In this case, 4 shedding cams are mounted on cam shaft which rotates at 50 r.p.m. The primary motions, their frequency and controlling loom shaft for plain

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History of Weaving 1. Egyptians made woven fabrics some 6000 years ago. 2. Chinese made fine fabrics from silk over 4000 years ago. 3. A shedding mechani sm was originally invented in China in the 3rd century and introduced in Europe. 4. In 12th century, completely wooden hand looms were used as standard designs in England. 5. The developments in the design and performance of looms have taken place during the pa st 850 years. 6. The fly shuttle , invented in 1733 by John Kay, was hand operated. 7. It was an important cornerstone to improve the productivity. 8. This shuttle, running on four wheels, was moving over the lower side of the warp sheet. 9. Two wooden tenders connec ted to a small cord commanded by the hand were used to propel the shuttle. The weaver sitting in the middle of the loom threw the shuttle by pulling the cord very easily. Power Looms 1. E. Cartwright invented the power loom in 1785 2. In the early 1800s, loom s made of cast iron were operated by powe r . 3. In the 1830s, there were some 100,000 shuttle looms operating in England. 4. In 1895, many looms, all driven by an electric engine were invented and then became spread. 5. At the beginning of 1930’s, eventually, each weaving machine driven individually by an electric motor was developed; this loom drive concept has remained in use until the present. Automation 1. The automatic loom stopping system was invented by R. Miller in England in 1796. The loom was automatically stopped when a short pick occurred. 2. In 1894 Northrop devised a means for automatic weft replenishment without stopping the loom which was called aut omatic loom . Shedding Mechanisms 1. The first dobby operated by a punched card was invented by B. Bouchone in 1725. 2. A machine controlling bundles of harness cords with healds was constructed by J.M. Jacquard in 1801. 3. The first shuttle change motion enabling weft threads of different colors to be inserted was constructed by J.P. Reid and T. Johnson in 1835. 4. One significant invention in the field of design was that of Keighley dobby by Hattersley and Smith in 1867. 5. Rotary dobbies are manufactured in 1990s. Weft Insertion Systems 1. Projectile w eaving m achine was invented in 1924 by an engineer named Rossmann became commercial in 1953.

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2. The first patent for the rapier w eaving m achine was granted in 1898, then followed the Gabler system in 1925 and the Dewas system in 1930. Production of rapier w eavi ng m achine started in 1972. 3. The first air – jet system was invented in 1914 but it became important commercially after 4. Continuous w eft insertion on a circular w.m. was proposed before the end of the 19th century. 5. After mid 90s, multi phase w eaving m achine has showed new developments. Weaving Technology Weaving is the most popular way of fabric manufacturing. It is primarily done by interlacing two orthogonal sets (warp and weft) of yarns in a regular and recurring pattern. Actual weaving process is preceded by yarn pre paration processes namely winding, warping, sizing, drawing and denting. Winding converts the smaller ringframe packages to bigger cheeses and cones while removing objectinable yarn faults. Pirn winding is performed to supply the weft yarns in shuttle loo ms. Figure below shows various yarn packages used in textile operations (from left to right: ringframe bobbin or contains a large number of parallel ends in a double flanged beam. Sizing is the process of applying a protective coating on the warp yarns so that they can withstand repeated stresses, strains and flexing during the weaving process. Finally the fabric is manufactured on looms which perform several o perations at proper sequence so that there is interlacement between warp and weft yarns and continuous fabric production. Figure 1.2: Types of yarn packag es

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1. Heald: It is also called Heddle. It holds the warp yarns in a place.It also helps in shed formation. It is used for determining the warp thread density in a fabric. 2. Heald shaft: It is also known as harness.the wood or metal frame that holds the heddles in a certain position in the loom is called harness. Number of harness available in loom usually more than one. 3.Shuttle: This is used for the interlacement of the warp & weft yarns. 4. Shuttle box: It is a box which is used to retain the s huttle in the picking motion. 5. Picker: It is placed in the shuttle box. It may be formed by leather or other metals. 6. Beams: It is a cylindrical body in which the multiple warp ends is used in such way that permits the removal of yarns as a warp she et. 7. Front rest: It is a fixed roller placed in front of the is situated above the cloth beam & work as a guide for the cloth to wind. 8. Lease rods: The division of warp yarns into one & one, two & two etc is termed as lease. The two rods pass ed between the two divisions of warp yarns.those are called lease rods. 9. Slay: Slay contains the reed. 10. Reed: It is generally comb which is used to separate also beats up the yarns in

