Pressure-dependent shape adaptive multi-jet polishing for edge effect restraint

Abstract

Fluid jet polishing (FJP) can achieve high surface quality and form accuracy in finishing freeform surfaces. Due to its advantages, FJP has been widely used in the ultra-precision manufacturing process of high-end components. However, the edge effect in FJP poses a great challenge to the uniform material removal control at the edge, which has not been investigated in depth hitherto. The non-uniform material removal at the edge deteriorates the form accuracy and affects the functional performance of components, especially in the field requiring extremely high precision. The traditional strategy for restraining the edge effect through the movement system is limited by the extremely high acceleration speeds within a small distance. To address this problem, the cause of the edge effect in FJP is first revealed by computational fluid dynamics (CFD) simulation. Hence, this study presents a pressure-dependent shape-adaptive multi-jet polishing (PDSAMJP) system to restrain the edge effect. The material removal discrepancies were compensated for by adjusting the jet pressure, rather than modifying the feed rate of the machine tool. A surface generation model at the edge was established to optimize the jet pressure distribution. The effectiveness of the PDSAMJP system was validated by jet pressure response measurements and a series of polishing experiments. Compared to traditional jet polishing, the PDSAMJP method enhanced the radius of curvature of the edge surface from 15.2–41.4 μm to 73.2–143.9 μm by mitigating edge collapse. The success of this study provides an approach to restraining the edge effect of FJP, thereby enhancing the manufacturing accuracy of ultra-precision freeform surfaces. Furthermore, the principles established herein can be applied to other polishing processes, such as bonnet polishing, to achieve uniform material removal by adjusting a parameter with a fast response, without compromising the stability of the movement system.