Denim A-Z

PROJECT REPORT_______________________________________________________________________________________________________ PRESTON UNIVERSITYMS Word Export To M ultiple PDF Fi les Softw are - Please purchase license.

PrefaceAll praise is to Allah, Lord of the Worlds, the most Beneficent, the most Merciful and every grace of Allah is on His Prophet Muhammad (P.B.U.H), who is always a source of knowledge and guidance for humanity as a whole. It is a matter of great satisfaction and pleasure for us to present this project. This project report is a part of our Degree program which is done during fourth year of our studies. We chose Denim sector of Textile field as it is a Shinning, growing and challenging field. The entire contents of this report are based on our project in US DENIM. Our major emphasis has been on process, machine and product with the calculations involved. We have included in this project report the technical as well as the Mechanical aspects. We moved department wise covering various aspects. These days of Industrial training enhanced our spirit, courage and confidence. We also improved our presentation and technical skills. Even though every precaution has been taken, it may be possible that any mistake(s) is found. We will feel grateful, if it is intimate.

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PROJECT REPORT_______________________________________________________________________________________________________ PRESTON UNIVERSITY

ACKNOWLEDGEMENTSFirst of all we thank Almighty Allah who brought this moment in our life when we came in US DENIM for the project. It has been a great experience to work with all of you and we are feeling proud that we can say we have worked in US DENIM which is not only one of the best DENIM manufacturer & Exporters in Pakistan but also all over the world and where the management and the workers have demonstrated a very good performance in all areas of the business. US DENIM is a dynamic organization with professionals loving and professionals making setup. As it is said Time Spent in Training is time Well-spent. The golden time, which we spend here and the practical, conceptual and industry- related knowledge, which we gained here will be a milestone in our professional carrier. We would like to thanks US DENIM MANAGEMENT Mr. Asif (HR Manager US Denim) Mr. Haroon (Admin) Mr. Bilal Tariq (Production Manager) Mr. Faisal (MT) US APPAREL MANAGEMENT Mr. khurram (HR Manager US Apparel) Mr. Hanif Khan

We are grateful to our class advisor Mr. KASHIF MUNIR for arranging this project. We always remember the hospitality we received during our stay at the US DENIM. We are privileged to work with experienced personnel, who are the master of their skill and field. Their ever supporting behavior, kind advice, and professional approach taught us how to perform tough and critical tasks with utmost ease. We have very much enjoyed being amongst wonderful people. We wish each and every one everlasting progress, success and of course wish US DENIM a very prosperous future.

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Contents_________________________________________________________________________________________

U S Denim Introduction . . . . . .. . . . . . .... . ..... .. ... . . . . . . . . . . . .5

T A B L E O F C O N T E N T S

History Of Denim. . . . . .. . . . . .. .. . . . . . . . . . . . . ... . .6 Types Of Denim.10 Introduction of Cotton..... . . . . . ..13 Yarn Manufacturing..... . . . . . .....14 Warping...... . . . . . ....16 Warping in U S Denim...19 Warping Plan...22 Dyeing..... . . . . . .......24 Sulphur Dye.25 Vat Dye...................30 Denim Dyeing.............33 Rope Dyeing...........38 Dyeing in U S Denim..44 Rebeaming.... . . . . . ....46 Sizing.. . . . . . ....47 Weavers Beam.... . . . . . ....48 Weaving...... . . . . . ...49 Air-Jet Weaving.... . . . . . ........51 Weaving in U S Denim... . . . . . .........54 Finishing...... . . . . . ......56 Singeing............................58 Mercerizing.........62 Stenter.........64 Sanforizing...65 Inspection Department... . . . . . ....68 Packing.... . . . . . .....70 Faults... .. . . ....71

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Contents______________________________________________________________________________________________

U S Apparel Introduction..73 Store Room....75 Cutting Department...76 Embroidery Department...79 Stitching Department....80 Types of Stitch..83 Hems..90 Wet processing...93

Chemicals On Denim.98Denim Washing. . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . 110 Mechanical Washes. . . . . .. . ...... . . . . . . . . . . . . . . . . . .. . . . .111 Chemical Washes. . . . . .. . . . . . . . . . . .. . .... ...119 New Development in Denim Washes. .... . . . . . . .... . . . . . . .129 Trimming...132 Buttoning...133 Pressing....136 Finishing....137 Packing..138 Glossary Of Denim..139

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US Denim Mills is an upstart denim manufacturing company. We see ourselves as the foremost source of innovative textile products for today's apparel world and are committed to delivering value to our customers in terms of product development, on-time delivery and high quality. We are responsible to our shareholders for a good return on investment. As corporate citizens we work towards achieving the best environmental and ethical practices. No of Employees more than 500 Established in 2005 Location Lahore, Punjab-Pakistan.

U S D E N I M

WEAVING

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H I S T R Y O F D E N I M

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HISTROY OF DENIM:In fashion history, jeans and denim history continues to baffle. No one truly knows the perfect answer to where jeans began. As so often happens fashions often emerge together in various parts of the world and are the result of the sudden availability of a new fabric, cloth, dye or technique. But we do know that the phrase denim jeans are thought to derive from several sources. No one is totally certain where the words come from. A majority of source books suggest that denim derives from the English translation of the South of France French phrase 'serge de Nmes'. Denim fashion history is thus associated with Serge de Nimes. It may well be that the fabric which was made in France also had a version made locally in England and was called by the same name of denim in the same way that Cheddar cheese is called cheddar all over the world. The Serge de Nmes was originally a wool silk mix, twill weave. Certainly by the 19th century in England denim had a white warp and a navy woof (weft). Denim was considered a hard wearing sturdy fabric, ideal for heavy laboring. When talking about denim the name Levi s is one of the first to be mentioned. Levi s which stands for Levi Strauss is normally called the forefather of jeans.

When tracing back the history of these trousers to its origins it is true that Levi Strauss played an important role concerning their development and distribution but he had also other inventive business partners. Now the question is: who has sewn the first jeans and where does the history of this blue phenomenon begin? Levi Strauss in the year 1860 In 1847, at the age of 17 Levi Strauss left his Frankonian native country in Germany and emigrated to New York together with his family. The members of the Strauss family were capable and skilful businessmen and ran a pedlary at that time. So Levi and his brother followed their parents footsteps and also became peddlers. When his great gold rush began in 1850, however, he decided to take part and sent over to San Francisco in California. He took with him a spade, a pick hammer and a bale of fabric out of brown sail cloth which was meant to put up a tent. This did not happen, however: Levi found out that the gold diggers hard work in the mines made their clothes get worn out very quickly and he produced stout working trousers out of the sail cloth he had taken with him which 7


he called half overalls. When he continued producing these trousers he used cheap cotton fabrics coming from Genova. At that time Genova was a flourishing place where cotton was exported all over the world. The name of the town of Genova was modified into jeans in the American slang. At the end of the sixties of the 19th century he replaced the brown sail cloth by an indigo-dyed, wear resistant cotton fabric coming from France. The name of this fabric was Serge de Nimes. Serge is the French Expression for combined twill and Nimes is the French town where the fabric comes from. The fabrics name Serge de Nimes was quickly turned into Denimin American colloquial language. By applying this indigo-dyed combined twill the first jeans out of Denim was almost born or better sewn. The only thing missing were the famous metallic vets. The application of metal rivets for jeans is due to the Polish emigrant Jacob W. Davis, also called Jacob Youphes. Although the working trousers out of Denim were stout they had a tendency to get worn out where the pockets were. Jacob Youphes mended the trousers with a needle and thread. One day a customer inspired him to repair the torn off pockets with the help of rivets. From then on Jacob Youphes made a lot of money out of repairing trousers. Since he was worried that his invention might be stolen he wanted to apply for a patent. For doing so, however, he needed a financially strong partner. For that reason he addressed the manufacturer of the trousers that he mended, Mr. Levi Strauss. Levi Strauss agreed and together they applied for a patent to strengthen the pockets of the trousers and Levi Strauss acquired a share of 50%. This patent was written down in 1873 and can thus be called the true year of birth. Under the management of Levi Strauss the jeans were now produced in series. Since the trousers were so stout not only the gold diggers liked them but which is not surprising in America? The cowboys appreciated them very much, too. When the trousers were applied as working trousers for cowboys, however they got worn out at the crotch tip. This was no problem for Levi Strauss and Co. since they reinforced the trousers again with metal rivets at the crossing point of the four seams at the crotch tip. The metal rivet at the crotch had to be removed quickly since the way of living of the cowboys had not been taken into consideration. The cowboys used to repair their meals at the campfire and then they spent the rest of the evening sitting round the campfire. When the cowboy approached the fire too much at night, however he quickly learned the difference between the physical conductivity of cotton and metal. Those wearing these trousers were then suddenly startled out of their sleep. By knowing very well the need for such a stout garment and thanks to the good cooperation with Jacob Youphes as well as his very good instinct for marketing Levi Strauss is still an important brand name in todays textile industry. About 1947 denim made a break-away from work clothing image, chiefly in the area of sportswear and rainwear and an occasional appearance in high fashion collections as a "different-looking" evening dress. Jeans fashion history was truly made in the 1950s when film stars wore it in movies that the teenagers of the day followed with avid interest. For many years jeans were only used as work wear clothes, but by the 1940s they were considered leisure wear in America. Once pop and film stars like Elvis Presley, James Dean, and Marlon Brando sported them they became desirable internationally in the 1950s and are associated with rock and roll and pop music. Later in the 1960s, jean brands old and new were worn universally in the 8


