Nonferrous Pipe and Tubes

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Induction Bender

Nonferrous pipe and tubes: Although most of the equipment used to bend ferrous materials is also used for bending nonferrous materials, the details of bending do differ from those for ferrous materials and also vary between the several nonferrous materials themselves. Accordingly, it is wise to obtain specific procedural information from the materials’ producers or from other reliable sources such as the latest edition of The Metals Handbook.20 Certain nonferrous materials can be hot bent.

Aluminum and aluminum alloys can be bent cold using the same types of bending equipment used for ferrous materials. Alloys in the annealed condition are easiest to bend, but care is required in selecting tooling because of the low tensile strength and high ductility of these materials. Alloys with higher tempers and heat-treatable alloys require larger bending radii for satisfactory results. It is seldom necessary to heat aluminum for bending: however, non-heat-treated materials can be heated to 375°F (190°C) with minimal loss of properties, Heat-treated alloys require specific time-temperature control. More detailed information is available from the manufacturers of aluminum products.

Copper and copper alloy pipe and tube can be readily bent to relatively small radii. Although copper can be bent hot, the vast majority is done cold. For draw bending an internal mandrel is required and for other methods internal support is recommended. For very tight radii a snug-fitting forming block and shoe which practically surround the pipe at the point of bending are needed to preclude buckling. Hot bending of copper and copper alloys particularly in larger diameters and walls is common. Pipes are usually sand-filled, and contoured bending dies are recommended. See Table A6.1. More information can be obtained from the Copper Development Association.

Nickel and nickel-alloy pipe can be cold bent with the same type of bending equipment used for ferrous materials. Use of material in the annealed condition is preferred. For bends with radii 6 diameters and less, filler material or internal mandrels are required. Draw bending with internal mandrels is the preferred method for close-radius bending. Galling can become a problem, and chromium-plated or hard bronze-alloy mandrels should be used. Nickel and nickel alloys can be hot bent using the same practices as for ferrous steels. Sand filling is appropriate. Care should be taken to assure that the sand and heating fuel are low in sulfur and that any marking paints or crayons or lubricants have been removed. These materials can be bent over a wide temperature range. The best bending is usually between 1850 and 2100°F (1010 to 1149°C). Other nickel alloys may exhibit carbide precipitation and should not be worked in the sensitization range. Postbending heat treatment may be required. For more information contact nickel product manufacturers such as Huntington Alloys.

Titanium can be bent using draw bending equipment. However, those parts of the equipment which will wipe against the inner and outer surfaces of the pipe should be of aluminum bronze to minimize galling. For better formability, the pipe, the pressure die, and the mandrel should be heated to a temperature between 350 and 400°F (177 and 204°C). Unalloyed titanium can be hot worked in the temperature range of 1000 to 1400°F (538 to 760°C). Titanium alloy grade 12 requires a temperature range of 1400 to 1450°F (760 to 788°C). Heat treatment of titanium is recommended after forming. This is usually a furnace treatment at 1000 to 1100°F (538 to 593°C) for a minimum of 1/2 h for the unalloyed grades and 1 h for the alloy (grade 12). Prolonged exposure to temperatures in excess of 1100°F (593°C) will result in heavy scaling and require some type of descaling treatment.