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
and select the best cutting parameters in WEDM process. Scott et al [5] used a factorial design requiring a
number of experiments to determine the most favourable combination of the WEDM parameters. They found
that the discharge current, pulse duration and pulse frequency are the significant control factors affecting the
MRR and SF, while the wire speed, wire tension and dielectric flow rate have the least effect. Liao et al. [6]
proposed an approach of determining the parameter settings based on the Taguchi quality design method and the
analysis of variance. The results showed that the MRR and SF are easily influenced by the table feed rate and
pulse on-time, which can also be used to control the discharging frequency for the prevention of wire breakage.
Manna and Bhattacharyya [7] found open gap voltage and pulse on period as the most significant machining
parameters for controlling the metal removal rate using Taguchi method-based analysis for WEDM on
Al/SiCMMC..
In 2005 El-Taweel et al. [8] revealed that WEDM allowed success in the production of newer materials,
especially for the aerospace and medical industries. Using WEDM technology, complicated cuts can be made
through difficult-to-machine electrically conductive components. The high degree of the obtainable accuracy and
the fine surface quality make WEDM valuable. In addition, Luo [9] investigated the EDM with a small erosion
area by examining effects of spark off time. Takahata and Gianchandani [10] studied the use of electrode arrays
for batch EDM generation of micro-features. Scott et al. [11] used a factorial design requiring a number of
experiments to determine the most favourable combination of the WEDM parameters. They found that the
discharge current, pulse duration and pulse frequency are the significant control factors affecting the MRR and
SF, while the wire speed, wire tension and dielectric flow rate have the least. I. Cabanes [12] found that the main
challenges in WEDM is avoiding wire breakage and unstable situations as both phenomena reduce process
performance and can cause low quality components. They develop a real time control strategy for increasing the
performance of WEDM process. Sharma et al. [13] optimized the process parameters of WEDM process
parameters for cutting rate. It increases with increase in pulse on time and peak current and decreases with
increase in pulse off time and servo voltage.
Till now there is no work carried out using HSLA as a die material. As it is hard, wear resistant corrosion
resistant, so HSLA is choose as a work-piece for experimentation. To evaluate the effects of machining
parameters on performance characteristics, and to identify the optimal performance characteristics under the best
settings of machining parameters, a specially designed experimental procedure called Response Surface
Methodology has been used.
2. PROCESS PARAMETERS OF WEDM
Based on the findings of the many researchers, process parameters for WEDM process based on the quality of
the machining are grouped in various categories. The process parameters, their designated symbols and range are
given in Table 1.
Table 1: Process Parameters, Symbols and their Ranges
Process Parameters Symbol Range (machine units)
Pulse on Time T on (µs)
111-117
Pulse off time T off (µs)
36-50
Spark gap voltage SV (V) 30-50
Peak Current IP (A) 120-180
Wire Tension WT (grams) 6-10
The range of all the process parameters is selected for the present study based on the results obtained from
preliminary experiments.
2.1 EXPERIMENTAL METHODOLOGY
The experimental studies were performed using a Electronic Sprint cut 734 WED machine tool. A brass Wire
with a diameter of 250 µm was used as an electrode to erode a work piece of HSLA Steel (flat plate). The gap
between work piece and wire was flooded with a moving dielectric fluid (distilled water). Machining
Experiments for determining the optimal machining parameters for optimizing response characteristics were
carried out by using distilled water as a dielectric fluid. During the experiments the cutting of the work piece was
done. The size of work-piece is 5mm×5mm×18mm. The work material, electrode and the other machining
condition are as follows:
1. Work piece height : 18 mm
2. Conductivity : 20 mho
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