western world. 1970 American youth adopted denim as their favorite fabric. Part of a "back to nature" movement that emphasized ecology and the natural denim being a fabric created from a natural fiber was a primary factor. Since 1960 the jeans business has undergone an explosive transformation, from a source of tough, cheap clothing for cowboys, blue-collar workers and penniless youth into a fashion conscious market for a widening mass of people of almost all ages. Substantial growth in overseas sales of American jeans and denim. Exports of Americanmade blue jeans grew. Overseas manufacturers of jeans also grew. Production of indigo dyed denim started in Europe on an industrial level in 1972. Spreading of jeans fashions in the 1970s and doubling of denim capacity in U.S.led to the onslaught of imports. From 1976 to 1979 U.S. imports of denim into Europe enjoyed penetration levels between 33% and 42%. European textile industry saw in denim, an opportunity to restructure itself into a more capital intensive high technology industry, thus becoming more competitive against imports from lower-cost countries. From 1972 to 1976 capacities grew from approximately 20 million square meters to 130 million. All mills were basically running at capacity. It was a period of worldwide shortage of denim when demand was substantially greater than capacity. The 1976/7 fashion element subsided in Europe and U.S. Return to specialist jean manufacturer producing basic jeans, with relative little fashion styling. The introduction of "baggy" jeans originated in Italy where previous shortage led to youth wearing any size jeans available. Since 1978 specialized denim manufacturers re established positions mainly in terms of quality. Indigo denim first produced at Yarraville during 1965 on a narrow width Slasher dyeing machine designed and built on the area. This dyeing method has now been entirely replaced by the commissioning of the Morrison Rope Dyeing Machine on July 4th, 1980. Dyeing capacity 15 to 16,000,000 square meters of denim per annum are possible on this new Morrison dyeing Machine. By the 1980s ripped, frayed and torn jeans were a normal sight. Colored jeans from white through to pastels were also popular as were stonewashed blue jeans. In the 80s, designer jeans with names like Gloria Vanderbilt, Calvin Klein and Armani among so many fashion designers became the designer label jeans to be seen in. Stone washed jeans became a must. By the 1990s black jeans were very popular for a while and jeans in general were seen a lot in the early 1990s. But shades of blue are always loved and sometimes the darkest shade is high fashion and sometimes the most washed out faded pairs become the hottest. Colored jeans of all shades made an appearance. In 2000 designers were crystal beading and silver or gold spraying jeans amid tears, frayed slashes, and fur and feather decoration. Denim was hot yet again and used to make everything from footwear, jackets, bags, basque corsets to jeweled cuffs.

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TYPES OF DENIM While the original denim was a 100% cotton serge material, you can now get it in a variety of materials, including blends that give you the same wonderful look of 100% cotton denim with some great additional features. Denims unique look comes from the rich indigo blue in one shade or another woven together with white threads to give the depth that people associate with denim. Today, some denims no longer have indigo, but other colors with the white opposing threads, producing denims in a rainbow of shades. DRY DENIMDry or raw denim, as opposed to washed denim, is a denim fabric that is not washed after being dyed during its production. Most denim is washed after being crafted into an article of clothing in order to make it softer and to eliminate any shrinkage which could cause an item to not fit after the owner washes it. In addition to being washed, non-dry denim is sometimes artificially "distressed" to achieve a worn-in look. Much of the appeal of dry denim lies in the fact that with time the fabric will fade in a manner similar to factory distressed denim. With dry denim, however, such fading is affected by the body of the person who wears the jeans and the activities of their daily life. This creates what many enthusiasts feel to be a more natural, unique look than pre-distressed denim. To facilitate the natural distressing process, some wearers of dry denim will often abstain from washing their jeans for more than six months,[3] though it is not a necessity for fading. Predominantly found in premium denim lines, dry denim represents a small niche in the overall market.

Dry denim can be identified by its lack of a wash, or "fade". It typically starts out as the dark blue color pictured here. SELVAGE DENIM Selvage denim (also called selvedge denim) is a type of denim which forms a clean natural edge that does not unravel. It is commonly presented in the unwashed or raw state. Typically, the selvage edges will be located along the outseam of the pants, making it visible when cuffs are worn. Although selvage denim is not completely synonymous with unwashed denim, the presence of selvage typically implies that the denim used is a higher quality. The word "selvage" comes from the phrase "self-edge" and denotes denim made on old-style shuttle looms. These looms weave fabric with one continuous cross thread (the weft) that is passed back and forth all the way down the length of the bolt. As the weft loops back into the edge of the denim it creates this self-edge or Selvage. Selvage is desirable because the edge cant fray like lower grade denims that have 10


separate wefts which leave an open edge that must be stitched. Shuttle looming is a more time-consuming weaving process that produces denim of a tighter weave resulting in a heavier weight fabric that lasts. Shuttle looms weave a more narrow piece of fabric, and thus a longer piece of fabric is required to make a pair of jeans (approximately 3 yards). To maximize yield, traditional jean makers use the fabric all the way to the selvage edge. When the cuff is turned up the two selvage edges, where the denim is sewn together, can be seen. The selvage edge is usually stiched with colored thread: green, white, brown, yellow, and red (red is the most common). Fabric mills used these colors to differentiate between fabrics.

Most selvage jeans today are dyed with synthetic indigo, but natural indigo dye is available in smaller niche denim labels. Loop dying machines feed a rope of cotton yarn through vats of indigo dye and then back out. The dye is allowed to oxidize before the next dip. Multiple dips create a deep dark indigo blue. In response to increased demand for jeans in the 1950's, American denim manufacturers replaced the old shuttle style looms with modern projectile looms. The new looms produced fabric faster and wider (60inches or wider), yet lighter and less durable. Synthetic dyeing techniques along with post-dye treatments were introduced to control shrink and twist. Raw selvage is material that has not been washed once undergoing the dying process. It is especially desirable because the material will fade in the creases and folds of the jeans. This process is known as whiskering. Here are some of the newer types of denim on the market: STRETCH DENIM is usually about 98% cotton and 2% Spandex for a bit of that forgiving stretch we all love. This blend gives you wonderful ease of movement and at the same time some support for those trouble spots you arent so fond of around the hips or thighs. Stretch denim jeans are one of the fastest growing segments of the womens market for jeans manufacturers.

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POLY DENIM blends appeal to those who like the look of denim but prefer polyester blends that wash and dry quickly and are lighter weight and a bit dressier. These usually appeal to a slightly older market, but are also finding favor for pantsuits, etc. when the look is meant to be dressy but casual.

RAMIE COTTON DENIM blends are found in a variety of combinations, with a wide price variance. Ramie is a plant fiber usually added because it reduces wrinkling and adds a silky luster to the fabric. It isnt as strong as cotton, however, so it has to be blended with this stronger material in order to stand up as a denim material.

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COTTONThe botanical name of cotton is Gossypium.

COTTON PROPERTIESLength & Uniformity Upper Half Mean Length Below 0.99 0.99-1.10 1.11-1.26 Above 1.26 Uniformity Index Below 77 77-79 80-82 83-85 Above 85 Very Low Low Low High Very High Fiber Elongation (%) Below 5.0 5.0-5.8 5.9-6.7 6.8-7.6 Above 7.6 Fiber Fineness Fineness (millitex) Below 135 135-175 175-200 200-230 Above 230 Description Very Fine Fine Average Coarse Very Coarse Fiber Maturity Maturity Ration Below 0.7 0.7-0.8 0.8-1.0 Above 1.0 Description Uncommon Immature Mature Very Mature Very Low Low Average High Very High Short Medium Long Extra Long Fiber Strength (1/8 in. gauge strength in grams/tex) 20 and Below 21-25 26-29 30-32 32 and above Very Weak Weak Base Strong Very Strong

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YARN MANUFACTURINGThe initial stage of denim production is Opening and Blending. Opening begins with baled cotton fiber being separated into small tufts. A blend of cotton fibers is made on each opening line. These bales are selected using USDA High Volume Instrument (HVI) data, and PCCA's unique computer blending software produces optimal yarn strength. Cotton is delivered by air suction from the Opening and Blending lines, through additional cleaning and blending machines, to the Cards. The major functions of Carding are to remove foreign matter and short fibers, form the cotton into a web and convert the web into a rope-like form known as a sliver. The drawing process produces a single, uniform sliver from six card slivers. The additional blending, paralleling of fibers and cleaning in this process produces a sliver for Open End and Ring Spinning. For Ring Spinning, however, the sliver must pass through an additional process called Roving. Cotton Fibers are formed into a yarn by centrifugal action in Open- End Spinning. Individual fibers are laid down in the groove of a fast spinning rotor and twisted into yarn. After the cotton fibers are spun into yarn, the yarn is wound into a large package. The Open End Spinning Machines have robots on each side which automatically pieces up (repairs broken ends). On a different track, they have another robot that automatically doffs (removes full packages) and starts up a new package. The size and quality of each yarn end are monitored by the Barco Profile System to ensure uniformity. In Ring Spinning, the spinning frames receive Roving via a transit system from the roving machine. Yarn is formed from cotton fibers that are twisted together after being drafted by passing between three steel rolls and three rubber rolls. The yarn then is wrapped on a bobbin as it spins on a spindle by use of a traveler. The relationship between roll speeds, traveler speeds and spindle speeds controls the amount of twist in the yarn. Ends down levels and production information are gathered by the Uster Ring Expert System. The spinning frames automatically doff bobbins full of yarn and send them to package winding. ACG also has the capacity to produce Amsler Open-End yarn, also known as Faux Ring Spun yarn. This technology enables ACG to impart various slub patterns into an OpenEnd yarn. Denim made from this type of yarn has yarn character and surface interest that cannot be achieved with traditional Open-End yarn.

