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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
´
A continuous strand of textile fibers, filaments, or
material in a form suitable for knitting, weaving, or
otherwise intertwining to form a textile material.
FILAMENT YARNS
Monofilament yarns – single filament by itself
used as the yarn
´ Multifilament yarns – several filaments that
make up the yarn – extruded at once (30 to
several thousand) and twisted together
BASED ON FIBER LENGTH
Spun yarns: Made from
short-staple fibers.
´ Regular or smooth
Made
filament yarns:
y
from long, smooth
filament fibers.
´ Textured-bulk-filament
yarns: Made from
crimped filament fibers.
´
FILAMENT YARNS
´
Smooth-filament yarns: Regular or
´
Production: Used as produced or further
´
Uses: In
I smooth,
th lustrous
l tr
fabrics
f bri orr where
h r high
conventional filament yarns.
´
treatments added (dye, finishes, texture, etc.)
strength, compact yarns are needed.
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CHARACTERISTICS
´
´
´
´
´
More expensive than staple to produce; low
production rate, number of holes in spinneret equal to
number of fibers in yarn.
Smooth with low or no twist, except crepe twist yarns.
No p
protrudingg ends
Sheds soil
Compact with little bulk, cover, or loft
CHARACTERISTICS (CONT’D)




Strength related to fiber strength and multi-filaments
Fiber strength fully used
Size based on denier system; related to number & size
of filaments
Characteristics related to number and size of
filaments



TYPES
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
YARNS
Smooth-filament (mono or multi filament)
´ Tape yarns (fibrillated fibers/split films or slit
films)
´ Network yarns—similar to tape yarns, but with
ggreater bulk and comfort ((foamed p
polymer)
y
)
Monofilament
TEXTURING
TYPES
´
Multifilament
Bulky – sweaters, carpets
Crimped - thermoplastic
fibers – may be used for
some stretch
´ Textured – mechanical,
chemical and/or heat
treatments used; spun or
filament yarns
´
´
False twist: Continuous process where yarns are
twisted, heat set, uncoiled; widelyy used method.
Knife Edge: Heated filaments drawn over an edge.
´ Stuffer box: Filaments stuffed into heated box;
´
increases volume 200-300%; widely used method.
Air jet: Air tangles fiber; increases volume 50-150%;
little or no increase in stretch.
´ Knit-deknit: Knit, heat set, unknit.
´
´
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TEXTURED TYPES
BULK YARNS
Bulky: From inherently bulky fibers; less stretch
than stretch or textured yarns.
´ Stretch: High degree of potential stretch &
rapid recovery; moderate bulk.
´ Loopy/Textured: Bulky yarns with comfort
stretch.
´
´
´
Greater covering power or
apparent volume compared to
smooth filament yarn; also
called bulk continuous filament
(BCF) yarns.
Characteristics
«
«
«
«
«
«
HIGH BULK YARNS
SPUN YARNS
Part of tow is heat
stretched.
´ Two parts combined,
cut, and spun by
con entional methods.
conventional
methods
´ Immersed in hot water;
heat stretched fibers
shrink; non-heat set
fibers create bulk in
yarn.
´
CHARACTERISTICS
´
´
´
´
´
´
Fuzzy: Fiber ends protrude along length of yarn.
Yarn strength related to cohesiveness of fibers and number of
contact points along fiber.
Low twist yarns separate easily with force; yarn strength not
related to fiber strength.
Likely to pill as fiber ends break off.
More comfortable when in contact with skin (less area of yarn
in contact with skin, the more comfortable and less clammy &
confining it is).
More likely to create problems with soiling.
Continuous strand of fibers held together by
some binding mechanism, made from short
fibers.
SPINNING PROCESS – COTTON SYSTEM
´
´
Less smooth
More permeable to air & liquids
Less slippery
More comfortable (may be more
absorbent)
Less static prone
More bulk, cover, and elasticity
´
´
´
Opening: Loosens, cleans,
blends fibers; removes dirt;
helps determine yarn quality.
Carding: Partially straightens
fibers & forms into thin web;
produces carded sliver.
Drawing: Increases
parallelism of fibers;
combines carded slivers into
a drawn sliver; continues
blending for self-blended
yarn, decreases sliver size
(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
OTHER SYSTEMS
´
´
´
Woolen system: Wool fibers; soft, bulky, fuzzy yarns.
Worsted system: Wool fibers; more even fiber
distribution & more parallel; compact, smooth, strong
yarns.
yarns—shorter
Flax system: Tow yarns
shorter & less parallel fibers;
line yarns: longer and more parallel fiber.
SPINNING PROCESS (CONT’D)
Roving: Reduces size of drawn sliver, increases
fiber parallelism; adds small amount of twist.
Repeated several times (blending often occurs
here).
´ Inserting
g yyarn twist: Several options
p
to reduce size
& add full amount of twist; winds finished yarn on
bobbins.
´
WOOLEN (TOP) AND
WORSTED (BOTTOM) YARNS
INSERTING YARN TWIST
Ring or conventional: Series
of operations.
´ Open end rotor: Eliminates
roving & ring twisting (faster
process, but weaker yarn).
´ Friction spinning: Combines
rotor & air techniques; more
even yarns; freer of lint, &
loftier, but weaker.
´
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ALTERNATE SPUN YARN PROCESSES
Air jet: Similar to rotor, but twist formed by
moving air; rougher & less elastic yarns than
rotor spun yarns.
