Experimental investigation on grinding characteristics of optical glass BK7: with special emphasis on the effects of machining parameters

As a kind of widely used optical material, optical glass BK7 is machined by first grinding and then polishing in industrial production. However, the polishing process is time-consuming and high-cost. Therefore, it is very meaningful to produce high-quality BK7 workpieces by grinding. To understand the grinding characteristics of BK7, many studies were conducted and reported. But most studies available so far had low industrial relevance and were difficult to be applied to guide real production of BK7 glass. To fill this gap, in this study, BK7 grinding characteristics are investigated and special emphasis is laid on the effects of machining parameters in terms of machined surface morphology, subsurface damage, and grinding force. Results show that wheel depth of cut plays the most important role in BK7 grinding, and a little difference of it leads to completely different material removal modes. Wheel speed is the second important parameter. It cannot change the dominant removal mode but can slightly adjust the characteristics of machined surface, subsurface damage, and grinding force. Workpiece feed rate has a small impact on BK7 grinding. From the viewpoint of industrial application, it suggests that the wheel depth of cut of 1.0 μm, high wheel speed, and high workpiece feed rate are more rational and practical because under this condition the grinding process can produce BK7 workpieces, which possess crack-free surface and sublet subsurface damage, with high removal rates and stable grinding forces. The findings of this paper are expected to be meaningful to provide the experimental references for the studies of the BK7 grinding process and guide industrial production of BK7 optical components.