Optimal process parameters for thermoplastic polyetheretherketone joints fabricated using transmission laser welding and Lumogen® IR absorptive pigment

This study investigates the effects of the process parameters (laser power and irradiation time) on the bond quality of transmission laser welded polyetheretherketone. Commercially available Lumogen® IR pigment was added to the bulk of the polymer for laser absorption. Quasisimultaneous beam configuration was used to weld injection molded samples of 0.7 mm thickness in a lap joint configuration. Combinations of laser power (40–80 W) and irradiation times (10–50 s) were investigated. The laser power was found to have the most effect on weld strength, while irradiation time did not have a marked effect on weld strength. At optimal process conditions, the weld strength ranged from 20 to 45 MPa. High variability in weld strength was seen within groups with identical process parameters and was attributed to the variability in material morphology as a result of injection molding. X-ray tomography was utilized to view intact weld interfaces. A significant finding was the presence of voids (up to 0.5 mm diameter) at the weld interface.