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weaving process. 11. Treadle: The treadle is a paddle o r lever placed under a a thread is connected with the help of cords. 12. Temple: It is the roller device on a loom that hold the cloth at a proper width. Main parts of a loom is given below: 1. Heald Shaft This part is related to the shedding mechanism . The heald shaft is made of wood or metal such as aluminium. It carries a number of heald wires through which the ends of the warp sheet pass. The heald shafts are also known as or The number of heald shafts depends on the warp repeat of the weave. It is decided by the drafting plan of a weave. The main function of the heald shaft is as follows: It helps in shed formation It is useful in identifying broken warp threads It maintains th e order or sequence of the warp threads It determines the order of lifting or lowering the required number of healds for a pick. In other words it helps in forming the design or pattern in a fabric. It determines the warp thread density in a fabric, i.e. t he numbers of heald wires per inch determine the warp thread density per inch. 2. Sley or lay It is made of wood and consists of the sley race or race board, reed cap and metal swords carried at either ends. The sley mechanism swings to and fro. It is res ponsible for pushing the last pick of weft to the fell of the cloth by means of the beat up motion. The sley moves faster when moving towards the fell of the cloth and moves slower when moving backwards. This unequal movement is known as of t he It is needed in order to perform the beat up and also to give sufficient time for passage of shuttle to pass through the warp shed. The beat up of the lastly laid pick of weft is accomplished through a metal reed attached to the sley. 3. Shuttl e It is basically a weft carrier and helps in interlacement of the weft with the warp threads to form cloth. The shuttle which is made of wood passes from one end of the loom to the other. It travels along the wooden sley race and passes between the top a nd bottom layers of the warp sheet. The shuttle enters a shuttle box fitted at either ends of the loom, after passing through the warp shed. A shuttle normally weighs about 0.45 kgs.

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4. Shuttle Box It is the housing for the shuttle and is made of wood. It has a spindle and a picker. It may also accommodate the picker without spindle. The top and side of the box towards the sley race are open. The shuttle dwells inside the box for the intermediate period between two successive picks. 5. Picker The pick er is a piece made either of leather or synthetic material. It may be placed on a spindle or grooves in the shuttle box. It is used to drive the shuttle from one box to another. It also sustains the force of the shuttle while entering the box. 6. Reed I t is a metallic comb that is fixed to the sley with a reed cap. The reed is made of a number of wires and the gap between wires is known as dents. Each dent can accommodate one, two or more warp ends. The count of the reed is decided by the number of dents in two inches. The reed performs a number of functions which are enumerated as follows: It pushes the lastly laid pick of weft to the cloth fell It helps to maintain the position of the warp threads It acts as a guide to the shuttle which passes from on e end of the loom to the other. It determines the fineness of the cloth in conjunction with the healds. It determines the openness or closeness of the fabric. There are various types of reed such as ordinary reed, gauze reed, expanding reed, V reed etc. 7. Warp Beam This is also known as the beam. It is fixed at the back of the loom. The warp sheet is wound on to this beam. The length of warp in the beam may be more than a thousand metres. 8. Back Beam This is also known as the back rest. It is placed above the beam. It may be of the fixed or floating type. In the first case the back rest merely acts as a guide to the warp sheet coming from the beam. In the second case it acts both as a guide and as a sensor for sensing the w arp tension. 9. Breast Beam It is also known as the front rest. It is placed above the cloth roller at the front of the loom and acts as a guide for the cloth being wound on to the cloth roller. The front rest together with the back rest helps to keep t he warp yarn and cloth in horizontal position and also maintain proper tension to facilitate weaving. 10. Cloth Beam It is also known as the cloth roller. The woven cloth is wound on to this roller. This roller is

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placed below the front rest. It is also known as the cloth roller. The woven cloth is wound on to this roller. This roller is placed below the front rest. Types of Looms Hand Loom: This is mainly used in unorganized sector. Operations like shedding and picking is done by using manual power.T his is one of the major sources of employment generation in rural areas. Power Loom: It was designed by Edmund Cartwright in 1780s (during the industrial revolution). All the operations of the loom are automatic except the change of the pirn. Autom atic Loom: In this power loom, the exhausted pirn is replenished by the full one without stoppages. Under – pick system is a requirement for these looms. Multiphase Loom: Multiple sheds can be formed simultaneously in this looms and thus productivity can be increased by a great extent. It has failed to gain commercial success. Shuttle – less Loom: Weft is carried projectiles, rapiers or fluids in case of shuttle – less looms. The rate of production is much higher for these looms. Besides, the quality of t he products is also better and the product range much broader compared to that of Power looms. Most of the modern mills are equipped with different types of shuttle – less looms based on the product range. Circular Loom: Tubular fabrics like hose – pipes a nd sacks are manufactured by circular looms. Narrow Loom: These looms are also known as needle looms and used to manufacture narrow width fabrics like tapes, webbings, ribbons and zipper tapes . Primary Motions Figure 1.3 shows some basic component s of a loom. For fabric manufacturing through weaving, three primary motions are required namely shedding, picking and beat up.

