Long thin places which have lengths of approximately 8 cm and longer and cross-section if about 30 to 75% of average yarn diameter is
relatively seldom occurring in short-staple yarn. The long thin places could
result in short-serious cloth defects like streaks, variation in dye pick up
etc. Thus control of long thin places needs no further emphasis. This type of
fault is produced mainly by separation of sliver or roving in the process prior to spinning. This paper deals with various control measures that are required in
different departments of the mill and raw material management to minimize long
Carding is the heart of the spinning & rightly so as all
the quality related settings are primarily controlled in carding only.
Web falling in cards is a source of long thin places. The
major cause for this is loading of cylinder under casing. Frequent air cleaning
of under casing and petrol washing during full setting for cotton and tinted
synthetic material would help to avoid loading. The causes of loading would be
the condition of wire points, too high or too low tension draft, static generation in PV
and PC counts, etc.
Missing slivers in drawing process can also be the reason
for very long thin places in the yarn. The effectiveness of sliver stop motions
should be checked regularly. The piecing practice of tenters also needs
Rubbing of slivers in drawing can also be a source .The
mills can increase the gap between cans and slivers rubbing against the inner
surface of cans by suitable changing coiler speed change wheel/can bottom
Reducing creel tension draft and web tension draft in draw
frames, maintaining and smooth rotation of creel rollers would also help in the
The condition of trumpets should be good.
Sliver guides at feed should be adjusted in such a way that
the slivers run into the drafting system side by side but not crossing over
Too low top roller pressure would also cause long thin and
However, with the advent of very sensitive auto levelers the
faults from Carding & Drawing frames may be nullified.
Excessive roving stretch due to improper function of builder
mechanism and use of empty roving bobbins with wide variation in diameter are
cause for long thin places. Sliver stretch in the creel in speed frames due to
too higher creel draft has to be avoided. Creel tension draft should be as
minimum as possible; at the same time ensuring no sagging of drawing sliver. To
high break draft in speed frames and inappropriate selection of condensers are
other vital causes for long thin places.
The method of feeding slivers in fly frames and condition of
cans are important. Slivers crossing each other, damaged edges of drawing
sliver cans etc. would disturb the free withdrawal of slivers from cans.
Roller lapping in fly frames could be a reason for long thin
places. Excessive top arm pressure would lead to roller lapping and would
result in to long thin places.