Dimensional stability of poly(lactic acid) (PLA) parts fabricated using fused deposition modelling (FDM)

Abstract

The dimensional accuracy of a 3D printed part produced using Fused Deposition Modeling (FDM) is an important issue. In this work, polylactic acid (PLA) parts were produced using FDM at different platform temperatures. The dimensional stability of the parts was assessed by measuring the shrinkage, warpage and layer thicknesses of the parts. A sample of four different blades for warpage, two samples with different shapes and parts with fixed contact surface area but different heights were printed at a fixed nozzle temperature of 210°C while platform temperatures were varied from 60°C to 80°C. Deformation angles of the blades decreased with increasing platform temperature suggesting lower warpage due to the enhanced capability to dissipate thermal stress. Meanwhile, shrinkage decreased as platform temperature increased irrespective of the shape of the sample due to the lower temperature difference between platform and nozzle temperature leading to lower thermal contraction. However, a thin sample tends to shrink more compared with a thick sample with bigger differences at higher platform temperatures. No significant trend in density were observed on samples of different height with increasing platform temperature due to competing effects of increasing crystallinity that would increase the density and increasing layer contraction that would increase porosity as shown by the variation in the thickness of the top and the bottom layers of the samples and the formation of voids.