The Production of Extruded Valves

THERE are three processes by which internal combustion engine valves are made, differing chiefly in the initial stages. These are: (1) hand forging by drawing‐down the stem; (2) electric‐upsetting of the head; (3) the extrusion process. In each of the three processes the final shaping of the valve blank is done by stamping between dies in a suitable press.