Sustainability Issues in Electric Discharge Machining

Valaki, Janak B.; Rathod, Pravin P.; Sidpara, Ajay

doi:10.1007/978-3-030-03276-0_3

Cited by 10 publications

(3 citation statements)

References 38 publications

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“…But on the same side, addition of these powder dusts reduces the rate of the cooling at the end of machining. Besides these, hydrocarbon-based dielectrics (like kerosene) release some unsaturated carbon particles, fumes, toxic reagents, etc., which entertains an unhygienic breathing ambiance, causes skin problems, and is a serious concern for the operator's health [11]. Researchers claimed that the utility of vegetable oils as dielectrics can mitigate these difficulties because of having the following advantages: a. EDM machining with hydrocarbon medium often causes firing hazards because of the clotting of unsaturated hydrocarbons at the spark gap.…”

Section: Recent Trends and Sustainabilitymentioning

confidence: 99%

“…Studies claim that the hydrocarbon-based fossil fuels (like kerosene), which are globally treated as suitable dielectrics for the commercial and industrial purposes, are hazardous and unhygienic to the operators. The vegetable oils like jatropha, canola, sunflower, neem, and waste vegetable oils are experimentally tested as suitable substitutes of kerosene in some studies [11]. Before that, these oils are also experimentally certified as a suitable dielectric for high-voltaic transformers and capacitors.…”

Section: The Perception Of the Literature Reviewmentioning

confidence: 99%

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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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Section: Recent Trends and Sustainabilitymentioning

confidence: 99%

Section: The Perception Of the Literature Reviewmentioning

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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“…During the discharge, the micro-roughness that initiates the discharge evaporates from the surface of the workpiece, and the next discharge occurs at a different point with the highest strength of the electrical field, while the uniform distribution of discharges over the entire surface being treated provides a stable ED process [21][22][23][24]. However, the location of areas with the highest electrical field strength is also affected by contamination of the dielectric fluid in the IEG by electroconductive particles, which are produced during the EDM process [25][26][27][28]. The distribution of dispersed contaminants over the IEG volume is random and depends on a number of factors including the IEG dimensions [23,29,30], the applied voltage [30,31], the pulse frequency and duty cycle of the discharges [30][31][32][33][34], the workpiece and tool materials [33], the speed, at which the dielectric fluid (typically mineral oil) is pumped [30,35], the thickness of the workpiece being processed and the size of particles being removed from the IEG [35,36].…”

Section: Introductionmentioning

confidence: 99%

Physicomechanical Nature of Acoustic Emission Preceding Wire Breakage during Wire Electrical Discharge Machining (WEDM) of Advanced Cutting Tool Materials

Grigoriev

Pivkin

Kozochkin

et al. 2021

Metals

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The field of applied wire electrical discharge machining (WEDM) is rapidly expanding due to rapidly increasing demand for parts made of hard-to-machine materials. Hard alloys composed of WC, TiC and Co are advanced cutting materials widely used in industry due to the excellent combination of hardness and toughness, providing them obvious advantages over other cutting materials, such as cubic boron nitride, ceramics, diamond or high-speed steel. A rational choice of the WEDM modes is extremely important to ensure the dimensional quality of the manufactured cutting inserts, while roughness of the machined surface on the cutting edge is of great importance with regards to the application of wear-resistant coatings, which increases tool life. However, the stock control systems of CNC WEDM machines, which are based on assessment of electrical parameters such as amperage and voltage, are unable to timely detect conditions at which a threat of wire breakage appears and to prevent wire breakage by stopping the electrode feed and flushing out the interelectrode gap (IEG) when hard alloys with high heat resistance and low heat conductivity, such as WC, TiC and Co composites, are being machined, due to the inability to distinguish the working pulses and pulses that expend a part of their energy heating and removing electroerosion products contaminating the working zone. In this paper, the physicomechanical nature of the WEDM of hard alloy WC 88% + TiC 6% + Co 6% was investigated, and the possibility of using acoustic emission parameters for controlling WEDM stability and productivity were explored. Acoustic emission (AE) signals were recorded in octave bands with central frequencies of 1–3 and 10–20 kHz. It was found that at the initial moment, when the dielectric fluid is virtually free of contaminants, the amplitude of the high-frequency component of the VA signal has its highest value. However, as the contamination of the working zone by electroerosion products increases, the amplitude of the high-frequency component of the AE signal decreases while the low-frequency component increases in an octave of 1–3 kHz. By the time of the wire breakage, the amplitude of the high-frequency component in the octave of 10–20 kHz had reduced by more than 5-fold, the amplitude of the low-frequency component in the octave of 1–3 kHz had increased by more than 2-fold, and their ratio, coefficient Kf, decreased by 12-fold. To evaluate the efficiency of Kf as a diagnostic parameter, the quality of the surface being machined was investigated. The analysis of residual irregularities on the surface at the electrode breakage point showed the presence of deep cracks and craters typical of short-circuit machining. It was also found that the workpiece surface was full of deposits/sticks, whose chemical composition was identical to that of the wire material. The presence of the deposits evidenced heating and melting of the wire due to the increased concentration of contaminants causing short circuits. It was also shown that the wire breakage was accompanied by the “neck” formation, which indicated simultaneous impacts of the local heating of the wire material and tensile forces. Due to the elevated temperature, the mechanical properties the wire material are quickly declining, a “neck” is being formed, and, finally, the wire breaks. At the wire breakage point, sticks/deposits of the workpiece material and electroerosion products were clearly visible, which evidenced a partial loss of the pulses’ energy on heating the electroerosion products and electrodes. A further increase in the contamination level led to short circuits and subsequent breakage of the wire electrode. It was shown that in contrast to the conventional controlling scheme, which is based on the assessment of amperage and voltage only, the analysis of VA signals clearly indicates the risk of wire breakage due to contamination of the working zone, discharge localization and subsequent short circuits. The monotonic dependence of WEDM productivity on AE parameters provides the possibility of adaptive adjustment of the wire electrode feed rate to the highest WEDM productivity at a given contamination level. As the concentration of contaminants increases, the feed rate of the wire electrode should decrease until the critical value of the diagnostic parameter Kf, at which the feed stops and the IEG flushes out, is reached. The link between the AE signals and physicomechanical nature of the WEDM of advanced cutting materials with high heat resistance and low heat conductivity in different cutting modes clearly shows that the monitoring of AE signals can be used as a main or supplementary component of control systems for CNC WEDM machines.

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A Hybrid Multi-criteria Decision-Making Approach for Selection of Sustainable Dielectric Fluid for Electric Discharge Machining Process

Alam

Khan

Siddiquee

2021

Lecture Notes in Mechanical Engineering

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Sustainability Issues in Electric Discharge Machining

Cited by 10 publications

References 38 publications

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

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

Physicomechanical Nature of Acoustic Emission Preceding Wire Breakage during Wire Electrical Discharge Machining (WEDM) of Advanced Cutting Tool Materials

A Hybrid Multi-criteria Decision-Making Approach for Selection of Sustainable Dielectric Fluid for Electric Discharge Machining Process

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