The surface strips in WIRE CUT EDM

High-speed WIRE CUT EDM stripes is obvious

EMD cutting process and EDM forming process are the same in that both of them are based on the principle of electrolytic corrosion during pulse discharge between the tool electrode and the workpiece electrode to instantaneously ablate the workpiece surface. However, the two processes are different in that EDM forming must be done with the shaped tool electrode which has precise dimension in advance, while wire-cutting does not require a shaped tool electrode. Instead, it uses a long electrode wire as a tool “cutting” according to the predetermined trajectory, like the woodworking saws used for sawing wood. Various complex parts are machined by this way (That is, curved surface formed by a straight line as a bus.). Therefore, as long as the electrode wire moves unevenly during machining or servo feeding is not balanced, certain cutting stripe will appear, more or less, which will affect the surface quality. This happens especially in HIGH SPEED WIRE CUT EDM, the fast moving speed of the electrode wire, the inability to control the tension, and the non-stop commutation and direction changing, all will cause the instability of the electrode wire movement and servo feed, thus result in the frequent generation of cutting stripe. And it shows a black and white cross, the stripes are very obvious.

Although the LOW SPEED WIRE CUT EDM also occasionally shows cutting stripes, the probability of streaking is small, and the stripe depth is not as deep as those generated by the HS WIRE CUT EDM.

Zeng Qian, Head of Quality Inspection Center for Special Machine tools in China, explained in details in his article published in (EDM) magazine issue 3 of 1998. See chart 6-1 below.

It can be seen that the strip depth formed by HS WIRE CUT EDM is obviously deeper than those formed by LOW SPEED WIRE CUT EDM.

   6 -1 STRIPS resulted from WIRE CUT EMD