Effect of in-process laser interface heating on strength isotropy of extrusion-based additively manufactured PEEK

Fused Filament Fabrication (FFF) 3D printing provides an effective solution for fabrication of custom components at affordable cost and in short time. Nevertheless, relative to the conventional methods, the anisotropic properties exhibited by FFF 3D printed parts cause the mechanical strength to be less satisfactory. In order to resolve the problem, we propose an in-process laser local pre-deposition heating (LLPH) method, which is capable of enhancing thermal relaxation at inter-layer interface and reinforcing inter-layer adhesion, that ultimately resulted in an increase in tensile strength along the build direction. This improvement in tensile strength of the build parts with in-process laser power has been demonstrated in this manuscript. Besides, the subsequent relevance with polymer relaxation, reptation and entanglement has been discussed. As verified by mechanical testing, tensile strength was improved by 350% compared to control sample and 99.5% isotropy was achieved (build-direction strength divided by in-plane strength) with the application of laser. Scanning Electron Microscope was used to make observation of isotropic behavior at inter-layer interface.