Experimental Investigation of MRR, Surface Roughness and Overcut of Aisi 304 Stainless Steel in EDM

EDM has become an important
and cost-effective method of machining
extremely tough and brittle electrically
conductive materials. It is widely used in the
process of making moulds and dies and
sections of complex geometry and intricate
shapes. The workpiece material selected in
this experiment is AISI 304 Stainless steel
taking into account its wide usage in
industrial applications. In today’s world 304
stainless steel contributes to almost half of
the world’s production and consumption for
industrial purposes. The input variable
parameters are current, pulse on time and
duty cycle. Taguchi method is applied to
create an L27 orthogonal array of input
variables using the Design of Experiments
(DOE). The effect of the variable parameters
mentioned above upon machining
characteristics such as Material Removal
Rate (MRR), Surface Roughness (SR) and
Overcut (OC) is studied and investigated.
The tool material is copper.
The results obtained showed that current
was the most significant parameter followed
by pulse on time and the least significant
was the duty cycle for the entire three
responses namely Material removal rate,
Surface roughness and overcut. With the
increase in current and duty cycle MRR
increased but for pulse on time it increased
only up to 100 μs and then started to
decrease. SR increased significantly with the
increase in current; for pulse on time it
increased up to 100 μs and after that there
was no significant increase; and in case of
duty cycle SR increased up to 70% and then
started to decrease. OC increased with the
increase in current and pulse on time but in
different fashion and in case of duty cycle,
OC increased up to 70% and then started
decreasing.