# Optimization of Machining Parameters for Corner Accuracy Improvement for WEDM Processing
## 5 Verification Experiments  
The verification experiments were carried out to verify the proposed optimization method and system. The corner error verification was mainly to control the corner accuracy error. The verification experiment was divided into two parts. The first part used the developed optimization HMI to obtain the optimal machining parameters. The second part performed the machining using the original parameters and the optimized parameters. Furthermore, the corner errors were measured and compared. Table 12 shows the original parameters and the optimized parameters for the 30, 60, and 90 degree corners that were obtained through the developed optimization system.  
Figure 10: WEDM corner accuracy and machining speed optimization human–machine interface.  
After we performed machining using the original parameters, the corner errors were measured, and they showed that the corner errors of the 30, 60, and 90 degree corners were 0.091, 0.030, and 0.018 mm, respectively. Meanwhile, the predicted corner errors calculated by the proposed system were 0.096, 0.035, and 0.018 mm, respectively. Therefore, the accuracies were 94%, 86%, and 99%, respectively, as shown in Table 13.  
The corner errors for the 30, 60, and 90 degree corners that resulted from the conducted machining using the optimized parameters were 0.056, 0.024, and 0.011 mm, respectively. Meanwhile, the predicted corner errors calculated by the system were 0.056, 0.022, and 0.010 mm, respectively. Hence, the accuracies were 99%, 91%, and 90%, respectively, as shown in Table 14.  
It can be seen from the Tables 13 and 14 that the difference between the measured and predicted value is very small, which indicates the regression equation obtained after analysis has high accuracy prediction. Table 15 shows the comparison corner error values before and after optimization. It can be seen the corner errors decrease for the 30, 60, and 90 degree corners. In other words, the corner accuracy increased by 39%, 20%, and 33%, respectively, as shown in Table 15.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Corner Degree**} & **Predicted Corner Error (mm)** & **Measured Corner Error (mm)** & **Prediction Accuracy (\%)** \\ \hline
30 & 0.056 & 0.056 & 99 \\
60 & 0.022 & 0.024 & 91 \\
90 & 0.010 & 0.011 & 90 \\ \hline \hline \end{tabular}
\end{table}
Table 14: Corner error using optimized parameters.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{2}{c}{**30\({}^{\circ}\) Corner**} & \multicolumn{2}{c}{**60\({}^{\circ}\) Corner**} & \multicolumn{2}{c}{**90\({}^{\circ}\) Corner**} \\ \cline{2-7}  & **Original** & **Optimized** & **Original** & **Optimized** & **Optimized** & **Original** & **Optimized** \\  & **Parameter** & **Parameter** & **Parameter** & **Parameter** & **Parameter** & **Parameter** \\ \hline OV & 11 & 10 & 11 & 11 & 11 & 11 \\ ON & 10 & 8 & 10 & 8 & 10 & 8 \\ OFF & 10 & 11 & 10 & 10 & 10 & 12 \\ SV & 38 & 37 & 38 & 38 & 38 & 38 \\ WT & 12 & 14 & 12 & 14 & 12 & 14 \\ WA & 3 & 2 & 3 & 2 & 3 & 2 \\ \hline \hline \end{tabular}
\end{table}
Table 12: Original parameters and optimized parameters obtained from the developed optimization system.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Corner Degree**} & **Predicted Corner Error (mm)** & **Measured Corner Error (mm)** & **Prediction Accuracy (\%)** \\ \hline
30 & 0.096 & 0.091 & 94 \\
60 & 0.035 & 0.030 & 86 \\
90 & 0.018 & 0.018 & 99 \\ \hline \hline \end{tabular}
\end{table}
Table 13: Corner error using original parameter.