Surface integrity and material removal mechanism in fluid jet polishing of optical glass

Fluid jet polishing (FJP) is a promising technology that has been increasingly used in the superfinishing of complex optical lenses, mirrors, and molds on several materials. The influence mechanism of polishing parameters on the damage characteristics, element composition, and surface quality of optical glass was studied through a series of FJP experiments to achieve the high-efficiency and low-damage ultra-precision polishing requirements of optical components. A numerical model for FJP was developed based on computational fluid dynamics (CFD), and the effects of slurry pressure and particle size on the flow field and particle motion characteristics were studied combined with statistical theory. The brittle-ductile transition model and erosion model when abrasive particles eroded optical glass were established to obtain a better understanding of the material removal mechanism during FJP. The damage control strategy can be clarified according to the coupling relationship between the impact velocity and particle size of abrasive particles when radial and transverse cracks are generated in the optical glass. The experimental results verify that the established model can predict the material removal characteristics well. The simulation results also indicate that the erosion removal of the optical glass by abrasive particles is a completely ductile mode under the polishing experimental conditions in this study. The results can provide solid theoretical support for equipment upgrade and process optimization of FJP. •The influence mechanism of polishing parameters on surface and subsurface quality was revealed.•A numerical model was established to investigate the flow field and particle movement characteristic.•The brittle-ductile transition model was developed to clarify the erosion mechanism.•The slurry pressure and particle size affect the impact velocity and spatial distribution of abrasive particles.•The damage control strategy for optical glass was established based on experimental and numerical results.