Improving material removal rate and surface roughness in macro electrolyte jet machining of TC4 titanium alloy using tools with a converging-diverging Laval-type electrolyte channel

In macro-electrolyte jet machining, improving the material removal rate and surface roughness is a key topic. The distribution of the flow field in the machining area significantly affects the material removal rate and surface roughness. This paper proposes tools with a converging-diverging Laval-type electrolyte channel to enhance the material removal rate and surface roughness by optimizing the flow field distribution in the machining area. The simulation results of the flow field show that compared to the standard tool, the tool with a convergent-divergent Laval-type electrolyte channel can reduce the low flow rate area of the electrolyte in the machining area, increasing the average flow rate of the electrolyte on the groove surface in the machining area. The experimental results indicate that in comparison to the standard tool, the tool with a convergent-divergent Laval-type electrolyte channel can improve the material removal rate and surface roughness of the workpiece. To further enhance the material removal rate of the workpiece, based on the determination of the convergence-divergence angle of the Laval-type electrolyte channel, the influence of the front-end area of the tool feed direction on the material removal rate of the workpiece was investigated. It was found that compared to the tool with a 2-mm front-end length, the tool with a 6-mm front-end length increases the material removal rate of the workpiece from 139.0 to 216.2 mm 3 ·min −1 and reduces the workpiece surface roughness Ra from 6.31 to 1.85 μm. Furthermore, a schematic diagram of the electrochemical dissolution behavior of the workpiece surface during machining is established to explain the significantly reduced surface roughness of the workpiece.