Novel multiphase jet polishing for complicated structured components produced by laser powder bed fusion

Powders and burrs inside an additively manufactured spacecraft heat exchanger must be removed to avoid catastrophic failure during launch and service in aerospace. However, polishing the inside of heat exchangers with intricate architecture is either impossible or exceedingly laborious. In this regard, heat pipes made of aluminum (Al) alloy must be enclosed in skins made of Al alloy, which adds weight. Even so, there is a chance of powders and burrs sliding off due to skin damage with this measure. To address this issue, a novel approach of multiphase jet (MPJ) polishing was devised in this study to polish the inside of heat pipes with intricate structures printed with three distinct linear energy densities. After polishing, adhered powders and burrs were removed from the interior of heat pipes, achieving the desired weight reduction and avoiding the possibility of powders and burrs falling. The material removal rate for MPJ polishing is 1.64 mg/min to polish a heat pipe with a length of 400 mm, and the length to diameter ratio is 87:1. The surface roughness of the inlet after polishing is reduced from Sa 5-0.214 & mu;m, a 23-time improvement in surface quality over the pristine surface. It has been discovered through computational fluid dynamics simulations that projecting defects such as balling and satellites can cause a 5 times greater impact rate and a larger impact angle, resulting in a greater loss of impact speed. The phenomenon of preferential removal of balling and satellites by abrasive jets was discovered for the first time, elucidating the benefits of jet polishing for additively manufactured components. These findings provide new insights into how to polish and fabricate high-performance components with complex structures, resulting in effective weight loss and avoiding catastrophic spacecraft failure.

Automated summary

A novel multiphase jet (MPJ) polishing method was devised to polish the inside of heat pipes with intricate structures, achieving the desired weight reduction and avoiding the possibility of powders and burrs falling. The material removal rate for MPJ polishing is 1.64 mg/min to polish a heat pipe with a length of 400 mm and a length to diameter ratio of 87:1. The surface roughness of the inlet after polishing is improved by 23 times compared to the pristine surface, providing new insights into how to polish and fabricate high-performance components with complex structures.