A comprehensive investigation of abrasive barrel finishing on hardness and manufacturability of laser-based powder bed fusion hollow components

One of the main issues of laser-based powder bed fusion (LB-PBF) parts is surface quality and dimensional deviations, which require post-processing. Conventional post-processing such as turning and milling cannot machine internal surfaces and therefore is not suitable for hollow components. In this paper, Ti–6Al–4 V components with different hollow shapes were printed by LB-PBF and post-processed by centrifugal barrel finishing (CBF). Samples were printed based on Taguchi L18 design of experiments (DoE) on the (L18: 21 × 33) matrix and polished in abrasive solution by porcelain triangular media 2 × 2 mm. The effect of process parameters including rotation direction, speed, time and volumetric percentage of abrasive on hardness and manufacturability, including surface quality, material removal rate (MRR) and dimensional deviation, are discussed. The novelty of this work is the application of this process to clean both the internal and external surfaces of LB-PBF parts, where previously it has only been investigated for external surfaces. This paper scrutinized the performance of the CBF on internal geometries, and it was shown for the size of the investigated components, the hexagonal hollow achieved the highest maximum removal rate over the square and circular hollows. In addition, the effect of CBF on plastic deformation and microstructural characterization has been investigated to find the effect of this process on work hardening. The results of this study also show that the rotational speed and the volumetric percentage of the abrasive directly drive the MRR. A higher rotational speed increases the slope of the sliding path and the sliding speed between printed parts and abrasive media, which causes higher cutting and grinding, MRR and media wear rate.