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Figure 1.4: Shedding Except for jacquard shedding, warp yarns are not controlled individually during t he shedding operation. Healds ( Figure 1.5 ) are used to control a large number of warp yarns. The upward and downward movements of healds are controlled either by cam or dobby shedding mechanisms. The movement of the healds is not continuous. After reaching the top or bottom position, the healds, in after every pick i.e. the insertion of weft. Figure 1.5: Heald Picking The insertion of weft or weft carrying device (shuttle, projectile or rapier) through the shed is known

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as picking. Based on picking system, looms can be classified as follows. Shuttle loo m: weft package is carried by the wooden shuttle Projectile loom: weft is carried by metallic or composite projectile Airjet loom: weft is inserted by jet of compressed air Waterjet loom: weft is inserted by water jet Rapier loom: weft is inserted by flexi ble or rigid rapiers Figure 1.6 shows some weft carrying devices. Figure 1.6: Shuttle, rapier heads and projectile (from top to bottom) With the exce ption of shuttle loom, weft is always inserted from only one side of the loom. The timing of picking is extremely important specially in case of shuttle loom. The shuttle should enter into the shed and leave the shed when the shed is sufficiently open ( Fig ure 1.7 ). Otherwise, the movement of the shuttle will be obstructed by the warp yarns. As a result, the warp yarns may break due to abrasion or the shuttle may get trapped in the shed which may cause damage to reed, shuttle and warp yarns. Figure 1.7: Picking

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Beat – up Beat up is the action by which the newly inserted weft yarn is pushed up to the cloth fell ( Figure 1.8 ). Cloth fell is the boundary up to which the fabric has been woven. The loom component responsible for forward and backwards due to the crank – connecting rod mechanism. This is known as cra nk beat up. In modern looms, beat up is done by cam mechanism which is known as cam beat up. Generally, one beat up is done after the insertion of one pick. Figure 1.8: Beat up Secondary Motions For uninterrupted manufacturing of fabrics, two additional secondary motions are required. These are take – up and let – off. Take – up motion winds the newly formed fabric on the cloth roller either continuously or intermittently after the beat up. The take – up speed also determines the picks/cm value in the fabric at loom state. As the take – up motion winds the newly formed fabric, tension in the warp sheet increases. To compensate this, the weavers beam is rotated by the let – off mechanism so that some new warp sheet is released. Auxiliary Motions Auxiliary motions are mainly related to the activation of stop motions in case of any malfunctioning like warp breakage, weft breakage or shuttle trapping within the shed . The major auxiliary motions are as follows: Warp stop motion (in case of warp breakage) Weft stop motion (in case of weft breakage) Warp protector motion (in case of shuttle trapping) Primary Motions Three primary motions are required in the loom for weaving. Shedding Picking

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Beat up Shedding is the operation by which the warp is divided into two parts so that sufficient gap is created between them for the uninterrupted passage of the weft from one side of the loom to the other. Picking is the operation to transfer the pick (weft) from one side of the loom to the other. In shuttle loom, picking is done from both sides. However, in shuttleless looms, it is done from only one side of the loom (generally from left). Several systems are availabl e for the picking. Shuttle is the most traditional mode of picking and it is still being used in the industry. In shuttleless looms, following picking systems are used. Projectile Air jet Water jet Rapier Beat up is the operation to position the newly inserted pick up to the cloth fell i.e. the boundary up to which the fabric has been woven. Secondary Motions Two secondary motions are required in the loom for weaving. Take up Let off Take up motions ensure the winding of fabric conti nuously as soon as it is produced. Ensuring uniform pick spacing is also another function of take up motion. When the fabric is wound by the take up system, the tension in the warp increases and thus it is required to release the warp from the weaver’s bea m which is performed by the let off motion. The transmission of motions to some of the important loom components has been shown in Figure 6.1 . The loom pulley (machine pulley) gets motion directly from the motor pulley. The crank shaft, which has a specia l design, is connected with the loom pulley. The revolution per minute (r.p.m.) of the crank shaft is equal with the loom speed (number of picks inserted per minute or picks/minute). The beat up operation is done by the reed which is carried by the sley an d the latter is connected with the crank shaft. One revolution of crank shaft causes one beat up. Therefore, if 200 picks are being inserted per minute, 200 beat ups are required in one minute. Thus the r.p.m. of the crank shaft has to be 200.

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