WIRES

WIRES

Post 429 ⇒   by Gautam Shah 

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A Wire is a thin section material. It is long drawn or extruded in a single strand. Wires due to their process of formation have strongly aligned molecules or chains, giving it high degree of tensile strength. Wires during the production processes and due to the smaller section is highly susceptible annealing and surface hardening, and so acquire unique properties of malleability, hardness, etc. Wires generally have round section but could have square, rectangular or flat, oblong and serrated forms. Wires are of solid section but could also be of hollowed section.

Cello wires

Wires are made of metals, metal alloys, dual metals, glass and synthetics (Nylon, polypropylene, polyesters). Wires and filaments have similar properties, and the names are often used synonymously. Similarly spun fibres of natural or synthetic origins have few properties that are similar. Wires are used alone, singly or in strands, as encased with plastics, paper, rubber, and other composite materials, entwined or braided as ropes.

Multiple wires for resonance

Wire whisk

Wires due to their thin section have strong anisotropic properties that are directionally dependent, compared isotropy, which implies identical properties in all directions. So wires are used for carrying the tensile loads such as for ties, ropes, hangers, etc. Wires of different metals and stiffness are used in stringed musical instruments for sound resonance. Wires are used as the cutting edge for building stones, precious stones, cheese, butter and flour dough. Wires of certain alloys can be re-stressed to form coils and springs. Wires due to surface hardening combined with flexibility cannot be shear cut and move under high impact and so have been used as strands and as woven structure for shields for armour. Stiff wires are used for hangers, compressible connectors, reinforcement for handles in bags and purses, and spectacle frames. Very stiff (hardened) wires are used as cycle spokes, combs for carding cotton, wool, etc. and as weft separators in looms.

Wire Egg slicer

Sarangi India Wires of Animal Guts

Wires are very long linear products so form the continuous feed stock for production of nails, paper pins and clips, stapler pins, paper binding straps, needles, hairpins, other linear items produced with CNC machines, for soldering and continuous welding. Wires form the main body for electrical cables, encased with paper, asphalt, polymeric insulation, shielded or encased in other metal coverings. Wires are included in a selvage of clothes for very heavy curtains, sail fabrics and automobile tyres. Wires are used as bailing material for cotton, wool, and paper wastes bundle.

Wire chains for Russian Armour

Wires are used for straightening the teeth, holding bones together. Guts (dried and stretched animal intestines) a form of natural wire was till now used for surgical stitches. Wires are used as clothes line, fencing or barricading media, and as lightening arrester.

Dental bracing of wires

 

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Wires as long strand is used in many different compositions. Some are linear compositions, popularly known as multi stranded wires, cables and ropes. Entwined wires with twisted barbs are used for fencing. Clutch, gear changing and break wires for two wheeler bicycles and automobiles. Springs of ball pens to railway wagon buffers, sofas, cables for chain-pulley devices, cranes, guys for supporting tall towers and masts, coiled wires for bulbs’ filaments. Entwined wires are used for rubbing clean the insides of boiler pipes and tubes. Jari or metallic wires used for brocade weaving work and for decorative laces. These are very fine Gold. Silver or polyester wires entwined on polyester or copper cores.

Springs of wires could be for Tensile and Compressive purposes

Wires as a plain, long strand, multi-strands, entwined form are used for weaving planer compositions, such as wire clothes, screen printing bolting clothes, wire nett, sieving media, and paper pulp forming screens. Wire screens or woven lattices are used in agriculture to keeps off birds. Wire fabrics are used to catch signals.

Sofa or chair coiled springs

Wires are used to create space or 3D forms, such as in kitchen drawer baskets, luggage trolleys, packing stones for retaining walls, filigree style of light weight jewellery and for rolling shutters. Construction plain bars and rebars are form of wires.

