Influence of forming machine stiffness on product quality in hot forging operations

The quality of forged components is strictly dependent on the micro-structural phenomena occurring during the manufacturing chain that may cause significant changes in the physical and mechanical features of the final product. Some of these changes take place during the deformation phase and depend on the forming machine characteristics in term of machine kinematics, total elastic deflections of the press system and contact-time. The press stiffness influences the velocity-versus-time curve under load, varying the contact pressure and the heat transfer between the tools and the workpiece and, consequently, the global process conditions. This paper deals with the evaluation of the influence that the forging machine exerts on the process parameters and the quality of the final component in terms of its microstructure distribution after forging. The approach is based on a simulative environment that combines experimental measurements, FE simulation and inverse analysis techniques. A case study, in which operating conditions approximate hot forging of a turbine aerofoil section, is presented. Results of experiments show the influence of machine characteristics on the quality of final product.