Um estudo holístico da parametrização eficaz e eficiente da manufatura aditiva por deposição a arco (MADA) de paredes finas

Abstract

This work aimed at evaluating how different variables of the GMA (Gas Metal Arc) process relate to each other and how they can affect the functionality of thin steel walls deposited with Wire Arc Additive Manufacturing (WAAM). In the first stage of the thesis, the possibility of parameterizing thin walls for a feedstock is based on a pre-existing working envelope made with a different and ordinary (cheaper) material. Then, it was discussed the combined effect between interlayer temperature and travel speed on operational, geometrical and metallurgical features of thin walls with the same effective width, deposited using or not an active cooling approach. In the last stage of the thesis, a methodology was proposed to allow a systematic comparison of different shielding gases so that, then, the effect of three different argon-based blends on operational, geometric and metallurgical features of thin stainless-steel walls could be evaluated. The study of operational features involved, in the three stages of work, the evaluation of electrical signals (current and voltage), wire feed speed, temperature profiles, deposition times, surface aspect and metal transfer regularity. The geometrical features of the walls were quantified from the 3D scanner software used to digitize the walls or through a code developed in Python language. Optical microscopy and microhardness tests were used to assess the metallurgical features. The results showed that it is feasible to select parameters for thin walls deposited through WAAM with a lower number of experiments, using a pre-existing working envelope for another ordinary material. Evaluating the combined effect between interlayer temperature (IT) and travel speed (TS), it was verified that the increase of IT with TS decreased the external width, surface waviness (better surface finishing), layer height and deposition times for the same effective width, regardless of the cooling approach considered. However, for the same parameter combination, a shorter deposition time is achieved using near-immersion active cooling. The proposed methodology to evaluate the effect of different shielding gases allowed the building of thin walls with a higher number of constant variables and metal transfer regularity between different blends. Thus, the change in shielding gases can be evaluated in a consistent way. In summary, alternatives were proposed and confirmed in this work to allow robust, efficient and effective parameterization of thin walls for process users.