Monitoramento do risco ocupacional de campos eletromagnéticos para o soldador em processos de soldagem a arco e resistência elétrica

Abstract

Arc and resistance spot welding processes are widely used in the metalworking industry in a wide range of applications. In these processes, high levels of current varying from tens to thousands of amps are used and generate electromagnetic fields, whose harmful effects on human health are still under investigation by the scientific community. Thus, bureaus linked to occupational health have formulated guidelines that limit the exposure of workers to such fields. Moreover, studies show that, due to the different operational parameters commonly used in welding processes, these reference limits may be exceeded in some cases. therefore, the objective of this work is to carry out weldments by using arcelectric processes (Covered/Stick Electrode, TIG and MIG / MAG processes) and RSW process (Resistance Spot Welding) in order to evaluate the influence of the operational variables common to these processes on the intensity of electromagnetic field, both experimentally and through computer simulation, by using the Finite Element Method. The results obtained are then compared with the limits established by the appropriate ICNIRP directive. Both methodologies showed that the electromagnetic field is larger the greater the welding current and the lower the arc height. The electrode coating and the use of different base metals can influence the generation of the electromagnetic field by modifying the relative magnetic permeability of the medium. The shielding gases have relative magnetic permeability close to that of air, but are capable of interfering in the intensity of the electromagnetic field by modifying the arc geometry due to differences in thermal conductivity. Finally, in manual welding, the welder's hand is the point where the highest magnetic field values are recorded. In other regions of the body, the distribution of the magnetic field is heterogeneous and depends on the position of the welder, which varies depending on the welding process. Within the operational envelope established in this study, the ICNIRP reference limits are exceeded in spot resistance welding in the alternate current version.