Project Information

The application characteristics of components manufactured out of aluminium alloys are determined by the properties of the boundary layer. The input variables of the selected manufacturing strategy in finishing significantly influence the surface structure as well as the properties of the boundary layer. However, this is not yet realized for the conditioning of surface and surface layer of a component in the finishing process, although some effects, such as the relationships between the processing conditions and the physical properties of the surface layer, are already researched and described. To achieve a more systematic approach, a soft sensor technology for turning of EN AW-2017 will be developed. Thus, alterations of the boundary layer due to the machining process are predicted and the input variables are governed in situ to achieve a predefined fatigue strength. A subsidiary objective is the design and implementation of novel sensors for the in situ measurement of temperatures as well as electrical currents and voltages. This method is based on the Seebeck effect and the typically increasing cutting temperature between workpiece and tool during machining. Additionally, the flank wear of the tool is determined in situ by means of electrically measured variables. Furthermore, a sensor system is implemented in the test device, which is based on the electrical resistance change of the boundary layer. Thus, conclusions on the microstructure of the boundary layer (e. g. grain size) and the monitoring of the process are enabled. The in situ measured and the input variables of the machining process as well as the ex-situ measured variables referring to the boundary layer properties are correlated. The abovementioned dependencies and relations represent the mathematical foundation of the soft sensors. Based on statistical test plans and regressive considerations the robustness of the resulting surface properties (e. g. residual stress state) compared to the disturbance variables is evaluated. Thus, interference-specific feedback control variables can be introduced, reducing deviations compared to the targeted boundary layer properties. Therefore, a permanent adjustment of the fatigue strength in turning of aluminium alloy components will be guaranteed.