Robot-assisted optical measurement method for the wear analysis of cutting tools⋆

Accurate assessment of turning tool wear is essential for tool life and product quality. Yet existing cobot or robot-assisted optical systems suffer from >50 μm pose errors that prevent repeatable micrometer-scale wear mapping. To address the gap, an in situ measurement system integrating a chromatic confocal sensor, a robot arm, and precision linear stages was developed for a turning application. A Tool Coordinate System (TCS) based on the unworn insert edge was introduced to compensate robot positioning errors. Experiments on rhombic carbide inserts demonstrated a positioning precision of ≈6 μm, one order of magnitude better than the robot's nominal repeatability. The measured maximum wear width (VB_max) follows reference profilometry across cutting length from 50 m to 1400 m, with standard deviations between 4.5 and 1.6 μm. Compared to commercial cobots, the proposed method achieves substantially higher accuracy at the cost of longer acquisition time. These results confirm that the TCS framework enables reliable and repeatable 3-D tool geometry measurements and will provide benchmark data for predictive wear models and adaptive machining strategies.