The effects of each factor level on the quality characteristics were analyzed using the signal to noise (S/N)
ratio. The S/N ratio is plotted against test level for each
control parameter as shown in Figs. 2 and 3,
where Fig. 2(a–d) is shown for surface roughness and
Fig. 3(a–d) is shown for tool wear. From the S/N ratio
analysis in Fig. 2(a–d), the optimal cutting parameters