Electrochemical drilling with constant electrolyte flow

Electrochemical drilling (ECD) is a useful method to produce small holes with a large aspect ratio on hard-to-machine materials. Recently, instead of using an acid electrolyte, more and more research has focused on neutral salt electrolytes because they are less harmful to the environment. However, more problems have been caused to the removal of waste products, especially in deep-hole drilling. Traditionally, an electrolyte flow with constant pressure control is adopted in ECD, which might result in the poor removal of waste products at depth because of pressure loss. In this paper, an ECD method with a constant electrolyte flow has been proposed to obtain a consistent ability to remove insoluble waste products from machining gap. Experiments of ECD with both constant electrolyte pressure and constant flow are conducted on workpieces of Inconel 718. Machining currents and the profile of machined holes are compared between the two methods. The results show that when a constant electrolyte flow rate is applied, the machining currents are much smoother and the profile of machined holes is also uniform. In addition, the pressure variation in the constant flow method increases linearly with machining depth. ECD with a constant flow also has an increased feed rate.