To manufacture lightweight tubes, fabricators increasingly use incremental forming processes like radial forming or flow forming. The use of such processes requires a profound knowledge of material properties and process understanding.
A special process modification of flow forming is the ball spinning expansion process. It is generally used to reduce the tangential forces to a drift. A simple analytical method to calculate the forming forces and to generate process understanding of parameter variations is missing.
The following paper provides an overview about ball spinning and an analytical calculation method for a ball spinning expansion process. This method is validated by experiments and FEM simulations and the specific characteristics of ball spinning is described. Finally, the result of the parameter variations are illustrated in order to predict forming forces and stress state more easily.