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BALANCING OF A SPINNING LINE FOR DENIM MANUFACTURING Count 6 7 Production Required per day (kg) 8763 14235 Auto Coro Average Speed 70000 75000 TM 5 4.8 TPI 12.25 12.7 % Installed Efficiency 90 90 % waste 0.2 0.2 Prod/rotor/day 18.515 16.401 prod/day required 8763 14235 rotors 473 868 machines 1.97 3.62 rotors/mc. 240 240 production /month in tonnes 263 427 Count Speed/mt/min Installed n% Production /day Hank Delivered Production Required per day Passages % waste m/c required Cards Doffer dia/ inch Doffer rpm installed effe. % waste hank delivered tension draft production/hr in kg produc daykg production required Machines required Blowroom Lines efficiency Production/day prod required/day lines required 6 700 70 3788 0 8789 1 0.6 2.32 6 27 51 85% 5% 0.1 2 43 1036 8842 8.53 6 90 10800 9308 0.86 7 700 70 3788 0 14292 1 0.6 3.77 7 27 51 85% 5% 0.1 2 43 1036 14378 13.87 7 90 10800 9308 1.4 DrawFrame

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W A R P I N G

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WARPINGIn general terms, warping is transferring many yarns from a creel of single-end packages forming a parallel sheet of yarns wound onto a beam or a section beam. The warp beam that is installed on weaving machine is called the weavers beam. A weavers beam can contain several thousand ends and for different reasons it is rarely produced in one operation. There are four types of warping, which are as follows 1. Direct Warping 2. Indirect or Sectional Warping 3. Ball Warping 4. Draw Warping DIRECT WARPING In direct warping, the yarns are withdrawn from the single-end yarn packages on the creel and directly wound on a beam. Direct warping is used in two ways: a) It can be used to directly produce the weavers beam in a single operation. This is suitable for strong yarns that do not require sizing and when the number of warps on the warp beam is relatively small. This is also called direct beaming. b) It can also be used to make smaller, intermediate beams called warpers beams. These smaller beams are combined later at the slashing stage to produce the weavers beam. This process is called beaming.

INDIRECT OR SECTIONAL WARPING In Indirect warping, a section beam is produce first. It is also called band warping or drum warping. The section beam is tapered at one end. Warp yarn is wound on the beam in sections, starting with the tapered end of the beam. Each section has multiple ends that are traversed together slowly during winding along the length of the section to form the angle. Due to the geometry of the yarn sections, the last section on the beam will have a tapered end that will make the whole yarn on the beam stable. It is important that each layer on the beam contain the same number of yarns. The same length of yarn is wound on each section.

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After all the sections on the beam are wound completely, then the yarn on the beam is wound on to a regular beam with flanges, before slashing. This process is called rebeaming.

BALL WARPING Ball Warping is mainly used in manufacturing of denim fabrics. The warp yarns are wound on a ball beam in the form of a tow for indigo dyeing. After the dyeing process, the tow is separated and wound on a beam. This stage is also called long chain beaming or re-beaming.

DRAW WARPING Draw Warping is combining the drawing of filament yarns with heat setting and warping processes to achieve uniform stretching and heating for improved dye uniformity, end to end. It is used for weaving of thermoplastic yarns.

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WARPING IN US DENIM:In US Denim ball warping is used. There are three creel machines of GRIFFIN. Two creels have capacity of 420 cones each weather one creel has a capacity of 540 cones. The department is connected with dyeing section directly and working 24 hrs. R &D department inspects the cones which is converted in beams of required length and forwarded to dyeing section.

COMPONENTS OF MACHINE CREEL LEASING STAND TURN-AROUND ROLL TURN-AROUND STAND BALL WARPER Dual MOTOR DRIVE

CREEL:

Custom designed to meet package dimensions, end count requirements and available space. Electromagnetic Tension Control with individual post adjustment, 0-75 GPE tension range, with individual post-post calibration. Integrated Motion Sensor with 25 19


millisecond response time, end break indicator, end count confirmation, and recurring break indication for same package. LEASING STAND: Semi-Automatic lease insertion at programmable intervals with ertical oscillation to reduce wear.

TURN-AROUND ROLL: Provides additional length to the yarn path (in sheet form) to allow for recovery of lost or broken ends and reduces rolling in the trumpet at the end of the traverse stroke. TURN-AROUND STAND: Constructed of heavy duty steel with an aluminum flanged 300mm diameter x 125mm wide guide wheel. The guide wheel has a pneumatic disk brake for controlled stops. BALL WARPER: The Ball Warper is capable of producing a 1220mm width ball with diameters up to 1524mm (60) and safe operating speeds up to 500 mpm. DUAL MOTOR DRIVE: utilizes the latest drive technologies, including AC vector drive/motors, high strength polyurethane timing belts and heavy duty beveled gearboxes. The trumpet carrier; which has no bearings, is machined from thermoplastic to reduce weight and improve durability thus eliminating routine maintenance. Drive Rolls are rubber covered for maximum durability and are coupled to Dual Caliper Disc Brakes for quick stopping. The hold down arms provide programmable hold down pressure and are used in loading and doffing the beam. The Griffin Director is a PC based drive and control system that completely automates the operation of the machine. Operator interface is by 380mm Touchscreen. Customer support is provided through modem communication 24/7 by Griffin technicians. OPTIONAL EQUIPMENT: Automatic Traveling Cleaner, Inside loading/outside running creel design, Manual Post/Disc Tensions, Drop Wire Stopmotion System, Sheet Vacuum System (SVS).

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COMPARISON OF H AND V CREELH-CREEL Parallel warping is used for sectional warping as well as for direct warping. Suitable for comparatively low speed warping. Needs proper yarn guides. Provide low tension on whole beam. No free yarn from creel to the warping machine because proper yarn guides are required. More time consumable because of low speed. More space is consumed. In indirect warping, a constant speed drive is generally required to provide approximately uniform yarn speed on the surface of the beam. H-creel has a wide range of package change system. Example: with reversible package, with unrolling draw off, with fixed package frames, with package trucks, with swiveling package frames. V-CREEL V-creel is used for only in direct warping. Suitable for high speed yarn warping. No need of yarn guide Provide uniform yarn tension across the whole beam. Free yarn run from creel to the warping machine. Less time consumable. Less space is consumed. Surface friction drive and variable speed drive is commonly used to attain the uniform yarn speed. V-creel has a low range of package change. Example: reversible frames, reversible frames with automatic knotter, and with traveling package.

