A loom is a device used to weave cloth. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads. The precise shape of the loom and its mechanics may vary, but the basic function is the same.
Weaving is done by intersecting the longitudinal threads, the warp, i.e. "that which is thrown across", with the transverse threads, the weft, i.e. "that which is woven".
The major components of the loom are the warp beam, heddles, harnesses, shuttle, reed and takeup roll. In the loom, yarn processing includes shedding, picking, battening and taking-up operations.
With each weaving operation, the newly constructed fabric must be wound on a cloth beam. This process is called taking up. At the same time, the warp yarns must be let off or released from the warp beams. To become fully automatic, a loom needs a filling stop motion which will brake the loom, if the weft thread breaks.[1] An automatic loom requires 0.125 hp to 0.5 hp to operate.
A simple loom which has its roots in ancient civilizations comprising two sticks or bars between which the warps are stretched. One bar is attached to a fixed object and the other to the weaver usually by means of a strap around the back. On traditional looms, the two main sheds are operated by means of a shed roll over which one set of warps pass, and continuous string heddles which encase each of the warps in the other set. The weaver leans back and uses her body weight to tension the loom. To open the shed controlled by the string heddles, the weaver relaxes tension on the warps and raises the heddles. The other shed is usually opened by simply drawing the shed roll toward the weaver. Both simple and complex textiles can be woven on this loom. Width is limited to how far the weaver can reach from side to side to pass the shuttle. Warp faced textiles, often decorated with intricate pick-up patterns woven in complementary and supplementary warp techniques are woven by indigenous peoples today around the world. They produce such things as belts, ponchos bags, hatbands and carrying cloths. Supplementary weft patterning and brocading is practiced in many regions. Balanced weaves are also possible on the backstrap loom. Today, commercially produced backstrap loom kits often include a rigid heddle.
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Main article: Warp-weighted loom |
The warp-weighted loom is a vertical loom that may have originated in the Neolithic period. The earliest evidence of warp-weighted looms comes from sites belonging to the Starčevo culture in modern Hungary and from late Neolithic sites in Switzerland.[2] This loom was used in Ancient Greece, and spread north and west throughout Europe thereafter.[3] Its defining characteristic is hanging weights (loom weights) which keep bundles of the warp threads taut. Frequently, extra warp thread is wound around the weights. When a weaver has reached the bottom of the available warp, the completed section can be rolled around the top beam, and additional lengths of warp threads can be unwound from the weights to continue. This frees the weaver from vertical size constraints.
A drawloom is a hand-loom for weaving figured cloth. In a drawloom, a "figure harness" is used to control each warp thread separately.[4] A drawloom requires two operators, the weaver and an assistant called a "drawboy" to manage the figure harness.
| Elements of a foot-treadle floor loom |
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The earliest looms[citation needed] were wooden vertical-shaft looms, with the heddles fixed in place in the shaft. The warp threads pass alternately through a heddle and through a space between the heddles (the shed), so that raising the shaft raises half the threads (those passing through the heddles), and lowering the shaft lowers the same threads—the threads passing through the spaces between the heddles remain in place.
Looms used for weaving traditional tapestry are classified as haute-lisse looms, where the warp is suspended vertically between two rolls, and the basse-lisse looms, where the warp extends horizontally between the rolls.
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Main article: Power loom |
Edmund Cartwright built and patented a power loom in 1785, and it was this that was adopted by the nascent cotton industry in England. A silk loom was made by Jacques Vaucanson in 1745, which used the same ideas but it wasn't developed further. The invention of the flying shuttle by John Kay had been critical to the development of a commercially successful power loom.[5] Cartwright's loom was impractical but the ideas were developed by numerous inventors in the Manchester area in England, where by 1818 there were 32 factories containing 5732 looms.[6]
Horrocks loom was viable but it was the Roberts Loom in 1830[7] that marked the turning point. Before this time hand looms had out numbered power looms. Incremental changes to the three motions continued to be made. The problems of sizing, stop-motions, consistent take-up and a temple to maintain the width remained. In 1841, Kenworthy and Bullough produced the Lancashire Loom[8] which was self-acting or semi-automatic. This enables a 15-year-old spinner to run six looms at the same time. Incrementally, the Dickinson Loom, and then the Keighley born inventor Northrop working for the Draper Corporation in Hopedale produced the fully automatic Northrop Loom which recharged the shuttle when the pirn was empty. The Draper E and X model became the leading products from 1909 until they were challenged by the different characteristics of synthetic fibres such as rayon.[9]
From 1942 the faster and more efficient shuttleless Sulzer looms and the rapier looms were introduced.[10] Modern industrial looms can weave at 2000 weft insertions per minute.[11] Today, advances in technology have produced a variety of looms designed to maximize production for specific types of material. The most common of these are air-jet looms and water-jet looms.
