THERE are three processes by which internal combustion engine valves are made, differing chiefly in the initial stages. These are 1 hand forging by drawingdown the stem 2 electricupsetting 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.
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Jun 1, 1940