A new criterion for quality monitoring of pulsed laser spot welding using an infrared sensor Part 1: The radiation feature as a criterion for quality monitoring

Abstract

Many manufactured goods use pulsed laser spot welding in joining and weld quality has to be controlled in particular. This paper suggests a criterion for quality monitoring of pulsed laser spot welding of thin metal sheets using a point infrared (IR) sensor. A new radiation feature is derived from a mathematical model and its properties are examined. Weld quality is closely related to temperature profile and there are many cases that can generate the expected weld quality. Change in weld quality should be detected from the variation in temperature profile. Simulation results show that the radiation feature can be used to detect the change in the initial temperature profile. In the experiments, radiation features and weld cross-sections were examined for various welding conditions. Results show that the radiation feature could detect the dimensional variation of the heat-affected zone (HAZ).