The extrusion process is one of the cold forming techniques forcing the material to flow in the open space between a die and a punch. In this technique, the material can move either forward (forward extrusion) or backward (backward extrusion) however, many products use a combination of both extrusion (combined extrusions).
Material is forced forward by the punch through an orifice in the die, producing a smaller cross section than the initial blank. 75% reductions are possible with this technique.
Material is contained in the die and forced backward around the punch, producing blind holes and cups. The bottom of the cup should be thicker than the walls. Area reductions of 20-75% are possible with this technique.
As many designs include both extrusions, the creativity of the design engineer can enable both techniques to be used simultaneously to minimize production costs.
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