Limits of Lubrication in Backward Can Extrusion: Analysis by the finite-element method and physical modelling experiments

The increasing demand in industry to produce cans at low reduction by the backward extrusion process involves better understanding of this process. To analyse the process, numerical simulations by the finite-element method and experimental simulations by physical modelling using wax as a model material have been performed. These simulations gave good results concerning the prediction of the flow modes and the corresponding surface expansions of the workpiece material occurring at the contact surface between the can and the punch. These predictions set the limits of the can height, depending on the reduction, the punch geometry, the workpiece material and the friction factor, in order to avoid the risk of damage caused by stiction of the workpiece material to the punch face. The influence of these different parameters on the distribution of the surface expansion along the inner can wall and bottom is determined. The numerical and experimental simulations showed good accordance.