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Home , Distaff, Spinning jenny, Spinning mule, The Textile Institute, Water frame

LECTURE OUTLINE

PROCESSING FIBER INTO

I. The History of Fiber Processing 11. Material Opening and Cleaning A. Preparing the bale lay-down 1. Selection of bales 2. Bale arrangement for blending 3. Removal of bands and bagging B. Opening and cleaning equipment 1. Weigh-pan feeders 2. Magnetic and electronic cleaners 3. Dust removers 4. Beater type cleaners 5. Positive-fed saw-type cleaners 111. A. Opening of fiber B. Cleaning as a hction C. Reducing or drafting D. Packaging of stock IV. Drawing A. Drafting and fiber orientation B. Blending and uniformity V. A. Combing preparation 1. Drawing for Iapper 2. Lapping B. Principles of combing operation I. Feeding of laps 2. Nipping of fiber 3. Circular combing 4. Detaching 5. Top combing V. Combing (continued) C. Primary functions 1. Removal of short fiber () 2. Removal of trash D. Secondary functions 1. Reducing and drafting 2. Blending and packaging VI. A. Definition and description of B. Description of product C. Purpose of roving machine 1. Drafting 2. Twisting 3. Packaging a. laying b. winding c. building VII. Types of A. Intermittent spinning 1. 2. Saxony Wheel- B. Continuous spinning 1. Cap spinning 2. Centrifugal spinning 3. Flyer spinning 4. a. definition and description of process 1. drafting of fibers 2. twisting of yarn 3. packagmg of yarn aa. laying bb. winding cc. package building b. other ring spinning factors 1. ring and traveler 2. speeds and rpms C. Open-end spinning 1. Definition and methods a. pneumatic-Murata Air Jet b. friction-DREF I, 11, III c. aero-mechanical-rotor 2. Rotor spinning a. feed assembly b. drafting c. transporting d. condensing e. twisting f. packaging g. other aspects affecting rotor spinning 1. opening roller type and speed 2. rotor type and speed 3. navel surfaces and false twist devices 4. trash extraction 5. component wear THE HISTORY OF FIBER PROCESSING

The art of spinning yarn from fibers is so old that it antedates recorded history. From artifacts that have been discovered, it is evident that a form of cloth woven fiom fibers was used by cavemen while the mammoth, the giant sloth and the saber-tooth tiger roamed the earth during the Stone Age. Ancient Egyptian hieroglyphics picture men and women engaged in spinning and . Cloth made of spun yarn so fine that it cannot be duplicated by modem and processes have been unearthed from the tombs of the Pharaohs of 6,000 years ago. The earliest known method of spinning was by drafting the fibers by hand and winding them on a or rod. Hand spindles have been found among the excavated ruins of ancient civilizations in many parts of the world. Spinning is not the discovery or invention of any one man or era. Rather, it is the accumulated howledge and technological advances of myriad people through thousands of years of striving for better ways to obtain the necessities of everyday living. The evolution of spinning from a home-based handicraft to a industry has been within the last two centuries. Fairly accurate records of the development in spinning during what is often called the Machine Age are available, but details of some of the early machines are sadly lacking. The invention of the Saxony Wheel by Johann Jurgen of ~runswick,'Germanyduring the latter part of the sixteenth century was the first break-through in the of spinning. The Spinning Jenny, invented by in 1764, was actually a modification of the Saxony Wheel with a number of spindles. James Wyatt is credited with the invention of drafting with rolls, and he built a spinning machine as early as 1730. worked with Wyatt and patented a spinning machine in 1738, and another in 1758. However, these first machines were not successful due to the lack of intermediate processes to prepare the fibers for final drafting. claimed credit for the invention of both roller spinning and the Spinning Jenny and won a court suit against , who held a number of patents on these developments. However, there had always been some doubt about the authenticity of High's claims. Richard Arkwright is given credit for developing the first successful machines for manufacturing spun yam. He patented a spinning machine in 1769. Finding that preparatory processing was needed for the fibers, he developed and patented carding, drawing, roving, and spinning machines in 1775. invented the , a cross between the Jenny and the Jack, or , in 1779. The water frame was so called because the first models were pulled by water- power. Christopher Tully is given credit for building the first spinning machine in America. This machine, a Spinning Jenny, was placed in the mill of Samuel Wetherill in Philadelphia, Pennsylvania in 1775. Although he was not the first to manufacture yarn with machines in America, was the first to build and use machinery based on the Arkwright system. These machines were built from memory (before coming to America, Slater had worked eight years for Jerediah Strut7 a partner of Richard Arkwright) and there is no record of Slater actually inventing any of them. However, there is no doubt that by Sam Slater equipping his mill at Pawtucket, Rhode Island with successful machines in 1793, it was one of the greatest stimulants to the invention and enterprise in making the United States a world leader in both and machinery building. Paul Moody, superintendent of the Boston Manufacturing Company mill at Waltham, Massachusetts, invented the filling throstle in 1819 and eliminated the costly winding process of transfening the filling yarn to filling bobbins. It was in the basement machine shop of this mill at Watharn, founded by Francis Cabot Lowell in 1813, that the present-day Saco Lowell Shops had their beginning. Moody invented the dead system of thostle spinning in 1821, which was predominated in Northern New England until after the Civil War. Two notable spinning inventions of this era were cap spinning, patented by Charles Danforth in1 828 and ring spinning, developed by John Thorp in 1830. Ring spinning gradually became the predominate spinning system throughout the world, especially on stock.'

1. Platt Saco Lowell, Instruction Manual S~inomaticS~inning Frame, Fifth Edition, pp. 8- 11. GLOSSARY OF SHORT PROCESSING TERMS (In Order of Occurrence)

Blending: The technique of mixing two or more dissimilar fibers in a very uniform mixture. Can be done prior to carding or at the drawfhme.

Opening: A preliminary operation in staple fiber processing that separates compressed masses of fiber into loose turfs and removes heavier impurities.

Cleaning: Separating the non-lint £tom the lint.

Carding: The disentanglement of fibers by working them between two closely spaced, relatively moving surfaces clothed with wire, pin, or saw teeth.

Sliver: As assemblage of fibers in rope fom without twist, produced at carding, drawing, and combing.

Drahg: The process of attenuating raw stock, , and roving to reduce their mass per unit length.

Drawing: Textile operations by which a number of slivers are blended (doubled) into a single sliver and made more uniform by drafting and by parallelizing the fibers.

Doublings: A number of laps, slivers, or feh simultaneously into a machine for drafting into a single strand usually to promote regularity and homogeneity of a product at each stage of processing.

Lapping: Combining a number of slivers together in lap form for combing preparation.

Combing: The straightening and parallelizing of fibers to remove short fibers and impurities by using a comb, or combs, assisted by brushes and rollers and sometimes by knives.

Roving: Intermediate state between sliver and ring spinning where the sliver is condensed and a small amount of twist is added for stability.

Spinning-Ring: A type of spinning incorporating ring and traveler in which, on leaving the delivery rollers, the yam passes through a guide arranged centrally above the top of the spindle, down and through a traveler positioned on the ring and onto a driven yam package which sits on the spindle.

Spinning-Open End: The production of spun by a process in which the sliver or roving is opened or separated to its individual fibers or tufts and is subsequently reassembled in the spinning element to form a yam.

Winding: Process of transferring yam from one type of package to another, more suitable, package for subsequent processing. Necessary in ring spinning to transfer yam from bobbins to cones.

Clearing Yam: The process of removing imperfections such as slubs, neps, or projecting impurities from the body of a yam.

Plied Yams: Yams made by twisting two or more strands of single yam together. Outline of Short Staple Processing (through yarn production) HunterWe6h Pan Hopper Feeders

Dust Remover -Condenser

r AMH Blender 1

Rieter Aemfeed

Carding Rieter C-4 Card Trashmaster

Piatt Saw Lowell DE-7C Drawframe

lC3Rieter E7/6 Comber Rieter RSB851 Drawframe

Saw Lowell Rovematic FC-1 B Roving Frame I Ring Spinning

Leesona Unconer Wnder

Non-ring Sphning OE-Rotor Spinning

Whitin Roberts Ring Twister

Fabric Formation: Weaving or Knitting MATERIAL OPENING AND CLEANING

When a bale of cotton arrives at a textile plant, it is tightly compressed and usually has a density of around 28 to 30 pounds/cubic foot. Cotton is usually shipped in weights of 480 pounds per bale, whereas man-made fibers are shipped in weights of 600 to 700 pounds per bale. Here again, this is compressed tightly, which is a practical necessity for shipment. Whatever the fiber may be, it must be opened and reduced in density before yarn can be spun.

Opening a bale of textile fiber is simply a matter of pulling the tightly compressed bulk apart and reducing the one single bale to many small tufts of fiber or even individual fibers. Yarn cannot be spun directly from a compressed bale, and the fibers must be pulled apart and dealt with individually before any textile product can be made. Besides this, cotton usually contains a certain amount of foreign material that originated in the fields and was not removed during ginning. It is important to remove as much of this foreign material as possible before spinning takes place. In cases where there is a great amount of trash such as cotton plant stems, leaf matter, and material from the field, all of this may not be removed by 1 2 3 4 5 6 7 textile opening and cleaning equipment. It will be carried on into the spun yam and even into Main elements of the bale opening machine woven or knitted fabric. 1. electrical feed cabinet 2. channel for electric chain cable The ideal situation would 3. covering belt 4. take-off unit 5. swivel tower be to remove all foreign 6. control panel 7. evacuation duct 8. drive rails material form the cotton 9. chassis 9 8 Example of Blending Machine 1. feedpipe 2. vertical filling trunks 3. conveyor belt 4. conveying roller 5. upright lanice 6. blending chamber 7. stripper roller 8. take off roller 9. filling trunk 10. opening and clean- ing roller with grating 11. waste collector 12. fibre delivery 13. exhaust air overhead piping 14. exhaust air into collecting duct

