A general flow line function is presented which is capable to describe the material flow for any die angle between 90° and 180°. A specific feature of the new function is that it is capable to describe the asymmetrical shapes of the flow lines using only three parameters. These parameters are obtained from a good fit of the flow lines that are observed in finite element simulations of the process. The new flow line function provides the velocity gradient field in an analytic form and can be used directly in polycrystal codes.
