Pit and rim formation during laser marking of acrylonitrile butadiene styrene plastic

Pit and rim formation on the acrylonitrile butadiene styrene (ABS) plastic surface was evaluated after it was irradiated by CO2 and Nd:yttrium-aluminum-garnet (YAG) laser beams. Our results show that the thermal effect floor was well observed at the outer wall of the pit with CO2 laser irradiation while it was not the case with Nd:YAG laser irradiation. The volume and depth of the pit formation increase proportionally with laser irradiation energy while there are significant differences in the slope, width, and full width at half maximum of the pit formation with two different types of laser irradiations. This result shows that CO2 laser irradiation leads to a better cooling contraction effect while Nd:YAG laser irradiation induces a better recoil pressure effect during the interaction between ABS plastic and laser beam irradiation. The shape of the laser marking could vary significantly depending on the traveling path of molten plastic during injection molding of ABS plastic. Therefore, the selection of material and molding process can have a great impact on the laser micromachining of plastic.