Laser welding in e-mobility: process characterization and monitoring

The global automotive industry is shifting to e-mobility, where the main challenge is addressed to battery’s mass-production. To keep up with the market demand, high speed production rates and quality products must be accomplished. Since laser welding of dissimilar thins sheets has earned rising demand for battery electrodes connections, a defect-free welding process has to be performed on behalf of a closed-loop monitoring system that updates corrective and/or preventive actions in order to obtain a reliable, “zero waste, zero stop” process. However, nowadays photodiode systems do not allow real-time modification of the parameters, they only tell, at the end of the process, if any signal has gone out of threshold. The objective of this paper is to find correlations between the data collected by the monitoring system with the typical process characteristics of laser welding. Materials investigated are pure copper 300 µm and aluminum 400 µm, processed by means of different sources, length tracks, wavelengths and scanning heads. In this contribution, a Precitec system has been implemented as a possible economical and industrial-oriented solution. The experimental data was analyzed offline and the relationships between technological and signals outputs were evaluated by means of statistical analysis with MATLAB for both Al-Cu and Cu-Al configuration. Findings plotted stable signals if high speeds were set. Results further suggested the power to be the most influent variable for the closed-loop monitoring system and the dependance on the first material irradiated and the laser source used to define the threshold value for the control of the welding process.