Estudo de um produto soldado: uma análise comparativa entre os processos de soldagem MIG/MAG manual e robotizada

Abstract

This work presents a comparative study between manual and robotic MIG/MAG welding processes applied to the manufacturing of a road suspension rocker arm component made of ASTM A36 steel. Analyses of productivity, macrography, microstructure, microhardness, mechanical testing, and visual inspection of the weld beads were performed. The methodology comprised welding samples using both processes, measuring production times, conducting metallurgical evaluations, and performing dynamic load tests. The results showed that the robotic process achieved a 37.8% productivity gain and an average efficiency of 87.4%, compared to 61.7% for the manual process, in addition to lower variability between samples and greater repeatability. The visual analysis revealed that 39% of the manual welds exhibited lack of fusion, whereas the robotic welds showed higher uniformity and absence of overlap. The macrographic analysis indicated similar bead geometries between the processes, though influenced by torch positioning and welding position. The microstructure of the manual welding presented a higher presence of acicular ferrite and grain size variation, characteristic of thermal fluctuation, while the robotic welding showed predominance of secondary ferrite and lower concentration of grain boundary ferrite, associated with more uniform cooling. The microhardness values showed a typical behavior of the MIG/MAG process, with peaks in the weld metal and similar averages between processes. In the mechanical tests, the manually welded components withstood 500 cycles without failure, while the robotically welded components showed fracture in lower beads due to local lack of fusion, causing cracks in adjacent welds. It is concluded that the robotic process provides higher productivity and dimensional control, while the final quality depends on the correct adjustment of welding parameters and torch positioning. [resumo fornecido pelo autor]