Textiles: yarns and how they are produced

Materials and
components yarns
· All fibres must be turned into yarns before
they can be woven or knitted into a fabric.
· A yarn is a fine, continuous length of fibre
with or without twist…read more

Continuous filament yarns
· Made from filament fibres
· All made from man-made fibres with one exception, silk
· Filament yarns are made by lightly twisting filament fibres together.
· They are smooth meaning they do not trap air
Smoothness
Smooth in appearance, they don't trap air so are poor insulators
Lustre
Have a high degree of lusture meaning fabric has a shiny appearance
Handle
A smooth yarn makes the fabric feel compact and denser
Regularity
Has regularity of thickness throughout the yarn length meaning the yarn is stronger
Continuous filament yarns can be divided into:
Mono filament yarn
Made from only a single, thick filament yarn e.g metallic yarns and fishing lines
Multi filament yarn
Made from more than one filament
They require little or no twisting to hold the multi filament together…read more

Staple Spun yarns
· Made from staple fibres
· These include natural fibres e.g. cotton and mandmade filament fibres which are cut up e.g.
Polyester
· They have to be carded or combed to lie in the same direction before twist is added
· There are many different spinning methods used to add twist depending on the fibre type and
the yarn produced
· Spun yarns may contain fibres of the same type or a blend of different fibres
Smoothness
They are hairy and the length of the staple yarn determines how hairy the yarn is
Lustre
Staple yarn lacks lustre which makes fabric dull
Handle
Has a fuller handle or feel
Regularity
When spinning a yarn from a staple fibre it is impossible to achieve a regularity of thickness,
Irregular yarns tend to be weaker and further processing takes place to make the yarn regular
along the length
Three Traditional spinning methods:
· Cotton spun yarns: this system uses short staple fibres and produces harder, leaner and less
regular yarns. Used to produce woven fashion fabrics and jersey knits
· Worsted spun yarns: produces a smooth yarn and is used to produce suits and fine knitwear.
Worsted spun yarns are regular, fine and lustrous because they are made from longer staple
fibres…read more

Core-spun Yarns
· They are multi-component yarns (made up of more than 1
filament)
· The yarn has a core that stays central and other staple fibres
are spun around it
· Stretch fabrics can be made from this method. The core would
be an elastane filament covered by a non-elastic natural or
man-made yarn…read more

Twist
· Fibres have twist added in staple-spun yarns to bind the fibres together. In continuous filament yarns, twist is
not that important and the filaments are only twisted enough to hold the fibres together
· Twist hold fibres together and gives strength to a yarn
Types of Twist
Twist can be inserted clockwise or anti-clockwise. These twists are known as `s' or `z' twists
Twist and yarn production
Majority of single yarns are spun with a Z twist and in single
yarns the direction of the twist does not affect the
behaviour of the yarn
Fabrics made from spun yarns usually have a Z twist in the
warp and a S twist in the weft
If a yarn is made up of 2 twisted yarns, then in order to be
more balanced and stop snarling, a yarn with a S twist is
folded with a yarn with a Z twist
Effects of twist
· Twist gives strength to a yarn
· High twist yarns are strong and hard and suitable for weaving as they can withstand the
warp tension in the loom
· Low twist yarns are softer, weaker and more bulky making them more suitable for
knitting or weft yarns
· If too much twist is put into a yarn it will cause the yarn to twist back and snarl…read more

Yarn construction
· Single yarn is the simplest type of yarn and it is produced by twisting
together a staple or filament fibre
· However, when spinning a single yarn from a staple fibre, it is
impossible to achieve a regularity in thickness. Irregular yarns are
weaker and need to be processed more to improve performance
· Yarns with more than 1 strand are call compound yarns:
Single Folded (plied)) Cable Novelty
Standard single yarns are Produced by twisting Forming cable yarns takes Decorative yarns used in
made from continuous together 2 or more single more than 1 operation both knitted and woven
filament fibres. Spun with yarns to make a thicker fabrics
1 strand with a Z twist and stronger yarn
Easy to make and Used for better quality 2 or more strands of They give interesting
inexpensive fabric as it helps to even already folded (plied) textures and effects
out the thick and thin yarns are twisted together
places
Not of an even thickness Folded yarns are more Cable yarns are stronger,
leading to weak spots lustrous than single yarns stiffer and more likely to
be used for industrial
applications…read more