ASSESSMENT OF RESISTANCE SPOT WELDING PROCESS BY USING A CENTRAL COMPOSITE DESIGN WITH 3 LEVELS Márcio de Andrade Batista , Vinicius C. do Nascimento e Louriel O. Vilarinho
Resumo: Abstract. This work aims to study the following parameters from the Resistance Welding Process (RSW): Welding time, Current intensity and Force applied on the electrode tip, by using a Central Composite Design (CCD) with three levels. This design technique aimed to show how these three parameters influences the spot diameter. One of the advantages of the CCD is that it can be built sequentially according to certain needs, since it is formed by three distinct parts. If the analysis happens in a specific region of the response surface, where the curvature is not important, than the whole quadratic model is no longer necessary and the factorial part of the design can provide a significative analysis. Therefore a linear model can be adjusted and a forward movement in the interest region of the surface response can be made. The CCD has been used to assess the existence of a possible curvature in the objective function, i.e., to assess the presence of non-linear terms in the regression model by using the axial points to verify the curvature significance. When the critical variables are not known, it is necessary to apply a screen experiment that aims to determine which variables are the most important an result in a better process performance. It can be concluded that in a RSW, the welding current has the most importance for the spot size.
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