14 3 11 floer so that the yam and subsequent fabric would be completely free of this. Opening machinery found in modem textile operations is generally designed to remove any material except the fiber itself. Even though man-made fiber arrives at a textile plant without any trash, the fiber is passed through opening equipment that is designed to clean as well-as pull the fiber apart. This arrangement seems to be entirely satisfactory, for many textile operations still process cotton either in 100% form or in blends with other fibers. In addition to opening and cleaning the incoming fiber, blending is another function of opening machinery. Even when 100% cotton is being processed, it is highly desirable and - virtually necessary to blend together the bales that are being fed to the opening line at any one time. Every bale of cotton is different from every other, and it is important to blend these as thoroughly as possible to give a yarn that has a high degree of homogeneity. If one bale at a. time is opened in its entirety and then followed by another bale, the resulting yam would have one section with the quality of the first bale, another the same as the following bale, and so on. The total yarn produced would possess extreme variations in quality. This is highly undesirable and generally unacceptable. In fact, a textile company operating in this manner would have a very difficult time using its own yam or selling it to some other company. The best possible quality is important in today's competitive market and thorough blending, regardless of the fiber being used, is very important. A great amount of yam and fabric is produced fiom blends of two or more fibers, and blending for the correct percentage is important along with homogeneity. This cannot be done in a haphazard manner, but it should be camed out very precisely in order to give the exact blend desired in the end product. Previously, a standard opening line would normally have at least four blending feeders, sometimes called hopper feeders, which take fiber fiom incoming bales and open and clean it. Blending feeders are normally positioned parallel with each other, each machine doing exactly the same thing and discharging opened and cleaned fiber. At the delivery end of these blending feeders, we normally find a conveyor belt or a suction pipe that carries the fiber to another location. It can be quickly seen that if half of the blending feeders are processing one fiber and half processing another fiber, theoretically there would be approximately a 50150 blend of the two fibers. Or, to state this in a different way, there would be 50% of one fiber and 50% of the other fiber blended together on the conveyor belt or in the suction pipe carrying the material to the next process. While this appears to be an acceptable manner of blending, actually it is not quite good enough. At the delivery end of each blending feeder is a set of weighing scales, generally called fiber meters or sometimes referred to as weigh pans. The purpose of these devices is to catch the fiber as it is being removed from the blending feeder and hold the amount delivered fiom each machine until all of the machines have opened and delivered a pre-determined amount of the fiber fed to them. These weighing devices can be pre-set to collect a precise weight, and by doing this an exact blend can be formed with any of the fibers fed. An accurate balance of the two or more fibers that are being fed to an opening line will result, and for this reason blending feeders with weighing scales are used by virtually all textile companies. With the popularity of blends today, it would be almost impossible to operate an efficient production unit without fiber meters. With the advent of bales of uniform density, it is now possible to use more sophisticated machinery for opening the bales. This consists of a traveling head, which travels to and fro along a row of bales, removing a proportion of the top of each bale with a pair of large-toothed rollers. The fiber pulled from the bale is then transported from the head to the next machine. When the blend of fibers leaves the bale opening machinery, it quite often goes to another or possibly two more machines that do basically the same thing. We should remember that if cotton is being used, as much of the foreign material as possible needs to be removed. For the man made fibers involved in the blend, these simply need opening and nothng more. Whatever the case, there are usually one or two machines positioned after the blending feeders to accomplish opening and cleaning. The traditional means of processing raw stock was to continue opening and cleaning with a machine called a picker. This machine is rapidly becoming obsolete in textile operations in the United States. It has been replaced by a simple transporting arrangement made up of ducts with a strong air current that carries the opened and cleaned fiber from the opening machinery to the cards. This arrangement is referred to as a chute feed. The cotton fibers, having been reduced to large tufts by the bale-opening machine, are often passed through a metal detector. This causes the offending particles to be collected separately from the body of fibers, thus preventing costly damage to more delicate machine parts further downstream, such as opening rollers, grid knives, and card clothing. In addition, removal of metal diminishes the likelihood for fire caused by sparks. The stock is generally passed into a simple cleaning machine, which beats the tufts of fibers to release loosely entrained trash. This is typically accomplished by striking the tufts in free flight by means of pegs attached to a rotating cylinder. The trash released by this action falls through grid bars while the cleaner cotton tufts are drawn forward to the next machine. If the stock has been removed from the bale by a bale-opener, there will have been little opportunity for blending to occur. It would be obtained when the stock is fed onto a conveyor to form a sandwich of fibers, each layer being provided by the stock from a hopper feeder. Consequently, pre-cleaned fiber is usually supplied to a blending machine. In essence, this piece of equipment arranges for the incoming material to be laid down in horizontal strata, building up a very thick bed of material from which stock is removed in a vetical direction. Irrespective of whether the stock was blended by means of hopper feeder or blending

machine, the next process is often one which begins to make serious attempts at reducing the tuft . size in an effort to release entrapped trash particles. In such a cleaning machine a mat or batt of fibers is pulled forward by a feed roller assembly and simultaneously fed to a toothed roller. The stock is gripped by the feed-rollers from which the teeth of the rotating roller tease tufts. This action releases trash, which is expelled through gnd bars while the cleaned cotton travels around the circumference of the roller to be ejected into the air stream pulling material to the next machine. Often, tufts of material may be drawn onto a perforated. cylinder through which air is withdrawn. The cylinder rotates rapidly, but the stock accumulates on the screen and can then be released to a subsequent machine by appropriate positioning of a damper. The air removed from this machine, known as a condenser, is usually dust-laden. A third cleaning treatment is generally applied to cotton, much like the previous one in which gnpped fibers were fed to a rotating toothed roller. In this case, however, the intensity of opening is much greater to permit further reduction in tuft size and more cleaning. n Other cleaning An Example of a machines exist, also, Positively-Fed Saw-Type Cleaning often utilizing other Machine principles such as air- 1. material supply 2. feed head with fan stream deflection to 3. exhaust air piping (can be installed overhead separate heavier trash or below the floor) 4. delivery of the material particles. In general, the 5. laminar chute filled with material number of cleaning 6. plain drum 7. dust cage points within an opening 8. feed rollers 9. knife grid line increase as the trash 10.opening and cleaning beater content of the intended 1l.suction duct 12.waste chamber supply of cotton which can be con- nected to an auto- becomes greater. matic waste removal system Fiber from the 13.driving motor 14.waste removal pipe last cleaning machine is fed to the chute feed system for the card by means of a material- handling fan. The chute collects the fiber as loose, small, open tufts and delivers the material as a batt to the feed roll of the card. Ensuring that the cotton is in a well-opened state allows the card, an intensive cleaning machine, to individualize the fibers with a reduced risk of fiber damage. Typical through puts of material for a sequence of individual machines can vary from 800 to 1500 pounds per hour. The combined objective of the various machines in the sequence is to open, blend and clean the cotton. CARDING AND DRAWING

I. Carding A. Purpose and principle of process 1. Settings and speeds 2. Waste removal and collection 3. Cleaning areas of card a. Mote knife to lickerin b. Flats to cylinder B. Safe operation and maintenance 1. Cleaning of the card 2. Upkeep and repair C. Fiber drafting in the card 1. Batt weight 2. Sliver weight and quality 11. Drawing A. Purpose and principle of process 1. Settings and speeds 2. Drafting ratios 3. Sliver weight and quality B. Safe operation and maintenance 1. Cleaning and care of rubber rolls 2. Upkeep and repair C. Fiber drafting in the drawfiame 1. Sliver doublings 2. Sliver delivery 3. Sliver weight and quality CARDING

