Types of selvedges on woven fabric

1. CHAPTERCHAPTER
FOUR:FOUR:
SELVEDGESELVEDGE

3. 4.1 Requirements of Selvedges
The basic function of selvedge is to lock the outside threads of a piece
of cloth and so prevent fraying.
It is easy to achieved if the weft yarn is inserted continuously from
one package, such as a pirn on a conventional shuttle loom, because,
each time the package carrying shuttle reverse its direction, a hairpin of
weft yarn will form round the last thread in the cloth provided that this
end changes its position between picks.
 Requirement for selvedge:
1.Strong enough to withstand the strains during finishing process.
2.The selvedge should have a neat and uniform appearance.
3.Uniform to allow garment manufacture to line-up one edge of the
fabric; layer upon layer so that many layers can be cut simultaneously
and accurately.

4. 4.2 Types of Selvedges
4.2.1 Conventional Selvedge
• Produced on a conventional shuttle loom.
• Required strength for the post-weaving
process to withstand the rubbing-action of the
shuttle as it enters and leaves the warp shed.
• Strength is also necessary to counteract the
pulling of the weft thread as the shuttle
traverses the loom, and this function must be
performed by the outside ends of the fabric.

5. Conventional Selvedge
• Uniformity of appearance may be a
problem if the outside ends in the
fabric do not change position every
pick.
• Happens in twill and satin-type
weaves.
• If the appearance of the selvedge is
unacceptable when one of these
weaves forms the ground structure,
then it will necessary to use some
special technique of threading up or
to introduce a plain-weave selvedge
for a width of up to 1 cm at each side
of the fabric.
• Alternatively, it may be quite
satisfactory to make only the outside
end in the fabric change position
after each pick and it is known as a
catch cord or catch end.

6. Conventional Selvedge
• The fabric surface must be absolutely uniform
from one side of the cloth onto the other.
• It is thus not possible to vary the construction of
the fabric in any way in the selvedge.
• Under these circumstances, a thread of strong
monofilament yarn or a length of flexible wire is
used as the catch cord.
• This thread, which is fastened to a point on the
frame at the back of the loom, changes its
position after each pick.
• However, it extends for only 1-2cm into the
fabric.
• As the cloth is drawn forward, it will slide of the
thread to leave a small loop of weft at the side of
the fabric, but there will not be an increase in
thickness.
Small Loop of Weft at the Side of the Fabric

7. 4.3 Tuck and Fringe Selvedges
• There are several instances in which special selvedge
consideration become necessary because the yarn is
severed, namely:
– at the centre of a wide fabric that is cut at the loom so that
several narrow fabrics are produced side by side.
– at both of a fabric in which the weft is cut after each pick
length.
– at one side of the fabric in which the weft is cut after every
two picks.
– Tuck and fringe selvedges are most commonly used under
these circumstances.

8. 4.3.1 Tuck Selvedge
• Probably the more effective in
preventing fraying and yet achieving
the necessary standards in strength
and appearance.
• A trail of yarn, which extends beyond
the last selvedge end, is pulled into
shed formed for the next pick.
• Provided that the last end changes
position after each pick to catch loop,
a selvedge is produced that is
acceptable for a wide range of uses.
• In many instances, it is necessary to
reduce the number of ends/cm in the
selvedge to compensate for the
increase in weft density.

9. 4.2.2.2 Fringe Selvedge
• The most successful in
preventing fraying and
providing strength but as
successive picks are beaten-up
the weft tails are made to point
up and down alternately by the
crossing end so that the fringe
does not appear.
Leno Structure with the
Outside Ends

10. 1. The simplest fringe selvedge requires only a
chain, illustrated below:
• The standard end is held in a
fixed raised position by a loop.
And the crossing end passes
through the eye of a heald on the
back shaft and also through a ring
mounted on the end of the chain.
• When the back heald is down,
the chain is pulled round the
standard end, but, on the other
pick, when the heald is raised,
the chain pulls the crossing end
to the opposite side of the
standard end.

11. • Another method, requires an additional mechanism, uses
wires with holes in their upper end as the diagram below:
• These methods control the crossing
ends that are in the raised position
when the weft is inserted.
• Between picks, they fall and then rise
again in the same vertical plane by
means of cam operation.
• In the meantime, the standard ends
that are permanently in the down
position are given a side traverse by a
second cam when the crossing ends
are in their lowest position.
• The direction of the side traverse is
reversed after each pick.

12. 2. Leno structure by twisting the outside ends around
one another
Leno Structure by Twisting
the Outside Ends
Disc Carrying Two Bobbins Disc, Fell and Cloth

13. 3. Leno structure by locking the outside ends with an additional fine
monofilament thread, which is stitched into the edge of the fabric:
• Requires an additional mechanism and it’s
unpopular.
• The sewing needle must oscillate once every
one or two picks depending on the openness
of the weft set.
• The locking needle oscillates vertically with
the same frequency from a second cam to
catch and hold the sewing thread.
• The fringe selvedge is basically untidy, and a
neater appearance is generally essential.
• Such an improvement can be achieved if all
the protruding weft threads are cut off to the
same length and as near to the body of the
fabric as possible.