Development and implementation of in-process, orbiting laser-assisted healing technique on fused filament fabrication

Fused filament fabrication is one of the most widely used additive manufacturing processes for producing thermal plastic polymer materials due to the affordable cost and capability to build objects with complex structures. However, parts fabricated with this process exhibit lower mechanical strength when compared to parts manufactured using traditional methods. In this work, an in-process orbiting laser healing technique is developed and implemented on a 3D printer to enhance mechanical strength by improving interlayer adhesion. The orbiting laser assembly can position and align the laser-heated spot before the change of nozzle direction occurs, ensuring that the previous layer is heated prior to material deposition. This laser-heating technique increases the bending strength along the build direction by 40% and reaches 88.9% of the strength along the longitudinal direction. With this technique, the displacement at fracture also increased by 54.3% compared to control sample. The thermal profile of the melting pool and fracture surface was further characterized using a thermal camera and SEM to support the effect of laser heating on polymer microstructure, respectively. Due to its enhanced print quality and lower cost, this technique has the potential to expand the application field of fused filament fabrication to small batch and series production that are currently dominated by injection molding, as well as the high-quality prototyping field.