Dissimilar Laser Welding of Plastic to Stainless Steel with a Flat-Top Heat Source: Numerical Simulation and Experimental Investigation

Diode laser with a flat-top beam was very suitable for the joining of plastic and metals as its uniform energy distribution to fine tuning the temperature, which facilitates the melting of plastic achieving a sound bonding and prevents the decomposition of plastic forming undesirable bubbles. Therefore, the control and study on the temperature field during diode laser welding of plastic to metals are of importance. In this paper, a flat-top thermal source model was established to assist the simulation of the transient temperature field distributions of laser conduction welding of 304SS and PET. With the increase in welding speed from 10 to 30 mm/s, the peak temperature at the PET side decreased from 702.14 to 591.9 K, which was even below the PET decomposition temperature ~ 659 K thus eliminating the formation of bubble within PET. Two regions were observed in the laser joints which corresponded to the PET melting region and PET glass transition region base on the comparatively study between numerical simulation and experimental investigation.