Woven Fabrics - Fairchild Books

In filament yarn, the diameter is uniform and the
filaments cannot slip when the yarn is pulled. Twist is
not needed to hold the filaments in place. For these reasons,
plying does not improve filament yarns as it does
spun yarns. However, plying of filament yarns can be
done to produce unique effects on novelty yarns and
metallic yarns (see p. 80).
Ply yarns require better-quality fiber, more labor,
and special machinery. Because of this expense, ply
yarns are more costly than singles. Thus, most fabrics
are made of single yarns.
Yarn Spinning
Staple fibers are spun into yarns by a variety of methods.
The most widely used is ring spinning where fibers are
carded to bring them to a more parallel position and
bundled into a loosely formed rope about one inch in
diameter, known as sliver. Multiple slivers are grouped
together and then drawn or pulled slightly to decrease
into a smaller diameter, known as roving. Further drawing
and more twist are needed to form the desired yarn
size with the required turns per inch. The final yarn is
then wound onto a cone or package. (See Figure 4.8.)
Ring spinning can produce anything from uniform
yarns to the more complex, novelty yarns. It can produce
yarns in a wide range of sizes and excels in the
finer counts (see p. 81). Ring spinning produces yarns
with the softest hand available and are noted for making
fabrics that feel soft. However, low production rates
and additional steps make this a more costly process.
Figure 4.8
Yarn winding on a package at a
textile plant.
FABRIC SCIENCE
A 74 F
Products made from ring spun yarns are advertised to
promote their quality and are found in t-shirts, hosiery,
sheets, towels, and even denim, all for the luxury market.
Open-end (OE) spinning is a method of producing
spun yarns. It is different from conventionally spun yarn,
frequently called ring-spun yarn, in that only one process
from carded sliver to spun yarn is required. Substantially
higher rates of production, coupled with savings in
space and power requirements, are realized in OE spinning.
Carded sliver is fed to the open-end spinning unit,
which separates the fibers, twists them together to form
the completed spun yarn, and then winds the yarn onto
spools or cones. Yarns made by this process are sometimes
called roto-spun yarns or turbine-spun yarns.
Some advantages of OE spun yarns are better regularity
and uniformity; improved abrasion resistance,
especially in high-twist types; improved distribution
of fibers in blends; and improved absorption, resulting
in brighter shades and print-pattern definition. Two
important shortcomings are that yarn strength averages
20 percent lower than conventionally spun yarns, and
manufacture is limited to coarse and medium-size yarns.
These yarns are more uniform, somewhat weaker,
and less expensive than ring-spun yarns. Their rate of
production is 10 times faster than ring spun yarns. It
has a limited range for yarn sizes and is best when under
Ne 20 (see p. 82). Almost all yarn produced for denim
is spun with this method. End yarns are used in fabrics
such as interlock, fleece, and almost all yarns used in
denim for mass markets.
Air-jet spinning, also known as Vortex spinning,
uses compressed air to aide in the spinning process. In