Wheel Life and Cutting-Edge Wear in Mirror-Grinding Using a Coarse-Grained cBN Wheel Treated by Microdressing

Abstract

This paper presents the wheel life and wear behavior of the cutting edges of a coarse-grained, microdressed cubic boron nitride (cBN) wheel used in mirror-grinding of hardened roll-steel. Many grain-cutting edges with smooth, ductile-mode cut surfaces and numerous brittle-mode-fractured micro dents are formed on the wheel’s working surface after microdressing with a fine-grained diamond dresser. Cylindrical mirror-grinding experiments are conducted using a metal-bonded cBN wheel with a mesh size of #140 (Average grain size d_a=105μm). A mirror surface with a roughness below 0.2 μm Rz can be efficiently formed with the wheel surface treated by the abovementioned microdressing method. This wheel surface can perform mirror-grinding with precision for more than nine hours. A flat plane formed via attritious wear of the cutting edge gradually extends with increasing accumulated stock removal, and simultaneously, the unevenness due to wear streaks on this flat plane increases. This increase in the unevenness of the worn flat plane is the main factor causing an increase in the roughness of the mirror surface.