# Optimization of Machining Parameters for Corner Accuracy Improvement for WEDM Processing
## 3 Experiment and Discussion
### Effect of Parameter on Corner Error
#### 3.1.1 Effect of Pulse-on Time (ON) on Corner Error  
The \(p\)-value for the ON term was less than 0.0001, and the F-value was large, which indicates that this parameter is highly significant. It is desirable as it indicates that the ON parameter has a significant effect on the response. Additionally, the results showed that the ON\({}^{2}\) term provides secondary contribution to the 30\({}^{\circ}\) corner as shown in Table 3. Meanwhile, the interaction between the ON and OV terms provides secondary contribution to the 60\({}^{\circ}\) corner as shown in Table 4. Table 6 shows the experimental result of corner machining for different pulse-on time (ON) parameter settings. It can be seen that when the pulse-on time (ON) parameter increased from 8 to 12, the corner error for 30\({}^{\circ}\), 60\({}^{\circ}\), and 90\({}^{\circ}\) increased from 0.076, 0.029, 0.018 mm to 0.101, 0.041, 0.023 mm, respectively. Moreover, the corner error increased more the more narrow the degree of the corner. Regarding the machining speed, when the pulse-on time (ON) parameter increased from 8 to 12, the machining time decreased from 50.13 to 33.56 min.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**ON Parameter (Code)**} \\
**Corner Degree** & \multicolumn{3}{c}{**Corner Error (mm)**} \\ \cline{2-3}  & **8** & **10** & **12** \\ \hline
30\({}^{\circ}\) & 0.076 & 0.091 & 0.101 \\
60\({}^{\circ}\) & 0.029 & 0.034 & 0.041 \\
90\({}^{\circ}\) & 0.018 & 0.022 & 0.023 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Pulse-on time (ON) vs. corner error.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Source** & **Sum of Squares** & **df** & **Mean Square** & **F-Value** & \(p\)**-Value (Prob \textgreater{} F)** & **Remarks** \\ \hline Model & 0.000586 & 27 & 0.000022 & 5.15 & \textless{}0.0001 & Significant \\ ON & 0.000115 & 1 & 0.000115 & 27.19 & \textless{}0.0001 & Significant \\ OFF & 0.000029 & 1 & 0.000029 & 6.81 & 0.0149 & Significant \\ OV & 0.000075 & 1 & 0.000075 & 17.78 & 0.0003 & Significant \\ SV & 0.000038 & 1 & 0.000038 & 9.00 & 0.0059 & Significant \\ WT & 0.000197 & 1 & 0.000197 & 46.82 & \textless{}0.0001 & Significant \\ WA & 0.000035 & 1 & 0.000035 & 8.26 & 0.0080 & Significant \\ ON OFF & 0.000001 & 1 & 0.000001 & 0.27 & 0.6097 & \\ ON OV & 0.000000 & 1 & 0.000000 & 0.06 & 0.8025 & \\ ON SV & 0.000000 & 1 & 0.000000 & 0.00 & 0.9840 & \\ ON WT & 0.000000 & 1 & 0.000000 & 0.02 & 0.8870 & \\ ON WA & 0.000002 & 1 & 0.000002 & 0.56 & 0.4621 & \\ OFF OV & 0.000003 & 1 & 0.000003 & 0.65 & 0.4288 & \\ OFF SV & 0.000000 & 1 & 0.000000 & 0.03 & 0.8646 & \\ OFF WT & 0.000001 & 1 & 0.000001 & 0.16 & 0.6910 & \\ OFF WA & 0.000000 & 1 & 0.000000 & 0.00 & 0.9501 & \\ OV SV & 0.000000 & 1 & 0.000000 & 0.12 & 0.7332 & \\ OV WT & 0.000001 & 1 & 0.000001 & 0.27 & 0.6097 & \\ OV WA & 0.000000 & 1 & 0.000000 & 0.04 & 0.8470 & \\ SV WT & 0.000011 & 1 & 0.000011 & 2.64 & 0.1162 & \\ SV WA & 0.000002 & 1 & 0.000002 & 0.47 & 0.4969 & \\ WT WA & 0.000001 & 1 & 0.000001 & 0.29 & 0.5979 & \\ ON\({}^{2}\) & 0.000005 & 1 & 0.000005 & 1.28 & 0.2685 & \\ OFF\({}^{2}\) & 0.000000 & 1 & 0.000000 & 0.01 & 0.9144 & \\ OV\({}^{2}\) & 0.000010 & 1 & 0.000010 & 2.42 & 0.1318 & \\ SV\({}^{2}\) & 0.000056 & 1 & 0.000056 & 13.31 & 0.0012 & Significant \\ WT\({}^{2}\) & 0.000001 & 1 & 0.000001 & 0