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of motion of workpiece’ and ‘Y-infeed after one revolution’ improve the geometrical
accuracy because the synchronized rotary motion control is controlling the spark gap
and maintains it constant. Spark gap managed by spark gap voltage up to 30(µm) is used
for the precise discharge amount of energy. Experiment plots shows that MRR changes
the direct proportion to the ‘Y-infeed after one revolution’ whereas the change of SR is
sudden.

The experiment-3 was performed to investigate performance parameters using
developed synchronized rotary motion control. From the outcomes obtained based on
ANOVA, results show that the sum of squares, mean square and percentage contribution
of individual and interaction parameters on MRR and SR. The most individual affected
parameter on MRR is Ip where the percentage contribution is 62.03%. The most
individual effected parameters on SR are Ip and Pon where percentage contribution is
61.58% and 19.90% respectively. The ‘degree of motion of workpiece’ and ‘Y-infeed after
one revolution’ also effect MRR and SR with a large amount of interaction effect with
other parameters.

To avoid the chances of manual calculation errors a software named ‘ANOVA analyzer’
has been developed which helps in calculating the same terms/values of ANOVA. It is
found that residual error for GCr15 material are 11.65 % for MRR and 11.67% for SR,
during the calculation of % contribution of independent factor which leads us to find
interaction effects between each factor. Undoubtedly, the parameters Pon, Poff and Ip
found interaction effects between ‘Degree of motion-DOM’ and ‘Y-infeed after one
revolution-Infeed’ in experimental results using Design-Expert software.

In process of modeling responses it is found that interaction effects for MRR %
contribution of Pon*DOM (3.37%), Poff*DOM (2.11%), Poff*Infeed (3.10%), Ip*DOM
(2.41%) and Ip*Infeed (0.67%) and for SR % contribution of Pon*DOM (0.59%), Poff*DOM
(4.82%), Poff*Infeed (1.22%), Ip*DOM (2.81%) and Ip*Infeed (1.83%). All mentioned
interaction effects are well justified by graphical interpretation through the 3D surface
and contour graphs included in the respective part of theses.
Through the development of mathematical model generation and verification, for each
response relationship is identified between independent variables and dependent
variable. Coefficients of correlation equations determined by design expert under coded
units i.e. mathematical regression equations obtained for MRR and SR for GCr15
Material.
Through this research, to investigate the multiple performance characteristics in the
CWEDM process the orthogonal array with the GRA and MOORA technique are used. It is
found that for GCr15 material highest grey relational grade is 0.8 in GRA and the highest

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