Design of experiments to compare the reprocessing effect with Fused Deposition Modeling printing parameters on mechanical properties of Polylactic Acid specimens towards circular economy

Abstract

Distributed Recycling via Additive Manufacturing (DRAM) is a closed-loop material reprocessing solution that promotes circular economy. There are several literature gaps related to material properties and recycling cycles at different stages of the DRAM process. With an approach to filling these gaps, a small contribution has been made through this work by comparing the effect of reprocessing cycles (recycling) with the effect of FDM printing parameters such as Raster angle orientation, Infill density and Extrusion Temperature. These four parameters are ranked based on their impact on the tensile properties of Polylactic Acid (PLA) dog bone specimens. The Design of Experiments via Taguchi Analysis is carried out to avoid analysis of a large number of samples. The results show that recycling has the maximum impact on the tensile properties of PLA samples and can reduce the tensile strength by up to 75% in the course of four reprocessing cycles. The specimens had Ultimate Tensile Strength (UTS) values in the range of 20–26 MPa at the first reprocessing cycle which dropped significantly to a range of 7–9 MPa after the fourth reprocessing cycle. Additionally, a novel analysis on time and the number of specimens to be 3D printed at each reprocessing stage has also been conducted to help future researchers manage their printing schedule, especially in the recycling domain.

Recycling as a Key Enabler for Sustainable Additive Manufacturing of Polymer Composites: A Critical Perspective on Fused Filament Fabrication

“…As the average molecular weight decreases, the rheological behaviour changes [151], and the printability worsens with it [152]. When FFF parts are crushed and recycled for printing again, the mechanical strength of the printed parts can be retained over a few re-processing cycles, typically 1 or 2, but is then expected to drop [135,[153][154][155][156][157]. In an experimental study that investigated the potential of close-looped recycling of PLA, commercial granules were extruded and printed.…”

Design of Experiments to Compare the Mechanical Properties of Polylactic Acid Using Material Extrusion Three-Dimensional-Printing Thermal Parameters Based on a Cyber–Physical Production System

“…For 3D-printed parts, improving mechanical properties is a topic that has acquired great importance in recent years [ 7 , 8 ]. Several research papers have studied the correlation between printing parameters and mechanical properties, such as the ultimate tensile strength (UTS) [ 9 , 10 , 11 ], even after recycling cycles [ 12 ] or changes in the color of the filament [ 13 ]. The results of these studies have demonstrated the non-linearity of the process and the complex interaction between parameters; in most cases, this results in parts with anisotropic mechanical properties [ 11 , 14 , 15 , 16 ].…”