Estudo das propriedades mecânicas, tribológicas, de qualidade dimensional e condutividade elétrica de peças impressas em PLA e ABS com e sem grafeno

Abstract

Additive manufacturing is a technology that makes it possible to manufacture products with complex geometries that could not be manufactured by conventional processes. One of the additive manufacturing technologies is fused deposition modeling, which has been widely used to produce good quality products, complex geometries, and efficient manufacturing and delivery logistics. Due to the evolution, it has been used as an alternative process to that of injection moulding that added to the other characteristics, has generated a scenario of great research opportunities, both in materials as in processes and applications. In this research, the changes in the mechanical, tribological, dimensional quality and electrical conductivity properties of printed samples through the process of fused deposition modeling were analyzed by using PLA and ABS raw materials with and without graphene addition. The improvement of these properties is associated to the study of the several parameters of the process of fused deposition modeling and the use of new materials. In the planning of experiments to evaluate the interference of the process parameters, the percentage of fill and layer thickness were selected, which, by the bibliography researched, these have great influence in the properties. The results were analyzed and compared with the properties obtained through the same manufacturing process and using the same raw materials, ABS and PLA, but without graphene. Mechanical properties (tensile and bending) improved the increasing fill percentage and layer thickness for both PLA-graphene and ABS-graphene. However, the addition of graphene improved these properties for PCs using PLA-graphene compared to PLA and worsened for ABS-graphene compared to ABS. The impact energy was higher in the pieces that used ABS-graphene compared to PLA-graphene. In the conductivity tests performed on the sample manufactured with PLA-graphene the obtained value was zero (non-conductive) while the ABS-graphene had, on average, the value of 0,24 $ (\Omega.m)^{-1} $.The results of the tests that determined the coefficient of friction decreased with the increase of the normal load, for both PLA-graphene and ABS-graphene, except for injection moulding parts (PLA-colorless granules). Wear values increased with increasing normal load in all tests. The IT quality index of parts produced by the FDM process with PLA-Graphene had values between 12 and 13 whereas for the parts produced with ABS-graphene this value was between 12 and 14. The roughness measured in the sample manufactured through the process modeling and that utilized the PLA-graphene raw material, was superior to the results obtained in the measurements in the sample manufactured through the same process and that used the ABS-graphene. However, these results are conclusive only for these raw materials and process as they change significantly when the raw materials and parameters of the manufacturing process are modified.