A novel approach of jet polishing for interior surface of small grooved components using three developed setups

It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm. Traditional polishing methods are disabled to polish the component, meanwhile keeping the structure intact. To overcome this challenge, small grooved components made of aluminum alloy with sizes less than 1 mm were fabricated by a custom-made printer. A novel approach of multi-phase jet polishing is proposed using a developed polisher, consisting of solid, liquid and gas phases. In comparison, an abrasive air jet polishing is suggested through a customized polisher, including solid and gas phases. After jet polishing, surface roughness (Sa) on the interior surface of grooves decreases from pristine 8.596 to 0.701 and 0.336 μm by abrasive air jet polishing and multi-phase jet polishing, respectively, and Sa reduces 92% and 96%, correspondingly. A formula is given out for the relationship between linear energy density and unit defect volume. The optimized parameters in additive manufacturing are that linear energy density varies from 0.135 to 0.22 J∙mm-1. Defect volume of unit area achieved by optimized parameters lessens 1/12 that of non-optimized ones. Computational fluid dynamics simulation reveals that material is removed by shear stress, and the alumina abrasives experience multiple collisions with the defects on the heat pipe groove, resulting in uniform material removal. This is in good agreement with the experimental results. The novel proposed setups, approach and findings provide new insights to manufacture complex-structured components, polish the small grooved structure, and keep it unbroken.