Estimation of the plasma spectrum RMS signal as an alternative spectroscopic approach for arc-welding quality monitoring

Abstract

Plasma spectroscopy has demonstrated its potential within the framework of welding process quality monitoring. The analysis of the welding plasma spectrum, which is formed by several emission lines from the different elements participating in the process, gives rise to spectroscopic parameters exhibiting a direct correlation to the quality of the resulting seams. The plasma electronic temperature has been the traditional selection in this regard, mainly by using an approximation where only two emission lines from the same species are involved in the calculations. However, for a completely automated system, the computational cost involved in the process could be a serious drawback. In this paper we propose the use of the plasma spectrum RMS (Root Mean Square) signal as an alternative spectroscopic approach, as it will be demonstrated that this parameter can be also used to identify the appearance of weld defects in an on-line quality monitoring system.