Many technologists and manufacturers consider carding to be the most important textile process between opening and spinning. A greater degree of opening is done by this machine than any other and, except for the comber that is used for removing short fiber prior to spinning combed yarns, it does more cleaning than any other machine. It takes fibers in a mat from the opening line and separates these to a point of working with the fibers almost individually. In doing so it removes a great amount of the foreign material found in cotton, reduces the overall bulk of the material to a strand of fibers called a "sliver," and packages this in a can. Therefore, it can be seen that the four functions of a card are opening, cleaning, reducing, and packaging. Some technologists believe that the card also aligns the fibers parallel with each other, but this is questionable. For the most part, the fibers are tangled together without any appreciable degree of parallelization. There are others who consider the card to be a blending machine in addition to its other functions, and this is true on a short-term basis. That is, as the machine takes the mat of fibers coming in at the back, it blends the fibers together at this point, but long-range blending is really not accomplished. For the purpose of this study, these notes will include a description of the four functions that were given above. These will be discussed one at a time so that a proper understanding can be obtained. For may years the material coming to a card was in the form of a picker lap, a mat of fiber 40 inches wide rolled into a roll that was approximately 50 yards long. This was a standard procedure, and the card was designed to take the picker lap, unwind it slowly and then perform the four functions we have mentioned here. A relatively new development uses an airflow and distribution system that feeds loose and opened tufts of fiber to the card directly from the opening line through a chute feed. The fiber entering the card is measured in so many ounces per yard. This is a linear yard of the material entering and not a square yard. The standard cotton card is still 40 inches wide. The fiber being fed will normally be controlled at a weight between 12 and 18 ounces per yard. Perhaps we should make one point of explanation. The carding machine we are discussing is used in the cotton system of yam manufacture and is commonly referred to as a "cotton card." However, this does not mean that only cotton is processed in this machine. The accompanying diagram should be referred to in gaining an understanding of the operation of the card and how it accomplishes its four functions. The mat of fibers coming in at the back of the machine is fed in by a feed roll over a feed plate. The movement is quite slow in order to accomplish the opening function that takes place at this point. Just inside the machine beyond the feed roll and feed plate is a rotating 9-inch cylinder known as lickerin. This is covered with saw-tooth type wire that is designed to catch the fibers as they are fed in slowly by the feed roll. The difference in speed here is important, for it is intended that each wire tooth on the lickerin removes only very few fibers from the entering mat. The ideal situation would be to have one fiber on each lickerin wire, but more normally it is likely that these teeth will pull in small groups of fibers. However, it is obvious that a considerable amount of opening is done at this point. There is a drastic change from a mat of fiber weighing approximately one pound per linear yard to the removal of these fibers by the wire of the lickerin. Flat With opening done to such a high degree, it is easy to see that cleaning can also take place at this point. (Though man-made fibers do not need to be cleaned, cotton does.) Even the highest grades of cotton will have some amount of foreign material included with the fiber, stripping I Combing and the point where the fibers are 2L Stripping pulled fiom the entering mat by the lickerin is an excellent place for the cleaning. To facilitate this, a specially designed set of grids, called mote hives, and a screen are used in conjunction with the lickerin, or a system using a screen and a fiber retriever may be used. The hives and screen surround the under portion of the lickerin and prevent the fiber from being discarded at this point, but the foreign material, which has a greater density, is permitted to be thrown away from the fiber. This cleaning operation is a matter of the different densities of the fiber and foreign material and the centrifugal force involved in carrying both around the curve created between the surface of the lickerin and the screen positioned below it. The screen terminates at a point between the surface of the lickerin and that of the cylinder, and at this point the fibers are thrown away from the lickerin onto the surface of the cylinder. Please note from the accompanying diagram that both surfaces are moving in the same direction. The cylinder is a much larger part of the card than the lickerin, and although it is revolving at a lower rate of speed, its surface speed is somewhat greater than that of the lickerin. The surface of the cylinder may be quite similar to the wire of the lickerin, or it could be covered with round wire rather than the saw-tooth design. Whichever it is, the points of the wires of saw-tooth material cany the fibers along a series of wire-surfaces flats or a stationary surface made of a similar material. The process of carding is quite old, and at one time it was done by hand. A person simply took two boards covered with wire, placed a supply of fibers on one of these boards and carded, or brushed, the fibers back and forth between the two wire surfaces. This accomplished the functions of opening and cleaning, for as the fibers were pulled.apart, any foreign material was permitted to drop out. After the fibers were properly carded, they were removed from the two wire surfaced boards and were ready for spinning with a . Today, the production of a carding machine is much greater. The carding action takes place between the surface of the cylinder and the wire-covered flats or stationary surface -. positioned on top of the cylinder. In either case, the separation of the fibers continues until they are pulled to the front of the cylinder where they are thrown off by centrifugal force onto the surface of the . Here again, the cylinder and doffer are turning in the same direction at the point where they meet, and the speed of the doffer is considerably less than that of the cylinder. The doffer carries the fibers around 180" to its front side where the fibers are removed in a thn web by doffing rolls. The web is then pulled through a trumpet, then calendar rolls and a sliver is then formed. This is then coiled into a can where it is stored for the next process. In studying these notes and using the accompanying diagram, it should be obvious that the opening takes place between the mat of fibers fed and the lickerin, and then again between the surface of the cylinder and the wire-covered flats that are positioned above it. As the fibers are opened, they can be cleaned if necessary. The third function'of the machine, reducing, is normally called drafting. The overall draft, the amount of reduction, can be calculated mechanically or it can be determined by the weight per yard fed to the back of the machine and the weight per yard of the sliver that is delivered from it. It is sufficient to understand at this time that draft is a measure of the reduction of the mass of fibers that pass through a machine, in this particular case the card. The fourth function, packaging, is accomplished by reducing the web of fibers from the machine to a sliver and then coiling this into a can at the front of the machine. The mechanism with which this is done is rather interesting, but it does not warrant study at this point. It will be helpful to understand the relative positions and speeds of various working parts of the card. As we have indicated, the feed roll turns quite slowly as it brings in the mass of fiber from the chute feed system. The surface speed of this roll is a matter if just a few inches per minute. The lickerin, which is nine inches in diameter, is covered with saw-tooth wire and revolves at speeds between 400 and 1500 rpm. The contrast in surface speeds is by design, for it is intended that one or just a few fibers are to be removed by each tooth of the lickerin wire. The lickerin carries the fibers past the mote knives and screen to a point very close to the surface of the cylinder. The cylinder has a diameter of 50 inches and rotates at speeds between 300 and 800 rpm. In high speed carding today, this part of the machine usually rotates at the upper edge of this range. When revolving flats are used with the cotton card, they move very slowly to the front along the cylinder surface that perfoms the carding. Normally, this movement is only two to six inches per minute. Some cards no longer have revolving flats but have a stationary carding surface mounted over the cylinder in the same position that would be occupied by the flats. Whichever system is used, the carding of the fibers is accomplished between the two surfaces. A plate covers the cylinder surface between the flats and the doffer so the fibers will not be thrown off the cylinder by centrifugal force. At the point where the cylinder and doffer come closest together, the fibers are removed fi-om the wire surface of the cylinder onto the same surface of the doffer. The doffer is 27 inches in diameter and rotates according to the production desired for the machine. An extremely slow speed would be five rpm, while top speeds are around 75 to 80 rpm. A more common speed for the doffer would be approximately 45 to 55 rpm. The doffing rolls that remove the web of fibers form the doffer, the calender rolls that condense the web into a sliver, and the coiling mechanism all operate at speeds sufficient to take the newly formed sliver and place it in a can. It is obvious, therefore, that the major parts of the card are the feed roll, lickerin, cylinder, flats, or stationary carding surface, and the doffer. All other parts of the machine operate in conjunction with these to perform the four functions that have been listed for carding. Drawing Drawing is the process that follows carding in the cotton system of yarn manufacturing. The functions of a drawing machine, more normally called a drawing frame, are blending, straightening the individual fibers to make them parallel with each other, drafting, and packaging. Most textile operations will use at least two drawing processes, and in some cases as many as four or five are employed for special purposes. For this study, we would like to consider that two drawing processes are used immediately after carding. The first of these is called breaker drawing and the second is referred to as finisher drawing. These are not parallel processes, but rather all the carded sliver is processed through breaker drawing, and then this sliver is taken to finisher drawing. The purpose in this arrangement is to assure that a high degree of parallelization is given to the fibers and that these are will blended together. Ideally, blending at drawing will be such that the fibers eventually spun into yarn will make up a homogeneous mix so that no part of the yarn will be any different from another. A drawing frame is so constructed that the strands of card sliver can be pulled from the individual can into the back of the machine for blending and fiber straightening prior to reducing the designated number of slivers to one sliver, which is coiled back into a can. This. is accomplished by having rolls that pull the card slivers from their respective cans, and these rolls are followed by a series of drafting rolls that reduce the combined ends of sliver to one end before packaging into another can. The reducing, or drafting, is accomplished by a series of rolls, each pair of which is turning at a successively faster rate of speed. When we refer to a "pair" of rolls, we are describing a steel bottom roll with a top roll mounted on it. The bottom roll is driven by the power source of the machine, while the top roll is simply rotating against the power-driven roll and is held tightly in position by a pressure system. The top roll is covered with a synthetic compound, much like rubber, to prevent slippage of the fibers as they pass between the two rolls. Many drawing DRAW FRAME ROU ARRANGEMENTS frames have four pairs of rolls, each of the bottom 414 DRAFT steel rolls driven by the power source of the machine - and each of the top rolls held Breaker Intermcdlate Flnkher Draft Zone Draft Zone Draft Zone in position by a high I I I I pressure arrangement. The pairs of rolls are so positioned that as the strands of sliver enter at the back, 314 DRAFT fT they will be moved directly e from one set of rolls to the next, which is turning at a &eaker Finis* Draft Zone Draft Zone slightly faster speed. This I+ Total oraft continues until the slivers entering ILLUSTRATION OF DRAFTING PROCESS have passed through all four sets of rolls and have been reduced in bulk because of the increasingly higher speed of the rolls. By the time the bulk of fibers exits between the top and bottom front rolls, it has been reduced so that its weight per yard is approximately the same as any one of the slivers entering at the back. The stock is in web form at this point, but after being pulled through a trumpet, then calender rolls; it is formed into a sliver once more and is coiled in a can for the next process. It should be understood that the pairs of drafting rolls are normally set far enough apart so they will not be gripping both ends of a fiber at any given time. In order to properly control the fibers, the top roll in each pair is held tightly against the bottom roll as they pass through. If one pair of rolls is set too close to the next, both ends of the fibers will be held a the same time. Since each successive pair of rolls is turning faster than the previous pair, the fibers would be stretched and perhaps broken. This is undesirable and unacceptable for satisfactory processing. Card room technicians are experienced in this matter, and they will properly set the rolls so that drafting by a drawing frame can be done without damaging the fibers being processed. To better understand the operation of a drawing frame, we need to refer to the accompanying diagrams. These show the four sets of rolls and the sliver being fed to the back and delivered at the front. Standard procedure is for eight strands of sliver to be fed to the drawing frame, .and these will be blended and reduced to one sliver. Obviously, the ratio of reduction is around eight to one, and frequently the draft measurement of this machine will be very near 8.0. The draft of a drawing frame can be calculated mechanically or it can be determined by measuring the weight per yard of all eight slivers fed and the weight per yard of the single sliver delivered form one drawing head. This particular aspect of drawing is important in that the size of the product delivered from each process has to be known. It has to be known in order to properly organize and balance a textile-manufacturing hme when a specific weight is needed for subsequent processes as we move toward spinning of the final yam.

first thing that happens is that the fibers in the slivers are held and controlled by the gripping of the back pair of rolls. As these rolls turn, all fibers are pulled forward and will be caught by the next pair of rolls. The pairs of rolls are set sufficiently far apart so that the individual fibers will not be held by both at the same, and the rolls turning faster will pull the fibers they control past those fibers still held by the back pair of rolls. Causing the fibers controlled by the faster motion to be slipped past the others creates an action that will straighten all the fibers. Then, as we go further through the machine toward the front, the fibers are caught again by a faster turning pair of rolls, and the action to slip the fibers past other and straighten them continues. This process takes place throughout the machine and serves to fulfill two of the hctions of this process-straightening the individual fibers and making them more parallel with each other, and drafting. In as much as one head, a drawing frame normally takes eight slivers and reduces these to one, a relationship between the speed of the back pair of rolls and that of the front rolls can be seen. The surface speed of the front rolls, that is the motion that controls the flow of fibers through the machme, is approximately eight times that of the back rolls. While the weight per yard of the sliver delivered is about 118 of the total fed, the speed at the front of the machine is eight times that at the back. The speed of the front roll is normally f~edthrough a direct drive from the machine's power source. The speeds of the second, third, and back pairs of rolls can be altered by changing a gear, or perhaps two, in the train gears driving all parts of the machine. This gear change can slow down or speed up the other rolls in relationship to the front pair of rolls, and this changes the amount of draft used by the machine to reduce the eight slivers to one. We have stated that it is the desire of the textile manufacturer to have the end product, yarn or fabric, constructed as homogeneously as possible. This is necessary from a quality standpoint, for another firm buying the yarn or fabric produced by a given company does not want it to change in quality fiom one shipment to the next, to say nothing about variations within a given shipment. With this in mind, the value of blending at drawing becomes more important. Rber Hooks Blended Card /L;lpper --- fabrics have become commonplace, ring Wnmg something like a Card D 1 ' DII SCver Sliver Sliver cottodpolyester blend

"0R&np is regularly used in a / 1 Uocks shcidd be ksding ink^ comber, Open End & Friction Sphnmg. variety of apparel and Open End Spirniw Hooks shdd lx troaing into 8 Fricbon Rmgt Spinning &Air Jet Spinring. home furnishing

