Optimization of porthole die extrusion by Grey-Taguchi relational analysis

Porthole die extrusion has been more and more utilized to produce hollow complex cross-section profiles. The porthole die is characterized by complex shapes and various geometric variables have to be set properly for the process optimization. Numerical simulations combined with optimization methods are effective strategies, which can be used for a proper die design reducing the experience and “trial and error” sequences. In this study, 12 geometric variables of a standard porthole die, used to extrude profiles with circular section, were identified and varied on three levels. The entire solution space was investigated using a Taguchi method based on a special design of orthogonal array with the grey relational analysis. Firstly, the influences of the investigated geometric variables on three extrusion outputs, e.g., the required ram load, the maximum pressure inside the welding chamber, and the material flow homogeneity, were highlighted by ANOVA technique. Afterwards, the Grey relational analysis was introduced determining an optimal combination of the investigated parameters that optimize all the process outputs according to specific process needs.