PROCEDURE OF WARPING: The creel stand has maximum capacity of five cones per stand. The yarn from the cones is unwounded and passes from rod by cross wound, holed by a catcher guided to the tensioning zone when cone rotates anticlockwise. There are three types of tension in warping i.e. catcher tension, rod tension, and sacker tension. Magnetic tensioner is used for yarn tension. Then the yarn comes to the winding zone or headstock. Combs straighten the yarns towards pressure drum, which supports beam, and yarns in an alignment so that each and every yarn end can wound separately. Static charges due to friction of yarns on metal surface cause static charges, which are removed through an anti static device. Then the yarn is wounded on beam in this way for a required length if beam is changed after one filling of beam then knotting of yarns is made. Similarly if cones are finished on one frame side then trolley system of cone changing is used in this way chains rotates the whole frame of empty side and new filled side of frame is forwarded again knotting is done between the new cones yarn and already winded yarn. Extra yarn is then removed through cutting. Sensors sense any type of yarn breakage and in case of yarn breakage knotting is done. 21


WARPING PLANThe warper gets the required no of ends and the number of beams from the weaving department and then he made the warping plan that how to complete that task whether on one creel or on more no. of creels. Some examples are given below to show the concept of warping plans using one creel and two creels. For example; If, No. of ends = 1080 No. of beam = 4 Count = 10/s No. of cones in one bag = 16 No. of warper's beams with no. of ends on each = ? Length per beam = ? No. of Bags of 100 lbs = ? Plan for one Creel Then, The total no. of ends on the weavers beam = 1080 x 4 = 4320 ends Cone wt. = bag wt. / no. of cones in bag Cone wt = 100 / 16 = 6.25 lbs Length of yarn on one cone = cone wt. In lbs x count x 768.1 Length of yarn on one cone = 6.25 x 10 x 768.1 = 48006 m lessen the length up to 1 % because of variation in yarn length among different cones length of yarn on one cone = 47600 m no. of ends x no. of beams = total no. of ends 617 x 6 = 3702 618 x 1 = 618 4320 ends so, 7 warper's beams i.e. 6 beams of 617 ends and 1 beam of 618 ends Length / Beam = length of yarn on one cone / no. of beams Length / Beam = 47600 / 7 = 6800 m / beam

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Bags required = No. of ends on warper beam / no. of cones in one bag Bags required = 618 / 16 = 39 bags approx. For example; If, No. of ends = 1140 No. of beams = 4 Count = 10/s No. of cones in one bag = 24 No. of warper's beams with no. of ends on each = ? Length per beam = ? No. of Bags of 100 lbs = ? Plan for two Creel The total no. of ends on the weavers beam = 1140 x 4 = 4560 ends Cone wt. = bag wt. / no. of cones in bag Cone wt = 100 / 24 = 4.16 lbs Length of yarn on one cone = cone wt. In lbs x count x 768.1 Length of yarn on one cone = 4.16x 10 x 768.1 = 31952 m lessen the length up to 1 % because of variation in yarn length among different cones length of yarn on one cone = 51600 m no. of ends x no. of beams = total no. of ends 570 x 8 = 4560 ends so, 8 warpers beams 0f 570 ends each No. of beams per creel = no. of warpers beam / no. of creels No. of beams per creel = 8 / 2 = 4 Length / Beam = length of yarn on one cone / no. of beams per creel Length / Beam = 31600 / 4 = 7950 m / beam Bags required = No. of ends on warper beam X no. of creels / no. of cones in one bag Bags required = 570 X 2 / 24 = 48 bags approx.

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R O P E D Y E I N G

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DYEINGDyeing is a process in which we impart colour to the fabric. All commercial textile dyeing processes take place by the application of a solution or a dispersion of the dyes to the textile material followed by some type of fixation process. The dye solution or dispersion is almost always in an aqueous medium. A major objective of the fixation step is normally to ensure that the coloured textile exhibits satisfactory fastness to subsequent treatment in aqueous wash liquors. Dyeing is mainly depends on the type of fabric, structure of fabric and the properties of dyes. Dyes use for Denim Sulphur Dyes Vat Dyes SULPHUR DYES: Sulphur dyes are widely used on cotton mainly because they are economical to use. They have good to excellent wash fastness and good light fastness in dark shades. Light fastness of pale shades is poor. Sulphur dyes are usually dull in shade since the molecular structures are complex. As a class, the sulphur dyes are not resistant to chlorine containing bleaches. Chemical nature of sulphur dyes

Partial chemical structures involved in dyeing with sulphur dyes

Dyeing with sulphur dyes of various types

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CHARACTERISTICS OF SULPHUR AND LEUCO SULPHUR DYES ON COTTON: Sulphur dyes have the dullest range of colours of all dye classes but are relatively inexpensive. They are used to dye medium to deep, dull shades on cellulosic materials. There are several excellent blacks giving dyeings with good wet fastness properties. In fact, when black, and deep brown, blue and dull olive green shades are needed, with good washing and satisfactory light fastness at reasonable cost, sulphur dyes are irreplaceable. There are few green sulphur dyes and no true reds. There are, however, an abundance of blacks, blues, yellows and browns. On a world basis, sulphur dyes constitute one of the major dye classes. Sulphur dyes are used in cotton dyeing for woven goods using jig dyeing machines and also in continuous dyeing. They are commonly used for the continuous dyeing of corduroy. They are now being used more widely in jet machines. Sulphur dyes are also used for dyeing denim olive, brown and maroon, rather than the traditional Indigo blue, as well as to bottom or top Indigo dyed cotton warps. To bottom or top means that a sulphur dye is applied either before or after the Indigo. The fastness to wet processes and to crocking can be varied almost as required to satisfy the demand for the faded look so popular for denim. This is achieved by allowing premature oxidation of the leuco dye during dyeing, by using short dyeing times so that there is inadequate time for dye penetration into the fibres, and by poor rinsing and soaping after dyeing. The dyeings can then be subsequently treated to produce the faded worn look by removing the surface colour. Although cellulosic goods dyed with sulphur dyes usually have good washing fastness, it can be further improved by resin finishing. The light fastness varies from moderate to good in heavy shades. A major characteristic of sulphur dyes is the poor fastness to chlorine, which distinguishes them from most quinone vat dyes. Dyeings with sulphur dyes cannot be bleached with hypochlorite. In fact, these dyes are readily distinguished from other cotton dyes by their dark, dull colours and the bleaching that occurs when a dyeing is spotted with hypochlorite and allowed to dry. Cotton dyed with some sulphur blacks becomes tendered on storing under warm humid conditions. This is a consequence of the formation of sulphuric acid from oxidation of the sulphur dye in the fibres. It can be minimised by thorough washing after dyeing before the oxidation of the leuco dye, by a final alkaline rinsing with soda ash solution, and by resin finishing. Such tendering is avoided by dichromate oxidation of the leuco dye. DYEING METHOD: Initially the goods are wet out in the bath. Since the dyeing liquor contains appreciable amounts of sulphide, copper fittings must be avoided. If wetting or penetrating agents are used these should be of the anionic type since non-ionic surfactants form stable, nonsubstantive complexes with the leuco thiols. An anionic product such as phosphated 2ethylhexanol is suitable. The bath may then be set at 40 with some sodium C polysulphide . Polysulphides in the leuco dyebath prevent premature oxidation of the dye and reduce the tendency to bronziness of deep dyeings of blues, navies and blacks. An addition of a sequestrant such as EDTA avoids precipitation of the leuco thiolate by calcium and magnesium ions. The leuco dye is then added slowly and, since the leuco dyes only have low to moderate substantivity for cellulose, some salt may be added initially, or in portions during dyeing, to promote exhaustion. After dyeing the goods are rinsed, the leuco dye oxidised and the dyeing is soaped as for a conventional vat dye.

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Sulphur dyes usually have acceptable substantivity, particularly in the presence of salts, so that stripping in a fresh reducing bath is not easy. Dyeing is often conducted at the boil but this decreases the degree of exhaustion. Sulphur dyes require less salt than reactive dyes and usually have reasonable exhaustion. Low sulphide leuco dyes require more salt and no polysulphide. They do not give good exhaustion in heavy shades and the use of a low liquor ratio is recommended. For popular shades such as black, it has long been common practice to use a standing bath. This is a dye bath that is re-used for subsequent dyeings after addition of more reduced dye. Any free sulphur that tends to accumulate is dissolved by addition of sodium sulphite to give thiosulphate. This prevents it sticking to the goods. The actual dyeing temperature can vary. At higher temperatures around the boil, the bath exhaustion is less but penetration of the leuco dye into the fibres is better than at lower temperatures. POST-DYEING TREATMENTS: After dyeing, good rinsing before oxidation helps reduce bronziness and poor rubbing fastness by removing loosely adhering surface leuco dye solution before oxidation precipitates the insoluble pigment. Once the rinsing is completed, the leuco dye in the fibres is oxidised to the insoluble pigment. Some leuco dyes can be oxidised in air, others need chemical oxidation. Sodium dichromate, hydrogen peroxide, or sodium percarbonate or perborate are used in warm, weakly alkaline solution. The peroxy compounds used for vat dyes can be used for sulphur dyes, but some leuco dyes (redbrowns) are not oxidised by these agents. Some blues are over-oxidised, probably by oxidation of the disulphide links between the heteroaromatic units to form ionic sulphinate and sulphonate groups. This increases the water solubility, decreases the wet fastness and results in staining of other goods during washing. Even sulphur blacks oxidised with peroxides tend to be bluer, lighter and somewhat less fast to washing. The best washing fastness is obtained by oxidation of the leuco dye with sodium dichromate and acetic acid. Sodium bromate (NaBrO3) is now more widely used as an oxidant, particularly in North America. It requires a small amount of metavanadate ion (VO3 ) as catalyst. Some dyeings are treated with copper sulphate, or with this and sodium dichromate, to improve the light fastness, and in some cases the wet fastness. Fabrics for use inside rubber articles should not be copper treated. Some yellowbrown dyes are treated with copper sulphate to improve light fastness but theeffect is lost on washing. The use of chromium salts is now declining because of their adverse environmental impact. Because of their dull colours, dyeings with sulphur dyes are often topped with the much brighter basic dyes. The sulphur dye pigment acts as a mordant for the cationic dyes. Dyeings with sulphur dyes may also be shaded with some sulphide stable direct dyes, but this tends to lower the washing fastness. DYEING WITH SOLUBLE SULPHUR DYES: Large amounts of such dyes are sold in liquid form. They are of two types 1. Watersoluble reduced leuco dyes, and-2. solubilised sulphur dyes the former being far more important. The water soluble leuco dyes are completely in solution and contain far less insoluble matter than a sulphur dye powder. This is beneficial in package dyeing. They often still require a small addition of sodium sulphide or another reducing agent. These liquids contain the stabilised leuco dye, sodium sulphoxyate-formaldehyde or sulphide and sodium carbonate. The solubilised sulphur dyes are thiosulphate esters prepared from the leuco thiols with sodium sulphite . They usually have low substantivity for 27


