Abstract
In machining with a micro-machine tool and a super-precision machine tool, monitoring the state during the cutting process is extremely difficult since the point where the cutting occurs is very small. In addition, the cutting phenomena involve microscopic behavior. Also, adjusting the height of the cutting tool edge in facing process with a lathe is important because it causes cutting defect at the center of the end face and worsen the surface roughness. In order to examine the relationship between the acoustic emission (AE) signal and the state of cutting surface, AE signals from cutting experiments of end face with different cutting tool edge heights were measured.