CO2 Laser Engraving of Injection Moulded Polycarbonate: Experimental Investigation

The laser engraving process on a 3.2 mm thick polycarbonate sheet using a low power CO₂ laser is investigated herein. For this purpose the scanning speed, laser power and laser focal position are considered as laser input parameters. Depth of laser beam penetration, engraving width and heat affected zone (HAZ) are supposed to be the process output parameters and the measurements of these areas were made by optical microscope. It should be noted that the pressure of laser assist gas is the same in all samples. In this process, in some samples, the quality of the laser engraving was very suitable, with a maximum penetration depth of 1.25 mm. It is shown that the penetration depth of laser engraving increases with increasing laser power and decreasing the laser speed due to increasing heat input. In addition to the heat input, laser focal point is effective on the interaction time of the laser beam with the workpiece. It was supposed that with decreasing laser focal point and the laser scanning speed, then the laser beam has more interaction time with the polycarbonate sheet, resulting in more significant amount of evaporation, which increases the penetration depth of the laser beam into the workpiece.