Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Comparison of impact resistance of annealed 3d printed PLA according to different Izod ASTM test standards
Submission Author:
Lucas Melo Queiroz Barbosa , MG , Brazil
Co-Authors:
Felipe dos Anjos Rodrigues Campos, Lucas Melo Queiroz Barbosa, Kauã Ferreira de Almeida, Pedro Henrique Veiga Oliveira, Thiago de Oliveira Santos, Leonardo Rosa Ribeiro da Silva , Álisson Rocha Machado
Presenter: Lucas Melo Queiroz Barbosa
doi://10.26678/ABCM.COBEM2023.COB2023-0505
Abstract
The additive manufacture through the Fused Filament Fabrication (FFF) process is one of the most utilized techniques of 3D printing nowadays, which consists of the extrusion of a thermoplastic filament, provided. continuously from a spool, through a nozzle extruder heated for the material deposition in layers. In this process, the deposited polymer cools rapidly for the layer solidification, and then it is reheated with the deposition of the upper layers, making important the study of the thermoplastic properties in accord to the pieces thermal history, especially in relation to the glass transition temperature (Tg) and the crystallization temperature (Tc). The first indicates the temperature from which the polymeric chains gain mobility and relates with the adhesion between the deposited layers. The second marks the organization tendency of the macromolecules in crystals, that normally make the material more resistant, though less ductile. Due to this phenomenon, the FFF printed part’s mechanical properties become dependent on parameters such as nozzle and table temperatures, and layer height, in addition to post-processing operations like annealing. In this sense, this research aimed to evaluate the influence of the printing parameters mentioned and annealing on the impact resistance of FFF fabricated polylactic acid (PLA) parts. It utilized a complete factorial type experimental planning with 2 levels and 4 variables (24), for 2 different types of specimens, that allowed use of variance analysis (ANOVA) to identify which are the most significant factors for the impact resistance evaluated according to the standards ASTM D4508 and ASTM D256. The annealing process was identified as the most influential parameter, since only 20 minutes reheating was enough to increase the piece’s average resistance by more than 300% on average. The crystallinity change was discussed according to the change in the translucency of samples. The results demonstrated notable efficacy of the reheating process on improving the mechanical properties, pointing to a great cost-benefit strategy for the industrial segments and for professional consumers to improve their FFF printed parts.
Keywords
Additive Manufacture, annealing, Impact Resistance, crystallinity
