Improvement of precision grinding performance of CVD diamond wheels by micro-structured surfaces

Abstract

Chemical vapor deposition (CVD) diamond grinding wheels are used in precision and ultra-precision grinding owing to the high grain density, uniform dispersion of abrasives, and excellent wear resistance. However, the small chip space on the CVD diamond abrasive surface easily interrupts the grinding, which limits the practical applications of these wheels. In this paper, a novel micro-structured CVD diamond wheel was presented for precision grinding of optical glass, to improve the grinding performance. First, continuous and clear micro grooves of 4–6 µm width and 8 µm depth were ablated on the surface of a CVD diamond by a pulsed laser. Different from the conventional structured wheels, the grain size of the CVD diamond was refined from 10 to 20 µm to 5–15 µm by laser micro-structuring. Second, the effect of the micro-structures on the grinding force, force ratio, and ground quality were investigated for optical glass. The normal forces decreased by 48–65%, whereas the tangential force dropped by 25–54%. The normal-to-tangential grinding ratio also clearly reduced owing to the increasing abrasive edges and change in the rake angle of most grains. The measurement results of the ground surface showed that roughness Ra decreased by 5–20% and subsurface damage depth reduced by approximately 25%. In addition, the wear morphology exhibited that abrasion flattening occurred not only on the CVD diamond grain tips but also on the side edges of the micro grooves. This implied that the micro-structures effectively participated in the grinding process, and thus, resulted in an increase in the grain density and enhancement of the cutting effort.