Air Jet Spining fabrics. It is generally considered better to I I blend as early as possible, and when there are no prohibitive reasons, cotton and polyester should be blended at the first opening machine. This has already been described, and it will be recalled that these machines are equipped with metering devices to give an exact blend between various fibers. There are some reasons, however, why blending in the opening is not practical. For example, one large firm produces millions of yards of sheeting fabric for percale sheets, and in this type of sheet, the cotton must be combed to remove the short fibers. (Percale sheets are always made fiom combed cotton, which has had short fibers removed, while muslin sheets are made from carded-only yams.) In this case, it would not be practical to blend the polyester and cotton in the opening room, for there is no need to comb the polyester. (All the polyester fibers shipped from the fiber producer will be the same length, and there would be no short fibers to comb out.) Besides that, the cotton comber is designed to deal with cotton only and very likely could be damaged by attempting to comb a man-made fiber. Therefore, the textile company producing the percale sheets from cotton and polyester will handle these fibers separately until after the cotton has been combed. The comber produces sliver again and because the combing action makes an irregular sliver, that material must be taken through drawing once more. This presents the opportunity to blend the polyester and cotton at drawing. Uster Spectrogram Chart for RSB 51

Chart is calculated as follows:

Total draft = 8.03 (Nw1=29 Nw2=39)

Backdraft Vv = 1.14 (W4 = 25) Calender Tension = 0.998 (Aw 1 = 25 Aw 2 = 33) Feed Tension = 0.999 (W3 = 50 Z = 37) Jockey Roll Tension VZG = 1.009 (W1= 23 W2 = 33) Top Rolls = .40 mm

Top Rolls: 1. 40 x 2. 40 x 3. 40 x

A. Calender Roll 55 x B. Front Steel Roll 40 mm 40 x B. Front Steel Roll 48 mm C. Middle Roll 30 x xmain draft D. Back Roll 30 x x total draft E. Scanning Roll 94 x x total draft F. Jockey Roll Drive 28 x x total draft G. Calender Drive Shaft

H. Cross Shaft

J. Same as D K. COMBING

I. Combing Process A. Lapping of slivers B. Feeding C. Nipping D. Combing (noils removal) E. Detaching F. Top combing 11. Change Components A. Top comb B. Circular comb C. Sliver condenser 111. Speed Variables - A. Draft at combing heads B. Nipping rate C. Brush rpm D. Final drafting values IV. Machine Settings A. Detaching distance (ecartment) B. Top comb penetration depth C. Index disk and fiber splice D. Nipper adjustment V. Noils Removal and Collection VI. Sliver Packaging COMBING

Combing is a textile manufacturing process that removes short fibers contained in cotton and continues the preparation of the remaining long fibers for high quality yarn. The process and the equipment used are designedfor cotton only, as man-made fibers purchased in a given lot should all be the same length. Because cotton is a natural fiber and depends upon nature for its quality, yams and fabrics are made from the long fibers only, and therefore the short ones must be removed. We should understand that all cotton is not combed; this process is reserved for preparing quality cotton for use in high quality yarns. Some cotton is not suitable for combing. If extremely short cotton, such as one with a staple length of 718 or 29/32 of an inch, should be used in an attempt to make combed yam, a great portion of this fiber would be combed out. Normally, cotton used for combed yarns will not be shorter that 1 1/16 inches, and usually the length is somewhat greater than this. Fine, high quality combed yams are often spun from long staple Acala, Pima, or American Egyptian which have lengths of 1 118 inches and longer. The general rule here is that in making a high quality product, it is necessary to start with a high quality raw material. Also, the intent is to remover the short fiber from long staple cotton rather than trying to use short cotton where much of the fiber would be combed out. It would be impossible to make long staple material from the original short raw fiber, and no amount of processing will convert short fibers into longer ones. There are two machines involved in the combing process. The first is called a lapper and its only function is to take drawn slivers and combine a specific number of these into a lap, which is fed to the combing machine. In modem lappers, 48 slivers are wound side by side into a lap. Combing is done rapidly at a high degree of efficiency, and a high quality lap is required for this operation. Again, the sole purpose of the lapper is to wind the drawn slivers into a package for the comber. There are three different types of combers used by industry today. One of these uses eight laps and produces two slivers. The laps are positioned parallel with each other and the combing is done on one side of the machine only. The noils are collected at the other side (back) of the machine. At this point, four slivers are reduced to one, the other four are reduced to one, and these are then packaged (coiled) separately into cans. Not only do the drafting rolls serve to reduce the eight slivers to two they also blend and even the slivers. Cotton Combing This is important because Head the intermittent combing and detaching action results in very irregular sliver.coming from each of the eight heads. Another comber model has six parallel laps on each side. The functions of this machine are exactly the same as the other type, and two slivers are again delivered. The major difference is in appearance, with combing to both sides and the noils collected beneath the machine. This model reduces the slivers coming from the six heads on each side to one sliver and these are coiled separately into cans as before. The most recent comber design has eight parallel laps on a single-sided machine. On this type of comber, slivers from the eight combing heads are blended into one delivery. As with the other comber models, the sliver is coiled into a can. Noils are collected in a central duct and transported by suction to a drum winder and from there to a baler. Since the primary purpose of the comber is to remover short fibers, all other functions of the machine become secondary. These are reducing or drafting, blending, and packapng. The actual removal of the short fibers is done by a mechanism that operates with a high degree of precision. It must be timed properly, and the various parts of the combing head must be set precisely at the proper distance from the others. A cross-section view of the comber is included with these notes, and some time should be spent in studying it in order to develop an understanding of the combing action. The basic actions will be described separately, although it should be noted that these are actually parts of one overall operation. Before any combing can be done, the leading edge of the lap must be fed to the combing head. Feeding is accomplished due to the synchronized motion of the feed rolls, which pulls the lap into the combing zone and by the rolls that support the lap. A short length of the lap is moved into the combing zone, and then the feed and lap rolls stop. At this point, clamps called nippers close on the fibers so they will be held securely while the combing takes place. Nipping, therefore, must be timed so that the fibers will first be fed in and then will be held by the nipper plate and nipper knife for combing. After this, combing can be accomplished. The heart of the machine is the cylinder, which rotates with a constant speed and is covered on one side with the combing needles and on the opposite side with a counter-balancing section called the segment. The combing needles are mounted on a machine part called the half-lap and are in rows running across the surface of the half-lap so that the entire width of the lap of fibers being fed will be combed at one time. There are normally 17 rows of these needles, each row setting a short distance behind the preceding row so that the cotton held by the nippers will be fully combed. The fibers not held in the nippers will be removed by the 17 rows of needles, and when the cylinder on which the needles are carried makes half a revolution, a rapidly moving brush removes the short fibers from the needles. These are caught in an air current and carried to a collection point at the lower part of the machine. The short fibers are called noils and are collected for sale or reprocessing. These are used for coarse yams and other products, and when they are scoured and bleached, they can be used in cosmetic and medical .items. Scouring removes the natural wax from cotton and the fiber's ability to absorb moisture is greatly increased. Noils treated in this manner are often used in absorbent cotton balls. Also, a great amount of the better noils are scoured, bleached, and sterilized for hospital and surgical needs. When the half-lap containing the rows of needles is on the back side of the combing cycle, the previously mentioned segment is in a position near a set of specifically-designed rolls used for detaching. These rolls work with the segment to attach the fibers that have just been combed to the tail end of those that have already been moved out of the combing head. Detaching is the piecing action necessary for continuing the steady flow of fibers through the machine. When detaching is taking place, the nippers are open to permit these fibers to be pulled away and fastened to those already combed and moved out of the head. As previously mentioned, the combing needles are being cleaned at the time this action is occurring. Immediately following the detaching, the cycle starts over again with the feed rolls feeding forward another small amount of the lap, the nipper knife closing on these fibers, the half- lap with the needles removing short fibers, and then finally the detaching taking place all over again. The only action that has not been mentioned so far is one called top combing. This is accomplished by having a comb-just one row of needles that reached from one side of the combing head to the other -on an arm that moves back and forth into the combing zone. While the regular combing cycle is taking place, the top comb moves up out of the way so that the single row of needles will not come in contact with the 17 rows that are mounted on the half-lap. When the detaching is occurring and the nipper knife is opened away from the nipper plate, the top comb arm moves down into the combing zone. It serves to comb through the tail end of the fibers that are being fastened to those that have already been combed and moved out of the head. The purpose of top combing is to comb through the portion of fiber that was held by the nippers to remover any short fibers that were held there. It is possible that a very short fiber could be held exactly between the nipper knife and nipper plate and if some provision is not made to remove this, the short fiber will continue through the machine with those that have been combed. Therefore, top combing is simply a finishing action that hopefully will remove any short fibers that were held by the nippers and not removed by the normal combing cycle. Merthis complete combing process has been accomplished, the detaching rolls move the combed fiber out of the combing head where they slide down a plate and are converted back into a sliver by a trumpet and calender rolls. Each combing head produces a single sliver. As previously mentioned, these are blended together through a series of drafting rolls to form one sliver, so the reduction here is substantial. First, the lap that is made up of 48 individual slivers is reduced to a single sliver and then this sliver is blended with either three, five, or seven others, depending on the type of comber being used to form another single sliver. In as much as it is desirable and usually necessary to produce a sliver of a given size (graindyard), it is important to know the drafting arrangement of the machine. It is also important to use draft gears that will give the desired drafts through the machine, and that will give the desired sliver from the laps fed. It has already been mentioned that the short fibers removed at combing are called noils. At the same time the machine combs these out, small tangles of fibers called neps and certain foreign particles are also removed. All of this material is collected in containers and is removed from the machine on a regular schedule. The percentage of noils ranges from about eight percent up to about 16 percent in some cases. Twelve percent is average for a standard operation, and many companies are reluctant to go higher than this because of the cost of the raw material. It should be understood that the short fibers removed by this machine cost the same as the long ones, although the resale value of these short fibers is much less than the original price. In some cases where fine, high quality yarns are being spun, the percentage of noils will be fourteen to sixteen percent. Generally, however, the average of 12 percent is found throughout industry. As one might imagine, the combing operation adds cost to the remaining fibers while at the same time requiring the use of the lapper, comber, labor to operate these machines, floor space and the necessary electrical energy. The removal of a certain percentage of the raw material purchased and the cost involved in accomplishing combing results in a much more expensive yam and end product. An example of this would be a comparison of muslin and percale sheets. The muslin sheet is made &om carded yarns (yarn spun f?om cotton that was not combed) while percale sheets are always made from combed cotton. Comparing the prices of these at any department store will show that the percale sheet is a more expensive item. It is simply a matter of using a more costly raw material to start with, processing this through additional equipment with additional labor, and removing a percentage of the fiber. All this adds up to a higher priced yam and fabric. ROVING

