Simultaneous gas electrical discharge and electrochemical jet micromachining of titanium alloy in high-conductivity salt solution

Electrochemical jet machining (EJM) has attracted considerable attention in alloy manufacturing due to its versatility and flexibility. However, for EJM of titanium alloys, the Material Removal Rate (MRR) is low due to the formation of the refractory oxide layer and the non-participation of end face of tool electrode. In order to improve the MRR in this study, a novel hybrid method called gas electrical discharge and electrolyte jet simultaneous machining, which combines electrical discharge machining (EDM) and electrochemical jet machining (EJM), is proposed to effectively reduce the oxide layer and promote the participation of the end of electrode tool in machining process. In the hybrid EDM-EJM method, an instantaneous high voltage spark discharge breaks down the air between two electrodes to remove instantaneously the oxide layer, and then the workpiece is machined to a smooth surface by subsequent and highly efficient EJM. Each point on the workpiece surface is treated successively via EDM and EJM, so the entire surface is machined by the two separate machining modes. The EDM and EJM act simultaneously on the workpiece and in synchronization throughout the machining process. Also, the end face of the workpiece contributes to material removal, hence the MRR is improved. Due to the periodic change of the machining voltage at the EDM stage, the reflection angle of the flowing electrolyte also changes periodically, and this is conducive to increasing fluctuations in the flow of electrolyte and hence accelerating the removal of the electrolysis products. Our studies shows that this new combined approach improves not only the MRR, but also greatly reduces erroneous corrosion effects and reduced the surface roughness Ra from 0.800 & mu;m to 0.177 & mu;m.