Definition of Yarn  - an assemblage of fibers that is laid or twisted together to form a continuous strand

     Spinning - the process of converting fibers into yarns

     History of Yarn Spinning
     -Hand spinning
     -Spinning wheel
     -Mechanization
     -1830 - ring spinning
     -Open-end spinning   3 times faster than ring spinning
     -air-jet spinning   10 times faster than ring spinning

     Types of yarns.

         1.  filament - made from long, continuous strands of fiber.  May be monofilament or multifilament.
 

Silk and manufactured fibers come in filament form
 

        2.  staple (spun) yarn -made from short, staple fibers that must be held together by some means
             (usually twisting) in order to be formed into a long, continuous yarn.  Natural fibers except silk are staple
             fibers;  manufactured fibers and silk are usually filament but can be cut into staple lengths.
 

      Yarns Classified by Number of Parts

     Single yarn - made from a group of filaments or staple fibers twisted together; if untwisted, it will separate into the
     individual fibers
     Ply yarn - two or more single yarns are twisted together to make a single yarn; if untwisted, it will separate into the single
     yarns which will separate into individual fibers

2-PLY AND 3-PLY YARNS

      Cord yarn - two or more ply yarns are twisted together; if untwisted, it will separate into the plied yarns which will then separate into single yarns which will separate into individual fibers.

     Yarns classified by similarity of parts

     Simple yarns  -yarns with uniform size and appearance; may be single, ply, or cord.

     Novelty (fancy, complex) yarns - yarns that have a decorative effect; not uniform in size and appearance
      Novelty yarns will be discussed later

     Core-spun yarns - yarns that have a central core of one fiber around which is wrapped or twisted an exterior layer of
     another fiber
 

     Yarn Twist

     -Direction of twist: (diagram page 227)
         When fibers are twisted to make a yarn, they are twisted to the right  or left
         This twisting is called S or Z twist.  Most yarns are made with a Z twist.
         The direction of twist does not usually affect the characteristics of the yarn or fabric.

    - Amount of twist

         The amount of twist affects the characteristics and properties of a yarn including appearance, behavior and
     durability.
     Generally, higher twist creates yarns that are
         stronger
         more firm
         smaller in diameter
         smoother
         resistant to snagging and abrasion
         resilient
         good conductors of heat
 

     Generally, lower twist creates yarns that are

        weaker
         softer
         larger in diameter
         fuzzy
         prone to snag and abrade
         crush easily
         resistant to heat transfer

     Filament yarns often have little or no twist because they are continuous and strong; the fibers will not break or separate
     from the yarn as easily as spun (staple) yarns

      SPUN (STAPLE) YARNS

     Making staple fibers into yarns

     Insertion of twist into yarns

     Ring Spinning - produces a finer, smoother yarn than the other types of  spinning but is slower
 
 

     Open-end spinning - produces a yarn of even diameter, lower in strength, subject to abrasion, and do not recover from
     creasing easily.

     Air-jet spinning - air jet used to wrap fibers around interior fibers.

     Core-spinning - continuous filament core surrounded by twisted fibers or other yarns.
     Yarn Size

     Differences in yarns and thread

     Thread is usually used for sewing together parts of a garment or other textile product.
     Yarns are used for fabric construction (weaving, knitting, etc.)

     Yarns are designated by standard sizes.  (table 15.1, page 229)
     Direct Numbering System - the higher the number, the bigger (coarse) the yarn
     Tex - weight in grams of 1000 meters of yarn
     The ISO (International Organization for Standardization) is encouraging all countries to use Tex as the designation for
     yarn size.

     Denier- weight in grams of 9000 meters of yarn
     The higher the number, the bigger the yarn.

     Indirect Numbering System - the higher the number, the smaller (finer) the yarn.
     Cotton - size is designated as the number of 840-yard hanks of yarn in one pound.
     For example, if it only takes 10 840-yard hanks to make one pound, the yarn size must be bigger than if the yarn size is
     100.  If 100, it would take 100 840-yd hanks to make one pound.  Therefore, the yarn would have to be small in size to
     be able to fit all 100 in that one pound.

 FILAMENT YARNS

     Filament yarns are made from long, continuous strands of fiber.

     The processing of filament yarns is:

     1.  cleaning if necessary (only for silk)
     2.  align fibers
     3.  twist
     4.  texturing (if done)
     5.  winding on spools

     Filament yarns are smooth and slippery to the touch.  Often they are bulked or textured to give them more volume,
     softness, covering power.
 
 

     COMPLEX (FANCY, NOVELTY) YARNS (see diagrams , page 224)

     =Complex yarns are made to create decorative effects in the fabrics into which they are woven.
     =Complex yarns are usually weaker than simple yarns
     =Complex yarns are usually woven into the filling direction of the fabric
     =Complex>yarns usually exhibit more snagging and wear 

     Complex yarns usually have three main parts:
     1.  core (ground) yarn
     2.  effect yarn
     3.  binder yarn