cellulose and are useful for package, padding and padjig applications. Reduction is necessary before or during dyeing and the usual aftertreatments are needed. CONTINUOUS DYEING WITH SULPHUR DYES: Sulphur dyes are used for continuous dyeing of cotton goods using a padsteam wash process, with three groups of wash boxes for rinsing, oxidising and soaping. Padding may take place at up to 80 to reduce the substantivity of the leuco dye for the C cotton fibres. This reduces the problems of selective absorption and the resulting initial colour tailing that it causes. As for other vat dyes, steaming is carried out in air-free saturated steam. Then the dyeing is rinsed at 4060 and oxidised with sodium C bromate plus metavanadate catalyst at pH 4 in the presence of acetic acid. In the remaining wash boxes, the best possible soaping and rinsing is done. For black dyes tending to produce sulphuric acid by oxidation on storage, a final soda ash rinse may be added. In some instances better appearances result using a two-pad method. This involves padding with the sulphur dye suspension or solution, followed by intermediate drying, padding with sodium sulphide solution, steaming, and the usual aftertreatment sequence. EXAMPLES OF IMPORTANT COMMERCIAL SULPHUR DYES

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VAT DYES:Vat dyes are mainly applied on cellulosic fibres, but some can be applied to protein fibres. They usually have outstanding colour-fastness properties. Vat dyes are more expensive and difficult to apply than other classes for cellulose such as directs, sulphurs, and reactive. Indigo is a special case in the vat dye class. Indigo is attractive for its pleasing blue colour and for the unique fading characteristics of garment dyed with it. Vat dyes are characterized by the presence of a keto group. Vat dyes in keto form are water insoluble pigments. CHEMICAL CONSTITUTION OF QUINONE VAT DYES

CI Vat Red 42 (1); leuco compound formed by reduction (2); vat acid formed by protonation of the anionic leuco derivative (3); CI Vat Blue 4 (4)

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Reducing vat dyes with hydros

THE SUBSTANTIVITY AND DYEING CHARACTERISTICS OF VAT DYES FOR CELLULOSIC FIBRES BASIC STEPS IN THE DYEING PROCESS: The dyeing of cellulosic materials with quinone vat dyes follows a four-step sequence: (1) Preparation of the vat containing the leuco forms of the dyes; (2) Dyeing of the material, in which the fibres absorb the water-soluble leuco compound; (3) Oxidation of the absorbed leuco compound back to the parent pigment inside the fibres; (4) Soaping of the dyed material to remove pigment loosely adhering to the fibre surfaces and to develop the true shade and fastness properties. DYEING WITH INDIGO AND INDIGOID VAT DYES: Natural Indigo was rapidly displaced from the market once the synthetic product became available. The quality of natural Indigo was quite variable because of the presence of other coloured impurities. The fastness properties of Indigo dyeings are not up to the standards expected from the vat dye class as a whole. It is, however, the appearance of faded Indigo in denim that is so fashionable today. After dyeing, various wet processes, such as stone washing, deliberately enhance this faded effect. Indigo builds up primarily on the cotton fibre surface. This is one reason for the somewhat inferior fastness properties of Indigo compared to quinone vat dyes. APPLICATION OF INDIGO TO COTTON: Dyeing cotton yarn for blue jeans is an important use of Indigo. In a typical batch operation, concentrated reduced Indigo is added to a dyebath from which oxygen has been removed with little alkaline hydros. The goods are entered and fully immersed to avoid oxidation. After about 15 min at 2025 the goods are removed and well C, squeezed before air oxidation. Indigo does not exhaust well because of its limited substantivity for cotton, not surprising considering its small molecular size . Deep shades must be built up by repeated dipping in the dyebath after each oxidation. The use of too concentrated a dyebath is not effective for deep shades as it results in poor rubbing fastness. Some salt may be added to aid exhaustion. After dyeing, the goods are well soaped. The final dyed material may be aftertreated to produce a faded, worn look. Continuous methods are used for dyeing ball warps, warp beams and piece goods with Indigo. This is usually carried out in a series of 46 wash boxes with upper and lower rollers and nips at the exits. The goods are threaded through each box and may be skyed at the mid-point. The first box is used to wet out the material. In subsequent boxes, the goods are immersed in the leuco Indigo solution for 1030 s at a linear speed of about 25 m min1, squeezed and skyed for 2 min to oxidize the leuco dye to Indigo. The boxes are 31


fed with a stock vat of leuco Indigo and the liquor in the boxes is circulated to maintain constant dyeing conditions. This process of several dips and oxidations is then repeated in a second series of boxes, and so on. Several rinsing and washing boxes complete the process. INDIGOID VAT DYES: Besides Indigo itself, there are a number of other important indigo and thioindigo derivatives used for dyeing cellulosic fibres. These include chlorinated and brominated indigo and thioindigo dyes in which the nitrogen atoms of Indigo are partially or totally replaced by sulphur atoms. Compared to the anthraquinone type vat dyes, Indigoid vat dyes give much paler yellow to brown leuco compound solutions. The vatting process is also slower and requires less alkali.

SOLUBILISED VAT DYES: The solubilised vat dyes provided a means of avoiding the difficult vatting process required for quinone and indigoid vat dyes. The preparation of a solution of a leuco vat dye requires care and time, and protection of the solution from excessive exposure to air. The solubilised vat dyes avoid these problems. These dyes are preprepared sulphate esters of the leuco vat acid. The first product of this type was that derived from Indigo . Later solubilised leuco dyes derived from quinone vat dyes were marketed.

Cotton absorbs these dyes directly from a neutral or slightly alkaline solution but they are not very substantive even in the presence of added salt. Although a leuco sulphate ester has the same negative charge as the normal leuco dye, its charge is localised in the sulphate groups whereas that of the phenolate ion is delocalised. Cotton therefore repels a leuco sulphate ester molecule more strongly than the normal leuco compound. Because of their limited substantivity, solubilised vat dyes are generally only suitable for pale shades. After dyeing, the goods are rinsed or hydroextracted to remove superficial dye solution, and the vat dye pigment is developed in the fibre by oxidation with sodium persulphate or acidified sodium nitrite solution. After neutralising with dilute soda ash solution, the goods are soaped as in the case of normal vat dyeing. The dyeing has the same fastness properties as one prepared from the original vatted pigment. The low substantivity of the leuco sulphate esters avoids the problems of the high strike of leuco vat dyes. Since they can be used in solutions close to neutrality, they can also be used for wool dyeing. Unfortunately, the dyeing and oxidation conditions for each dye vary so it is important to follow the suppliers instructions. The use of these dyes was never widespread and has declined in recent times. They are not particularly competitive because of their high cost. 32


DENIM DYEING:The classical jeans was produced out of indigo-dyed Denim fabric. The special character of this fabric only the warp thread is dyed makes it necessary to carry out dyeing in yarn form. The yarns applied for Denim were exclusively produced on ring spinning machines in former times. The development of OE(open end) yarns by applying smaller rotors with a spinning speed of up to 200 m/min has led to the application of OE rotor yarns both for warp and weft. The yarns applied for weaving must be of high quality: a high fiber for strength, regularity as well as a small part of shortstapled cotton fibers belong to the basic features of the denim yarn. For regular jeans qualities the warp yarns are spun in a fineness of 50 to 90 tex, for the weft yarn the fineness ranges are mainly 75 to 120 tex. If Denim is made out of Tencel or Modal especially for jeans shirts the finenesses are up to 25 tex. Indigo, sulphur and indanthrene are mainly used in the dyeing process. Two methods are applicable for continuous dyeing with indanthrene dyes: rapid dyeing and vat dyeing. While processing the basic colored denim, reactive dyes are used and fixed with hot caustic soda solution. The dyeing process is mainly influenced by the dyestuff characteristics, dyeing temperature and necessary chemicals used in the process. Indigo dye is the most popular choice as it has good depth of shade and suitable rubbing and washing fastness. When cotton yarn is dyed with indigo, it leaves a ring-dyeing effect, because of which the outer layer of warp yarn is coated with indigo, and the core of the yarn remains undyed. This gives the denim garment a unique faded look and a rich blue shade after repeated use and wash. Originally, the warp yarns or ends were put through the dye bath side by side to form a sheet of yarn, which passed continuously through several dye baths, squeeze rollers or airing sequences. However, if there were breaks in the yarn (and there would be, as each yarn had to take the tension of being pulled through these processes virtually on its own), the dyeing process had to be stopped. The yarns would be then mended, or else it would lead to very bad tangling. These stoppages would in turn cause large shade variations, and the yarn breaks would show up as bad faults in the fabric. Now, an infinitely more efficient system has been introduced. Special attention shall be paid here to Indigo, the king of dyestuffssince it plays an important role in obtaining the jeans effect. Indigo belongs to the category of waterinsoluble dyestuffs. It was first mentioned in a book 13 BC; at that time the name Indian blue indicated the country the color came from. It is said to have been used for dyeing in India and China 2000 years BC already.