I. Roving Process A. Drafting B. Twisting C. Laying D. Winding E. Building

11. Change Components A. Flyer grommet B. Roving condensers

111. Speed Variables A. Break draft B. Main draft C. Spindle speed D. Tension draft

W. Machine Settings A. Nipping distance 1. Break draft zone 2. Main draft zone B. Packaging 1. Laying-placement of roving 2. Winding-proper tension 3. Building-taper angles ROVING

Defmition: The roving process changes the drawing sliver into a strand called roving. Tne machine that transforms the fibrous material at this stage of fiber processing is known as a roving frame. Hank roving is the complete technical term used to identify the strand that is wound on a bobbin. Roving is a material form fed to the ring spinning hme. This form is necessary for most cotton systems and system spinning. Open-end and modified worsted spinning frames process sliver directly into yarn. Modified worsted spinning is primarily for carpet staple fiber yams. A roving frame may be thought of as a preparation machine for the ring . It resembles the spinning machine somewhat since it has the following similar operations: Drafting Twisting Laying Winding Building Delivery packages at the roving frame are only at the front of the machine. A cotton system ring spinning frame has its delivery bobbins on both sides. The modified worsted system spinning frame for carpet yarn has sliver at the back and yarn packages at the fiont. This worsted yarn is very coarse and therefore the spinning is more like the roving frame. A roving hmeis a long and narrow machine. There are about 60 to 100 spindles on the frame. The exact number depends mainly on the size of the delivery package. Machine manufacturers call the space between the spindles, as required by the size packages, the frame gauge. Frames that use smaller bobbins usually have a larger number of spindles. A very important reason for the different sizes in bobbins is due to the coarse and fine roving strand variations produced. Another and probably more important factor is when the particular roving frame was manufactured. Some conventional or older frames are still in use. The frames being made today have larger packages and are referred to in this chapter as the high-speed type. Due to the roving frame's length, several large supporting sampsons are equally spaced between the foot and head ends. A large motor is located at the head end. A number of gears are at the top of the head end for the drafting operation. Below the draft gearing and nearer the floor are considerable gearing, chains, and sprockets for the other operations. Power components are also located along the entire length of the frame. The carefully positioned roving placed on a cylindrical bobbin that is tapered at the top and bottom requires a large number of power ROVING

Definition: The roving process changes the drawing sliver into a strand called roving. The machine that transforms the fibrous material at this stage of fiber processing is known as a roving frame. Hank roving is the complete technical term used to identify the strand that is wound on a bobbin. Roving is a material form fed to the ring spinning frame. This form is necessary for most cotton systems and worsted system spinning. Open-end and modified worsted spinning frames process sliver directly into yam. Modified worsted spinning is primarily for carpet staple fiber yams. A roving frame may be thought of as a preparation machine for the ring spinning frame. It resembles the spinning machine somewhat since it has the following similar operations: Drafting Twisting Laying Winding Building Delivery packages at the roving frame are only at the front of the machine. A cotton system ring spinning frame has its delivery bobbins on both sides. The modified worsted system spinning hefor carpet yarn has sliver at the back and yarn packages at the front. This worsted yam is very coarse and therefore the spinning is more like the roving he. A roving frame is a long and narrow machine. There are about 60 to 100 spindles on the frame. The exact number depends mainly on the size of the delivery package. Machine manufacturers call the space between the spindles, as required by the size packages, the frame gauge. Frames that use smaller bobbins usually have a larger number of spindles. A very important reason for the different sizes in bobbins is due to the coarse and fine roving strand variations produced. Another and probably more important factor is when the particular roving frame was manufactured. Some conventional or older frames are still in use. The frames being made today have larger packages and are referred to in this chapter as the high-speed type. Due to the roving frame's length, several large supporting sampsons are equally spaced between the foot and head ends. A large motor is located at the head end. A number of gears are at the top of the head end for the drafting operation. Below the draft gearing and nearer the floor are considerable gearing, chains, and sprockets for the other operations. Power components are also located along the entire length of the frame. The carefully positioned roving placed on a cylindrical bobbin that is tapered at the top and bottom requires a large number of power mechanisms. These power components are needed for the twisting, laying, winding, and building operations. It is difficult to separate these operations individually because they are closely interrelated. An appreciation of this may be gained by comparing these operations with the combing cycle operations for the comber. Hank Roving: Roving is gven a size classification according to the number of hanks to the pound. The basis for all roving sizes is the standard 840 yards for one hank. Another way to word this is to say that 840 yards of one hank roving weighs exactly one pound. All other rovings are designated to have a size relative to the one hank. The hank of the roving may be defined as the number of hanks required to weigh one pound. By comparison, 1.OO hank roving is coarse, 2.00 hank is medium, and 3.00 is fine, with respect to size. There are 1680 yards to the pound for two hank and 2620 yards for three hank. If the hank roving is -50, there are 420 yards in a pound. The main concern with a range of hank rovings is that they be proportional in size with the coarse, medium, and fine yams for which they are used. It is customary to test 12 yards of roving to determine the hank number. A reel, which has a small wheel resting on a large wheel with a crank is used to unwind 12 yards of roving from the bobbin. The 12 yards are weighed on the grain scale. Its grain weight is divided into 100 to get the hank roving. The origin of the 100 is a ratio of 7,000 grains per pound and 840 yards per pound for the one hank roving:

This reduction formula is used to save time and fibrous material. The 12 yards serve the purpose for roving sizing. However, more than one test may be made as a double check or toget an average. A conversion table is usually used to get the roving size. The 12-yard grain weight is located in one column. In another column adjacent to the grain weight will appear the hank roving size. Two illusions of sizing a bobbin of roving are as follows:

1) 100 = grain weight of 12 yards -100 = 1 hank roving 100

2) 67 = grain weight of 12 yards -100 = 1.5 hank roving 67 Mathematically, only one yard of sliver is used when finding the hank roving of sliver. Hank sliver is used for determining roving fiame draft. Five yards of sliver may be weighed and an average determined. The conversion factor for sliver is 8.33. The origin of this constant is as follows: 7000 mains per pound - -8.33 840 yards per pound of 1 hank 1 An illustration for finding the hank roving size for a sliver follows:

50 = grain weight for 1 yard of sliver -8.33 = 0.1665 hank sliver 50 Hank roving is stated in either a decimal description or a fraction. High Speed Roving Frame: Roving fiame spindle rpm is the standard way of designating this machine's speed. The overall frame parts will have speeds proportional to the spindle speed. Frames now being manufactured can operate at much higher speeds than older machines because of the mechanical changes that have been made. Purpose of Roving Frame: The real purpose of the roving frame is to produce a suitable fibrous strand for the ring spinning hme. In order for this machine to transform a sliver into a roving, certain operations must be carried out. It may be considered that there are three primary operations: 1) Drafting, 2) Twisting, and 3) Packaging. Packaging involves three very closely related operations: laying, winding, and building. Drafting: Drafting is necessary to reduce the sliver to a much smaller size strand. The amount of draft will depend primarily on which of the three general types of yam are being produced. If a coarse yarn is to be spun, the roving and spinning drafts will be smaller than in the case of fine and medium count yarns. It should be understood that there would be difference in the size rovings for those wide ranges of yarns. Twisting: Twist is inserted in the drafted strand to give it strength. There is sufficient bulk in sliver for the fibrous strand to remain together without the need of twist. Twisting the roving strand arranges the fibers in a slight spiral pattern to bind them together. Twist in the roving is a requirement for the fibrous strand to withstand the pulling force on the bobbin when it is unwound at the spinning fiame. The strength that twist gives is also necessary at the roving package. Centrifugal force action would break up the strand if the fibers were not bound together by twist. Packaging: a) Laying: The first of the three packaging operations is laying. Roving must be placed or laid on the bobbin accurately and uniformly during the formation of the entire package. The machine places the circles or wraps of roving side by side vertically and horizontally. The vertical direction is a series of coils and the horizontal, a series of layers. b) Winding: Winding is the second of the three packaging operations. The roving must be wound on the bobbin at such a rate that it will not have either a tight or a slack movement. A properly wound package may be described as having the desired density as a result of a medium slachess and tightness in its movement fiom the front roll through the flyer and onto the bobbin. As a more technical explanation, the desired winding is obtained by having the machine set up to give the correct tension. c) Building: Building describes the building up of the roving package taper. The taper angle is a concern with the maximum amount that can be placed on the bobbin. A large angle is desired for this reason, but the taper becomes improper at a certain angle because the roving will slip off the ends. This is called "sloughing off." Combed cotton and man-made fibers are more slippery and may require a smaller angle. Taper angles are controlled by the size taper gear. The taper gear is meshed with the cone rack. It gets its movement from the builder. The builder assembly also takes care of the cone belt baverses in order to control the variable winding and laying speed. TYPES OF SPINNING

1. Intermittent Spinning A. Hand spinning B. Saxony Wheel-Spinning Jenny 11. Continuous Spinning A. Cap spinning B. Centrifugal spinning C. Flyer spinning D. Ring spinning 1. Definition and description of process a. Drafting of fibers b. Twisting of yam c. Packaging of yarn i. laying ii. winding iii. package building 2. Other ring-spinning factors a. Ring and traveler b. Speeds and rpms 111. Open-end Spinning A. Definition and methods 1. Pneumatic-Murata Air Jet 2. Friction-DREF I, 11, and I?J 3. Aero-mechanical-rotor B. Rotor spinning 1. Feed assembly 2. Drafting 3. Transporting 4. Condensing 5. Twisting 6. Packaging 7. Other aspects affecting rotor spinning a. Opening roller type and speed b. Rotor type and speed c. Navel surfaces d. Trash extraction e. Component wear TYPES OF SPINNING

Yarn spinning can be placed into three broad categories: intermittent spinning, continuous spinning, and open-end spinning. Intermittent spinning is a method of staple spinning in which yam production and package building proceed alternately1 (see Figure 1, below). The oldest example of this is hand spinning; next, the Saxony Wheel. Mule spinning, which was invented in 1779, lasted through the early part of this century. With the perfection of the spinning mule, yam production moved from a cottage craft to a manufacturing industry. Continuous Spinning is a system of staple spinning in which roller delivery, twisting, and winding onto a package operate simultaneously and without interruption2,examples of continuous spinning are cap, centrifugal, flyer, and ring spinning. Cap Spinning incorporates a stationary cap in which, on leaving the top of the cap, the yam passes through a guide arranged centrally above the top of the cap spindle and downward under the edge of the cap onto the driven package3 (see Figure 2). Centrifugal Spinning involves a revolving cylindrical container in which on leaving the delivery rolls, the yarn passes down a central guide tube and is then canied by centrifugal force to the inside of a rotating cylindrical container4. Flyer Spinning incorporates a stationary cap in whlch, on leaving the delivery rolls, the yarn passes through a guide arranged centrally, partially around one of its legs, through the flyer- leg guide and onto the packageS (see Figure 3). A modem example is the roving machine. Ring Spinning incorporates ring and traveler in which; on leaving the delivery rolls, the yam passes through a guide arranges centrally above the top of the ring spindle, through a traveler on the rig and onto a driven yarn package6 (see Figure 4). The Open-end Spinning process of producing yarn from staple fiber incorporates an opening device that individualizes the fibers, which are subsequently reassembled in a spinning element into yarn7 (see Figure 5). Examples of this method of spinning include pneumatic, friction, electrostatic and rotor. In these processes of yam formation, the fibers are disassociated from a coherent assembly (sliver or roving) to be collected onto the rotating tail of the newly- formed yam. Figure 1:Intermittent spinning (Source: me S~innin~Mule p. 68)

