A novel phase-field description for the anodic dissolution during electrochemical machining

Electrochemical machining (ECM) exploits the effect of anodic dissolution to modify the surface roughness of a metal and the shape of the workpiece, allowing the machining of particularly hard metals without causing undesirable microstructural changes such as formation of dislocations [1]. The chemical reactions that take place are highly dependent on the local material properties. In our previous work [2], we presented a homogenized description based on the use of effective parameters. We described the processing of the metal using a dissolution level as an internal variable, assuming its evolution based on Faraday's law of electrolysis. The dissolution process is enabled by the contact of the metal’s surface with the electrolyte and thus, considering the finite element simulation approach, only the finite elements located at the surface can dissolve. The contact between the metal and the electrolyte is ensured by introducing an activation function which is 1 if the respective finite element is located at the surface and 0 if it represents the bulk of the workpiece. To avoid numerical instabilities due to the Heaviside approach, we propose a phase- field ansatz to model the dissolution of the anodic material. The novel formulation allows a smooth transition between the dissolving surface regions and the bulk material. To demonstrate the ability of our model to predict the complex machining process, we will show some first numerical results.