Cathode design for complex shapes in electrochemical machining

Electrochemical machining (ECM) is one of the most efficient nontraditional machining processes to provide bright surface finish, machining difficult to cut materials and manufacturing complex shapes. However, due to some challenges like the lack of dimensional accuracy, process control and monitoring and environmental factors, implementation of ECM process has been limited. This study presents a mathematical model to design cathode surfaces for machining freeform surfaces. This mathematical model is based on solving 3D Laplace equation by using Finite Element Method (FEM) to determine the potential distribution between the anode and cathode surfaces. A desktop size electrochemical (EC) machine was designed and constructed to carry out the experimental works. Experimental studies were carried out on AISI 1040 carbon steel using copper, brass and stainless steel as cathodes. Nine different cathodes have been designed via feed rate and electrical conductivity variables to investigate the validity of this mathematical model. A 3D scanner was used to measure and compare of the electrochemical machined anode surfaces with the CAD model. The experimental results showed that NaCl type electrolyte cause over machining at the edge where the electrolyte transferred to the gap domain. In the middle of gap domain similar dimensional error (DE) values have been obtained due to well-made electrolyte transition. From the 3D scanned machined surfaces, it has been observed that higher value of electrical conductivity with higher feed rate has been producing a more accurate shape. Furthermore, three different ECM freeform surface drawbacks investigated and designed control mechanisms have been presented.