Rapid on-machine cutting tool geometry characterisation using 3D laser line scanners

Variation in cutting tool geometry can have a profound impact on the mechanics of cutting and, as a result, affect the quality of the machined surface and the component’s geometric conformance. By characterising the true geometry of cutting tools, the impact of the tool’s key geometrical features on these factors can be quantified, and the accuracy of virtual machining simulations can be improved by enhancing the accuracy of the tool definition in the model. The complexity of cutting tools necessitates the use of 3D inspection, which is typically conducted in a laboratory environment away from the machine tool, taking several minutes or even hours. To address this, a new tool inspection system has been developed using high-resolution laser line scanners to characterise the tool geometry in a machine tool environment within seconds. This results in minimal machine downtime, preservation of the tool setting, and measurement of the true instantaneous geometry of the tool in the machine tool spindle as it is as presented to the workpiece. This study focused on characterising solid end milling tools using the developed on-machine inspection system. A methodology has been established to extract the tool’s key geometrical features, namely the revolved profile, edge radius, and runout, as well as pitch, helix, rake, and relief angles. The on-machine scans were found to take under 10 seconds, compared to over 20 minutes for lab-based measurements taken on an industry-standard 3D focus variation microscope. The on-machine measurements were also in agreement with the lab-based measurements to within 1% for all of the tool’s key features besides edge geometry, which was measured to be an order of magnitude too high and thus requires further development.