Another possible reason is based on SEM observations. At low cutting speed, grooves develop on the flank wear land (Fig. 24). When such a cutting edge is engaged with a workpiece, the defects in part will be copied on to the newly generated surface. In such event, it is likely that the surface will be rough. With an increase in cutting speed, the grooves will gradually be reduced; thus, the cutting edge and wear land will become smoother (Fig. 24). The influence of wear land grooves on surface roughness was also observed by Yan et al. [34], Fang et al. [35], Yao et al. [36] and Singh et al.[37]. They summarized that with the formation of grooves, surface roughness increases and largely depends upon the depth of the grooves.