Teachless process monitoring for single item production

At the Institut für Fertigungstechnik und Werkzeugmaschinen (IFW) in Hannover a method for teachless process monitoring was developed, which offers robust and reliable monitoring for production starting with the first manufactured item.

Process monitoring of machine tools is an established method used within automated batch production to ensure high process stability and availability. However, process monitoring systems have to be taught reference data during a ramp-up process. In single item production a ramp-up process is not available, thus a teach-in of the process monitoring is not feasible in this case. At IFW in Hannover (Germany) a method for teachless process monitoring was developed, which offers robust and reliable monitoring for production starting with the first manufactured item.

In order to substitute the ramp-up process, a reference for parameterization of monitoring limits was simulated during the process planning phase (see image below). Relevant information of process planning (CAD/CAM, NC-based simulation) was used to simulate monitoring limits. Hence, teaching of the monitoring system during ramp-up is completely substituted by a simulation during process planning. Thus, an NC-based simulation is not only used to validate and optimize the planned process, which is common practice, but also provides process factors to calibrate the monitoring limits.

Concept of teachless process monitoring

By accessing existing simulation systems to calculate the tool path of a machine tool based on G-code, a way-based simulation of material removal is provided. For calculation of material removal the simulation system “CutS” developed at IFW was used. A tool path based on G-Code was generated by a virtual machine tool. This combined information guarantees a way-based synchrony of simulated reference data and measured signals. The described approach enabled the parameterisation of robust monitoring limits parallel to the process.

Combination of NC-based simulation and process simulation 

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