Acoustic emission at the laser weld site as an indicator of weld quality

An experienced laser operator can hear when the desired weld quality is reached by the harmonic content, or timbre, of the sound produced during laser welding. This perceived timbre is the portion of the acoustic emission signature which lies within the audio range. Recent work by several research groups has focussed on finding relationships between the acoustic emission signature and various welding parameters. The purpose of this paper was to analyze acoustic emission signatures to isolate the factors producing the timbral changes perceived by the operator.