Chap 4 Yarns
description
Transcript of Chap 4 Yarns
YARNS AND SEWING YARNS AND SEWING THREADSTHREADS
- Chapter 4 -
Spider Silk tapestry: http://www.npr.org/templates/story/story.php?storyId=113223398&ft=1&f=1001
Tonight’s topics• Fibers spun into yarns
• Wide variety of yarns
• Yarn types affect fabric properties
• Unique size systems exist for yarns
• Different equipment is required to weave or knit with different yarns
• Fabric finish choices affected by yarn type
• Garment designs influenced by yarn types
• Sewing threads similar to yarns
Spun Yarn Filament Yarn
SPUN YARNS
• Staple fibers twisted together
• Twisting creates stronger yarns
• Identify by untwisting yarn fibers; spun yarn pulls apart into individual short fibers
FILAMENT YARNS• Continuous filaments as they come from
spinnerette/cocoon– Little or low twist
• Smooth lustrous surface
– Tightly twisted filament yarns• Crepe-filament yarns
• Strength of yarn depends on individual fiber strength and number of filaments
Monofilament• Composed of one filament
Multifilament• Composed of many filaments
• Most filament yarns are multifilament– More flexible than single filament yarns of
same diameter
TAPE & NETWORK YARNS• Tape Yarns
– Inexpensive– Produced in sheet form; then slit into .1” strips
– Common for olefins and metallics
• Network Yarns– Air included in solution to make foam; air pockets pop
when fiber is drawn, creating a network of interlocked fibers– Industrial uses where bulk and low density are more
important than high strength
Carded And Combed Yarns(1 smoothing step) (2 or more smoothing steps)
• Fabrics of combed yarn look better, feel smoother, are stronger, and are more expensive than fabrics of carded yarn
• Fabrics of combed yarn retain shape better and pill less
• Fabrics of carded yarn are bulkier, softer, and fuzzier.
Linen Yarns
• Tow = short fibers = coarse texture = rough finish; homespuns
• Line = long fibers = smooth texture = fine finish; handkerchief linen
Wool Yarns
• Woolen– Made of carded yarns– Noils (snarls)– Fuzzy– Uneven diameter– Bulky– Wide range of fiber
lengths– Sizing called run and
written like this: 2/50
• Worsted– Made from combed yarns– Smooth with little fuzz– Even diameter– Tightly twisted– May shine– Firm– Size called worsted and
written like this: 2/50
Woolen
Yarn
Worsted Y
arn
http://www.youtube.com/watch?v=qUEDWjd9cLk
Spinning Methods Ring (Conventional) Method
• Opening– Loosens the bale, blends and cleans fibers, forms lap
• Carding– Cleans and aligns fibers, forms carded sliver
• Drawing– Makes parallel and blends fibers, forms drawn sliver– May create fiber blends now
• Combing– Makes parallel and removes short fibers (noils), forms combed
(top) sliver (used only for long-staple cotton or worsted)
• Roving– Reduces size, inserts slight twist, forms roving
• Spinning– Reduces size, twists, winds the finished yarn on bobbins
• Winding– Rewinds yarns from bobbins to spools or cones
www.frontierspinning.com/locations/photo_tour/tour01.shtml
Other Spinning MethodsOpen-end Rotor Spun Method (O-E)
– eliminates some aligning steps
– 4x faster production than ring method
– coarser yarns with poorer uniformity and poorer strength
– commonly used for denim fabric
Air-jet Spun Method– coarser, weaker, and less elastic
– better cover (bulk)
Vortex Spun Method2x faster than OE
20-30 x faster than ring spinning
Not as uniform as ring spun
BLEND = two or more fibers mixed in one yarn – intimate blends– combines good and bad properties of fibers– spun blends most popular; filament blends available
COMBINATION = ply yarns; each ply is 1 generic type of yarn– Metallics; fasciated yarns
MIXTURE = yarns of different generic types used within a fabric (warp is 1 type, weft is another)
YARN TWIST• Turns per inch = tpi
– Soft twist • Soft, fluffy yarns; napping twist; 2 - 12 tpi
– Average twist • most durable staple yarns; not used with filaments
– Hard twist • high or voile twist; smooth, firm and kinky yarns; 20 - 30 tpi
– Crepe twist• highest twist; lively yarns; require special treatment; 40-80 tpi
• Filament yarns - very low twist (1/2 - 1 tpi)
Effects of Twist on Yarn and Fabric
• Fineness• Contraction• Bending behavior• Absorbency• Covering power• Permeability• Softness or hardness
• Tensile strength• Extension and
recovery• Resistance to creases
and abrasion• Pilling behavior• Luster
Up to the
left
S twist
Left – Right Twist
Up to the
right
Z twist
ZS
Why is Yarn Plied?
