Avaliação da vida útil dos eletrodos revestidos e não revestidos para solda a ponto

Abstract

This study looks at resistance spot welding (RSW) of galvanized steel sheets in order to evaluate the service life of different types of electrodes. These are uncoated and face-coated. During the welding process, the service life of the electrode is influenced by the degradation processes of the electrode face as a function of the welding parameters, zinc layers on the sheet and their contaminants, as well as some important process variables such as the flow rate and temperature of the water used to cool the electrodes. During the tests, it was found that the electrodes coated in the process improve production performance because there is no need to clean and resharpen the tips throughout their useful life. This process is known as milling. The current range observed during the service life of the coated electrode is relatively higher due to the growth rate of the electrode face and in some cases could cause problems in relation to the quality requirements of the weld. During the work, the degradation of the uncoated electrode face can be controlled by the milling process, which guarantees better control of the process in terms of the quality requirements of the joint to be welded, but in some cases can affect the production process by increasing the cycle time of the cell. This work therefore evaluates the practical advantages and disadvantages of using each type of electrode used in the RSW process, assessing some important requirements such as weldability, cost per weld point, production capacity and not least the quality of the joint to be welded.