Piyre 2: Cap spinning Figure 3: Flyer spinning Source: Textile Terms and Definitions, p. 41. Thread Guide

Bobbin

Ring

Figure 4: Ring spinning (Source: Textile Terms and Definitions, p. 42)

or Transf er Tube.

spinning Element {Rotor or Turbine 1

Figure 5: Open-end spinning (Source: Textile Terms and Definitions, p. 136) References: 1. Famfield, Carolyn A. and P.J. Alvey, ed., Textile Terms and Defmitions, Seventh Edition, , Great Britain, 1975, p. 100. 2. Ibid., pp. 40-42. 3. Ibid., pp. 40-41. 4. Ibid., pp. 40-42. 5. Ibid., p. 42. 6. Ibid., p. 42. 7. Ibid., pp. 135-136. Ring Spinning

A ring spinning bmecontains the necessary mechanisms to effect drafting from one or more strands of fiber, twisting the fiber into yam and placing it upon a bobbin. Staple fiber from either roving or sliver passes through guides into the back rolls of the drafting element. The bottom rolls of the drafting element are made of steel and have helical flutes, and the top rolls have contact surfaces covered with cots of rubber or similar material. The middle rolls are equipped with aprons to better effect transport and control of the drafted stock. The bottom rolls of the drafting element are driven by change gears, which effect different counts of yarn. The top rolls are either spring-loaded or contain permanent magnets to provide constant pressure between the rolls in the drafting element. The stock enters between the back set of rolls and passes through a drafting zone where it is passed onto a second set of rolls. This set of rolls is revolving faster than the previous, effecting draft in the fiber strand. The fiber mass, while still being gripped by the back pair of rolls, is straightened and drawn out by the action of fibers being nipped by the second set of rolls. An apron passes over the middle bottom roll and a bar near the front bottom roll, and is matched by a similar apron on the top. These aprons serve to transport the fibers evenly and hold them in an orderly manner for the final drafting, which takes place between the middle and front pairs of rolls. The front pair of rolls, which revolve much faster then the preceding pair, draws out the fibers into a final form. In the drafting system, the yarn size is determined by the size of the feed stock, also the speeds of the various elements. The break draft occurs between the first two sets of rolls and ranges from 1.12 to 2.50. The final drafting zone between the middle and front rolls can have a draft ranging from about 10 to 50 or more. The drafted fiber is twisted by the revolving package. The front rolls hold one end of the strand while the other end is a part of the package being wound. Each revolution of the package inserts one turn of twist in the yam if the yarn were stationary. That is to say, if the package turned only fast enough to collect the yam there would be no twist. In order to put twist in the yam, the package must turn faster than the yam is being wound. This is where the ring and traveler come into play. The strand of ya,m pulls the traveler, which passes through it and is free to revolve around the ring. When the tension of the yam overcomes the weight of the traveler and its friction on the ring, it follows the revolution of the package. As the yam is fed from the front rolls, slack is created and the drag of the traveler exceeds the tension of the yarn, causing the traveler to lag behind the bobbin, thus winding the yam onto a package. No yarn would be wound onto the package if the traveler matched the package revolution for revolution. Twist is actually inserted ' into the yarn at the rate of one turn per revolution. There exists a slight variation in the turns of twist put into the yam by the foregoing method, due to the angle- the yam make on an empty bobbin compared to a full bobbin. The Ring Rail Thread Guide smaller angle created by a full bobbin, moves the Bobbin traveler around the rig at a slightly higher speed, inserting more twist. This increased twist is not a Ring Traveller significant amount. Packaging of the yam is correctly done by: laying, winding, and building. Laying Spindl places the yam on the bobbin in circles side by side built vertically to effect a desirable package. Winding is caused by the correct combination of ,:Ring Spinning yam size, spindle speed (rpm), twist, traveler size, and ring diameter. A correctly wound package should have a desired density, which is based on winding tension. Building causes the yarn to be wound by raising and lowering of the ring rail, filling the bobbin in a tapered build from bottom to top. Yarn packages having correct laying, winding, and building will present no problem at the winding process. At this point, other factors affecting the ring spinning process should be discussed. During the spinning process, a balloon of yam is formed between the yarn guide (centrally located above the spindle) and the traveler. Balloon separators keep the gyrating balloons of neighboring spindles from colliding and from stationary or moving machine parts that would otherwise snag the yam and interrupt spinning. Balloon size is one of the limiting factors of ring spinning. Another factor that is limiting to the ring spinning process is the ring diameter. The smaller the ring, the faster the spindle can be driven. However, this becomes self-defeating in that a smaller ring necessitates more frequent doffing of a small package of yam. A large ring will allow a larger package of yam to be spun but restricts the maximum spindle speed to less and less as the ring diameter is increased. Due to these limits imposed by ring diameter, coarse-count yams are better suited for machines having a large diameter ring whereas fine count spinning, where more twist is required, is more suited for machines with rings of small diameter. Care and maintenance of ring spinning frames must be done in good order to ensure efficient operation and a quality end product. Frame set up, for correct alignment and to ensure that spindles are plumb, must be checked on a regular basis. Proper cleaning and lubrication must be consistently done. Cots must be buffed and aprons changed before excessive wear occurs. Travelers today are extremely durable but need changing before wear starts to affect yam quality or spinning efficiency. For example, travelers on a ring frame with two-inch diameter rings and a spindle speed of 12,000 rpm would be sliding at more than 70 mph. A steel traveler of modem design with a spinning life of 300 hours would slide a total distance of 21,000 miles or almost around the earth in a gravitational field of about 4,000 g'. Rings are especially hardened but can become worn and need replacing. No technology is forever. In the United Stated, the birthplace of the ring kame, ring spinning was quick to replace its predecessor, the spinning mule. By 1939, of 27 million spindles, more than 99% were ring spindles. Today, the dominance of ring spinning is being challenged by open-end spinning. Beginning in the early 1970s, rotor spinning began to be used in the United States on a commercial basis. Today, rotor spinning accounts for more than one- half of all yam spun and is gaining. Competition was first in the coarse count range, but as open- end technology continues to improve, ring spinning dominance in the finer yam counts begin to be threatened. Automation and higher production rates continue to make open-end spinning a more desirable yarn production method. Although ring spinning is now highly automated, restrictions of production limits, with extra processing before and after spinning, favor the open-end methods.

References: 1. Catling, Harold, The Svinninn Mule, David and Charles: Newton Abbot, Great Britain, 1970, p. 187. OPEN-END SPINNING

I. Open-end Spinning Process A. Drafting B. Fiber transport C. Condensation D. Twisting E. Winding 11. Spinning Components A. Sliver condenser B. Feed roll-feed plate C. Opening roll (combing roll, beater) D. Transport tube E. Rotor F. Navel (yam trumpet) G. Exit tube (twist trap) H. Delivery roll I. Yam package III. Speed Changes A. Draft B. Twist C. Opening roll rpm D. Rotor rpm E. Delivery F. Winding tension IV. Component Design Variations A. Opening roll B. Rotorlfeed channel C. NaveVtwist trap OPEN-END (ROTOR) SPINNING: PRINCIPLES, PRACTICE, AND APPLICATION

1. DEFINmON Open-end spinning (formerly hown as "break spinning") refers to yarn formation processes in which fibers are disassociated from a coherent assembly, to be collected onto the rotating tail of a newly formed yam. 2. RING SPINNING In ring spinning, fibers are supplied from either one or two roving bobbins (see Figure 1 in Ring Spinning Section). The strand of fibers (roving) is passed through a series of pairs of weighted-rollers, each pair being driven more rapidly than the one before. In this way, the number of fibers in the cross section of the strand is reduced. When the fibers go through the front rollers of the machine, they are of sufficient numbers for the desired size of yam. As the strand of fibers is made finer, fibers are forced to slide against each other, causing them to become more parallel.

The assembly of parallel fibers must now be twisted so fibers can contribute to yarn strength. This is done by rotating the yam about itself by means of a traveler on a ring, which is pulled by the yarn as it is wound onto a rotating package. At every point in the spinning process, fibers are always in contact with each other from roving bobbin to ring tube. The winding and twisting processes are performed simultaneously, which imposes many limitations on the productivity of the process.

In ring spinning, there are two distinct phases: drafting and the combined operation of winding and twisting.

3. OPEN-END SPINNING 3.1 There are five phases in the open-end spinning process, namely: Drafting, Fiber Transport, Condensation, Twisting, and Winding. There are several methods of open-end spinning, generally classified by the method of twist insertion. This can be done pneumatically or electro-statically. However, the most successful method is aero-mechanical usually known as rotor spinning. A cross-sectional view of a typical rotor spinning unit is shown in Figure 2.

Fibers in the form of sliver are drawn into the opening box by the feed roller. The sliver is pressed against the feed roller by a spring- loaded feed plate. The condenser, located prior to the feed roller, controls the position and dimensions of the sliver.

3.2 Drafting The fibers are issued from the feed assembly in the form of a beard, which is brushed by the clothing of the revolving opening roller (also termed beater or combing roller). The clothing of the opening roller may be helical wound saw-toothed wire or pins, which tease fiom the beard those fibers which are released from the nip point between feed roller and Figure 2: Spinning Element (Rotor or Turbine) plate. This is the major drafting point in the process, and fibers are now in a very free, potentially uncontrollable state.

