Yarn Formation CHAPTER 7

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OBJECTIVES

´ What is a yarn? ´ What are the different types of yarns available? ´ How are yarns made? ´ How Yarn Formation CHAPTER 7

YARN BASED ON FIBER LENGTH ´ A continuous strand of textile fibers, filaments, or material in a form suitable for knitting, weaving, or ´ Spun yarns: Made from otherwise intertwining to form a textile material. short-staple fibers. ´ Regular or smooth filament yarns: Made from long, smooth filament fibers. ´ Textured-bulk-filament yarns: Made from crimped filament fibers.

FILAMENT YARNS FILAMENT YARNS ´ Smooth-filament yarns: Regular or ´ Monofilament yarns – single filament by itself conventional filament yarns. used as the yarn ´ Production: Used as produced or further ´ Multifilament yarns – several filaments that treatments added (dye, finishes, texture, etc.) make up the yarn – extruded at once (30 to ´ Uses: In smooth, lltrustrous ffbriabrics or whhrere high several thousand) and twisted together strength, compact yarns are needed.

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CHARACTERISTICS CHARACTERISTICS (CONT’D)

´ More expensive than staple to produce; low Strength related to fiber strength and multi-filaments production rate, number of holes in spinneret equal to Fiber strength fully used number of fibers in yarn. Size based on denier system; related to number & size ´ Smooth with low or no twist, except crepe twist yarns. of filaments ´ No pgprotruding ends Characteristics related to number and size of ´ Sheds soil filaments ´ Compact with little bulk, cover, or loft Fine fibers—soft & supple yarn Coarse fibers—stiff & abrasion resistant yarn Fibers as long as the yarn and the fabric from which they are removed

TYPES YARNS ´ Smooth-filament (mono or multi filament) ´ Tape yarns (fibrillated fibers/split films or slit films) Monofilament Multifilament ´ Network yarns—similar to tape yarns, but with gg(py)reater bulk and comfort (foamed polymer)

TEXTURING TYPES

´ Bulky – sweaters, carpets ´ Crimped - thermoplastic ´ False twist: Continuous process where yarns are fibers – may be used for twisted, heat set, uncoiled; widely used method. some stretch ´ Knife Edge: Heated filaments drawn over an edge. ´ Textured – mechanical, ´ Stuffer box: Filaments stuffed into heated box; chemical and/or heat increases volume 200-300%; widely used method. treatments used; spun or ´ Air jet: Air tangles fiber; increases volume 50-150%; little or no increase in stretch. filament yarns ´ Knit-deknit: Knit, heat set, unknit.

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TEXTURED TYPES BULK YARNS ´ Greater covering power or ´ Bulky: From inherently bulky fibers; less stretch apparent volume compared to than stretch or textured yarns. smooth filament yarn; also called bulk continuous filament ´ Stretch: High degree of potential stretch & (BCF) yarns. rapid recovery; moderate bulk. ´ Characteristics « Less smooth ´ Loopy/Textured: Bulky yarns with comfort « More permeable to air & liquids stretch. « Less slippery « More comfortable (may be more absorbent) « Less static prone « More bulk, cover, and elasticity

HIGH BULK YARNS SPUN YARNS ´ Part of tow is heat stretched. ´ Continuous strand of fibers held together by some binding mechanism, made from short ´ Two parts combined, cut, and spun by fibers. conventional methods. ´ Immersed in hot water; heat stretched fibers shrink; non-heat set fibers create bulk in yarn.

CHARACTERISTICS SPINNING PROCESS – COTTON SYSTEM ´ Opening: Loosens, cleans, ´ Fuzzy: Fiber ends protrude along length of yarn. blends fibers; removes dirt; helps determine yarn quality. ´ Yarn strength related to cohesiveness of fibers and number of ´ Carding: Partially straightens contact points along fiber. fibers & forms into thin web; ´ Low twist yarns separate easily with force; yarn strength not produces carded sliver. related to fiber strength. ´ Drawing: Increases ´ Likely to pill as fiber ends break off. parallelism of fibers; ´ More comfortable when in contact with skin (less area of yarn combines carded slivers into a drawn sliver; continues in contact with skin, the more comfortable and less clammy & blending for self-blended confining it is). yarn, decreases sliver size ´ More likely to create problems with soiling. (to a roving.) ´ Combing: Select yarns of high quality fibers; removes short fibers & increases parallelism of fibers.

