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Abstract:
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In the manufacture of carded cotton yarn, a certain
amount of waste must be removed from the raw stock in order
for the finished yarn to meet specifications in Appearance
Index, Uster Imperfection Count, Uster Evenness, %CV, single
end strength, elongation, adjusted break factor, and others,
depending on the end product.
Waste, which includes trash, both cellulosic and noncellulosic,
and non-spinnable fiber is deliberately removed
at the initial cleaning processes of opening, picking, and
carding. Also, some spinnable fiber is sacrificed as a byproduct
of the various cleaning process.e.s.
Although various mlll standards for waste removal
have been in use, there have been no proven criteria for
waste removal levels at the various cleaning processes and
their effects on resultant yarn quality and the economics of
waste removal. Therefore, it was decided to investigate the
effects of the combinations of six levels of waste removal
at opening and picking with five levels of flat speed, and
hence levels of flat strip waste, at carding with respect to
the resultant effects on yarn quality and economics.
Using Strict Low Midling, inch and one-sixteenth cotton,
yarn was produced from each of the thirty waste removal combinations. The yarn was then tested for adjusted break
factor, single end strength, single end elongation, Uster
Evenness, %CV, Uster Imperfection Count, and Appearance Index.
Several conclusions were drawn from the investigation.
Increasing the per cent waste at opening and picking' had a
highly negative effect on the yarn qualities of adjusted
break factor, single end strength, and single end elongation
because of the fiber damage associated with the amount of
processing necessary to achieve the higher levels of waste
removal. No strong relationships were found to exist between
flat speed, per cent flat strip waste, per cent total
card waste, or per cent total waste, opening through carding,
and any of the yarn qualities tested.
The data suggested that the opening and picking conditions
used damaged fibers, the damage becoming apparent at
carding. For a particular total waste level, the waste
should be removed at the card rather than at opening and
picking, if the pre-carding equipment is the same as that
used in this thesis.
The lowest per cent total waste, opening through
picking, used in the thesis, 2.34 per cent, resulted in yarn
qualities which were generally equal to or better than the
yarn qualities resulting from the higher per cent total waste
levels. Therefore, it was suggested that mill standards for
waste removal might be lowered, resulting in a significant
reduction for the cost of waste removal.
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