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Study on the influence that hard water had in high-speed wire electrical discharge machining

  • Yanbin Zhang
  • Zhidong LiuEmail author
  • Ming Zhang
  • Mingbo Qiu
  • Hao Zhang
ORIGINAL ARTICLE
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Abstract

High-speed wire electrical discharge machining (HS-WEDM) using hard water working liquid results in the machined surface losing metallic luster and reducing the cutting speed comparing with distilled water working fluid. Scanning electron microscopy (SEM) was used to observe the microscopic surface of the workpiece. The chemical composition of the machined surface was analyzed via energy-dispersive X-ray spectroscopy (EDS). Results indicated that the primary cause for lost metallic luster of the machine’s surface was the Cl present in hard water, which was easily adsorbed on the surface of the workpiece under high-temperature and pressure inter-electrode conditions, resulting in pitting corrosion. By analyzing the conductivity and the continuous discharge waveforms of distilled water and hard water working liquid, it was determined that the reduced cutting speed was because the hard water working liquid contained ions such as Ca2+ and Mg2+, which were adsorbed by the colloid in the working fluid. This resulted in the loss of dielectric property for the working fluid. Furthermore, the conductivity of hard water working fluid is higher, making it easier to be broken down under the same voltage, which results in a larger discharge gap and reduced cutting speed. A method of distilling the hard water to remove the ions was presented to circumvent this; after which, the cutting surface recovered metallic luster and the general machining speed increased.

Keywords

HS-WEDM Hard water Metallic luster Cutting speed 

Notes

Acknowledgments

We extend our sincere thanks to all who contributed in the preparation of these instructions.

Funding information

This project was financially supported by the National Natural Science Foundation of China (Grant Nos. 51575271 and 51675272).

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Copyright information

© Springer-Verlag London Ltd., part of Springer Nature 2019

Authors and Affiliations

  • Yanbin Zhang
    • 1
  • Zhidong Liu
    • 1
    Email author
  • Ming Zhang
    • 1
  • Mingbo Qiu
    • 1
  • Hao Zhang
    • 1
  1. 1.College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and AstronauticsNanjingChina

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