Abstract
An in-process monitoring system was developed to monitor CO2 laser welding quality with two photo sensors set at different aiming angels to detect long-term power stability as well as underfill and pitting defects, and has been used in production line for tailored blank welding of automotive parts since 1993. Stability of the laser power can be monitored by long-term recording of the average intensity of the plasma emission. The underfill can be recognized by decrease in the light emission detected by the low angle sensor, since the hot core of the plasma plume is hidden by the surrounding material.
Small pits can be detected by sharp decrease in the light intensity recorded by the high angle sensor.
