Design and finite element analysis of innovative tooling elements (stress pins) to prolong die life and improve dimensional tolerances in precision forming processes

This paper proposes the use of stress pins as an innovative pre-stressing element, and presents the results of a design methodology investigation through combined finite element analysis (FEA) and design of experiment (DOE) studies for large and non-axisymmetric precision forming tooling (i.e. as in hydroforming and precision forging of connecting rod) where conventional shrink-fit solutions cannot be applied effectively and economically. In summary, smart pre-stressing elements (i.e. stress pins) are implemented to overcome very fundamental and practical problem of prolonging the die life, preventing die failures and improving dimensional part tolerances by applying local and controlled pre-stressing effects.