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
The effect of different applied voltage on surface roughness for keeping other parameter constant is shown in
Fig. 4. The applied voltage considered for the experiments were 45V, 50V and 55V. R a increases with increase
in applied voltage because at higher voltage, higher energy discharge takes place during sparking, which causes a
deeper crater on the machined surface.
15.0
14.5
14.0
0.25mm Dia.
13.5
R a
(µm)
13.0
12.5
12.0
11.5
11.0
40 45 50 55 60
Voltage (V)
Fig. 4 Effect of applied voltage on the R a for the 0.25mm brass wire diameter
4.2. Influence of pulse on-time on MRR and R
The MRR increases with increase in different pulse on-time for keeping other parameter constant as shown in
Fig. 5. It is clear from the graph that pulse on-time affects the material removal rate, the MRR increases steadily
with the increase in level of pulse on-time. The material removal rate is thus a function of the pulse on-time. The
value of MRR is the lowest with the pulse on-time at 0.20ms and the highest with the pulse on-time at 0.40ms.
An increase in the pulse on-time implies that more time has been allowed to machine the workpiece for a fixed
duration, because only during pulse on-time material removal takes place. In alternate way, with an increase of
pulse on-time, average current density increases which leads to the increase of dissolution efficiency. Dissolution
efficiency increases rapidly in the range of 0.20ms to 0.40ms causing a rapid increment of MRR in this zone.
a
1.20
1.18
0.25mm wire Dia.
1.16
MRR (mm 3 /min)
1.14
1.12
1.10
1.08
1.06
1.04
0.20 0.25 0.30 0.35 0.40
T ON
(ms)
Fig. 5 Effect of pulse on-time on the MRR for the 0.25mm brass wire diameter
The experiments have been carried out with varying pulse on-time at 0.25mm brass wire diameter. Fig. 6
illustrates that surface roughness increases with increase in pulse on-time. R a increases with increase in pulse on-
575