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COMPARE CARDED AND COMBED YARNS

WOOLEN (TOP) AND OTHER SYSTEMS WORSTED (BOTTOM) YARNS ´ Woolen system: Wool fibers; soft, bulky, fuzzy yarns. ´ Worsted system: Wool fibers; more even fiber distribution & more parallel; compact, smooth, strong yarns. ´ Flax system: Tow yarns—shorter & less parallel fibers; line yarns: longer and more parallel fiber.

SPINNING PROCESS (CONT’D) INSERTING YARN TWIST

´ Roving: Reduces size of drawn sliver, increases fiber parallelism; adds small amount of twist. ´ Ring or conventional: Series Repeated several times (blending often occurs of operations. here). ´ Open end rotor: Eliminates ´ Insertingyg yarn twist: Several options to reduce size roving & ring twisting (faster & add full amount of twist; winds finished yarn on process, but weaker yarn). bobbins. ´ Friction spinning: Combines rotor & air techniques; more even yarns; freer of lint, & loftier, but weaker.

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ALTERNATE SPUN YARN PROCESSES ALTERNATE SPUN YARN PROCESSES

´ Air jet: Similar to rotor, but twist formed by ´ Vortex: Twist develops as fibers swirl around moving air; rougher & less elastic yarns than spindle; eliminates shorter fibers. rotor spun yarns. ´ Twistless: Eliminates twist; holds fibers ´ Direct: Similar to conventional; roving eliminated. togggether with starch or sizing; soft, lustrous, opaque fabric with good dyeability & durability. ´ Compact: Variation of ring spinning that condenses the roving before final twist ´ Self-twist: Inexpensive way to ply 2 yarns of insertion; smoother & stronger yarn. different twist (1S & 1Z) direction.

ENVIRONMENTAL IMPACT SPINNING FILAMENT TOW INTO SPUN YARNS ´ Tow-to-top (sliver system): Tow converted into ´ Hearing protection required. staple by diagonal cutting (cut to desired length) or ´ Opening steps create air-borne dust break stretch (stretched until fiber breaks at (controlled by vacuum heads or humidity weakest point, uneven length) and formed into sliver; spun by conventional system. levels). ´ ´ Tow-to-yarn: Direct spinning system where fibers Waste recycled whenever possible. are broken at weakest point and spun into yarns in ´ Ring spinning often in low cost labor countries continuous process. with related issues of social responsibility.

TWIST TYPES OF YARN TWIST

´ Spiral arrangement of fibers within a yarn. ´ Direction: S or Z (Z is most common) ´ Amount of twist: Varies with length of fiber, yarn size, & end use; low, nappi igng, reglgular, high/voile, or crepe twist.

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LOW TWIST YARNS SPUN YARNS

´ Smooth and textured bulk filament yarns: very ´ Napping Twist: Low twist, usually filling low twist. direction to facilitate brushing fibers to surface (napping); for flannelette, flannel, blankets, etc.

SPUN YARNS SPUN YARNS

´ Average Twist: Most common type of twist, neither low nor high, used for most end uses. ´ Voile Twist: high twist, used for voile

SPUN YARNS YARN SIZE

´ Crepe Twist: very high twist, produces lively, ´ Yarn number: Cotton, woolen, worsted systems are yarn indirect systems; length per unit weight (finer yarns, higher numbers). ´ Denier: Direct system; weight per unit length (g/9,000 m)—finer yarns, lower numbers; denier used for yarns and fibers. ´ Tex system: Weight per unit length (g/1,000 m); finer yarns, lower numbers (decitex or dtex).

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YARN TYPES SINGLE, PLY, AND CORD YARNS

´ Simple: All parts are alike. ´ Single: Spun or filament. ´ Ply: Two or more singles; increases diameter, strengthtr gth, andd performancerf r (usuall lly spun yarns)r ). ´ Cord: Ply yarns are twisted together. ´ Uses: Industrial products.

CORD (RIGHT), SINGLE (LEFT), AND PLY SEWING THREAD (BOTTOM) YARNS ´ Yarn intended for stitching materials together by machine or hand process. ´ Available in several sizes and structures: ply, corded, cable, braided, textured filament, smooth filament, monofilament, and core spun. ´ LbiLubricant or wax fiihfinish to filifacilitate sew ing. ´ Many fibers used. ´ Sized as denier, tex, count, yarn number, or ticket number.

