Insights into the friction stir processing of fused filament fabricated polymers with multiple reinforcements

Abstract

ABSTRACT Friction stir processing (FSP) is a most widely used severe plastic deformation (SPD) technique used for enhancement of mechanical properties and refinement of microstructure in metals, alloys and also in surface alteration, surface composites, and metal matrix composites. This work deals with the integration of FSP with fused filament fabrication (FFF), a popular additive manufacturing (AM) method. The research work comprises of four parts, first being 3d printing of poly lactic acid (PLA) and acrylonitrile butadiene styrene (ABS) parts through FFF, then multiple reinforcements like multi-walled carbon nanotubes (MWCNTs), aluminum oxide (Al2O3) and silicon dioxide (SiO2) are filled into the grooves, then in the third step FSP is performed on the 3D specimens with variations in rotational and travel speed of the tool with threaded pin profile. Finally, tensile strength is examined and the effect of different reinforcements is studied. The results indicate that MWCNTs reinforced PLA is found to have the highest strength (37.41 MPa) which is 72.6% more than the lowest strength (21.67 MPa) obtained for SiO2 reinforced PLA. However, in the case of other polymer, SiO2 reinforced ABS exhibited maximum strength (14.71 MPa) amongst other reinforcements for ABS. The ductility is decreased for all the FFF specimens after FSP and PLA composites exhibited improved surface profiling parameters as compared with ABS composites after FSP. Also, fractography is performed to understand the failure modes of specimens filled with different reinforcements.