Noncontact acoustic analysis monitoring of plasma arc welding

This paper addresses the problems involved in the automatic monitoring of the weld quality produced by plasma-arc keyhole welding. The acoustic signal of plasma arc welding was acquired by using a condenser microphone at high speed and analyzed with the aid of computers. It is shown that the overall AC power of the acoustic analysis, especially the low frequency part (0–100 Hz) of the acoustic signal power spectra, greatly varies with the variation of the statuses of the weld pool. A method for detecting the behaviours of the keyhole effect of plasma-arc welding was developed. The experimental results indicate that the method is a usable, practical one in the penetration quality monitoring of plasma-arc welding for on-line quality control.