Based on the screening experimental results, the
Taguchi method was selected for the DOE. Within
Taguchi method, the experiments are performed as per
standard orthogonal arrays while the optimum level of
input process parameters (control factors) are decided on
the basis of a statistical analysis of the experimental
results [6]. The tool used in the Taguchi method is the
orthogonal array (OA). The OA defines the values of the
parameters for each experiment. The Taguchi method
employs a generic signal-to-noise (S/N; frequently it is
abbreviated as SNR as well) representing the magnitude
of the mean of a process compared to its variation.