks on dielectric nature and their impacts on the responses and surface properties. Finally, this article highlights some compromise solutions which are probably capable of mitigating the hurdles to some extent, so that the sustainable machining can be encouraged in real sense.

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Pulsed ultrasonic assisted electrical discharge machining for finishing operations

Cited by 27 publications

References 25 publications

Self-Flushing in EDM Drilling of Ti6Al4V Using Rotating Shaped Electrodes

Self-Flushing in EDM Drilling of Ti6Al4V Using Rotating Shaped Electrodes

Analysis of Discharge Channel Characteristics Based on Three-Phase Flow Dielectric Characteristics in USV-MF Assisted WEDM-LS

Feasibility assessment of some alternative dielectric mediums for sustainable electrical discharge machining: a review work

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