Development of curved hole drilling method by EDM with suspended ball electrode - Optimization of suspending parts structure and possibility of curved hole drilling-

A new machining method of curved hole by EDM using a suspended metal ball electrode with a lead wire from the head of ED machine is newly proposed in this study. The EDM characteristics, such as removal volume and machined hole diameter were compared using CuW ball electrodes of 5.5mm in diameter suspended with thin wire, foil, and chain, in order to optimize the suspending part structure and the machining conditions. Experimental results showed that the removal rate using the suspended electrode with the chain was higher than that using a rod electrode under the optimum conditions. It was also clarified that the servo voltage and discharge current were dominant parameters to keep a stable machining performance. Moreover, bending holes with various bending angles and complicated curve holes were created, and the high possibility of this method was shown.