The upper bound approach is used to analyze the early stage of impact extrusion of a thin or thick-walled cup. It is shown that during the early stage of extrusion with a flat ram the ram pressure increases linearly with increasing penetration of the ram, increased area of contact between the tool and the workpiece, and poorer lubrication. With the same friction and process geometry the early stage of extrusion is made easier by using a nosed ram instead of a flat one. The optimum nose contour can be determined by a minimization technique.

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