Erosion threshold and surface roughness maps in hydrodynamic cavitation abrasive finishing process

Abstract

Recently due to the advancement in technologies, manufacturing processes have seen greater heights. One of which is the rise of Additive Manufacturing (AM). However, AM components tend to obtain higher surface roughness. For example, components manufactured using direct metal laser sintering (DMLS) process tend to obtain surface roughness of 14-16 μm. As such, there is a need to surface finish the external surface of the AM components. This study presents the outcome of the experimental analysis of the effect of the Hydrodynamic Abrasive Finishing (HAF) on the external surface of the AM components. Furthermore, this study also presents the outcome of the experimental analysis of the erosion rate and synergism due to Hydrodynamic Cavitation Abrasive Finishing (HCAF) on the external surfaces. The experiments are conducted on squarical as-built nickel-based alloy Inconel 625 parts manufactured using DMLS technique. Controlled erosion due to entrained Silicon Carbide (SiC) particles resulted up to 75 % reduction in the average surface roughness (Sa) on the external surfaces. Scanning electron microscope (SEM) observation illustrated controlled erosion due to entrained SiC particles removed majority of the surface irregularities on the samples. Application of controlled cavitation erosion with additional entrained SiC particles have resulted in up to 94 % synergistic effect. A synergistic effect from the HCAF is examined and explained using the surface morphology observations. Findings have illustrated that the addition of abrasive particles enhances the effect of the cavitation erosion in HCAF which increases the material removal and hence increases the surface quality.