3.3 Transport The fibers are either swept around with the air currents of the opening roller, or are engaged with the projections of the opening roller by friction. After the opening roller has turned about one-half of a revolution, the airflow from the fiber transport duct strips the fibers from the opening roller. The fibers are accelerated by the airflow along the tapered duct when some fiber straightening occurs. This is the transport phase of the process whch involves some drafting. 3.4 Condensation On leaving the transport duct, the fibers are laid onto the inner surface of the spinning rotor, which is intended to be rotating at a higher speed than the fibers when contact is made, to ensure that fibers do not fold or crumple. The fibers then slide into the vee of the collecting surface of the rotor. More fibers are laid down sequentially with successive revolutions of the rotor until the number of fibers in the cross section of the layer is the same as that required for the yam.

3.5 Twisting At some point on the rotor surface, fibers are twisted and peeled from the groove into the yarn. For yarn to be formed, the peeling point has to move around the rotor. The most stable condition arises when the peeling point moves faster than the rotor.

Under normal conditions, fibers are continuously supplied and laid into the rotor groove, one after another, while the tail of the forming yam moves around the rotor at speed of about 1% of the rate at which the fibers are deposited. The mechanism of fiber deposition/yam removal has been aptly compared with the action of a snowplow moving in a circle during a snowstorm.

For every revolution of the rotor, the yam is twisted about itself, once. In addition, the yam is also withdrawn over a trurnpet-like component known as the navel, sometimes referred to as the doffing tube (see Figure 2). Under normal spinning conditions, the yarn slides radially over the navel but rolls over it in a tangential direction. This gives an additional twisting action (false twist) in the length of the yam within the rotor.

3.6 Winding The yam is withdrawn from the rotor by the nip formed between the withdrawal shaft and a pressure roll, to be wound up on a surface-driven cone using a traverse motion. The winding phase does not involve twisting of the yam, allowing larger packag;es of yam to be produced without the power and dimensional restrictions of the ring frame. The mass of the twisting mechanism (rotor) is considerably reduced, and higher rotational speeds can be achieved.

ADDITIONAL FEATURES OF THE ROTOR SPINNING PROCESS 4.1 Production of Airflow Air is necessary to strip fibers from the opening roller and to transport them into the rotor. Most machines use a fan at one end of the machine to pull air through the spin- boxes, over the rim of the rotor and into a central, common duct running the length of the machine.

At least two machinery makers make use of the spinning rotor to generate airflow through the spin-box, by using holes in its back wall. In this case, the rotor is referred to as a turbine. Air movement is conducted by an externally located fan, which usually serves a number of machines. 4.2 Trash Extraction Because the fibers are intensively opened when the fiber beard is struck repeatedly by the projections of the opening roller, much dust and trash is released. By introducing a port in the wall of the opening roller housing, a considerable amount of dust and trash can be removed from the system (see Figure 3). Generally, the particles are allowed to fall under their own momentum out of the opening roller housing, to be transported either mechanically or pneumatically to a collection box.

Trash extraction devices in the spinning unit are only a safeguard. Dust, in particular, will follow the airflow around the opening roller. Some of the dust collects in the rotor groove, some will be removed by the sweeping action of the tail of the newly formed yarn, and the remainder will be entrained in the exhaust air.

By allowing residue to accumulate in the rotor, the shape of the groove is altered, which vanes the character of the yam, generally in a detrimental manner. It is, therefore, better to ensure that the cotton is thoroughly cleaned before the spinning process rather than to rely totally on the trash extraction system.

VARIABLES ON TKE ROTOR SPINNING MACHTNE AND THEIR EFFECT ON YARN PROPERTIES 5.1 Speed Variation All machinery manufacturers provide means of varying the speeds of components to maximize spinning performance. The settings which are commonly varied are as follows: Draft, Twist, Opening Roller Speed, Rotor Speed, and Winding Tension.

5.2 Design Variation In addition, the performance and character of the yarn may be varied by the use of different components. Typically these are: Navel, Opening Roller Type, Rotor Type.

The effects of each of these variables on yam properties and performance will be discussed in turn, with reference to trend curves.

5.3 Machine Draft The machine draft is the ratio of the yam withdrawal speed to the sliver input speed, and governs the size of the yam produced. The weight of the sliver supplied is chosen to give the desired yam count within the range of adjustment on the machine. As a general rule, rotor-spun yams require a minimum of 100 fibers in the cross section for successful spinning. Ring-spun yams can be spun with as few as 60 fibers in the cross section.

Fiber yarns require higher twist levels for stable spinning because of the reduction in the number of fibers in the cross section. Finer yams are also weaker even when strength is related to size, more irregular and more difficult to spin.

5.4 Twist The mechanism of yam formation is different in rotor spinning than in ring spinning. The forces on the fibers are lower at the point of formation in rotor spinning, resulting in structural difference between rotor-spun and ring-spun yams. The surface fibers have lower twist than the fibers at the yam core and measurement of the twist in the yam always produces a lower value than the nominal or machine twist for this reason.

The mechanical twist is the ratio between rotor speed and yarn withdrawal speed. Generally, the twist levels are greater than TRASH EXTRACTION those used in ring spinning, particularly when strong cotton yarns are required. Coarse fibers and fine -. yams both require higher twist levels for stable spinning.

The effect of twist on

Extraction yam strength varies with material. Of the fibers, which are usually rotor spun, cotton is unique in that higher twists are required for maximum strength, probably the result of the fiber length being less regular than for synthetics. 5.5 Opening Roller Both the speed and design affect spinning performance and yam properties. 5.5.1 Effect of Speed Low speeds do not tease fibers from the beard in an effective manner, and there is an increased likelihood that fibers will be released in aggregates or clumps. Because of the lower centrifugal force, there is a danger that the fibers will adhere to the clothing rather than be released into the air stream. The fibers clinging to the clothing attract more fibers until the mass of the aggregatk is so large that they are released into the rotor en masse.

High speeds, however, gve good combing action at the fiber beard, but there is a danger of fiber damage. At excessive speeds, fibers are chopped to give short fibers and the dust so generated collects in the groove of the rotor. Both dust and short fibers result in weaker yam. 5.5.2. Effect of Angle of Clothing The clothing of the opening roller may be pins (needles) or saw-tooth wire. The most important design parameter is the leading (or forward) angle of the pin or wire,' which is termed either "positive" or "negative," relative to the radius of the opening roller and its direction of rotation.

Clothing having a positive leading angle penetrate more effectively into the fiber beard, tending to ensure the individual release of fibers. However, the release of the fibers into the air stream is difficult. Negative leading angles give an inferior combing action at the beard, but release the fibers more effectively into the fiber-transporting air stream to the rotor, and may be used at lower speeds.

The selection of the design of the clothing depends upon the fiber being processed. Cotton is best processed with positive leading angles, whereas easily damaged fibers or those with high fiber-to-metal friction e.g. polyesters and nylon, are most successfully processed on more negative designs, sometimes at the expense of yam properties. Acrylics and rayon require a design between these two extremes. 5.5.3. Choice of Clothing Opening rollers are clothed with either pins or wire. Pinned opening rollers have a very intensive opening action and require lower speeds to avoid fiber damage. Superior yams can result. Compared to wire, pins have superior wear resistance for metallurgical reasons and have become increasingly more popular. However, wire- wound opening rollers still have their use, particularly with sensitive fibers.

5.6 Rotors The speed, diameters, and profile of the rotor can generally be varied according to requirements.

5.6.1 Rotor Speed Increasing the rotor speed produces a decline in yam quality, largely as a result of the increased spinning tension in the rotor arising from centrifugal forces. The choice of rotor speed is primarily dependent on rotor diameter, but the required twist levels and size of the yarn also have influence. Typical rotor speeds are \ Groove given in Table I. Figure 4: YARN WITHDRAWAL FROM ROTOR 5.6.2 Rotor Diameter As a general rule, the diameter of the rotor should be greater than the longest fiber to be processed.

An increase in rotor diameter gives an increase in spinning tension (holding speed constant) which adversely affects yam properties.

Larger rotors, although requiring a lower speed for successful spinning, permit the use of longer fibers. Also there is an increased action which produces more regular yams. Both of these factors enable spinning to be sustained at lower twist levels. The fiequency of "wrapper" fibers is also reduced (see Section 7). 5.6.3. Rotor Profile Some machinery manufacturers produce rotors with different groove shapes. Stronger yams generally result from rotors with narrow grooves, but these are more difficult to keep clean. Wider grooves are more suitable for coarse yams, are easier to clean, but produce weaker yet more even yams.

5.7 Navel The action of the navel is to supplement the twist inserted directly into the yam by the rotation of the rotor, by generating "false twist." The amount of false twisting depends on the surface characteristics of the navel. The rougher or the higher the frictional resistance of the navel, the more twist that is inserted, allowing lower twist levels to be used. This feature is obtained at the expense of the tensile properties and regularity. However, with certain fibers, it is possible to achieve stronger yarns with grooved navels than with smooth navels. Rougher navels produce hairier yarns, but tend to improve the stitch clarity in knitted fabrics.

TKE EFFECTS OF TIME Spinning for sustained periods can lead to a deterioration in yarn quality. In the short term (hours or days), dust or fiber debris accumulating in the rotor groove is a major concern, and is largely dependent on the fibers in use. In the long term (weeks or - months), the effects of component wear are apparent. The life of components again depends on the fibers being spun. As mentioned previously in Section 4.2, dust in cotton collects in the rotor, effectively changing the shape of the groove fiom a narrow vee to a wider vee. Dust generation can also occur with synthetic fibers, particularly fiom fiber damage by the opening roller. The alteration in the effective rotor groove produces weaker yet bulkier and more even yam. However, there is a danger that the deposit in the rotor will not be evenly distributed in the groove, but will exist in lumps. The presence of such a lump prevents fibers from being evenly distributed over the inner surface of the rotor. This produces a thin place followed immediately by a thick place in the yam, occurring at intervals equal to the circumference of the rotor. This produces the well-known moire effect illustrated in Figure 5. 6.2 Long-term Effect Wear can occur at any fiber-to-metal contact surface. Machinery makers have increased the component life by the selection of more resistant metals or by the application of wear- resisting coatings. However, wear still occurs, particularly on the opening roller, navel and rotor, and accidents may cause damage to the opening roller housing and fiber transport duct. All cause a deterioration in yam quality, spinning performance or both.

6.3 Opening roller Wear on the opening roller teeth arises in the softer, lower portion of the tooth in the form of a nick. The nicks are formed by abrasion of the fiber and prevent fibers from being released to the transporting airstream. Eventually they are released in an aggregate, resulting in uneven yarn or in a break.

6.2.2. Navel With use, navels show "chatter marks" or "scalloping." In other words, smooth navels become rougher, with consequent reduction in yarn properties.

