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MANUFACTURING STEPS DRAWING Steel wire ropes are made of steel wires. Steel wires comes from drawing of rod. Through several drawing steel rod becomes a wire of diameter and predetermined characteristics. Steel wires are protected by an appropriate lubrification. Nevertheless maritime steel wire ropes or ropes working in very agressive environment or in extreme climatic conditions are made of galvanized wires. Galvanization of wire is made by immersion in a bath of molten zinc. Wiers can be galvanized after last galvanization process (final galvanization) or galvanized and then drawn. Zinc quantity is expressed by zinc mass on wire surface in gr/m2, according to EN10264-2. STRANDING Several wires are twisted around a central core made by a wire, or a strand or a natural or synthetic fiber core. CLOSING It is when several strands are closed to make up a rope. More strands are closed around a central fiber or metallic core. Before this manufacturing step, strands are PREFORMED in order to give them an helical shape. Preformation gives to rope the following advantages: - when rope is cut, strands don't open and binding or welding aren't needed; - rope behave in a better way under fatigue; - in case of broken wires, they keep their position; - handling and fittings application are easier. COMPACTING Ropes with compacted strands are special ropes produced with strands with high filling coefficient. Compacting process deforms strand's wires so that they fill all existing empty spaces between wire and wire. As result compacted strand has a bigger metallic section and uniformly smooth surface. Moreover deformation of wires extends surfaces in contact and as consequence reduces pressures during normal work of the rope. Combined effect of compacting process is that compacted ropes have got higher breaking load, higher resistance to fatigue, to abrasion and to pressures of pulley, drum, etc. |