FANCY, NOVELTY, OR SPECIALTY YARNS PARTS OF A NOVELTY YARN

´ Single: 1 part ´ Complex: 2 or more parts « Ground or foundation or core component « Fancy or effect component « Binder ´ Uses: Usually in filling only; adds interest; may add crease resistance to fabric; decreases durability; increases cost; fashion component.

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EXAMPLES OF NOVELTY YARNS TYPES

´ Slub or flake: Single, spun fancy thick-thin yarn. « The twist can be varied at regular intervals. « The thicker part can be twisted less than the thinner part. ´ Spiral or corkscrew: Two parts twisted together; differ in color, size, or texture. ´ Ratiné: Spiral effect with loops at intervals. ´ Knot, spot, nub, or knop: Effect twisted many times in one spot.

TYPES FABRICS WITH NOVELTY YARNS

´ Spike or snarl: Open loops at intervals. ´ Loop, curl, or bouclé: Closed loops at intervals. ´ Metallic: Metal incorporated with yarn. ´ Chenille: Short pil e fibers held in pl ace by two bind er yarns twisted together.

EFFECT PLY FOR SEVERAL KINDS OF FANCY YARNS FIBER BLENDS ´ Blend: Intimate mixture of different fibers (varied by type, length, size, color, etc.) in one yarn. ´ Mixture: One type of yarn used in one fabric place (i.e., warp) & another type used in another fabric place (i.e., filling). ´ Combination: Two unlike yarns twisted together to form a ply (simple or novelty yarn).

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REASONS FOR BLENDS BLENDS

´ Combine different fibers to get better ´ Blend levels: Related to end use and performance combination of characteristics in product; specifications. achieve characteristics that are combinations ´ Stage of blending: Earlier in processing, blend is of the fibers in the blend more uniform. Light density fiber works to outer edge ´ Improve processing and uniformity of yarn. ´ Obtain better hand, texture, and appearance ´ Other possibilities ´ Economize « Blended filament yarn: two unlike filaments blended ´ Obtain cross-dyeable effects together « Fasciated yarns: filament & broken filament

FIBER DISTRIBUTION IN YARNS COMPOSITE YARNS

´ Regular in appearance with unlike components. ´ Types: « Covered: Yarn wraps around spandex/rubber. « Core-spun: Fiber completely covers core of another fiber. « Wrap spun: Staple fiber core wrapped with filament. « Fasciated: Filament wrapped with staple fibers or filament yarn wrapped with filament fibers. « Polymer with staple fibers; inexpensive.

YARN PERFORMANCE YARN QUALITY ´ Thin spots assessed to minimize problems with ´ Characteristics & performance measured to processing, fabrication, and finishing. ´ Neps: Small knot of entangled fibers; assessed to ensure consistent fabric and product quality minimize problems with dyeing and finishing. and performance. ´ Hairiness: Excessive fiber ends on yarn surface make the yarn more sensitive to abrasion and « Size, twist, bulk, evenness, & appearance pilling; assessed to minimize problems with « Strength, resistance to abrasion, & other fabrication and performance. performance aspects

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SUMMARY

´ A yarn is a continuous strand of staple fibers, filament(s), or some other ´ Yarns can twist in a clockwise or counter-clockwise direction: z-twist or s- material that can be used to make a textile. twist. The z-twist is the most common. ´ The categories that yarns can fall into are: spun yarns, smooth filament ´ Yarns can have a low amount of twist or a high amount. This will affect what yarns, or textured filament yarns. type of fabric and ultimately, what type of end-use the yarn is for. « Filament yarns can be either monofilament or multifilament. They can also be made as ´ Yarns can be twisted into a certain type of grouping: single spun, ply yarn, tape or network yarns. cord or fancy yarn. « Textured filament yarns can be created in a variety of ways and utilized for texture, bulk, stretch or comfort. ´ Yarns can be blended in a variety of ways and for different reasons. ´ Filament yarns are created through the extrusion process previously covered ´ Quality must be monitored at every level. ´ Spun yarns refer to staple length fibers. They go through a general process of cleaning, combing in various ways and stages, and twisting to form the yarn. « Spun yarns can go through more or less combing, which affects how strong and smooth the yarn is. If it goes through less combing it is called either combed (cotton process) or woolen (wool process); if it goes through more combing it is called carded (cotton process) or worsted (wool process).