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The Indigo plant is used for preparing Indigo

(Indigo tinctoria L.) This plant came to Europe in the 16th century via India and gradually replaced the woad which was one of the most important dyeing plants up to this time. Only the leaves were used for good qualities whereas the leaves together with the stalks were applied for normal qualities. In a vat filled with water and partially with human fermented urine as alkali donor stems and leaves were exposed to a putrefactive process. During this putrefactive process hydrogen was created by means of micro-organisms which, as a reduction agent, transformed the dyestuff contained in the Indigo plant into a watersoluble form. When this process was over the whole mass was filled into a liquid where the fermented mass was stirred with poles. The reason for doing so was to transform the Indigo into its water insoluble form again by air oxidation. In a last step the water-insoluble dyestuff particles could then deposit on the bottom of a stationary vat. Then the liquid standing above was drained and what was left was a thin mash which was dried in the open air and was put on the market in pressed or in powder form

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As shown in figure trading form of Indigo at that time, approx. 9 cm length of edges and 163 g in weight. When looking at these methods one can easily imagine that the reduction of Indigo was considered to be an evil-smelling trade. In 1880 Adolf von Baeyer succeeded in carrying out the first synthetic production of Indigo. In the year 1897 the Badische Anilin- und Sodafabrikin Ludwigshafen -hich is nowadays called BASF - was able to carry out an industrial-scale production of the Indigo dyestuff for the first time. A few years later this synthetic dyestuff replaced the indigo coming from British-India almost completely. As was already mentioned Indigo is a dyestuff insoluble in water. In order to be able to apply it on cotton it must be transformed into a water-soluble form. Similar to the former production of Indigo this is done by reducing the dyestuff (ill. 4). In practice this is nowadays carried out with sodium dithionite or hydroxiacetone in the alkaline range.

INDIGO REDUCTION C16H10O2N2 + Na2S2O4 + 4NaOH . C16H10O2N2Na2 + 2Na2SO3 + 2H2O OXIDATION REACTION Na2S2O4 + O2 + 2NaOH . Na2SO4 + Na2SO3 + H2O + C16H10O2N2Na2 + O2 + H2O + Sodium Hydrosulfide C16H10O2N2 + 2NaOH

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Fiber cross-section of a yarn dyed with Indigo This is Fiber cross-section of a yarn dyed with Indigo simplified description of the reduction/oxidation of Indigo In former times dyeing with Indigo was carried out in wood or metal vats, normally in rope form.

Indigo sample dyer as very clearly visible on the above picture, at the bottom side of the rope the water-soluble Leuco form of the indigo is yellowish and on the side of the rope oxidized with air the indigo blue can be seen again. Nowadays, yarn dyeing with indigo is done continuously. Here the various dyeing processes with different concentrations of chemicals as well as the subsequent yarn sizing exert an influence on the quality and the appearance of the ready fabric.

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HOW TO MAKE INDIGO SOLUTION In a tank of 1000 liters: a. take 400 litres of water (soft) b. add setamol ws--> 4 g/l (stirring) ( dispersing solution) c. Add 100 kg of Indigo ( at 1.8 % shade -see the indigo calculations- stirring) d. add caustic soda --> stirring ( for solubilising and pH) e. allow to cool it for 2/3 hours f. Add hydrosulphide ( As reducing agent) g. Make the solution to 1000 l by adding water. If pH is fluctuating, if it is > 11.7 then hydro is added (2-3 kg), if ( 1.8 kg of Indigo 5000 kg of yarn needs --> 90 kg of dye at 100 gpl 100 gms of dye = 1 lit of solution 90 kg of dye = 900 litres 900 litres should be completed in 583.3 min 1 litre would be completed in = 583.3/900= 38.8 seconds so flow rate will be 38.8 seconds / litre Similarly flow rate of caustic and hydro can be determined Hydro is taken around 100 gpl caustic is taken around 90 to 100 gpl

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There are three processes in the practice for continuous dyeing: 1) Rope Dyeing 2) Slasher Or Sheet Dyeing 3) Loop Dyeing

ROPE DYEING:Indigo Rope Dyeing When dyeing according to the rope dyeing or cable dyeing method.350 - 400 warp threads are bound on the ball warper to very thick cables of 10000 - 15 000 m length. On the continuous dyeing installation, 12 to 36 cables are led side by side, wetted, dyed and dried after the dyeing process on cylinders and put into cans. Then the cables are dissolved to warps on the long chain beamer. The warps are added to the sizing machine, sized and then led together to warp depending on the total numbers of threads. In practice, this method has proven to be very good through obtaining an optimum indigo dyeing. However it is important that the cables have a constant tension in order to avoid warp stripes. The disadvantage compared to other methods is that yarn breakages do occur more often. Size of the dyeing unit is between 60 - 80 m. normally, 6 dyeing vats are in use. There are nevertheless variations with 3 to 8 dyeing vats. The dyeing methods described here do not allow a total penetration of the dyestuff during the short dyeing time and give the desired and necessary ring dyeing important for the jeans effect. The sizing process follows the dyeing process of the yarn; this is already visible by the machine sequences and is necessary to stabilize the warp thread against the high mechanical stress while the weft thread is being fed. For sizing the warp, PVA, CMC and acrylate sizes are used besides starch-containing products. ENTERING FEEDING

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DYEING

AIR TIMING

DRYING

DELIVERY

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PROCESS CONTROL OF ROPE DYEING FOR DENIM 1. Concentration of Hydrosulphite It is measured by vatometer. It should be from 1.5 gpl to 2.5gpl , or by redox potential of dye bath which should be from -730 mV to -860 mV. 2. Caustic Soda or pH value Should be from 11.5-12.5 3. Dye concentration in Dye bath it is measured by spectrophotometer. It should be in g/l Guidelines High Indigo Concentration --> Shade is greener and lighter Low Indigo Concentration --> Shade is dull and Red. High pH or Caustic Concentration --> Redder and lighter Low pH or caustic concentration --> greener and darker Dipping Time Longer the dipping time, better will be the penetration and lesser will be the ring dyeing effect. It varies from 15-22 seconds. Squeeze Pressure High pressure will lead to lower wet pick up and result in lesser color and better penetration. At rope dyeing, squeeze pressure is 5-10 tonnes, ie. wet pick up is as low as 60%. Hardness of squeeze roller is about 70-75 deg. shores. It sqeeze rolls are too hard then there are chances of slippage and uneven yarn tension.. If squeeze rollers are too soft then shading will occur. Surface of the squeeze rolls should be ground twice a year.

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Airing Time it should be 60-75 seconds. Longer airing time results in high tension on the yarn and subsequent processes will become difficult. Drying Insufficient or unevenly dried yarns will result in poor rebeaming Calculation of Replenishing Dye feed/min Conc. of stock vat is g/l= 90 range speed in yards/min=25 count = 7s totoal ends = 4100 Wt of yarn dyed /min= (4100*25*1000)/(7*840*202)= 7924 gms shade desired = 2% Amount of dye to be replenished/min= 158.5 gms Effect of pH At pH of 10.5 to 11.5, there will be formation of more monophenolate ions, which lead to higher color yield, as strike rate of the dye to the yarn bundle is very high, and wash down activities will be very good. At pH higher than this, dye penetration will be less and wash down characteristics are also poor. Testing 1. Alkalanity in Dye Bath Liquor Pipet 10.0 ml of vat liquor into 100ml of distilled water in a 150 ml beaker. place under continuous agitation and insert the electrodes of a pH meter caliberated at pH 7.0 with standard buffer solution. Titrate with tenth normal HCl ( 0.1 HCl) to pH 7.0 (ml = A) calculate g/l of NaOH = A *0.40 2. Hydro in Dye bath Liquor Add 2 ml of 37% HCHO to 150 ml beaker. Add 2 ml of dye range liquor . Add 6 ml of 41


