OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
A DETAILED REVIEW OF THE CURRENT RESEARCH TRENDS IN
ELECTRICAL DISCHARGE MACHINING (EDM)
Sumit Ganguly
Assistant Professor, Department of Mechanical Engineering,Lingayas University, Faridabad, Nachauli, Jasana, Old
Faridabad Road, Faridabad – 121002, Haryana, India; Email: sumitgang@rediffmail.com ,Mobile Phone No:
9899677962, 9211891433
Abstract - Electrical discharge machining (EDM) is a non-traditional concept of machining
which has been widely used to produce dies and molds. It is also used for finishing parts for
aerospace and automotive industry and surgical components Electrical discharge machining
(EDM) is one of the earliest non-traditional machining processes. EDM process is based on
thermoelectric energy between the work piece and an electrode. A pulse discharge occurs in a
small gap between the work piece and the electrode and removes the unwanted material from
the parent metal through melting and vaporising. The electrode and the work piece must have
electrical conductivity in order to generate the spark.
The detailed study presented in this paper is on current EDM research trends carried out by
researchers on machining techniques viz. sinker EDM machining, dry EDM machining, wire
EDM, EDM for small hole drilling and EDM in water and modeling techniques in predicting
EDM performances. The areas are selected because of the novel techniques employed, the
environmental aspect and effort towards validating and predicting EDM performance. Each
topic will present the activities carried out by the researchers and the development of the area
that brings it to the current trends.
Keywords— sinker EDM, dry EDM machining, wire EDM, EDM in water, modeling techniques
1. Introduction
Electrical Discharge Machining (EDM) process involved removal of material by erosion. Series
of persistent electrical discharges emerge between the tool and the work piece in dielectric fluid
and remove the unwanted material. Metal erosion by spark discharges was first observed by Sir
Joseph Priestly as early as 1768. In 1943 two Russians B.R. and N.I Lazarenko discovered that
precision machining can be achieved by EDM. Since then, exploration were done globally and
locally to expand EDM potentials. It is an alternative machining method which is not defeated
by the mechanical strength of materials. With the emerging of harder, tougher and stronger
materials in manufacturing together with the needs of ultra-precision machining, EDM has been
one of the important methods in machining. Basic EDM process consists of electrode, work
piece materials, dielectric and the range of pulse rate, current and voltage. The functions of the
dielectric are: transportation of removal particles, to increase the energy density in plasma
channel, recondition of the dielectric strength and cooling of the electrode. Dielectric fluid is
pumped through the arc gap to flush away the eroded particles between the work piece and the
electrode. Most common dielectric fluids are mineral oil, kerosene, paraffin, distilled water and
deionised water. Recent trends involve the use of clear and low viscosity fluids to make cleaning
easier. After cycles of usage, dielectric performance will reduce and must be replaced. Hence
this situation draws interest in investigating the consumption of dielectric in EDM process.
Ideally, EDM can be seen as a series of breakdown and restoration of the liquid dielectric inbetween
the electrodes. However, caution should be exerted in considering such a statement
because it is an idealized model of the process, introduced to describe the fundamental ideas
underlying the process. Yet, any practical application involves many aspects that may also need
to be considered. For instance, the removal of the debris from the inter-electrode volume is
likely to be always partial. Thus the electrical proprieties of the dielectric in the inter-electrodes
volume can be different from their nominal values and can even vary with time. The interelectrode
distance, often also referred to as spark-gap, is the end result of the control algorithms
of the specific machine used. The control of such a distance appears logically to be central to this
process. Also, not all of the current between the dielectric is of the ideal type described above:
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