Numerical Modelling of AlSi7 tubular components flowformed at elevated temperature

In small batch manufacturing, flowforming may represent an optimal semi-finishing process for axisymmetric parts, due to its versatility, the reduced material waste, the good geometrical tolerances as well as the improvement of the mechanical characteristics it allows to attain. However, the main limiting factor often lies in the lack of knowledge for the process design, which implies expensive industrial trials often based on trial-and-error approaches. Due to these reasons Finite Element (FE) numerical simulation can provide a significant help in the design and management of the process, but its application is still facing relevant issues, mainly linked to: (i) the complex contact conditions between tooling and part, (ii) the high computation effort due to the 3D geometry rotating at high speed, and (iii) the complex strain paths that the material undergoes. The paper presents an optimized FE model of the flowforming process of AlSi7 alloy tubular components carried out at elevated temperature. An implicit solution scheme and an arbitrary Lagrangian-Eulerian meshing was adopted, while the constitutive parameters of the material model were calibrated on the basis of experimental compression tests carried out in the same thermo- mechanical conditions of the industrial reference process. The influence of the main process parameters, namely thickness reduction, feed rate and mandrel rotation speed were investigated and an algorithm for parametric process charts derivation was finally proposed.