25% glacial acetic acid solution prepared by diluting 1 part acid with 3 parts water. Add 2 ml of starch/KI indicator. Add ml of water. Titrate with 0.046 N ( prepared by diluting 460 ml of 0.1 N Iodine to one liter ) solution until the color changes from emarald green to bluish purple. G/l of hydro= mo fo 0.046N of Iodine Importance of High Concentration of Free Hydrosulphite The clearest shades with minimum reddish streaks are observed at by relatively high conc. of hydrosulphite. On the other side, with lack of hydrosulphite, the leuco indigo is less dissolved and thereby adheres to a greater extent to the fibres. With lack of hydrosulphite furthermore, the amount of unreduced dyestuff by oxidation at the upper level of the liquor and through activiation of unfixed dyestuff, gets separated from the fibrous material would constantly rise as the reducing agent for creating leucoform would be missing. Under these circumstances a reddish bronze like shade results due to dispersion of not reduced dyestuff in the yarn. The min. proportion of hydrosulphite should be around 1.3 to 1.5 gpl in case of rope dyeing and 3-4 gpl in case of sheet dyeing. Also to avoid the lack of hydrosulphite or Indigo at certain places in the immersion, vat, the whole quantity of the liquor should be circulated 2-3 times every hour. Reaction Time At very short reaction time, an adequate liquor exchange ( i.e. the amount of chemicals consumed and replaced by fresh addition of reduced indigo) is not assured. This has a negative influence on dyeing and depth of dye penetration. In addition to this the time available for diffusion of dyestuff until oxidation commences is too short. To ensure an even and good depth of dye penetration by dyeing in several passages, the reaction time should be 20-30 sec. for each vat (eg. at a speed of 20m/min for a reaciton time of 10 seconds, the immersion path should be maximum 3.3 meters). A reaction time exceeding 60 seconds should be avoided as the amount of dyestuff again get reduced and released may again supersede that of additionally take up dye stuff, resulting in higher shades. Softening Agent: 8 g/lit Drying: Rest humidity should be 30% and then sized. Addition of chemicals 1. Red Tinge: reduce addition of NaOH, increase slightly Na2S2O3 2. Darkish Red: increase Hydro 3. Light Greenish: decrease Hydro 4. Dark Green: Increase Caustic

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PROCESS OF DYEING OF SULPHUR COLOR: 1st Wash tank: mercerisation by taking 22% NaOH ie. 250 gpl 2nd Wash Tank: Hot Wash 3rd Wash Tank: Cold Wash In 1st and 2nd dye bath take sulphur color 6-8% on the weight of the yarn sheet. Temperature 90 deg. cel. The solution contains the following: 1. solubalised sulphur color: 150 gpl 2. Na2S--> reducing agent: It is added to increase its reducing power 3. Caustinc Soda --> 10 gpl--> reducing agent 4. Wetting agent--> 2gpl 5. Antioxident Sulphide ( Glucose paste--> 5gpl). This is added to prevent the oxidation of of Sulphide solution. It will always remain in reduced form ( Alos if the shade is slightly greyish, one can add tiny tinge of sulpher blue--> 20gpl) in III, IV and V dye bath--> cold wash in 6th dye bath. We take H2O2(30%)+Acetic Acid(2:1 by weight). H2O2 acts as an oxidising agent. But as it acts on neutral pH (=7) and after cold bath the solution is slightly alkaline, to make it neutral wil add acetic acid. Acs in alkaline pH, oxidising action of H2O2 will be similar to the bleaching action, which may cause tendering in the fabric. 7th and 8th Dye Bath: Cold Wash Wash Box Number 4: Here washing is done with detergent and soda ash at 60-70 deg.c 5th and 6th Wash Box: Hot Wash 7th wash Box: Here softner is added at 25 gpl. It is cationic softener with pH 4.5 to 6.5. As during oxidation of sulphur, strength is reduced by 10%. On a yarn sulphur is of two types : 1. Free Sulphur 2. Reacted Sulphur. The free sulphur will react with moisture in the atmosphere to form: H2O + S --> H2SO4 Which tenders the yarn. Now at acidic pH reaction is much faster. So we add only a small amount of softener (25 gpl) as against that in indigo which is 100gpl. 3rd Point Over all during sulphur dyeing and storing, the yarn strength is reduced by 15% as compared to Indigo. 4th point If ball formation takes place of sulphur dyed warp at loom shed, then we can taken in 4th dye bath little Na2S+Caustic to reduce the free sulphur.

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DIFFERERENCE BETWEEN SLASHER AND ROPE DYEINGROPE DYEING SLASHER Warp yarns are assembled on the ball Warp yarns are directly wound on a beam warper to form a rope. in the form of a sheet. Ropes are drawn through dyeing range Dyeing is done in sheet form side by side. After dyeing they are dried on a drum drier and deposited in cans. The ends are spread out on long chain beamer Or on a rebeamer, and the yarn sheet is wound onto warp beams. These beams are then taken to sizing. After sizing they are dried and assembled on the weaving beam. Good depth of shade is achieved In rope dyeing we have very high productivity but the limitation is that it is very expensive for short lots. It can only run for coarse yarn as the tension on rope breaks the yarn Time consuming processes are rebeaming and then sizing As the dye bath is less exposed to air so dye is affected less. The oxidation time is greater for fixation The wetting time is greater and so dye is applied uniformly The rope dyeing machine is much expensive than Slasher. Rope opening is avoided After dyeing the warp sheet is dried on the same machine in continuous process by drying cylinders and then sizing is done on the same machine and after drying it is wound on a weaver beam Depth of shade is not good In Slasher dyeing productivity is less but it is feasible for short lots. It can run for fine yarns too Rebeaming is not required and sizing is done after dyeing. Setting up or stabilization of the dye baths is affected faster. The immersion and oxidation times are much shorter Owing to the paralleled warp threads, the wetting process is shorter and a wetting trough may be adequate. The sheet dyeing machine is smaller than a rope dyeing machine, which means that the prime costs are lower Warp sheet entanglement is a danger

DYEING IN US DENIM:The Rope Dyeing section is equipped with Morrison's Rope Dyeing Range. Morrison has more than 200 Rope Dyeing systems installed the world over, making it the globally recognized "first quality" method of indigo dyeing is the world. Dyed Lots are inspected at US Denim's in-house Dyeing Lab to ensure the fabric shade as per customer requirements. The Inspected Lots are then transferred to the ReBeaming section for further processing. Dyeing department is present on first floor. There are two working shifts in the department each of 12 hours a day. 44


MORRISON'S ROPE DYEING RANGE Features:Custom designed Indigo Rope Range for maximum flexibility with minimum waste Dyes multiple yarn weights with multiple dye classes Runs short or long production lots with light or heavy depths of shade Pretreatment consists of counter flow scour / wash boxes Mercerizing adds improved dye affinity, luster, strength & fashion effects Multiple dips of indigo & oxidation time in the skier section for shade depths Multiple wash boxes for rinsing & chemical application Coilers lay ropes into drums in a pattern that facilitates Re-beaming operation

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RE-BEAMINGAfter rope dyeing, dyed yarn is rebeamed. This is also called warper beam. Features Heavyweight [66 tax (G 75's)] to lightweight [2.25 tax (1800's)] yarn processing capabilities High energy efficiency by utilizing AC generated power Tension-controlled motors in creel to drive the size box & head end motors Greater yarn stability through fluted rolls Precise tension control Individual beam tension control in the creel via load cell tension rolls & AC tension controlled motorsMachine Layout

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SIZINGAlthough the quality and characteristics of the warp yarns coming out of the winding, warping and dyeing processes are quite good, they are still not good enough for the weaving process for most of the yarns. The weaving process requires the warp yarns to be strong, smooth and elastic or extensible to certain degree. To achieve these properties on the warp yarns, a protective coating of polymeric film forming agent (size) is applied to the warp yarns prior to weaving; this process is called slashing or sizing. The main purposes of slashing are as follows: To increase the strength of the yarns To reduce the yarn hairiness that would cause problems in weaving process To increase the abrasion resistance of the yarn against other yarns and various machine elements To reduce fluff and fly during the weaving process for high speed weaving machines. DRYING ZONE:After the size box the yarns go through the dryer section. The wet yarns are dried by using cylinder drying. Cylinder drying is done using steam heated hot rolls called the drying cylinders. The cylinders are coated with Teflon to prevent sticking of the yarns on the cylinders. SIZING MACHINE

Brand Make Quantity Germany 01

Features

Modern control systems for reproducible quality and efficient handling Individual drives & precise measuring systems Pre-wetting technology significantly reduces size & increases weaving efficiency Precise sizing control Perfect beams for better weaving results Reproducible size preparation - manual or fully automatic

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WEAVERS BEAM:The yarns are wound on to weavers beam at the headstock. A pressing roller is pressing the warp yarn for uniform tension winding. A guide roller guides the yarns to the weavers beam. A pressing roller is pressing the warp yarn for uniform tension winding.

TRANSPORTATION OF BEAMS:After the winding of dyed warp beams the form the head stock the samples of the yarn are taken to laboratory for testing and then it is transported to the weaving department.

