July 11, 2009

Wire

Wire is a usually flexible metal rod or thread of uniform diameter. It has many uses, particularly in electrical wire and cable applications; in medical, farming, and industrial tools; and needles, and in hardware such as bolts, nails, nuts, screws, rivets, and needles. In construction, steel-wire cables are used to reinforce suspension bridges. Wire is also used in more delicate apparatuses, such as stringed instruments and watch springs.

Production
Wire is made by drawing out metals such as copper, iron, brass, aluminum, gold, silver, and platinum. In wire drawing, the metal is first heated and then run through a series of rollers that press it into thin rods. The rods are then coiled by machine, allowed to cool, cleaned with sulfuric acid or other chemicals, neutralized, and lubricated, followed by reheating to alleviate brittleness. They reach their final form by being drawn through a series or progressively smaller holes, known as dies, which reduce their diameters and increase their lengths. The finished wire is then wound around a rotating drum.

History
Wire was used as an ornament by the Egyptians as early as 3000 ac. Although the Romans used perforated places of iron as drawing dies, until the Middle Ages wire drawing was largely done by hand; the resulting threads has to be hammered and joined to each other to produce wire of a desired length. The first mechanical wire drawing equipment was developed (c. 1350) by Rudolf of Nuremberg.

Because of the industrial Revolution, the demand for cable suspension bridges, the telegraph, the telephone, and the electric light, as the growing demand for fencing and barbed wire, spurred production of greater lengths and strengths of wiring. In this century, carbide drawing dies were developed that could withstand high speed and long wear and provide increased accuracy. With a die capable of standing up to the drawing of greater quantities of wire at the desired gauge through a single hole, machines that drew continuously came to the fore. Advance welding techniques now long, continuous coils rod and wire to be drawn.

Cable
A cable is a cord or rope made from strands of fiber or wire, of great tensile strength, used to support a bridge or cable car, to secure a ship at anchor; for towing, hauling, and construction work, or for similar purposes. Transmission cables carry electric power or communications signals.
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