An Experimental Investigation on Response of cBN Super Abrasive’s Grinding Performance and Failure Characteristics to the Grinding Speed

Abstract

Cubic Boron Nitride (cBN), a kind of super abrasive material with excellent properties, is widely applied into the manufacturing of high end grinding tools especially for high speed machining fields. During the actual grinding process, abrasive failure phenomena take place, which affects the grinding tool performance, and then the final machining quality. Considering the high speed applicability of cBN grinding tools, it is of significance to investigate the failure mechanism and grinding performance of cBN abrasives at different grinding speeds, in particular under high speed condition. Therefore, this paper carries out an investigation of cBN abrasive failure behavior taking grinding speed sensitivity into consideration. Given that the random and diversity of multi-abrasives distributed upon grinding tools contributes to the complexity of the study, single cBN abrasive cutting experiments are conducted under four grinding speed levels of 40, 60, 80 and 100 m/s, respectively. When all experiments are completed, abrasive failure patterns can be identified through observation on the morphology of ground cBN abrasives bonded on cutting inserts using Scanning Electron Microscope (SEM). Based on the analysis of experimental results, it is shown that for the cBN abrasives studied in this paper, abrasive breakage occurs at low grinding speed, but as speed increases, cBN abrasives tend to get worn. The change of grinding forces, as well as roughness Ry values, can show the detailed failure behavior of tested cBN abrasives with time dependent features. In addition, G ratio rises with the increase of grinding speed, which demonstrates the high productivity potential of cBN high speed grinding. Finally, an in-depth analysis concerning on cBN material’s crystal characteristics and energy threshold (binding energy) is discussed, which provides an intrinsic explanation on the influence of grinding speed upon cBN abrasive failure mechanism.