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W E A V I N G

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WEAVINGThe process of producing a fabric by interlacing warp and weft threads is known as weaving. The machine used for weaving is known as weaving machine or loom. Weaving is an art that has been practiced for thousands of years. The earliest application of weaving dates back to the Egyptian civilization. Over the years, both the process as well as the machine has undergone phenomenal changes. As of today, there is a wide range of looms being used, right from the simplest handloom to the most sophisticated loom. BASIC WEAVE DESIGNS There are three basic weaves: 1) Plain weave

2) Twill weave

3) Satin Weave

Most of the other weaves are derived from these three basic weaves. The immediate derivatives of these three structures are warp rib, filling rib, and basket weave. 50


Classification of Weaving Machines: Weaving machines are classified according to their filling insertion mechanism. The classification is as follows:

LOOM

SHATTLE

SHATTLE-LESS Air-Jet Rapier Projectile Water-Jet

AIR-JET WEAVING: Air-jet weaving is a type of weaving in which the filling yarn is inserted into the warp shed with compressed air. Air-jet system utilizes a multiple nozzle systems and a profiled reed. Yarn is drawn from a filing supply package by the filing feeder and each pick is measured for the filling insertion by means of a stopper. Upon release of the filling yarn by the stopper, the filling is fed into the reed tunnel via tandem and main nozzles, which provide the initial acceleration. The relay nozzles provide the high air velocity across the weave shed. Profiled reed provides guidance for the air and separates the filling yarn from the warp yarn.

Here are some of the common fabric defects and their troubleshooting as observed on Denim weaving Airjet looms. I have included the damages observed on Tsudakoma looms, but I am sure the principles can be applied on other airjet looms also:

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a. BENT PICK 1. Check catch cord drawing in and its position 2. Air pressure of all nozzles 3. Heald Frame height and shed crossing 4. Check stretch nozzle timing and position 5. Reed dent gap opposite to stretch nozzle. 6. Check condition and position of weft rubber stopper. 7. H1 Feeler head condition to check for any damage etc. 8. Heald frame side play to check 9. Binding of Leno Yarn b. WEFT PATTI 1. Check pressure of AGS 2. Check AGS piston 3. Check beam gear and beam drive pinion 4. Check beam bearing bush, clamper condition and beam bearing 5. Check ELO timing 7. Check tension lever rod freeness and shock absorber position 8. Check take up gear and take up belt condition 9. Check press roll spring tension 10. The machine should not be stopped for long duration c. WEFT FLOAT 1. Check Air pressure 2. Check leakage of air pipes 3. Check nozzle jet timing 4. Check catch cord end drawing in position 5. Check stretch nozzle position against reed dent gap. 6. Check heald frame height and shed crossing timing 7. Check fringe length 8. Check LHS cutter timing 9. Check position and condition of rubber stopper 10. Check proper winding of weft turn on FDP 11. Check individual subnozzles for blowing 12. Check all warp ends are tight enough 13. RH/LH selvedge should run on last ring of the temple. d. MISSING END / CHIRA 1. Check all serrated bars are not in loose contact at the clamp 2. Serrated bars should be thoroughly cleaned with petrol/thinner 3. Dropper sensitivity to be checked 4. Electric connection at the cable with clamp should be checked. 5. Remove fluff from the serrated bars 6. Ensure that each warp end is attached with one drop pin.

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e. TORN OR HOLE AT THE TEMPLE 1. Check that temple cover is face to face with temple bracket 2. Ensure that temple bracket are fitted firmly on temple bar 3. Check heald frame height and shed crossing timing. 4. Check warp tension 5. Check bottom guide bar setting 6. Check press roll spring tension f. ABRASION MARK 1. Check position of warp stop motion separator 2. check cross ends 3. Check freeness of heald wires. 4. Check emery roll for any cuts etc. 5. Check freeness of temple rings 6. Check smoothness of temple covers 7. Bottom guide bar position and condition to be checked 8. Check reed-dent spacing g. NOZZLE MARK 1. check sub nozzle angle and height 2. Check scratches at tip of sub nozzle 3. Sub nozzles should be parallel 4. Check Reed dents h. JIRKY/ MISSING PICK 1. Check working of H1/ H2 feeler 2. Check feeler timing in I-board 3. Check setting of FU-203 (sensitivity of H1 and H2 feelers) 4. Clean H1 and H2 Feeler head i. TIGHT ENDS 1. Check that ends should be parallel 2. Remove entanglement of warp ends 3. Check that sticky ends of selvedge should not run in the body. j. OIL DAGHI 1. Check that no oily fluff is stuck to the warp sheet 2. Check that no oily fluff is stuck to the emery roll or pressure roll. k. BAD SELVEDGE 1. Check leno stop motion 2. check proper RH cutter setting 3. Check continuous working of batching winder

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WEAVING IN US DENIMIn US DENIM weaving is carried out through air Jet looms. Like some other departments weaving department is running 24 hours a day and meeting the sales requirements. Weaving department is playing a leading role in denim manufacturing at of denim at US DENIM. Air jet weaving is a type of weaving in which the filling yarn is inserted into the warp shed with compressed air. Air jet weaving utilizing a multiple nozzles system and profile reed. Yarn is drawn from a filling supply package by the filling feeder and each pick is measured for the filling insertion by means of a stopper. Upon release of the filling yarn by the stopper, the filling is fed into the reed tunnel via tandem and main nozzles. The tandem and the main nozzle combination provide the initial acceleration, where the relay nozzles provide the high air velocity across the weave shed. Profile reed provides guidance for the air and separates the filling yarn from the warp. A cutter is used to cut the yarn when the insertion is completed. Air jet machine has an extremely high insertion rate .Due to its exceptional performance, air jet machines are used primarily for the economical production of standard fabrics, covering a wide range of styles. Meanwhile, more and more special fabric segments are covered: heavy cotton fabrics such as denim, terry fabrics, glass fabrics, etc. The advantages of air jet weaving machines are: High productivity. Low initial outlay. High filling insertion rates. Simple operation and reduced hazard because of few moving parts. Reduced space requirements. Low noise and vibration levels Low spare parts requirement. Reliability and minimum maintenance. After the tandem and main nozzles are turned on, yarn is released from the clamp (stopper).When all the coils of the particular pick have been pulled off the feeder, the stopper closes the yarn decelerates and then will be beaten into the fabric. Thereafter, the air is turned off and the pick is cut to complete the cycle.

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WEAVING MACHINE:Brand Make Total looms PICANOL Belgium 86 looms

Features

Fast, simple width changes & symmetrical width reduction Modular feature equipped to fit a superstructure Newly designed relay nozzles & valves for highest performance Split frame for style change in less than 30 minutes Optimized insertion preparation for up to eight colors or yarn types Standard design for cam, dobby and jacquard motions Warp beam and cloth roll can be changed quickly without tools

TRANSPORTATION FROM WEAVINGA doff of required length according to Let off of the loom and quality of the fabric is removed from the loom and transported to the finishing department 55


F I N I S H I N G

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FINISHING OF DENIMA process done to fibers, yarns and fabric causing them to change in appearance, texture and performance. The term finishing covers all those treatments that serve to impart to the textile the desired end-use properties. These can include properties relating to visual effect, handle and special characteristics such as waterproofing and nonflammability. Finishing treatment is done to achieve the ultimate customer requirements. These are mostly value added processes. Finishing may involve Mechanical Finish Chemical Finish MECHANICAL FINISHING: Mechanical Finishing is defined as any operation performed to improve fabric appearance or function by physical manipulation. Steam or water may accompany the physical manipulation; however, chemicals other than lubricants are seldom used. Fabric luster, smoothness, softness, residual shrinkage and hand are examples of the properties that can be altered by mechanical finishing. Compacting (Shrink-proofing) Calendaring Raising (Napping, Sueding) Shearing Polishing Corduroy Cutting CHEMICAL FINISHING: Among chemical treatments one can further distinguish between treatments that involve a chemical reaction of the finishing agent with the fiber and the chemical treatments where this is not necessary (e.g. softening treatment). Some finishing treatments are more typical for certain types of fibers like easy care finishes for cotton antistatic treatment for synthetic fibers and mothproofing and anti-felt treatments for wool. In case of fabric the finishing treatment often take place as a separate operation after dyeing. In more than 80% of cases the finishing liquor, in the form of an aqueous solution/dispersion, is applied by means of padding techniques. The dry fabric is passed through the finishing bath containing all the required ingredients, and is then passed between rollers to squeeze out as much as possible of the treating solutions before being dried and finally cured. Washing as final step, tends to be avoided unless absolutely necessary. Following are some of the Finishes: Flat finish (singeing mercerizing- padding- sanforizing) Regular finish (singeing padding- sanforizing) Coating 57


FINISHING IN US DENIMUS DENIM finishing department is a well-established modern section with a suitable range of the finishing processes required for denim. WORKING IN FININSHING DEPARTMENT OF US DENIM: It is divided in to following main sections: Batcher formation Singeing Mercerizing (chemical treatment) Stenter Sanforizing Finishing is done according to the customer` s requirement and as per profit of the organization. Singeing, skewing, washing and sanforizing are done according to end use of fabric. Parameters of the finishing are set by testing unde

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