Machinability of the Stepped Cylindrical Electrode in the Electrical Discharge Machining

In this study, we investigated a modified electrode with a stepped cylindrical shape to improve machinability in the electrical discharge machining process. A stepped cylindrical electrode with varied land heights and shank sizes was designed. A copper electrode was used to drill holes at a machining depth of 45 mm on the tool steel. The results revealed that the material removal rate of the shoulder and relief angle designs increased by 277.54% and 269.91%, respectively, compared with those of a conventional electrode for a land height of 0.90 mm. The material removal rate decreased slightly with increasing land height for both electrode designs. The electrode wear ratio of all modified electrodes was less than 1%, and the lowest electrode wear ratio of approximately 0.45% was observed at a land height of 2.25 mm. In addition, the diameter of the drilled hole along the machining depth was greatest in the middle. The concave shape on the side wall of the drilled hole for the modified electrode was lower than that of the conventional tool. The concave shape of the drilled hole was drastically reduced with a sufficient decrease in the land height and shank size of the modified electrode. This was due to the lower area on the sidewall between the electrode and the drilled hole, with the stepped cylindrical design leading to easy elimination of debris particles from the sparking area and improved machining performance. Therefore, the machinability of the stepped cylindrical electrode was greater than that of the conventional machining.

Debris particles; Electrical discharge machining; Material removal rate; Stepped cylindrical electrode

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