The Hand Loom; Most popular weaving machine in the world

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The Hand Loom 

As with spinning, the principles of weaving are easily understood by reviewing the operations performed in hand weaving with hand loom. Many weavers continue to practice this craft. Weaving with hand loom requires that the warp yarns be held under tension. Having stretched out one set of yarns, the weaver then takes a second yarn and interlaces it with the warps. The simplest interlacing is made by moving the filling over the first warp, under the second, over the third, and under the fourth, and so on. In the second row, the filling moves under the first warp, over the second, under the third, and so on. The third row repeats the pattern of the first, and the fourth row repeats the pattern of the second row. Known as a plain weave or tabby, this is the simplest form of weaving. 

The filling yarns in hand loom, those running at right angles to the warps, can be introduced by hand. As the weaving process developed, weavers found it was easier either to use some device such as a needle, or to wrap the yarns around a stick. This latter method had the advantage of allowing the yarn to be unwound as the stick was moved through the warps. Ultimately, yarn was wound onto a bobbin, and the bobbin was placed into a boatlike shuttle. The pointed end of the shuttle allowed the carrier to move smoothly, while the bobbin allowed the yarn to unwind as it was needed.Filling yarns tended to be somewhat loose in placement and had to be pushed into place more firmly. The earliest weavers painstakingly pushed each yarn into place with a small stick. A later, more efficient method used a wooden stick, shaped like a sword that was slipped behind the filling yarns and pushed them tightly against the fabric that had already been woven. This weaver’s sword, or batten, became a permanent part of the loom, although its shape was transformed gradually into a comb-like device called a reed that was mounted on a frame. The frame retained the name batten, and a pull of the hand on the batten frame moved the reed forward, swinging the reed against the filling yarn and pushing it (beating up”) firmly into place. 

At first the finished cloth was probably the same dimensions as the hand loom, but Egyptian fabrics of long dimensions have been found, and it is possible that they may have used a roller beam system. A beam with warp yarns wrapped around it allowed yarns to be fed continuously to the” weaver, and as the fabric was woven, it was wrapped around a roller at the other end of the loom. In this way continuous lengths of fabric, longer than the loom, could be constructed. 

As long as each warp yarn had to be raised by hand before the filling was interlaced with it, the process of weaving remained slow and tedious. Inventive weavers improvised a means of speeding up the procedure of raising and lowering warp yarns. Alternate rows of warps were placed over a shed rod, a stick that lifted them above the level of their neighboring yarns. This formation of raised and lowered warp yarns is called the shed the bobbin could be thrust across the entire width of the cloth through the shed without stopping to raise each individual warp yarn. The alternate set of warp yarns was threaded through a series of string loops that were tied to another rod. This rod could raise the second set of yarns past those on the shed rod. By thrusting the bobbin under this second set of yarns that had been raised by an upward pull on the rod, the filling interlaced with an alternate set of yarns. Alternate raising and lowering of the rod made it possible to interlace warp and filling yarns quickly and efficiently. The rod that held the second set of warps was called a harness; the loops were called heddles. Variety in weave could be achieved through the use of multiple harnesses, each raising a different set of warps. 

The widespread use of silk probably brought about certain improvements in hand loom structure. Since silk filament yarns were fine and slippery, use of the shed rods made weaving more difficult. In silk weaving, the shed rod was replaced by a second harness with heddles, as the smooth, fine yarns tended to slide against the shed rod, while the heddles held them securely. The change from hand manipulation of harnesses to operation by foot treadle was another improvement. The hand loom was constructed so that pressure on a foot treadle raised and lowered the harness frame. This released the hand to operate the shuttle and the batten and increased the speed with which the weaver could work. 

Probably the single most important invention that preceded automation of the hand loom was the flying shuttle. The flying shuttle, designed by John Kay and patented in 1733, was a device with a spring mechanism that threw the shuttle across the loom from one side to the other. In hand weaving, Kay’s device was activated by a cord on either side of the loom that was pulled by the weaver. When the machine was mechanized, the flying shuttle was incorporated into the loom and operated mechanically. 

Following Figure depicts the basic handloom that had developed by the time of the Industrial Revolution. Handlooms used by weavers today have the same type of structure.

