The Manufacture of Alloy Stampings: The Production of Stampings for Crankcases, Pistons, Connecting Rods and Airscrew Blades

THE increasing demand for the mass production of light but strong articles to very close limits has caused a big advance in the technique of drop stamping, which is rapidly replacing casting in the manu‐facture of aero‐engine parts. Crankcases, pistons, connecting rods and airscrews, to mention but a few items, are now made in the stamp shop, as the metal is more uniform in structure and free from blow holes, hard spots or cavities. Machining is reduced to the minimum, the direction of the grain can be controlled, and waste material, an important item with the expensive aluminium alloys, is reduced to a negligible amount. It is common practice in acro‐engine work for only ten‐thousandths of an inch to be allowed for machining after stamping, which is a practically impossible limit for castings or forgings. A very high rate of production can be obtained, as a few blows with the hammer produces an article, perfect in contour, in a fraction of the time required by any other method.