# Effectiveness of Electrode Design Methodologies for Fast EDM Slotting of Thick Silicon Wafers
## 3 Results and Discussion
### Effect of Electrode Arrays on Machining Speed with Varied Electrode Leg Heights
#### 3.1.3 Analysis of Quality of the Machined Features on Silicon
\begin{tabular}{c} **Number of** \\ **Electrode** \\ **Leg** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Marking of** \\ **Leg** \\ \end{tabular}  } & \multicolumn{2}{c}{**Electrode**} & \multicolumn{2}{c}{**Workpiece (Entry)**} & \multicolumn{2}{c}{**Workpiece (Exit)**} \\ \cline{3-8}  & & & **Length** & **Width** & **Length** & **Width** & **Length** & **Width** \\  & & **(\(\mu\)m)** & **(\(\mu\)m)** & **(\(\mu\)m)** & **(\(\mu\)m)** & **(\(\mu\)m)** & **(\(\mu\)m)** \\ \hline \multirow{4}{*}{4 (1 \(\times\) 4)} & Leg-1 & 3576.67 & 3580.34 & 3951.09 & 4176.86 & 3786.45 & 3  
arrays, respectively. The average percentages of deviation (%) for the length are 9.46, 9.61, 7.51, 6.93, 6.57, and 5.96 for the electrode height 0.2\({}^{\prime\prime}\) and 8.58, 8.93, 7.73, 7.17, 7.66, and 6.33 for the electrode 0.3\({}^{\prime\prime}\), for arrays of 1 \(\times\) 4, 2 \(\times\) 4, 3 \(\times\) 4, 4 \(\times\) 4, 5 \(\times\) 4, and 6 \(\times\) 4, respectively. The reduction in the percentage array indicates the improved dimensional accuracy of the machined features with the increase in arrays of electrodes. Therefore, it can be said that both the surface quality and dimensional accuracy of machined features improve with increased arrays of electrodes, and this may be related to the improvement in the flushing conditions associated with larger arrays due to a higher number of flushing channels and increased dielectric flow in those channels. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Percentage of Deviation**} & \multicolumn{2}{c}{**Overall Percentage of**} & \multicolumn{2}{c}{**Percentage of Deviation**} & \multicolumn{2}{c}{**Overall Percentage of**} \\ \cline{3-8} \multicolumn{1}{c}{**Number of**} & \multicolumn{2}{c}{**in Arrays (\%)**} & \multicolumn{2}{c}{**Deviation in Arrays (\%)**} & \multicolumn{2}{c}{**in Arrays (\%)**} & \multicolumn{2}{c}{**Deviation in Arrays**} \\ \cline{3-8} \multicolumn{1}{c}{**Legs**} & \multicolumn{2}{c}{**for Height 0.2\({}^{\prime\prime}\)**} & \multicolumn{2}{c}{**for Height 0.2\({}^{\prime\prime}\)**} & \multicolumn{2}{c}{**for Height 0.3\({}^{\prime\prime}\)**} & \multicolumn{2}{c}{**(\%) for Height 0.3\({}^{\prime\prime}\)**} \\ \cline{2-8} \cline{1-1} \cline{2-8}  & **Length** & **Width** & **Length** & **Width** & **Length** & **Width** & **Length** & **Width** \\ \hline
4 (1 \(\times\) 4) & 9.46 & 10.42 & & & 8.58 & 10.65 & & \\
8 (2 \(\times\) 4) & 9.61 & 9.61 & & & 8.93 & 8.47 & & \\
12 (3 \(\times\) 4) & 7.51 & 8.06 & & 7.73 & 8.22 & & \\
16 (4 \(\times\) 4) & 6.93 & 7.04 & & 7.67 & 7.88 & 7.17 & 7.21 & 7.73 & 7.95 \\
20 (5 \(\times\) 4) & 6.57 & 6.38 & & & 7.66 & 6.76 & & \\
24 (6 \(\times\) 4) & 5.96 & 5.81 & & & 6.33 & 6.41 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Quality of the machined parts of the workpiece with arrays of electrodes and height. Figure 12: (a,c,e) Entry side of workpiece. (b,d,f) Exit side of workpiece for electrode height 0.2\({}^{\prime\prime}\) for Log-1 of Sample-1 for \(1\times 4\), \(2\times 4\), and \(3\times 4\) arrays of electrodes. Figure 13 and 14 show that for both heights of electrode legs (0.2\({}^{\prime\prime}\) and 0.3\({}^{\prime\prime}\)), higher arrays of electrode legs (6 \(\times\) 4, 5 \(\times\) 4, and 4 \(\times\) 4) were more accurate than lower (3 \(\times\) 4, 2 \(\times\) 4, and 1 \(\times\) 4) arrays of electrode legs, with the exception of 2 \(\times\) 4 arrays. In the case of 2 \(\times\) 4 arrays of electrode legs, they were found to be less precise compared to 1 \(\times\) 4 and 3 \(\times\) 4 arrays of electrodes. This percentage of deviation has been analyzed for other samples too. As shown in Table 8 the overall percentage of deviation for electrode leg heights of 0.2\({}^{\prime\prime}\) and 0.3\({}^{\prime\prime}\) is relatively close, with length percentages of 7.67% and 7.73% and width percentages of 7.88% and 7.95%, respectively.