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Preparing the Warp Yarns for Weaving in loom

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Preliminary Steps for warp yarn preparation:

Before their use on the weaving loom, warp and filling yarns must be prepared for weaving. The essential characteristics of suitable warp and filling yarns differ. Warp yarns undergo greater stress and abrasion during weaving than do filling yarns; therefore, warp yarns must be strong enough to withstand these pressures. Warp yarns must be clean, free from knots, and uniform in size. A single warp yarn is called an end warp yarns are wound onto the warp beam from many cylindrical packages of yarns, which are called cheeses. To strengthen and lubricate warp yarns, sizing or slashing is added. Size is made up of starches or synthetic polymers such as polyvinyl alcohol (PVA) that act as lubricants. The yarns are passed from one warp beam through a solution of sizing material. The sized yarns are dried immediately after treatment and are wound into another warp beam. Sizing is not always required on filament yarn warps.

The warp beam containing the sized yarns is placed on the loom. In preparation for weaving, each warp end (yarn) must be threaded through its own drop wire, heddle eye, and reed dent. The drop wire is a device that will stop the loom if an end should break, the heddle eye is the opening in a heddle that carries the yarn, and the reed dent is an opening in the reed, the comb like device that will push each filling yarn close against the completed fabric.Placing the warp yarns on the loom is done either by drawing-in or by tying-in. If warp yarns from a previously woven fabric are in place and if that fabric had the same number of warps, the new warps are tied into place by attaching them to the warps already on the loom.If the new warp is different from that previously woven or if there is no warp on the loom, then the warps must be drawn-in. To draw-in or tie-in each end by hand would be enormously time consuming; therefore, a variety of machines has been developed for drawing-in. A separate machine can be used fot each step (that is, drawing through the drop wire, the heddle eye, and the reed dent), or one machine can perform all three steps. When a loom makes the same fabric, warp after warp, the new warp can be tied-in to the old.

Heddle wires are held in frames called harnesses. The number of harnesses required for the loom is determined by the weave. 

The warp beam: - warp beam, located in the back of the loom, is a large roller on which all of the warp yarns to be used for the cloth are wound parallel to each other If the fabric is to have warp stripes, the various yarns are wound onto the beam in color groupings to obtain the desired colored stripe effect.

Heddles: - Each with a hole (eye) in the middle. Each warp yarn is threaded through the eye of one heddle. Thus being controlled by that harness.

Harnesses: - The warp yarns pass through the harnesses, which look like picture frames holding many thin vertical wires called heddles, each with a hole (eye) in the middle. Each warp yarn is threaded through the eye of one heddle. Thus being controlled by that harness. The purpose of the harnesses is to raise and lower the warp yarns. The number of harnesses varies from twc to about thirty, depending upon the complexity of the weave.

Shuttle:- A shuttle is used, which is a boat-like device to carry the filling yarn on a stick called a quill or bobbin, As the shuttle moves from one side of the loom to the other, it leaves a trail of filling yarn behind it. The shuttle passes over the lower set of warp yarns and under the upper set. The shuttle stays in a box located at the end of the shed. When a bobbin becomes empty, a full one automatically replaces it.

Reed:- The reed is a frame with thin, vertical non-movable wires. Narrow openings or dents exist between the wires, the purpose of which is to keep the warp yarns separated. The reed resembles a comb and pushes the loose pick in the shed up to the edge of the already made cloth and returns to a position near the harnesses. The shuttle passes in front of the reed.

Cloth roll:- The cloth is slowly wound onto the cloth roll, located in the front of the loom.

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Shuttle Loom | Popular and conventional weaving machine

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Shuttle Loom: 

The shuttle loom is very popular and conventional weaving machine. The conventional loom utilizes a shuttle that contains a bobbin of filling yarn, which emerges through a hole in the side. As the shuttle is batted across the loom it leaves a trail of the filling at the rate of about 110 to 225 picks per minute (ppm). 

The shuttle loom is the oldest kind of weaving machine. It is effective and versatile, but is has certain disadvantages. The shuttle sometimes causes abrasion on the warp yarns as it passes over them and sometimes causes thread breaks. This, in turn, results in machine stoppage in order to tie the broken yarns. Shuttle looms operate more slowly than some new types of  looms or weaving machine and they are, also noisier. 

In shuttle looms the shuttle traverses the cloth, and the filling yarn unwinds from the quill. Quills in the shuttle must be replaced when the yarn supply is exhausted. The frequency with which a quill has to be replaced depends on the fineness of the filling yarn. Coarse yarns require more frequent replacement; finer yarns need to be replaced less often. 

