# Sustainability-Based Analysis of Conventional to High-Speed Machining of Al 6061-T6 Alloy
## 4 Analysis of Experimental Data: Transitional Speed Machining (TSM)
### Specific Cutting Energy (SCE)  
The impact of machining parameters on SCE in TSM has been analyzed with ANOVA (Table 9). ANOVA results reveal the statistical significance of all machining parameters for SCE (all having a \(p\)-value less than 0.05). However, in terms of percentage contribution, feed has the highest influence, followed by depth of cut and cutting speed. This order of influence of cutting parameters on SCE in TSM is slightly different than that observed for CSM, in which cutting speed was observed to be more significant than depth of cut. In order to further probe the effect of cutting parameters on SCE, main effect plots for TSM were developed as shown in Figure 6.  
The main effect plot shows that SCE decreases when the cutting parameters are set at their respective highest values. From the slope of the main effect plots, a steep drop in SCE is observed when feed is increased from 0.1 mm/rev to 0.2 mm/rev. From 0.2 mm/rev to 0.4 mm/rev, a gradual drop in SCE is observed. A similar gradual drop is observed in the case of depth of cut. However, a trivial drop in SCE value was seen when cutting speed was increased. The relatively smaller drop in SCE with higher speed can be the result of increased power requirements at high speeds. The enhanced power requirements offset the gain in MRR, and as a result, the net value of SCE is little affected by the increasing cutting speed [19].  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Experiment.** & \(\mathbf{v}\) & \(\mathbf{f}\) & \(\mathbf{d}\) & \multicolumn{2}{c}{_SCE (J/mm\({}^{3}\))_} & \multicolumn{2}{c}{_Ra (\(\mu\)m)_} \\
**No.** & **(m/min)** & **(mm/rev)** & **(mm)** & **Ave** & **Std. Dev.** & **Ave** & **Std. Dev.** \\ \hline
1 & 750 & 0.1 & 1 & 0.76 & 0.008 & 2.54 & 0.042 \\
2 & 750 & 0.2 & 2 & 0.63 & 0.008 & 1.93 & 0.372 \\
3 & 750 & 0.3 & 3 & 0.60 & 0.005 & 3.17 & 0.041 \\
4 & 750 & 0.4 & 4 & 0.53 & 0.008 & 5.09 & 0.049 \\
5 & 1000 & 0.1 & 2 & 0.72 & 0.017 & 1.36 & 0.012 \\
6 & 1000 & 0.2 & 1 & 0.66 & 0.008 & 2.04 & 0.069 \\
7 & 1000 & 0.3 & 4 & 0.55 & 0.005 & 3.89 & 0.196 \\
8 & 1000 & 0.4 & 3 & 0.58 & 0.008 & 3.47 & 0.464 \\
9 & 1250 & 0.1 & 3 & 0.73 & 0.008 & 1.02 & 0.290 \\
10 & 1250 & 0.2 & 4 & 0.52 & 0.005 & 3.98 & 0.051 \\
11 & 1250 & 0.3 & 1 & 0.65 & 0.005 & 5.17 & 0.351 \\
12 & 1250 & 0.4 & 2 & 0.58 & 0.005 & 4.12 & 0.319 \\
13 & 1500 & 0.1 & 4 & 0.70 & 0.008 & 2.93 & 0.051 \\
14 & 1500 & 0.2 & 3 & 0.55 & 0.005 & 3.01 & 0.186 \\
15 & 1500 & 0.3 & 2 & 0.56 & 0.005 & 4.41 & 0.341 \\
16 & 1500 & 0.4 & 1 & 0.56 & 0.005 & 6.71 & 0.102 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Results of L\({}_{16}\) experimental plan for transitional speed machining range.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Variable** & **DOF** & **Seq. SS** & **Adj. MS** & **F-Value** & \(\mathbf{p}\)**-Value** & **CR (\%)** \\ \hline \(v\) (m/min) & 3 & 0.012189 & 0.004063 & 7.83 & 0.000 & 3.82\% \\ \(f\) (mm/rev) & 3 & 0.205819 & 0.068606333 & 132.17 & 0.000 & 73.36\% \\ \(d\) (mm) & 3 & 0.040714 & 0.013571333 & 26.14 & 0.000 & 14.06\% \\ Error & 38 & 0.019725 & 0.000519079 & & & 8.76\% \\ Total & 47 & 0.278447 & & & & 100.00\% \\ \hline \hline \end{tabular}
\end{table}
Table 9: Analysis of variance and percentage contribution results for SCE.