Prediction and compensation of material removal for abrasive flow machining of additively manufactured metal components

Abrasive flow machining (AFM) is a surface finishing process for internal channels and freeform surfaces that is based on the extrusion of an abrasive-laden viscoelastic media. AFM can be applied to additively manufactured (AM) components with high initial surface roughness, but the final geometry after AFM may not meet the required dimensional accuracy due to highly inhomogeneous material removal (MR). In this work, we developed a solution to predict the distribution of MR for a component, and then compensate by adding materials to the component during design. The feasibility and advantage of this new method were demonstrated on a laser sintered test coupon resembling a nozzle guide vane (NGV) section. First, a baseline for MR distribution was established by applying AFM was applied to the NGV without compensation. Profile measurements of an NGV blade before and after AFM showed that dimensional error was almost 600 mu m at some region of the blade profile. Then, based on the measured MR distribution, the NGV design was revised to compensate for MR and then fabricated. With this revised design, profile measurements before and after AFM showed that dimensional error was reduced to less than 200 mu m. The proposed solution of MR compensation has thus been successfully demonstrated. Lastly, to demonstrate the potential to scale this solution, computational fluid dynamics (CFD) simulation of the AFM process and an MR model were also developed. MR distribution predicted by the simulation showed a good agreement with experimental. Finally, pressure, media velocity and geometry were identified as key factors affecting the MR distribution on the NGV blades. The present CFD and MR model can be a tool to predict and compensate for MR during the component design phase, negating the need to obtain experimental MR distribution.