In the mechanical changer, full quills are kept ready in a revolving case. The weaving machine rams them into the shuttle when the shuttle comes to rest briefly after crossing the yarn. The pressure of the full quill crowds the empty quill out of the shuttle. It falls through a slot into a container under the shuttle loom. The new quill is pushed mechanically into place in the shuttle, which has a self-threading device that automatically picks up the yarn when the new quill is inserted. This allows the weaving to continue without a stop. 

A specialized process has been developed that allows winding of quills to take place at the loom. In the Unifil system, empty quills are carried on a conveyor belt to a point where yarn from a large package is wound onto an empty quill that is then returned to a position where it can be placed in the shuttle. This system requires that fewer wound quills be supplied, but it has several limitations. It is useful only for single-color picks, and because the cost of the system is high, it is most economical for coarse yarns that would require especially frequent quill replacement. Picking when two or more different colors or types of filling yarn are used requires two or more shuttles and a more complex and costly type of loom arrangement. A conventional shuttle loom has one shuttle box on each side of the weaving machine.

To insert yarns of different colors or types, a number of shuttle boxes must be moved up and down to bring shuttles into position to create the pattern. Such looms are often called pick and pick looms. Among the advantages of most shuttle-less looms is that they draw yarn for each pick directly from yarn packages, making it easier and less costly to insert a number of different colors or types of yarn. 

The rapid crossing of the shed by the shuttle leaves a layer of filling yarn. When the shed is changed, the yarn is locked into place by the change in warp positioning. However, to make the yarn lie flat and in its proper position, it must be beaten into place in finish is the mote durable. For heavy industrial fabrics made from heat-sensitive or thermoplastic fibers, hot melting devices cause the yarns to fuse together to form a tight selvage.

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Weaving Machine motion | Control of Loom Motions

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Weaving machine or loom is a essential part of fabric manufacturing technology. The weaving technology and mechanism is developing day by day. At past we used only hand loom which was powered by human strength. It was developing day by day. New we got the most powerful weaving machine and modern loom which can automatically produce the fabric according to the instruction. But in this article I will just describe about the essential loom or weaving machine motion control device. Although it is entry lave concept but you can get a clear concept about the topic. 

The essential motions in loom operation are the motion of the harnesses to form the shed and the activation of devices for carrying the filling through the shed. 

Cam Loom 

All types of motion of weaving machine is controlled by mechanical cam. The weaving machine is in the past the motions in most simple weaves were controlled by mechanical devices called cams. The shape or profile of the cam is followed by a device called the cam follower, and the irregularities in the cam shape are translated by the cam follower into the motions of the loom. In this way simple repeat patterns can be created. Repeats are limited to six or fewer picks, but this includes a substantial majority of the most commonly used fabrics. More complex designs require dobby or jacquard looms. Such looms are rapidly being replaced by more modern machines with electronic control of motions. 

Dobby Loom 

All types of motion of weaving machine are controlled by mechanical dobby. This dobby loom is faster than cam loom. The dobby loom is a conventional loom with a somewhat enlarged dobby “head.” The traditional dobby mechanism uses a pattern chain on which there are pegs. Needles or feelers contact the pegs in the pattern chain and are positioned by the pegs. The feelers cause hooks within the dobby head to be connected or disconnected, and the motion of the hooks is translated to the harnesses that move from up to down or to in-between positions as dictated by the pattern. 

From twenty-four to thirty shedding combinations are controlled in this way, so that the repeats are limited to about thirty rows in size. A machine called the double cylinder dobby loom has been developed that approximately doubles the size of the repeat that can be made. The fabrics woven on this loom are less complex than are jacquard patterns and usually consist of small fancy or geometrical figures or designs. Plain terry towels are also woven on dobby looms. With the development of electronic jacquard looms that can make both 

Jacquard Loom 

All types of motion of weaving machine are controlled by mechanical jaquard. It is faster than dobby loom. The jacquard loom is the descendant of an oriental loom, the draw loom, which was used to weave complex patterned fabrics. Operation of the draw loom required two workers: the weaver who threw the shuttle and operated the batten and a draw boy who raised and lowered a series of cords that controlled the pattern. The draw boy had to work from a platform above the loom while the weaver sat below. 

