Abrasive flow machining of laser powder bed-fused parts: Numerical modeling and experimental validation

Abstract

Abrasive flow machining (AFM) is considered one of the best-suited candidates for the finishing of complex components made by additive manufacturing. However, the AFM process leads to mass loss and consequent alteration of the part geometry and dimensions. A numerical tool is needed to reduce the number of time-consuming and labor-intensive experimental trials and allow the efficient prediction of machining allowances for the final geometry and surface finish of AFM-processed parts. This paper presents a combined numerical-experimental approach to predict the results of such a polishing process. The model devised simulates the indentation of abrasive grains to a workpiece and takes into account the initial surface roughness of the part as well as the velocity and pressure of a polishing medium abrading the surface, the latter obtained via computational fluid dynamics (CFD) simulations. To validate the model, an experimental study has been carried out on laser powder bed-fused Ti-6Al-4 V coupons containing multiple planar faces with different surface roughnesses resulting from their variable orientations during manufacturing. With respect to material removal, simulations and experiments provided very close results, and the relatively minor discrepancies observed may be reduced by refining the calibration protocol and adjusting the boundary conditions of the model.