# Optimization of Machining Parameters for Corner Accuracy Improvement for WEDM Processing
## 1 Introduction
[5] developed a simulation method to investigate the relation between the actual path and the programmed path of the wire, then used it to predict the actual path of the wire for sharp corner machining. In the WEDM process, electrostatic, electromagnetic, electrodynamics, and dielectric pressure act on the wire and will deflect the wire [6]. Large cutting error usually occurs while cutting sharp corners due to wire lag and other effects. [PERSON] et al. [7] found errors in corners due to the wire lag and wire vibration. Other researchers tried to modify machining parameters such as wire speed and pulse time in order to reduce the wire deflection, and, hence, found that the dimension accuracy and the flatness of the workpiece wall could be improved. [PERSON] et al. [8; 9] investigated several controlling methods including power control with path correction to increase corner accuracy and reduce machining time at the roughing stage. Increasing the wire tension can improve the accuracy of corner machining; however, when the wire tension is too large, it will easily break the wire during processing. On the other hand, when the wire tension is too small, the phenomenon of wire deflection and vibration will occur, resulting in the phenomenon of corner overcut during corner machining. Another study to enhance the machining process by adding nanopowder in the dielectric fluid was investigated by [PERSON] et al. [10]. Different concentrations of Al\({}_{2}\)O\({}_{3}\) nanopowder were used in the dielectric fluid, and the effects on the surface roughness, MRR, and recast layer thickness (RLT) were investigated. The experimental result showed that Al\({}_{2}\)O\({}_{3}\) nanopowder and pulse-on time have high contribution for surface roughness and recast layer thickness. [PERSON] et al. [11] investigated the effect of different wire materials on WEDM performance. Brass wire and zinc-coated brass wire were used during the machining of titanium alloy, and the effect on surface roughness and material removal rate were investigated. The experimental result shows that the zinc-coated brass wire could increase the cutting speed and better surface roughness. [PERSON] et al. [12] proposed a zinc-coated surface microstructure on wire electrodes (ZCSMWE) for improving the machining process. The experimental results showed that ZCSMWE can increase the MRR and reduce surface roughness. It also significantly decreased the recast layer and microcrack on the surface. As mentioned above, the corner machining accuracy can be improved by finding the suitable setting of machining parameters to reduce the error of corner machining. It is known that the WEDM process is complex, stochastic, and time-varying, involving many variables which make it extremely difficult for setting an optimal parameter setting. Different methods were proposed by researchers to solve this problem. [PERSON] et al. [PERSON] _et al._ (2018) investigated the performance of WEDM process parameters. The Taguchi method and RSM were used to investigate the effect of pulse-on time, pulse-off time, wire feed rate, and peak current on cutting time, cutting rate, overcut, and dimensional deviations. The results showed a significant effect of pulse-on/off time and peak current on the cutting time, while wire feed rate gave significant effect to cutting rate. [PERSON] et al. [PERSON] _et al._ (2018) used the L27 Taguchi method that involved 13 control parameters to analyze and investigate the geometrical accuracy. It was concluded that the significant factors for geometrical inaccuracy due to wire lag for rough cutting are pulse-on/off time and pulse peak current. [PERSON] et al. [PERSON] _et al._ (2018) proposed the L9 Taguchi method to optimize the machining conditions in order to obtain the best surface roughness. The signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) were used in the study. The observation concluded that the most influential factor on the surface roughness was discharge current. [PERSON] et al.