Pulsed thermographic inspection of spot welds

In automotive manufacturing, the lack of nondestructive methods for assessment of spot weld integrity has been a critical shortcoming, with enormous economic consequences for both domestic and foreign auto makers. At present, auto body welds are subjectively evaluated using destructive pull tests, or visual examination after the weld has been mechanically separated using an impact tool. Pulsed thermographic evaluation of spot welds offers a fast, noncontact method for quantitative assessment of the weld nugget. The technique can be applied using either one or both faces of the weld. Results on steel resistance welds will be presented, along with correlation to weld process parameters.