Design development and functional validation of an interchangeable head based on mini screw extrusion applied in an experimental desktop 3-D printer

摘要

In this work is proposed the conceptual and preliminary design as well functional validation of a head based on fused deposition modelling (FDM) technology using mini screw applied to experimental 3-D printer (Fab@CTI machine). The polymer Nylon 12 and the biopolymer ε-PCL (ε-policaprolactone) in powder form were used to design the barrel-screw and drive system set-up. The proposed head demonstrated the functionality to carry the powder material through the variable sections of the screw extrusion and has generated Nylon filaments with diameter of approximately 0.7 mm with the tip of 0.4 mm. The morphological characteristics of these filaments were observed in scanning electron microscopy (SEM) confirming the mixing of the powder, generating continuous filaments and structured parts. SEM tests were made with ε-PCL using material generated from the feed to compression zones of the screw extrusion head allowing the visualisation of the adhesion of the grains in feed section and the complete mixing in the compression zone for the ε-PCL.