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Twist
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This has two key elements:
a) The direction of the twist - see below twist orientation
b) The number of twist (turns) per meter - see below
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Twist orientation
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When a twisted yarn is held vertically, the individual filaments
are appearing in this case as the diagonal in the letter "Z".
The same can apply if several yarns have been twisted together:
their combined twist can again appear as the diagonal of the letter
"Z".
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When a twisted yarn is held vertically, the individual filaments
are appearing in this case as the diagonal in the letter "S".
The same can apply if several yarns have been twisted together:
their combined twist can again appear as the diagonal of the letter
"S".
| A multiple twisted
yarn is made from two single yarns, which are twisted in Z
direction. The twisted yarn itself will be twisted in the S
direction. The rotation of this twisted yarn is more or less a
single yarn twist and the result is, that the fibres will once
again lie parallel to the twist axis.
The possibility of variation
lies in the amount of the spun fibres as well as in the amount
of the twist rotation. The optimum characteristics of the
products can be brought out in this way. Stronger twists
for weaving mills and softer ones for knitting mills are the
general rule. |
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| The sewing thread is
normally made of three S-twisted single yarns, which are
twisted together in the Z direction.
A tear-resistant thread with a
round transverse section will thus be created. |
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| The voile is
produced from a spun fibre which is twisted in Z direction.
The special thing is, that the twisted yarn is also twisted in
the same direction, as the spun fibre (z direction). A hard
twisted yarn is the result, with a tendency to curl. The
fabric made from it, will be transparent, robust in grip.
Curtains were often produced from it years ago. To get a
higher transparency and also to produce luminous colours the
finished twisted yarn has to be gassed. This means that the
fibres which stick out are burnt off.
Very highly twisted yarns are
called crêpe twists. |
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| Fancy twists or nub
yarns are twisted yarns which are made from different kinds of
components such as nub, loop and other effects and are
produced on special machines. |
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| Special
constructions are multiple and multi stage twisted yarns,
which are in praxis of little consequence due to the price
factor. |
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Number of turns
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Stated in turns per meter (tpm. or T/m).
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Nominal number of turns
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The number of turns per meter (T/m) stated as a nominal value.
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Effective number of turns
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This is the nominal turns per meter (tpm. or
T/m) with variations
consistent with production processing.
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Coefficient of twist
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A measure of the level of twist of a yarn, determined by the multiplication
of the turns per unit length by the square root of the linear density
on a direct system, or the division of the turns per unit length
by the square root to the count on an indirect system.
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Doubling
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A yarn in which two or more single yarns are twisted together in
one operation. The initial twist and resultant doubling twist quoted.
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Winding direction
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The winding direction of yarns and twists on spools is marked with
the small letters p and q. The take up of a yarn or twist about
the head of the spool takes effect according to the direction of
turns of the thread and the winding direction. For the purposes
of this standard: The direction and twist per linear unit of flat
yarns and twisted yarns.
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p-winding
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Viewed from the front end of the spool, the end of thread falls
off to the left:
p-winding and S-twist has the tendency to open the yarn
p-winding and Z-twist has the tendency to close the yarn
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q-winding
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Viewed from the front end of the spool, the end of thread falls
off to the right:
q-winding and S-twist has the tendency to close the yarn
q-winding and Z-twist has the tendency to open the yarns
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