Impact of Carbon Nanofiber fillers on Surface Finish and Dimensional Accuracy in FDM-Printed Polymer Composites Parts

This paper examines the effect of carbon nanofiber (CNF) reinforcement on the surface finish and dimensional accuracy of the polylactic acid (PLA) composite produced using Fused Deposition Modeling (FDM). Twin-screw compounding was used to prepare PLA-CNF composite filaments with 0-3 wt.% CNF with extrusion of filaments (L/D ratio 30:1, 120 rpm). To prepare rectangular specimens (10 x 10 x 20 mm), the filaments were printed with the nozzle size of 0.4 mm, the layer thickness of 0.1 mm, the infill density of 100 percent, and the print speed of 5 mm/s. Dimensional accuracy was assessed by a digital vernier caliper with a resolution of ±0.01 mm, and surface roughness (Ra) was measured by a digital surface tester that was stylus-based. Every measurement was averaged three times, and the statistical examination of percent deviation and variance analysis of compositions was done. Findings show that CNF addition was important with respect to the dimensional stability and surface finish. The volume variation of the print decreased to 0.20% of PLA/3 wt.CNF compared to 0.30% of neat PLA, which is a 33 percent smaller variation of the dimensional accuracy. The surface roughness also reduced as 0.70 μm of neat PLA was reduced to 0.42 μm of PLA/3 wt.% CNF, which is a 40% decrease. It was statistically tested that trends of consistent improvement were observed between compositions. The findings indicate that CNF reinforcement result in a higher level of geometric accuracy and less surface morphology in FDM-printed polymer composites.