# Adjustment of Wire Vibrations in Order to Improve Geometric Accuracy and Surface Roughness at WEDM
## 6 Conclusions  
The article describes the technical design of a system for monitoring, and the subsequent adjustment of, the vibration amplitude of a wire tool electrode during WEDM. The solution was based on a detailed analysis of the obtained results of experimental measurements of the geometric deviations of circularity (\(y_{Cmax}\)), cylindricity (\(z_{Cmax}\)) and roughness (\(Ra\)) of the machined surface. A suitable technical solution for the minimization of the vibration amplitudes of the wire tool electrode was proposed as indirect vibration sensing by the means of acoustic emission sensors. When the critical frequency of the wire electrode vibrations is reached, the control unit temporarily adjusts the main technological parameters so that the vibrations are eliminated while maintaining the roughness quality parameter of the eroded surface. Through the active adjusting of the discharge energy according to the actual value of the acoustic emissions in the wire tool electrode guides, a substantial reduction in the geometric deviations of the eroded surface during WEDM is achieved, while maintaining a high productivity in the electrororosion process. The experimental research was oriented at the practical use of the achieved results, not only in theory, but also in practice. The proposed technical solution will thus enable to meet much narrower specifications placed on the quality of workpieces. Summary of experimental research results:  
* based on the results of experimental research, the maximum deviations from circularity (\(y_{Cmax}\)), cylindricity (\(z_{Cmax}\)) and roughness values (\(Ra\)) of the machined surface were identified for the individual machined profiles, \(\omega_{Ci}\) = 5.0, 20.0, 40.0, 80.0, and 120.0 mm, with machined material thicknesses of \(H_{w}\) = 10.0, 50.0, and 100.0 mm;
* it was found that the values of maximum geometric deviations from circularity (\(y_{Cmax}\)), cylindricity (\(z_{Cmax}\)) and roughness values (\(Ra\)) differed, not only for individual profiles (\(\omega_{Ci}\)), but also for individual thicknesses (\(H_{w}\)) of machined material;
* it was found that, in both cases, with increasing thickness of the machined material (\(H_{w}\)) and with increasing \(\omega_{Ci}\) of the machined profile, there is a decrease in the maximum deviation of the circularity (\(y_{Cmax}\)) and, conversely, an increase in the maximum deviations from cylindricity (\(z_{Cmax}\));
* the increase in the maximum geometric deviation of cylindricity \(z_{Cmax}\) was almost identical for all \(\omega_{Cy}\) profiles when thickness of machined material \(H_{w}\) changed from 10.0 to 100.0 mm--this increase was around 110%;
* at the same time, it was found that with the decreasing thickness of the machined material (\(H_{w}\)) and with increasing \(\omega_{Ci}\) of the machined profile, the roughness parameter of the machined surface (\(Ra\)) increases;  
Figure 12: Diagram of the location and wiring of sensors for measuring acoustic emission during WEDM. possible causes of geometric deviations from circularity and cylindricity of the machined surface after WEDM were identified and defined;
* a technical solution was designed for on-line monitoring of the vibration amplitude of the wire tool electrode using the acoustic emission method;
* and a system diagram was proposed to adjust the critical vibration frequency of the wire tool electrode during WEDM by controlling the settings of the main technological and process parameters. Conceptualization, L'.S. and L.C. ; methodology, L'.S. ; validation, L'.S. ; formal analysis, L'.C. ; investigation, L'.S. ; data curation, L'.C. ; writing--original draft preparation, L'.S. ; visualization, L'.C. ; project administration, L'.S. ; funding acquisition, L'.S. All authors have read and agreed to the published version of the manuscript. This research was funded by the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic, grant number VEGA 1/0205/19. Not applicable. All data are published with the paper.