Stone Baskets of wires

Metal wires are formed by drawing or pulling a linear piece or rod, through gradually receding sizes of holes. Synthetics and Glass wires are formed by extrusion or a spinerette. Drawing is a cold working process, but it may also be performed at elevated temperatures. Generally a drawing process heats up a wire to cause molecular changes. Gold and Silver are ductile but costly materials, so are co-drawn with a core of copper. Wires for jewellery are further dented, textured, chained or spring looped to create special effects, such as for bangles, bracelets, etc. Strips of drawn metals are passed through crescent shaped dies to form half or full hollow tubes.

Wire drawing dies

Two or more wires are wrapped concentrically but separated by insulation, to form coaxial cable. Stranded wire is composed of several smaller gauge wires. It is more flexible than solid wire of the same total cross-sectional area. It is also a better conductor than solid wire because of the greater surface area. At high frequencies, current travels near the surface of the wire because of the skin effect, resulting in increased power loss in the wire.

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ROPES

Post 317 – by Gautam Shah 

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A Rope is composition of fibres, filaments, yarns, thin stripes or wires, twisted or braided or kept together by ties, over winding, binders like an adhesive or fused partially. The geometric composition (it is not a composite, as there is no matrix agent) that remains flexible yet becomes lengthier and stronger in form. The composition retains its ‘winding’ or compactness through its manipulations such as bending, pulling, twisting, etc. Rope of very a thin diameter, is called string twine or a strand. Wire ropes are also called cables.

Natural fiber two strand twisted rope

Rope twister machine

Rope is formed by several methods. The basic technique involves twisting fibres (short-staples or long-filaments) to form yarn. Twisted ropes are made by twisting the yarn into strands, then three or more strands further twisted into rope. For Braided ropes the yarn is braided. Double-braided rope has a core of braided yarn and covered with braids. In the basic twisted rope structure, alternate stages are twisted in opposite directions to give torsional stability. In the right-laid or Z-twist, (compared with left-laid or S-twist), the rope twist is seen as a spiral in upward direction.

S & Z twist in ropes

Climbers Rope with braided sheath and twisted ropes inside

The braided or plaited rope structure provides torsional balance by crossing and re crossing rope components in maypole fashion. Smaller or thin diameter ropes are called cords. Cordage was made by braiding two or three strands of yarns of same thickness, and then combining several of them by twisting in the opposite direction. The ends of twisted rope were tied up to keep them from unravelling. The finished rope was beaten with a wooden implement or brushed to even out the stresses.

Braided rope with shackle

Manila mooring rope

The texture and the nature of a rope are determined by the fineness, stiffness, strength, and stretchability of the fibres or filaments used in its construction. Strength of a rope is chiefly governed by the degree of twist in the rope and strands. A greater twist, normally lowers the strength. Rope strength is not affected by repeated pulls or tensions, on the contrary it induces inner spatial adjustment of the yarn. Ropes of natural fibres deteriorate mainly due to fibre degradation caused by mould growth, whereas synthetic ropes deteriorate due to exposure to sunlight, elevated temperatures, and chemicals. Ropes when mishandled develop strand kinks (cockles). These are also caused by irregular twisting of rope.

Three strand rope

Ropes are made from natural fibres like, Cotton, Manila (hemp), coir, jute or sisal. Cotton ropes are, weaker and stretch, but being soft is used for drawing water from wells and similar handling purposes. Manila ropes are stronger and have good salt water resistance. Short-staple fibres of cotton, wool, Rayon and long-filaments of synthetics like Nylon, polypropylene, polyester and acrylic are spun into ropes. A heavier fiber or wire creates a stiffer rope than raw fibres that are finer. Wire ropes are stronger, stiffer, heavier, and less extensible when compared to fiber ropes. Early wire ropes were strands of wires strapped together by clips, and to prevent individual wires from flaying on breaking, a slight twist was given during the clipping. Electric sky grid wires are conductive ropes.

Prestress_Post_Tension_Anchor

Wire rope with thimble and ferrule

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Ropes and cables are used for their tensile capacity, such as in cranes, elevators, draggers, barges, tents, animal harness, curtains, for sails for the boats, suspension bridges, and pre-stressed concretes.

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