• Introduce different fiber yarns
• Combine spun and filament yarns
• Improve strength of a singles
• Make thicker, smoother strand
• Make more stable yarn and fabric
• Add texture or novelty yarn but maintain strength
• Add color interest
Ply Yarns ….
• Are more expensive
• Require better quality fiber, more labor, special machinery
• Most fabrics are made of singles
Yarn Size Systems• Relationship between weight of yarns and certain
length of yarn
• Yarn sizes– Yarn-count systems (spun yarns)
• cotton, lea, run, worsted
– Denier system (filament yarns)• d = denier• dpf = denier per filament
– Tex system (mostly for thread)• Tex and d-tex
• Yarn Count System– Larger the size number,
finer the yarn • Sheer lawn = 70s to 100s• Calico = 30s to 40s
– Written as 50/2 (yarn count + number of plies)
• Denier System– Higher the denier, larger
the yarn• 1 d yarn: 9000 meters of
yarn weighs 1 gram• 2 d yarn: 9000 meters of
yarn weighs 2 grams– Sheer hosiery = 20 d– Luggage = 100 d
• Tex System
• Spun yarns = yarn count system
• Spun yarns may be plied • Size is expressed as 50/2 count
(or if woolen or worsted as 2/50)
(2 yarns are twisted together & each yarn size
is 50/1 count)
• An equivalent sized singles yarn would be size 25 count (50 divided by 2)
• Filament yarns = denier system
• Filament yarns are seldom plied but when they are, the size is expressed as two-ply 80 denier– a singles yarn of comparable size would be
160 d. (80 x 2)
• 300-10-1/2 Z means a 300 denier multifilament yarn with 10 filaments (each 30 d.) with a half turn per inch and a Z-twist. This is NOT a plied yarn.
SPECIAL YARN TYPES
• MicrodenierMicrodenier
• StretchStretch
• Novelty Novelty
• ChenilleChenille
• MetallicMetallic
MICRODENIER YARNSMICRODENIER YARNS
• Developed in late 1980s
• Finer filaments than silk (less than 1 denier)
• Extremely soft and drapable
• Expensive
STRETCH YARNSSTRETCH YARNSPOWER STRETCH
• Holding power is required
• Highly elastic yarns
• High recovery force
COMFORT STRETCH
• Designed to yield with body movement
• Low recovery force• Fabrics look the
same as nonstretch
Types of Stretch Yarns
1. Bare Elastic
2. Covered Elastic
3. Core-spun
4. Textured yarns
Grin-through
Unrecovered stretch
• Covered elastic
• Core spun
Texturized yarns are widely used as comfort stretch yarns.
False-twist method Stuffer box method
Knife-edge method Air-jet method
Gear crimping Knit-deknit method
• Thermoplastic fibers made texturizing possible.
Slack mercerized yarns
Yarns with texture vs. texturized yarns
NOVELTY YARNSNOVELTY YARNS
• Fancies
• Yarns not uniform in thickness - seed - spiral or corkscrew
- nub - slub
- thick and thin - boucle
CHENILLE YARNSCHENILLE YARNS
• Pile twisted between 2 core yarns
• Low abrasion resistance
• Prone to pilling and balding
METALLIC YARNSMETALLIC YARNS
• Flat, ribbon-like– Tape yarns– Metallics and olefins
• Supported by wrapping with filament yarns– combination yarns– Fasciated yarns
• Usually for decorative purposes
SEWING THREADS• Main fibers: cotton, nylon, polyester, rayon• Main yarn types:
– Spun– Filament– Core spun
• Always plied• Highly twisted• Often treated with special finishes or
lubricants
THREAD FINISHES• Mercerization
• Soft
• Glace
• Bonded
• Flame resistant and heat resistant for high speed sewing
• Lubricated
THREAD SELECTION FACTORS
• Type of materials to be stitched together
• Type of seaming used
• Product performance expected
• Method of cleaning