The effect of laser beam transmission on the thermoplastic composite joint formation

The goal of this work was to analyse the influence of laser welding process parameters using different plastic transparency. To achieve this task the elemental composition of plastic PPAGF40 with 20 % and 30 % transparency parts were examined using EDS analysis and cross-sections were evaluated by using optical microscope. Burst pressure was performed to evaluate the strength of welded joints produced with different laser welding process parameters. Studies showed that welded joints with 20 % of transparency possessed burn spots on the surface of samples. Cross-section analysis revealed tendency, that plastics with 30 % transparency led to higher temperatures in welding seam using the same process parameters used for 20 % transparency, which caused pores to form inside joint. Laser power of 390 W, scan-speed 1000/800 mm/s and 3000 N of clamping force used for 20 % transparency plastic parts are not suitable for 30 % transparency plastic parts. Welding process optimization achieved by using 1400/1200 mm/s scan-speed and 2700-3000N clamping force, which showed improved burst pressure values from 7.2 to 7.9 bar. Reduced welding cycle-time achieved from 2.2 to 2.3 s with 30 % transparency of polymer PPAG40 material. (paper)