# Optimization of Machining Parameters for Corner Accuracy Improvement for WEDM Processing
## 6 Conclusions  
In this study, the optimization of machining parameters to obtain the smallest corner error and fastest machining speed was proposed. The experiments with different machining parameters such as pulse-on time, pulse-off time, open circuit voltage, servo voltage, wire tension, and flushing pressure were conducted. Three different corner degrees of 30, 60, and 90 were chosen for the experiment. The response surface methodology (RSM) was used to analyze and investigate the effect of each parameter on the corner error and machining speed. It was found that for machining 30\({}^{\circ}\) and 60\({}^{\circ}\) corners, the corner error was mainly due to the effect of the pulse-on time (ON) parameter, followed by the wire tension (WT) parameter. Meanwhile, when machining a 90\({}^{\circ}\) corner, the corner error was mainly affected by the wire tension (WT) parameter, followed by the pulse-on time (ON). In addition, when machining different corner angles, the main parameters affected will be different. In terms of machining speed, the pulse-on time (ON) and open circuit voltage (OV) parameters had an influence on corner error and machining speed. Although the wire tension parameter improved the corner accuracy, it had the smallest effect on the machining speed. Meanwhile, the pulse-off time (OFF) parameter had less influence on the corner error.  
The machining parameter data combined with the response surface value and the algorithm were used to determine the optimal machining parameters. A corner error and machining speed optimization system with a human-machine interface was built using the C# language program. The results of the verification experiments showed that the corner errors of 30, 60 and 90 degrees before optimization were 0.091, 0.030, and 0.018 mm, respectively, while the corner errors after optimization were 0.056, 0.024, and 0.011 mm, respectively. It can be concluded that the corner errors of 30, 60 and 90 degrees before and after optimization were increased by 39%, 20%, and 33%, respectively. In terms of prediction accuracy of the system, the prediction accuracy of 30, 60, and 90 degrees was 99%, 91%, and 90%, which proves that the proposed method can effectively improve the corner machining accuracy.  
The proposed optimization system in this study was used for WEDM rough machining corner error prediction. Therefore, the extension of the proposed optimization system for finishing machining is underway. In addition, the diameter wire and taper shape factors can be included in the future research.  
Conceptualization, S.-M.W. and [PERSON]-X.W.; methodology, S.-M.W. and [PERSON]-X.W.; software, J.-X.W.; validation, J.-X.W. and H.G.; formal analysis, S.-M.W., [PERSON]-X.W. and H.G.; investigation, [PERSON]-M.W. and [PERSON]-X.W.; resources, S.-M.W. and [PERSON]-X.W.; data curation, [PERSON]-X.W., [PERSON]-Q.T. and H.G.; writing--original draft preparation, [PERSON]-M.W. and H.G.; writing--review and editing, [PERSON]-M.W. and H.G.; visualization, [PERSON]-X.W., [PERSON]-Q.T. and H.G.; supervision, [PERSON]-M.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Ministry of Science and Technology, grant number MOST 110-2221-E-005-063, MOST 111-2221-E-005-080 -MY2, and MOST 111-2218-E-005-011.  
The authors declare no conflict of interest.