Influence of the Material on the Measurement of Surface Roughness Using Eddy Current Technology

To enable a property-controlled production by embedding a feedback of component properties into the machining process, an appropriate sensor system needs to be integrated into a production line. This study serves to analyze the possibility to measure the surface roughness of ferromagnetic and austenitic steel using the non-destructive eddy current technology. Thereby, it was possible to create a correlation between the measured voltage and the surface roughness. Arithmetic average surface roughness values greater than 1 µm and average maximum height of profile of over 4 µm can reliably be distinguished. Furthermore, a film sensor was developed to realise the inspection of cylindrical surfaces like shafts. Here, again a good correlation between the roughness of turned shafts and eddy current measurements could be found. Additionally, the influence of the excitation frequency on the measurement results, depending on the material tested, was analysed and a coherence between values gained by the Abbot curve was detected.