Since the draw boy could make mistakes in the selection of cords, later modifications of the loom structure introduced a mechanical device for raising and lowering the cords. In 1805 Joseph Jacquard, a Frenchman, perfected the principle of the mechanical draw loom. To this day, this same type of loom used in weaving complex patterns is known as the jacquard loom and the weave is known as the jacquard weave.

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Shuttle less Looms | Weaving Machine operates without shuttle

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Shuttle-less Looms 

Advantages of Shuttle less Weaving Machines: When patterned fabrics are woven on shuttle-less weaving machines, colors can be changed more easily. Unlike shuttle looms in which a different shuttle must be provided for each different color, the shuttle-less machines can be provided with a variety of colors directly from yarn packages. Other advantages include lower power requirements, lower sound levels, smaller space requirements, and higher speeds of fabric production. On the other hand, the higher production rates of shuttle- less machines requite that yarn quality be high to ensure trouble-free operation. 

Trends in loom purchases within the textile industry in the United States show clearly that shuttle-less weaving machines are replacing traditional shuttle looms. In 1985 there were 160,000 shuttle looms in place in the United States, and by 1997 that number had dropped to less than 70,000 (Isaacs 1998). 

Currently the most widely used machines worldwide are rapier and projectile types. Air-jet looms ate becoming more popular in North America. To overcome disadvantages of the shuttle loom, several different kinds of shuttle less looms have been developed. Each type uses a different method of picking, which provides specific characteristics and applications. 

Missile or Projectile Looms- 

These looms were developed in the 1950s in Switzerland and represent the first proven shuttle-less loom. The picking action of the missile or projectile loom is accomplished by a series of small bullet-like projectiles which grip the filling yarn and carry it through the shed and then return empty. All the filling yarn is inserted from the same side of the loom and a special tucking device is used to hold the ends of the filling in place at the edge of the cloth to form the selvage, or selvedge The missile loom has good versatility and is used for a wide variety of basic fabrics ranging from cotton-type goods such as percale and print cloth to worsted-type material. It does require a smooth, uniform yarn that is properly sized to reduce friction. The missile loom has speed of up to 300 ppm and yet is less noisy than the shuttle loom. 

Rapier Looms

Rapier loom is a competitor to the missile loom. There are several kinds, which may be subdivided into types. One early model uses one long rapier device that reaches across the width of the loom to carry the filling yarn from one side of the loom to the other. Another type utilizes a double rapier, that is, one on each side of the loom. The rapier may be any one of several constructions: rigid, flexible, or telescoping. In every case, one rapier feeds the filling yarn halfway through the shed of warp yarns to the arm on the other side, which reaches in and takes it across the rest of the way. These rapier looms are efficient. They operate at speed ranging from about 200 to 260 ppm at about the noise level of missile looms. They can produce a wide variety of fabrics ranging from muslin to drapery and upholstery materials. 

Water Jet Looms 

The water jet loom was first developed in Czechoslovakia in the 1950s and subsequently refined by the Japanese in the 1960s. Water jet looms were designed to weave faster and to relieve the tension on the filling yarn as it is carried through the shed. A pre-measured length of filling yarn is carried across the loom by a jet of water. 

These water jet looms can operate at relatively high speeds of up to about 600 ppm and at noise levels lower than the shuttle, missile, and rapier looms. Since the pick is tensionless, high quality, almost perfect warp yarns are required for efficient operation. A broken warp could deflect the floating pick out of the shed. Another disadvantage is that the water-jet looms are restricted to production of fabrics made of yarns that are not readily absorbent––such as filament yarns of acetate, nylon, polyester, and glass. Even then, the cloth must be dried before further processing. However, the water-jet looms can produce superior high quality fabrics that have good appearance and feel (hand). 

Air Jet Looms 

The air jet loom, invented in Czechoslovakia and later refined by the Swiss, Dutch, and Japanese were designed to retain the tensionless aspect of the picking action of the water jet while eliminating the problems caused by the use of water. These looms use a jet of air to propel the filling yarn through the shed at rates of up to 600 ppm. Air-jet looms require uniform filling yarns. They are more suitable for use with heavier than lighter yarns because the lighter weight yarns are more difficult to control through the shed. Yet, if the yarn is too heavy, the air jet may not be able to carry the filling across the loom. Within these restraints, the air-jet loom is effective and can produce a wide variety of textile fabrics. Also, the air-jet loom operates at a lower noise level than the shuttle, missile, or rapier looms. 

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