Formation Mechanism of Grain Cutting Edges in Micro Dressing of Polycrystalline cBN Grinding Wheels

Abstract

This paper presents a mechanism for the formation of grain cutting edges in the micro dressing of coarse-grain polycrystalline cubic boron nitrite (cBN) grinding wheels using a fine-grain diamond dresser. Many grain cutting edges having a flat surface consisting of ductile smooth surfaces as well as many brittle micro dents, are formed on the working surface of the coarse-grain (#80 mesh) cBN wheel by micro dressing using a fine-grain (#1200 mesh) diamond dresser. This result shows that the flat surfaces of cutting edges on the wheel surface are formed on the basis of a ductile removal process as well as a brittle micro-fracturing of cBN grains by the diamond cutting edges. Moreover, cylindrical grinding experiments with these wheel working surfaces were conducted to clarify the feasibilyty of creating a ground mirror-like surface. As a result, it was confirmed that high-quality mirror surfaces with roughness less than 0.03 m Ra can be efficiently formed using the working surface prepared by this micro dressing method.