manufacturing of chain-link fencing
The manufacturing of chain-link fencing is called weaving. A metal wire, often galvanized to reduce corrosion, is pulled along a rotating long and flat blade, thus creating a somewhat flattened spiral. The spiral continues to rotate past the blade and winds its way through the previous spiral that is already part of the fence. When the spiral reaches the far end of the fence, the spiral is cut near the blade. Next, the spiral is pressed flat and the entire fence is moved up, ready for the next cycle. The end of every second spiral overlaps the end of every first spiral. The machine clamps both ends and gives them a few twists. This makes the links permanent.
An improved version of the weaving machine winds two wires around the blade at once to create a double helix. One of the spirals is woven through the last spiral that is already part of the fence. This improvement allows the process to advance twice as fast.