Laser welding defects detection in automotive industry based on radiation and spectroscopical measurements

Laser welding is a common technique in the automotive industry. For economic reasons, it is of great importance to detect the defects that can appear. The CO₂ penetration laser welding process is characterized by the formation of an electron-free plasma whose radiation can be measured to detect the defects. This paper presents two different approaches to defect detection. The first is based on the correlation between the power spectrum of a photodiode-generated signal and the defects. The second approach is based on the plasma electronic temperature, which is correlated to the presence of defects. Results obtained in an industrial facility under production conditions are presented.