Optimization of forming force and Erichsen index using Taguchi design of experiments: Mathematical models and experimental validation

Design of experiments is a statistical approach from which an optimized number of experiments is determined. Taguchi design of experiments, applied on Erichsen tests, is chosen to be considered in this paper. The most important parameters in this forming process, Erichsen index ( IE), and maximum generated force ( Fmax), are experimentally and theoretically determined. Three input factors are selected, at diverse levels, in order to study their influence on Erichsen output results. The considered input factors are sheet thickness, punch diameter, and friction coefficient. New mathematical models which take into account the effects of these factors and their interactions are developed. Moreover, the influence of Erichsen test on the S235 steel microstructural behavior is experimentally examined as function of the sheet thickness. A good agreement between experimental and theoretical findings proves that the proposed models provide a precise prediction and an exact estimation of the Erichsen output parameters ( IE and Fmax). The efficiency of the adopted design of experiments via Taguchi method is well confirmed.