Waste vegetable oil based biodiesel has been used as biodielectric fluid for sustainable EDM.

1. Investigating Feasibility Through Performance Analysis of Green
Dielectrics for Sustainable Electric Discharge Machining
Janak B. Valaki1,2
and Pravin P. Rathod3
1
School of Engineering, RK University, Rajkot, Gujarat, India
2
Mechanical Engineering Department, Government Engineering College, Bhavnagar, Gujarat, India
3
Mechanical Engineering Department, Government Engineering College, Bhuj, Kuttchh, Gujarat, India
This work represents a feasibility study for the newly proposed vegetable oil-based green dielectric fluids, biodielectric1 (BD1) and
biodielectric2 (BD2) for electric discharge machining (EDM). Comparative analyses for BD1, BD2, and kerosene have been studied to assess
the performance in terms of material removal rate (MRR), electrode wear rate (EWR), and relative wear ratio (RWR) for
P20 þ cold-worked plastic injection mold steel using electrolytic grade copper electrode. Current, gap voltage, pulse on time (Ton), and pulse
off time (Toff) have been chosen as input parameters, and one variable at a time approach has been used for designing experimental plan for
investigating the feasibility of the newly suggested fluids. The results obtained show that the performance of the newly suggested biodielec-
trics BD1 and BD2 is better than commercially used hydrocarbon-based dielectric, i.e., kerosene, for MRR and RWR. Analysis of variance
results indicated that current is the most influencing parameter for MRR and EWR, while Ton is the most significant parameter for RWR.
Under the influence of current, BD1 and BD2 produced 38% and 165% improvement in MRR, respectively. Moreover, BD1 and BD2
resulted 30% higher and 7% lower RWR, respectively, under the influence of Ton.
Keywords Biodielectrics; EDM; EWR; Manufacturing; MRR; RWR; Sustainability; Vegetable oil.
INTRODUCTION
Electric discharge machining (EDM) is the most
widely practiced nonconventional material removal pro-
cess and fourth amongst all material removal processes
after milling, turning, and grinding [1]. EDM process
employs high-frequency discrete electric sparks to cause
thermoelectric decomposition of the dielectric fluid,
which generates intense amount of heat in the order of
8000–12,000 K, resulting in a rapid melting and vapori-
zation of the work material [2]. Discrete and controlled
electric sparks generate dimensionally and geometrically
accurate profiles on materials of any hardness. Hence,
EDM is the preferable metal removal process for the
manufacture of tools, molds, and dies; surface texturing
of steel rolls; surface alloying; production of compo-
nents for aero engines, electronics, surgical industries;
and manufacture of metallic prosthesis [3, 4].
In EDM, dielectric fluid undergoes partial ionization
due to rapid rise and fall of the intense temperature
and pressure during short spark cycles. Researchers have
reported that dielectric fluids such as kerosene and min-
eral oil produce emissions like solid metallic particles,
tiny droplets of liquid dielectric, emitted gases, and
waste dielectric sludge that cause environment pollution
and adversely affect operator health and safety [4–9].
Leao and Pashby [4] have also reported that the dielec-
tric fluid plays important functions regarding pro-
ductivity, costs, and quality of the machined parts.
The electrical, mechanical, and thermal properties of
the dielectric fluid influence the processes of discharge
initiation, plasma expansion, material erosion, debris
removal, and discharge channel reconditioning in
EDM [10]. Evertz et al. [11] have investigated that type
of dielectric fluid and its supply mode are significant to
have stable, efficient, and operator-friendly material
removal process. Valaki et al. [12] have categorized the
functions performed by dielectric fluids in EDM process
as primary and secondary functions. These functions act
as a basis for selection of desired properties of dielectric
fluids and compare various dielectrics.
Researchers have experimented using alternate dielectrics
with a view to improve process performance, better opera-
tor’s safety, minimize fire hazards, and lessen environmental
impact. Various types of fluids, such as water [13, 14] and
water-based solutions [15, 16], chemical compounds, and
mixed water-based dielectrics [17], have been proposed
and experimented. Leao and Pashby [4] reported that water-
and gas-based dielectrics need further investigations to make
it commercially viable alternates as dielectric. It has also
been reported that even though EDM with plain water
resulted in better performance under special conditions,
hydrocarbon oil-based dielectrics are superior in a broader
range of machining conditions. Zhang et al. [9] and Liu
et al. [18] have proposed and reported that water-in-oil
emulsions are superior to hydrocarbon oils when working
with high energy levels. Oil-in-water emulsions have been
Received March 17, 2015; Accepted June 9, 2015
Address correspondence to Janak B. Valaki, Mechanical Engineer-
ing Department, Government Engineering College, Bhavnagar,
Gujarat 364001, India; E-mail: janakvalaki@gmail.com
Color versions of one or more of the figures in the article can be
found online at www.tandfonline.com/lmmp.
Materials and Manufacturing Processes, 0: 1–9, 2016
Copyright # Taylor & Francis Group, LLC
ISSN: 1042-6914 print=1532-2475 online
DOI: 10.1080/10426914.2015.1070430
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