From Fibers to Yarns
Definition of Yarn
• A yarn is a continuous strand of textile fibers, staple or filament, in a form
suitable for weaving, knitting, or otherwise intertwining to form a textile
• A yarn is a constructed assemblage of textile fibers, which acts as a unit in
• Yarns may be:
➢ Staple or filament
➢ Single or plied
➢ Simple or complex
• In addition, filament yarns may be:
➢ Flat or texturized
Types of Yarn
1. Staple (short fibers) or
2. Single (one strand) or
3. Simple (same appearance along length) or
• Filament (continuous filaments)
• Plied (two or more strands, twisted)
➢ *Cord (Cabled)
• Complex (variable appearance along length)
Filament Yarns May Be
• Flat or texturized
• A t-shirt would probably be knit from a SIMPLE, SINGLE, STAPLE YARN.
• Fabric for a slip would probably be knit from a FLAT, SIMPLE, SINGLE
• Cord (TOP), Single (CENTER), and Ply (BOTTOM) yarns
• Staple fibers twisted together
• Filament fibers laid side by side, with some twist applied
• Single filament fiber
• Strips made by lengthwise division of a sheet of material
The Direction and Amount of Twist
• Twist in staple (spun) yarns is given in units of turns of twist per unit length,
either turns per inch (U.S.) or turns per centimeter (Europe, Asia).
• Tpi = tpc x 2.54 • Yarn properties are affected by the degree of twist, but not by the direction
(S or Z) of twist.
• Continuous strand of fabrics held together by some binding mechanism,
made from short fibers.
• Fuzzy: fiber ends protrude along length of yarn
• Yarn strength related to cohesiveness of fibers and number of contract points
• Low twist yarns separate easily with force; yarn strength not related to fiber
• 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 and confining it is).
• More likely to create problems with soiling.
Effect of Twist on Staple Yarn Properties
• As twist increases, yarn strength and yarn stiffness increase up to a point,
level off, then begin to fall at very high twist levels.
• Yarns with extremely high levels of twist are called “crepe yarns”; these
yarns possess a high degree of torque, which causes them to buckle and
decrease in length. Woven fabrics containing these yarns have a pebbled
Yarn Twist Staple Yarns
• Yarns with lower twist
➢ Pills more
➢ More comfortable skin contact
➢ Less cost
Types of Yarn Twist
• Crepe yarns, have a high tpi (turns per inch)
• Low Twist Yarns
➢ Smooth and texturized bulk filament yarns; very low twist.
• Spun Yarns
➢ Napping Twist: low twist, usually filling direction to facilitate brushing
fibers to surface (napping); for flannelette, flannel, blankets, etc.
➢ Average Twist: most common type of twist, neither low nor high, used
for most end uses.
➢ Voile Twist: high twist, used for voile
➢ Crepe Twist: very high twist, produces lively yarn 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/9000 m) – finer yarns,
lower numbers; denier is used for yarns and fibers.
• Tex System: weight per unit length (g/1,000 m); finer yarns, lower numbers
(decitext or dtex)
Continuous Filament Yarns
• Continuous filament yarns are assemblies of continuous filament fibers
twisted together; each individual fiber runs through the entire length of yarn.
• For flat (not texturized) continuous filament yarns, only a small amount of
twist (.05 to 2.0 tpi) is inserted, to maintain the coherence of the yarn.
• Smooth-filament yarns: regular or conventional filament yarns.
• Production: used as produced, no further processing required.
• Uses: in smooth, lustrous fabrics or where high strength, compact yarns are
• 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 protruding ends (no lint, no pills)
• Sheds soil
• Compact with little bulk, cover, or loft
• Strength related to fiber strength and multi-filaments
• Fiber strength fully used
• Size based on denier system; related to number and size of filaments
• Characteristics related to number and size of filaments
➢ Fine fibers – soft and supple yarn
➢ Coarse fibers – stiff and abrasion resistant yarn
• Fibers as long as the yarn and the fabric from which they are removed
• Smooth-filament (mono or multi-filament)
• Tape yarns (fibrillated fibers or slit films)
• Network yarns – similar to tape yarns, but with greater bulk and comfort Texturizing
• Fabrics made from flat continuous filament yarns exhibit specular
reflectance (shone) and are smooth with minimal surface friction.
• Continuous filament yarns are often texturized, in order to produce fabrics
with spun-yarn aesthetics: diffuse reflectance, matte surface, and increased
• Texturizing processes all increase yarn bulk, and most increase yarn stretch.
Texturizing continuous filament yarns are often referred to as BCF yarns
(bulked continuous filament yarns).