People Have Been Using Chains Made of Interconnected Metal Links

People have been using chains made of interconnected metal links since at least 225 BC. Early chains were hand-forged, but improvements in technology during the 19th century allowed for the gradual automation of the process. Today, machines perform most of the work needed to turn metal alloy into finished chain. Die Once a chain manufacturer creates a rod of metal alloy for use in chain-making, the rod is forced through a series of dies -- metal blocks with a hole, smaller in diameter than the rod -- to form it into wire of the desired size. Depending on the alloy used, the metal may be heated first or forced through the die cold. In addition to stretching and shaping the wire, dies also increases its strength and flexibility. Forming Machine The finished wire is wound onto drums and fed into a forming machine for the next step of the process. The forming machine performs a set of predetermined, repetitive movements to cut off a length of wire, form it into a ring, slide the next length of wire through the freshly-formed link, and shape it into an identical, attached link. With each new link, the chain grows in length until it is the desired size. Conveyor Oven Since the forming machine does not physically attach the edges of the links, a different machine is necessary to solder the ends together. Workers apply a soldering agent to the chain and remove the excess from the links. They coat the chain in talcum powder to prevent the metal from melting and sticking together when it's heated, and run it through an oven on a conveyor belt. The oven activates the soldering agent and closes the links. Diamond Cutting Tool Many chains used for jewelry are subjected to a process called diamond cutting to make them more reflective. The chain is wound around a large cylinder and frozen in place with ice crystals to hold it steady. A diamond cutting tool makes a tiny, very precise cut across the surface of each link as the cylinder rotates. Each of these cuts adds a flat, bright, highly polished surface to the chain, causing it to shine when light hits it. Source: ehow.com