Calibration of an on-board positioning correction system for micro-EDM machines

The work presented in this article focuses on a positioning and inspection contactless system aiming at improving the accuracy of the micro-EDM machining of film-cooling channels in turbine blades. These components are freeform and characterized by relatively high levels of uncertainty, which leads to a difficult on-machine positioning relying on traditional methods such as precision mechanical jigs and mechanical touch probes. The presented system is based on the 3D acquisition of the work piece via a laser triangulation sensor integrated in the micro-EDM machine tool. This system allows the acquisition of millions of data points and so to correct the work piece position inside the machine tool reference frame by means of dedicated algorithms based on surface fitting principles. Furthermore, the capabilities of the chosen senor allow for the after work inspection of the machined work piece. The system has been developed in close collaboration with SARIX SA, a Swiss machine tool manufacturer, and the experimental campaign is hereby included.