6.2.3. Rotors Most rotors were aluminum, and anodized for improved resistance to wear. Steel rotors have been introduced, and have much extended rotor life. Wear in a rotor normally occurs at some point near to the bottom of the groove, caused by constant abrasion of the yarn, resulting in the formation of a secondary groove. Particles of trash are easily lodged, and the resultant yam becomes very uneven. Spinning performance deteriorates. The impact of dust and fibers on the inner rim of the rotor also erodes the surface which presumably affects the ability of the rotor to keep the fibers straight, an important hctor in realizing yarn strength. Figure 5: MoirP eflect in the yarn caused by a deposit in the rotor groove.

6.2.4 Damage to surfaces Metallic fragments from other machines are occasionally transported by the sliver into the spinning unit. When struck by the opening roller, the fragrnent(s) achieve high velocity and can produce burrs in the housing of the opening roller and in the fiber transport duct. Similar damage can be caused by operative Figure 5: Moire Effect in the Yarn Caused By a Deposit in the Rotor Groove negligence, particularly when servicing a spinning unit. Fibers in free flight will collect on nicks and burrs to build up into a clump. When this clump is of sufficient size it is released into the rotor where it is either spun into the yam as a slub, or causes the yam to break. Spinning units which repeatedly give faults are often difficult to find, particularly when the damage is not severe enough to produce a high spinning break rate. The unfortunate consequence is that one such unit can cause the down-grading or rejection of many yards of fabric.

7. WRAPPER FIBERS Reference was made in Section 5.6.2 to the existence of "wrapper" fibers. These are fibers which wrap around the body of the yam over a short distance, and contribute little or nothing to yam strength. They are formed by a fiber prematurely attaching itself to the tail of yarn in the rotor as the yam passes the exit of the transport tube. Although the incidence of these fibers can be minimized by suitable choice of rotor diameter and relationship between rotor and fiber entry point, their presence restricts the use of open-end yams in applications where bulk is required, e.g. carpet yarns, high-bulk acrylic lcnitting yarns.

8. ADVANTAGES AND DISADVANTAGES OF ROTOR SPINNING COMPARED TO RING SPINNING Table I1 shows a range of attributes both for and against the use of rotor-spun yams. From a purely economic aspect, the advantages of large supply and resultant packages, lower power cost, reduced labor cost and high production rate are very favorable for the use of the rotor-spinning process. Rotor-spinning machinery is much more ~o~histicat'edthan the ring heand consequently is expensive. In combination with the higher twist requirement, the high machine cost offsets the other advantages when fine counts are being spun. The economic break-even count for new machinery was generally found to be about Ne24, but the introduction of automation and very high rotor speeds has increased the break-even count to about Ne35. The tabulation of the yarn characteristics show that rotor-spun yams have only one

major disadvantage - strength. This is particularly apparent when fine yams are spun. Although machinery makers have worked to improve yarn strength, particularly by alterations of the design in the region of the rotor, it seems unlikely that ring-spun strength will ever be matched my rotor-spun yarn strength from the same material at the best twist level. Consequently, the trend is currently toward the use of higher strength fibers to achieve the fabric strength specifications for ring yam. In spite of the lower tensile strength of the rotor-spun yams, weaving efficiencies are reputedly better as a result of reduced end-breakage rates, both in warp and filling. In terms of strength, fabrics reflect the differences shown between yarns. The abrasion resistance of fabric from rotor-spun yams is reputedly better than that from ring-spun yams, although there are instances where the reverse has been reported. Rotor-spun yams and their fabrics have always shown superior wiclang properties, resulting in more rapid water absorption rates and quicker dyebath exhaustion. The tendency for fabrics from rotor-spun yam to retain soil more than comparable ring yam fabric is probably due to the structural difference of the yams, in common with all other properties.

9. REFERENCES P.R. Lord, Spinning in the 70's, Merrow, Watford, England. 1970.

, P.R. Lord, Collection of Pavers on Oven-End Svinning, N.C. State University, 1974.

10. SUGGESTIONS FOR FURTHER READING H. Deussen, Rotor Svinning Technolonv, Schlafhorst, Inc. 1993. R. Nield, O~en-EndSvinninq, Textile Institute, Manchester, England, 1975. V. Rohlena, @en-End Spinning, Elsevier, New York, 1975. G. Trommer, Rotor Svinning, Deutshcher Fachverlag, 1995.

TABLE I: TYPICAL ROTOR SPEED RANGES Diameter Speed Ranges (rpm) 66 25,000 - 40,000 56 30,000 - 45,000 46 45,000 - 65,000 40 55,000 - 80,000 36 70,000 - 90,000 33 85,000 - 100,000 30 110,000 - 130,000 28 120,000 - 150,000

TABLE 11: ROTOR SPINNING VS. mGSPINNING Parameter Relationship to Ring Spinning 1. Process supply From drawframe sliver, eliminating roving frame Power Consumption Lower, per pound of yam Labor Cost Lover per pound of yarn Machine Cost Considerably higher Production Rate Three to eight times greater Package Sixteen times greater Twist Level 5% to 25% greater Minimum Fibers in Yam 100 for rotor-spun yarns, 85 for ring spun 2. Yam Characteristics Count Variation Improved Strength 5% to 20% weaker Strength Variation Less Extensibility 5% to 15% greater Non-uniformity (CV%) 10% to 30% less Fault Rate Fewer imperfections (I.P.I. and Classimat) Appearance Generally less hairy, more even and cleaner Bulk About 15% greater \ 3. Fabric Characteristics Size Add-on 10% to 20% less Break Rate in Weaving Reduced 25% to 70% Tensile Strength About 15% lower Tear Strength Up to 30% lower Abrasion or Pill Resistance Similar Handle Harsher Cover Improved Thermal Insulation Better Water Absorption More rapid Dye Uptake Quicker dyebath exhaustion Soil Release Inferior to ring spun

Typical Rotor-Spinning Specifications

1. For Strength Smooth navel Cotton: 5.0 TM Synthetic fibers (1 -5 in.): 4.0 TM Opening roller speed Cotton: 7,000 - 8,000 rprn Synthetic fibers: 7,000 - 8,000 rprn Rotor speed * 5,000 rprn 28 mm diameter 120,000 - 150,000 rprn 30 rnrn diameter 100,000 - 120,000 rprn 33 mm diameter 90,000 - 100,000 rprn 36 mm diameter 80,000 - 90,000 rprn 40 mm diameter 60,000 - 70,000 rprn

45 mrn diameter 45,000 - 60,000 rprn 56 rnm diameter 40,000 - 45,000 rpm

2. Low Twist Grooved navel and twist trap Cotton: 3.5 - 4.0 TM Synthetic fiber: 3.0 - 3.5 TM

For high bulk yam - hand Use grooved navel plus ridges spiral navel plus ridges For appearance Use shallow groove navel, higher TM

Spinning Interruption Fault Analysis 1. Entanglement related Slub: length greater than thickness Nep: length z thickness Seed coat

2. Trash related Leaf Bract Bark Grass Weeds - vegetative matter

3. Foreign matter Polypropylene Plastics Hemp, jute, sisal Metal Hair, feathers, etc.

4. Machine related High or low winding tension breaks High or low spinning tension breaks Faulty machine parts

5. Miscellaneous Thick or thin sliver Sliver jam is continued sliver unlcnown

Effects of Component Wear Comvonent Effect of Wear 1. Rotor Groove deepens losing its intended geometry 2. Opening roll Wears down on teeth and creates nicks in surface of teeth 3. Navel Smoothes grooves and creates J-shaped chatter marks 4. Edges Rough fiber flow surfaces and nicks and edges 5. Yam guides Opening enlargement and deepened grooves

- Trouble-shooting Rotor Spinning Fault Cause Remedy 1. Position will not spin. No a) Sliver not creeled in - Creel in sliver fiber entering rotor. b) Opening roll stopped - Check opening roll drive - Check that opening roll brake releases when unit closed c) Detector - Check for proper operation d) Sliver jammed in - Remove sliver by twisting condenser hard and pulling e) Clogged transport tube - Remove fiber and check opening roll for fiber wrap 2. Position will not spin but a) Rotor stationary when unit - Check that rotor brake is not fiber entering rotor closed engaged when unit is closed (rotor should be free) b) Wrong draft - Check draft set-up c) Wrong twist - Check twist set-up d) Excessive rotor speed - Match rotor rpm with rotor

I 3. Slub in yarn tail 1 a) Fiber accumulating in opening roll box surface in opening roll box b) Opening roll speed too Check fiber transport tube slow 4. Trashy slub in yam tail a) Trashy sliver - Remove portion of sliver that is trashy I b) Trash re-entering combing - Clean trash channel and trash roll housing brushes 5. Uneven yarn and frequent a) Opening roll loading - Check for damaged opening endsdown roll - Check opening roll speed - Check for yam on opening roll - Check for oil in opening roll area b) Irregular sliver - Check sliver for variability 6. Fiber ball in rotor deposit a) Insufficient air flow in - Check for blockage in air flow I spinning unit I tubes I - Check fan speed 7. No apparent cause a) Opening roller speed too - Check for fiber wrap on slow opening roll - Check for correct opening roll rPm b) Sliver feed stopped - Sliver condenser should match sliver size c) Thick or thin sliver - Replace with regular or even sliver 1) Insufficient twist - Check twist gearing - Check for proper navel and twist trap 8. Excessive lint accumulation i) Rough surfaces - Check guides for roughness and cracks - Check navel and yam tube 5) Excessive opening roller - Reduce opening roll rpm *s~eed - Use correct opening roll type 1 9. Excessive debris in rotor a) Excessive opening roll - Reduce opening roll rpm speed - Use correct opening roll type b) Opening roll-to-feed plate - Set proper gap between setting too close opening roll and feed plate / 10. Winding break a) Excessive winding tension - Set proper winding tension for correct package build b) Clogged yam guide - Remove debris and check for roughness c) Weak place in yam - Check for thin place in sliver - Check for a clean rotor d) Weak yam - Check for sufficient twist - Check for matched rotor rpm and rotor diameter e) Excessive delivery speed - Slow down rotor rprn 11. Sliver continues to feed a) Faulty feed roll clutch - Check power supply to clutch Lwith spinning stopped - Effect proper clutch operation b) Yam detector defective - Check power supply to detector. ~e~a;&replace 12. Noisy spinning unit a) Whining rotor - Check rotor for imbalance due to deposits I- Check for damaged rotor; Redace and discard anv damaged rotor b) Bad opening roll or rotor - Reolace and discard damaged bearing Em c) Metal-to-metal noise - Check for proper feed plate- to-combing roll setting - Check for opening roll hitting housing - Check for rotor hitting face plate; set proper clearance