´ Direct: Similar to conventional; roving
eliminated.
eliminated
´ Compact: Variation of ring spinning that
condenses the roving before final twist
insertion; smoother & stronger yarn.
´
SPINNING FILAMENT TOW INTO SPUN YARNS
´
Tow-to-top (sliver system): Tow converted into
staple by diagonal cutting (cut to desired length) or
break stretch (stretched until fiber breaks at
weakest point, uneven length) and formed into
sliver; spun by conventional system.
´
Tow-to-yarn: Direct spinning system where fibers
are broken at weakest point and spun into yarns in
continuous process.
TWIST
ALTERNATE SPUN YARN PROCESSES
Vortex: Twist develops as fibers swirl around
spindle; eliminates shorter fibers.
´ Twistless: Eliminates twist; holds fibers
g
g soft, lustrous,
together
with starch or sizing;
opaque fabric with good dyeability & durability.
´ Self-twist: Inexpensive way to ply 2 yarns of
different twist (1S & 1Z) direction.
´
ENVIRONMENTAL IMPACT
´
´
´
´
Hearing protection required.
Opening steps create air-borne dust
(controlled by vacuum heads or humidity
levels).
levels)
Waste recycled whenever possible.
Ring spinning often in low cost labor countries
with related issues of social responsibility.
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,
i & end
d use; low,
l
napping,
i g regular,
g l
high/voile, or crepe twist.
´
´
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LOW TWIST YARNS
´
Smooth and textured bulk filament yarns: very
low twist.
SPUN YARNS
´
Average Twist: Most common type of twist,
neither low nor high, used for most end uses.
SPUN YARNS
´
Crepe Twist: very high twist, produces lively,
yarn
SPUN YARNS
´
Napping Twist: Low twist, usually filling
direction to facilitate brushing fibers to surface
(napping); for flannelette, flannel, blankets, etc.
SPUN YARNS
´
Voile Twist: high twist, used for voile
YARN SIZE
´
Yarn number: Cotton, woolen, worsted systems are
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,
strength,
(usually
tr gth and
d performance
rf r
(
ll spun yarns).
r )
´
Cord: Ply yarns are twisted together.
Uses: Industrial products.
´
CORD (RIGHT), SINGLE (LEFT), AND PLY
(BOTTOM) YARNS
SEWING THREAD
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FANCY, NOVELTY, OR SPECIALTY 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.
L bi
Lubricant
or wax fi
finish
i h to ffacilitate
ili
sewing.
i
Many fibers used.
Sized as denier, tex, count, yarn number, or ticket number.
PARTS OF A NOVELTY YARN
Single: 1 part
´ Complex: 2 or more parts
´
« Ground
or foundation or core
or effect component
« Binder
component
« Fancy
´
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
´
Ratiné: Spiral effect with loops at intervals.
Knot, spot, nub, or knop: Effect twisted many times in
color, size, or texture.
´
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:
Chenille Short
Sh t pile
il fibers
fib
held
h ld in
i place
l
by
b two
t binder
bi d
´
´
yarns twisted together.
EFFECT PLY FOR SEVERAL KINDS OF
FANCY YARNS
FIBER BLENDS
´
Blend: Intimate mixture of different fibers (varied by
´
Mixture: One type of yarn used in one fabric place
type, length, size, color, etc.) in one yarn.
(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
Combine different fibers to get better
combination of characteristics in product;
achieve characteristics that are combinations
of the fibers in the blend
´ Improve processing and uniformity
´ Obtain better hand, texture, and appearance
´ Economize
´ Obtain cross-dyeable effects
´
BLENDS
´
Blend levels: Related to end use and performance
specifications.
´
Stage of blending: Earlier in processing, blend is
more uniform. Light density fiber works to outer edge
of yarn.
´
Other possibilities
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FIBER DISTRIBUTION IN YARNS
COMPOSITE YARNS
´
´
Regular in appearance with
unlike components.
Types:
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YARN PERFORMANCE
´
Characteristics & performance measured to
ensure consistent fabric and product quality
and performance.
« Size,
Size
twist,
twist bulk,
bulk evenness,
evenness & appearance
resistance to abrasion, & other
performance aspects
« Strength,
Blended filament yarn: two unlike filaments blended
together
Fasciated yarns: filament & broken filament
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 QUALITY
Thin spots assessed to minimize problems with
processing, fabrication, and finishing.
´ Neps: Small knot of entangled fibers; assessed to
minimize problems with dyeing and finishing.
´ Hairiness: Excessive fiber ends on yarn surface
make the yyarn more sensitive to abrasion and
pilling; assessed to minimize problems with
fabrication and performance.
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SUMMARY
´
´
A yarn is a continuous strand of staple fibers, filament(s), or some other
material that can be used to make a textile.
The categories that yarns can fall into are: spun yarns, smooth filament
yarns, or textured filament yarns.
«
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´
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Filament yarns can be either monofilament or multifilament. They can also be made as
tape or network yarns.
Textured filament yarns can be created in a variety of ways and utilized for texture, bulk,
stretch or comfort.
Filament yarns are created through the extrusion process previously covered
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.
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Yarns can twist in a clockwise or counter-clockwise direction: z-twist or stwist. The z-twist is the most common.
Yarns can have a low amount of twist or a high amount. This will affect what
type of fabric and ultimately, what type of end-use the yarn is for.
Yarns can be twisted into a certain type of grouping: single spun, ply yarn,
cord or fancy yarn.
yarn
Yarns can be blended in a variety of ways and for different reasons.
Quality must be monitored at every level.
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).
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