comparative study for mrr on die-sinking edm using electrode ... - ijater

International Journal of Advanced Technology & Engineering Research (IJATER)
in only one direction, resulting in properties or “grain” similar
to wood, that varied relative to the direction of pressing.
As an outgrowth of the space program, methods were developed
to isostatically press graphite such that its properties
became “isotropic”, that is the same in all directions. All
high quality, high per<strong>for</strong>mance graphites are now manufactured
this way. After compacting, the “green” compacted
material undergoes a series of thermal treatments that convert
the Carbon to graphite. Graphite has certain properties
quite different than wrought metal based electrode materials:
• Graphite has an extremely high melting point. Actually,
graphite does not melt at all, but sublimes directly from a
solid to a gas (just as the Carbon Dioxide in dry ice) at a
temperature thousands of degrees higher than the melting
point of Copper. This resistance to temperature makes graphite
an ideal electrode material.
• Graphite has significantly lower mechanical strength properties
than metallic electrode materials. It is neither as hard,
as strong, nor as stiff as metallic electrode materials. However,
since the EDM process is one of relatively low macro
mechanical <strong>for</strong>ces, these property differences are not often
significant. Due to the significant differences between metallic
electrodes and graphite, there are certain properties,
unique to graphite that are commonly specified and controlled.
Fig. 1 Die-Sinker EDM Set-up
1.3 Characteristics of die-Sinker
EDM
The characteristics necessary <strong>for</strong> die-sinker EDM are given
below in the table
Table 1 Process Parameters of Die-Sinker EDM Process
Mechanism of Processes Controlled erosion (melting
Spark gap
Spark frequency
Peak voltage across the gap
Metal removal rate (max.)
Specific power consumption
Dielectric fluid
Tool material
Machine-able materials
Shapes that can be produced
Limitations
and evaporation)
0.010 – 0.500 mm
200 – 500 KHz
30 – 250 V
5000 mm3/min.
2 – 10 W/mm3/min.
EDM oil, Kerosene liquid,
Silicon oil, Deionised water
etc.
Copper, Brass, Graphite, Ag-
W alloy, Cu-W alloy
All conducting metals and
alloys
Micro holes, Narrow slots
High energy consumption,
can’t machined nonconducting
materials
2. Literature Review
In this paper few selected research paper related to Diesinker
EDM with effect of metal MRR, surface roughness
(SR), workpiece material
2.1 Workpiece and tool material-
Dhar and Purohit evaluates the effect of current (c), pulseon
time (p) and air gap voltage (v) on MRR, TWR, ROC of
EDM with Al–4Cu–6Si alloy–10 wt. % SiCP composites.
This experiment can be using the PS LEADER ZNC EDM
machine and a cylindrical brass electrode of 30 mm diameter.
And three factors, three levels full factorial design was
using and analyzing the results. A second order, non-linear
mathematical model has been developed <strong>for</strong> establishing the
relationship among machining parameters. The significant of
the models were checked using technique ANOVA and finding
the MRR, TWR and ROC increase significant in a nonlinear
fashion with increase in current.
Karthikeyan et .al has presented the mathematical molding
of EDM with aluminum-silicon carbide particulate composites.
Mathematical equation is Y=f(V, I, T). And the effect
of MRR, TWR, SR with Process parameters taken in to
consideration were the current (I), the pulse duration (T) and
the percent volume fraction of SiC (25 μ size). A three level
full factorial design was choosing. Finally the significant of
the models were checked using the ANOVA. The MRR was
found to decrease with an increase in the percent volume of
SiC, whereas the TWR and the surface roughness increase
with an increase in the volume of Sic.
B.Mohan and Satyanarayana evolution the of effect of the
EDM Current, electrode marital polarity, pulse duration and
rotation of electrode on metal removal rate, TWR, and SR,
and the EDM of Al-Sic with 20-25 vol. % SiC, Polarity of
the electrode and volume present of SiC, the MRR increased
with increased in discharge current and specific current it
decreased with increasing in pulse duration. Increasing the
ISSN NO: 2250-3536 VOLUME 2, ISSUE 2, MAY 2012 171