A robot-assisted optical approach for the in-situ measurement of cutting tool wear development

Abstract

In-situ measurement of cutting tool wear is essential for understanding wear mechanisms and for improving machining reliability and process efficiency. However, most established measurement methods require periodic interruption of machining operations and tool removal, which prevents continuous observation of wear progression and may introduce measurement inconsistencies. This work presents a robot-assisted optical approach for the in-situ measurement of tool wear development directly on a CNC (Computer Numerical Control) machine. The system combines a chromatic confocal point sensor with a six-axis industrial robot and two precision linear stages. A tool coordinate system derived from the unworn tool geometry is introduced to compensate for robot positioning uncertainties and to ensure repeatable measurements of identical tool regions. The width of flank wear land is determined automatically from line-scan profiles using a segmentation-based algorithm. For flank wear land width determination, a standard deviation between 2.2 μm and 12.5 μm are obtained, which is mostly below the target uncertainty threshold of 10 μm (3% of the typical maximum allowable width of flank wear land of 300 μm). Finally, on-machine experiments conducted over the full life cycle of several cutting tools demonstrate that the proposed approach reliably captures tool wear progression under realistic machining conditions. The results show that robot-assisted chromatic confocal sensing enables quantitative in-situ wear monitoring without removing the tool from the CNC machine.