# EDM of D2 Steel: Performance Comparison of EDM Die Sinking Electrode Designs
## 3 Results and Discussion
### Analysis of Machining Time (MT)  
The effect of electrode designs on the time taken to complete the through-hole of 4 mm depth is presented in Figure 4. The cylindrical tool (D\({}_{\text{C}}\)) completed the desired hole in 22.25 min. This response has been taken as a reference to compare the machining time taken by other electrode designs. As can be seen that when the machining is performed by newly designed tools, there is significant reduction in machining time taken by all the electrodes compared with the time taken by cylindrical electrode. Among the relief angled design (D\({}_{\text{R}}\)), the time value ranges from 11.27 to 17.4 min. Five relief angles are varied within design type D\({}_{\text{R}}\). It can be observed that the time taken by 5\({}^{\circ}\) and 10\({}^{\circ}\) tools is close \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{3}{c}{**Tool Electrode Designs**} & \multicolumn{5}{c}{**Machining Responses**} \\ \hline \multirow{2}{*}{\begin{tabular}{c} **Design** \\ **Type** \\ \end{tabular} } & \multirow{2}{*}{**Design Name**} & \multirow{2}{*}{**Design**} & \multirow{2}{*}{**Exp.**} & \multirow{2}{*}{**Machining**} & \multirow{2}{*}{**Taper**} & \multirow{2}{*}{**Radial**} & \multirow{2}{*}{**Surface**} \\  & & & & & **Time** & & **Angle** & **Overcut** & **Roughness** \\ \hline \multirow{2}{*}{\begin{tabular}{c} **D\({}_{\text{C}}\)** \\ \end{tabular} } & \multirow{2}{*}{Conventional} & \multirow{2}{*}{\(\text{D}_{\text{CR0}}\)} & \multirow{2}{*}{0} & \multirow{2}{*}{22.25} & \multirow{2}{*}{2.34} & \multirow{2}{*}{464.50} & \multirow{2}{*}{13.70} \\ \cline{6-6} \multirow{6}{*}{\begin{tabular}{c} **D\({}_{\text{R}}\)** \\ \end{tabular} } & \multirow{2}{*}{Relief angle} & \multirow{2}{*}{\(\text{D}_{\text{R20}}\)} & \multirow{2}{*}{3} & \multirow{2}{*}{11.5} & \multirow{2}{*}{7.20} & \multirow{2}{*}{408.50} & \multirow{2}{*}{11.30} \\  & & \(\text{D}_{\text{R}}\) & 2 & 15.9 & 5.27 & 411.00 & 11.05 \\  & & \(\text{D}_{\text{R}}\) & 3 & 11.5 & 7.20 & 408.50 & 11.30 \\  & & \(\text{D}_{\text{R}}\) & 4 & 11.27 & 8.92 & 378.00 & 16.35 \\  & & \(\text{D}_{\text{R}}\) & 5 & 17.42 & 13.81 & 375.00 & 13.65 \\ \hline \multirow{2}{*}{\begin{tabular}{c} **D\({}_{\text{RL}}\)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Relief angle \\ with land \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} D\({}_{\text{RL}}\)5 \\ \end{tabular} } & \multirow{2}{*}{6} & \multirow{2}{*}{13.53} & \multirow{2}{*}{2.54} & \multirow{2}{*}{322.00} & \multirow{2}{*}{10.10} \\  & & \(\text{D}_{\text{RL}}\)10 & 7 & 11.73 & 2.93 & 404.50 & 8.40 \\ \multirow{2}{*}{\begin{tabular}{c} **D\({}_{\text{RL}}\)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} Relief angle \\ with land \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} D\({}_{\text{RL}}\)20 \\ \end{tabular} } & \multirow{2}{*}{8} & \multirow{2}{*}{12.13} & \multirow{2}{*}{2.85} & \multirow{2}{*}{357.00} & \multirow{2}{*}{11.90} \\  & & \(\text{D}_{\text{RL}}\)30 & 9 & 17.48 & 4.87 & 513.00 & 13.85 \\ \multirow{2}{*}{\
\begin{tabular}{c} **D\({}_{\text{RL}}\)5** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} D\({}_{\text{RL}}\)5 \\ \end{tabular} } & \multirow{2}{*}{10} & \multirow{2}{*}{18.65} & \multirow{2}{*}{6.09} & \multirow{2}{*}{624.50} & \multirow{2}{*}{11.70} \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Experimental results of EDM of D2 steel (1 st stage of experimentation). Figure 3: Machined holes produced through different electrode designs (D\({}_{\text{C}}\), D\({}_{\text{R}}\), and D\({}_{\text{RL}}\)). to each other since the change in the value of relief angle is very small. However, with the further increase in relief angles (20\({}^{\circ}\), 30\({}^{\circ}\), and 45\({}^{\circ}\)), the machining time gradually increases. For example, the tools with 5\({}^{\circ}\) and 10\({}^{\circ}\) relief (D\({}_{\text{R5}}\) and D\({}_{\text{R10}}\)) complete the hole in approximately 15.5 min and the time taken by 30\({}^{\circ}\) relief is found to be 11.2 min.