Development Of A Special Grinding Fluid For Ultra-precision Machining Of Optical Glass

With the continuous development of technology, ultra-precision machining ofoptical glass is facing increasing challenges. The ductile grinding can make opticalglasses fabricated in a ductile removal mode for a high-quality surface, while theductile grinding requires that the largest cutting depth must be less than the criticalcutting value of the work-piece. Therefore, the ductile domain grinding of the opticalglass calls for high requirements for the feed precision and spindle stiffness of themachine, resulting in soaring costs and limited range of application. As for thisproblem, a method that can improve the critical cutting value of the optical glass,reduce the requirements for machine tools and machining costs and obtain ahigh-quality machined surface was proposed in this paper by developing specialgrinding fluid for the optical glass. The special grinding fluid for the optical glass notonly own the characteristics that other ordinary ones all have, such as cooling,lubricating, antirust and cleaning properties, but also can react with the optical glass inthe grinding region.In this paper, the research that regarded the surface chemical modification ofoptical glass as the special characteristic of grinding fluid has been done. The reactionbetween water, sodium carbonate solution (concentration of5%,15%,25%) andquartz glass at80℃for5hours was inspected with ICP-AES method by theconcentration of Si. The results showed that the Si existed in the4solutions whichdemonstrated that the four kinds of solution had all reacted with quartz glass. Theconcentration of15%reacted had the highest Si concentration showing the strongestreacting strength. The optical surface morphology and mechanical properties variationof the optical glass after surface chemical modification were detected and analyzed bynano-indentation and scratch tests. The results showed that there was a layer of12nmmembrane on the quartz surface, the glass surface hardness and modulus declined andthe critical grinding depth value αcincreased by39.1%which reduced the difficultyof quartz glass grinding in ductile mode. Special grinding fluid for optical glass wasdeveloped by adding other additives to that. The orthogonal experiments of grindingquartz glass with the developed grinding fluid were done to ensure the types ofadditives and the best ratio among the components. Then grinding verificationexperiments and contrast experiments with commercially available grinding fluidwere carried, which proved that the surface quality of the quartz glass grinded with the special grinding fluid was better than that with the commercially availablegrinding fluid.