Development of a Self-propelled Multi-Jet Polishing Tool for Ultra Precision Polishing

As the needs of optical glasses are on the rise, the precision on shape, form, surface qualities and the scaling down of sizes are rising, too. The standards and surface finish of reference mirrors used in measuring appliances are crucial; hence, enhancement of the surface finish is indispensable in manufacturing industries. This paper proposes a self propelled multi jet polishing technique for ultra precision polishing process in which bladeless Tesla turbine was used as a prime mover. The turbine is characterized by high swirling velocity at the outlet; therefore, high kinetic energy in the course of away from the turbine was used as polishing energy. Simulation of the flow of the field of turbine blades using computational fluid dynamics software (CFD) has also been presented. With a newly designed and manufactured polishing tool, this paper investigates the optimal polishing parameters for surface roughness improvement of crown optical glasses using Taguchi's experimental approach; signal-to-nose (S/N) ratio and ANOVA analysis was also carried out to determine the effect of main factors on the surface roughness. Consequently, a 2.5 mu m size of Al2O3 abrasive, 10wt% abrasive concentration, 80rpm of polishing head, 6 numbers of nozzles, 6 kg/cm(2) of pressure, and 45min. of polishing time have been found to be the optimal parameters. It was observed that about 94.44% improvements on surface roughness; Ra, from 0.360 mu m to 0.020 mu m has been achieved using the optimal parameters. In addition to this; angular speed of polishing head, pressure and polishing time were found to have significant effect on surface roughness improvement.