Multiphysics Modeling Prediction of Electrochemically Machined through-Hole Geometries
Authors: Skinn Brian , Liu Danny X. , Hall Timothy D , Snyder Stephen , Rajurkar K. P. , Taylor E. J. 
Published: February 2020

Electrochemical machining (ECM) is a manufacturing technology that allows metal to be precisely removed by electrochemical oxidation and dissolution into an electrolyte solution. ECM is suited for machining parts fabricated from “difficult to cut” materials and/or parts with complicated and intricate geometries. In ECM, the workpiece is the anode and the tool is the cathode in an electrochemical cell; by relative movement of the shaped tool into the workpiece, the mirror image of the tool is “copied” or machined into the workpiece. Figure 1 shows photographs of a shaped ECM tool (cathode, panel A) and the resulting part (anode) surface after machining (panel B). Compared to mechanical or thermal machining processes where metal is removed by cutting or electric discharge/laser machining, respectively, ECM does not suffer from tool wear or result in a thermally damaged surface layer on the workpiece. Consequently, ECM has strong utility as a manufacturing technology for fabrication of a wide variety of metallic parts and components, and includes machining, deburring, boring, radiusing and polishing processes. ECM provides particular value in that application is straightforward to high strength/tough and/or work-hardening materials such as high strength steel, chrome-copper alloy (C18200), nickel alloy (IN718), cobalt-chrome alloy (Stellite 25) and tantalum-tungsten alloy (Ta10W), since the material removal process involves no mechanical interaction between the tool and the part. A variety of production applications are envisioned as well suited for ECM techniques.
One notable difficulty with ECM, common to a variety of manufacturing operations, is an inability to predict a priori the tool and process parameters required in order to satisfy the final specifications of the fabricated part. In this talk, Faraday will present results from ongoing development work of a physics-based design platform to predict optimal ECM tool shape using commercially available multiphysics simulation software. This predictive capability is anticipated to dramatically shorten the process/tooling development cycle, eliminating much or all of the iterative prototyping necessary in the absence of a predictive tool. The main focus of this talk will be a comparison of through-holes fabricated by CM in flat plate and/or tube geometries to those predicted by multiphysics simulation. The various physics included in the models to enable accurate simulations will be discussed, along with any (semi-)empirical simplifying assumptions made to accelerate execution of the simulations. The overarching objective of the current and future work, to demonstrate accurate modeling of ECM through-hole features of progressively increasing experimental complexity (e.g., the perpendicular and angled holes of panels C and D of Figure 1), will also be presented.

Figure 1 Caption

Photograph of shaped ECM tool (A), with resulting machined surface (B). Conceptual schematics of perpendicular (C) and angled (D) through-holes in a flat-plate part geometry.

Figure 1