A Study on the Performance of Brass and Zinc-Coated Wire Electrodes in WEDM
Date Issued
2010
Date
2010
Author(s)
Lee, Yu-Ju
Abstract
Many kinds of wire electrodes were used on wire electric discharge machining (WEDM), but the research of the wire electrode has few been discussed. In this study, the impact of wire electrode will be discussed, in order to be the reference of design the wire electrode in the future. In the article, brass wire and zinc-coated brass wire were used as electrodes in WEDM. Experiments were conducted with different workpiece thicknesses and different cutting processes. And material SKD-11 was used as the workpiece. According to the experimental result, zinc-coated brass wire is not only good at machining speed but also can form good shape accuracy and good surface roughness. It could be concluded that the three basic elements like heat, electric and evaporation were the main factors. This study focused on these three basic physical properties of zinc-coated brass wire and brass wire, and also designed and conducted the experiments with the characteristics of heat, electric and evaporation. It is discovered that there are some micro holes on the surface of zinc-coated brass wire while it is used as an electrode. Hence, the contact area between the fluid and the wire electrode will increase and that will lead to a better heat removal, being easy to evaporate and a better cooling mechanism because of the lower melting point and boiling point of zinc-coated brass wire. Moreover, the lower electron affinity of zinc-coated brass wire would lead to the larger gap distance during WEDM process. And with the characteristics of lower boiling point and induced higher saturated vapor pressure, zinc-coated brass wire can produce much more vapor resulting that the discharge debris could be easily eliminated to achieve the better flush-ability. At last, this study has figured out all the factors which can influence the efficiency of wire electrode and machine efficiency. A design with multi layers of electrode composed of different materials like the most inner layer with molybdenum or tungsten material with high boiling point and stiffness, the median layer with brass or copper which is good at conductivity and the outer layer with zinc-coated was proposed as an innovative electrode design. Multi-layer wire electrode would be the optimum choice to obtain a good stiffness, conductivity, heat removal rate and debris eliminating.
Subjects
WEDM
brass wire
zinc-coated brass wire
Type
thesis
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