The principles of Impact Extrusion have been used for well over 100 years. The earliest written record of the process is a patent granted in 1797 to Joseph Bramah in which a press was used to form tubing from soft metals or molten lead. In 1820 Thomas Burr constructed a hydraulic press for the production of pipe by extruding cast cylinders of lead. J. & C. Hanson developed an improved hydraulic press in 1837 for the extrusion of lead pipe. In 1894, Alexander Dick developed a press capable of hot extruding harder alloys such as copper, and in 1903 George W. Lee developed a process for cold extruding hollow bodies.
Modern cold extrusion of steel is rooted in the 1930s when a shortage of brass led to military demands for ordnance components from steel. Neumeyer Cable & Metalworks and Collis Metalworks in Germany developed phosphate coating and cold extrusion of steel with patents granted in 1937. A technical industrial intelligence committee sponsored by the U.S. military visited Germany immediately after World War II and learned of these developments.
Initial applications in the U.S. were for the military in which high volume capability, material conservation, and reduction of machining time were key requirements. Since then, the process of impact extrusion has grown to encompass multiple materials such as low-to-medium carbon steel, nearly all grades of aluminum, copper, brass, magnesium, and even stainless steel and titanium. Applications have grown within ordnance and expanded into automotive, truck, aerospace, agricultural, industrial, and recreational markets.
Impact extrusion has evolved into a technology well suited to the high quality, lean manufacturing culture in industrialized nations due to the inherent conservation of raw material through near-net shapes, the excellent mechanical properties achieved through cold work, and the high repeatability of the process
Formability of Metals
Low-carbon steels - Carbon steels up to 18 points are easily cold formed and can be case hardened or coated to improve wear characteristics.
Medium-carbon steels - Carbon steels 18 to 40 points are cold formable and respond to heat treatment, but generally cannot hold tolerances as tight as low-carbon steels.
High-carbon steels - Carbon steels over 40 points are not recommended for cold forming.
Alloyed steels - Alloy steels can be well suited for cold forming and respond well to heat treatment. Formability is somewhat comparable to medium-carbon steels.
Stainless steels - 302, 304, 316, and 321 stainless steels are cold formable to a limited extent.
Aluminum alloys - Many grades of aluminum alloys can be cold formed with the most common being 6061, 7075, and 1100. Formability in general is excellent.
Copper alloys - Copper and its alloys are well suited for cold forming with excellent formability.
Formability of Metals
METALS IMPACTED BY CECA
· 1518 MOD
· 8610 MOD
OTHER METALS THAT CAN BE COLD FORMED
Stainless steel: 302, 304, 316, 321