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The package of yarn produced on a ring spinning frame i.e.,
the ring cop is not a marketable package. The spinning mills
all over the world generally wind cones of yarn which are packed
after conditioning in bags or cartons and sold to the end-user
in the local market or exported on consignment basis. Cones
of yarn are wound on the winding machines. In producing a cone
package of yarn the winding machines perform many functions.
Winding yarn on cones with good winding - off properties, as
long a length of yarn as possible, extraction of all faults
unacceptable to the end-user, introduction of minimum number
of splices into the yarn, paraffin waxing of the yarn, achievement
of high machine efficiency, detection and elimination of mixed
yarn, winding constant length of yarn on each cone are the main
functions and a modern winding department should fulfil all
these requirements which are equally important.
However, of particular interest to the spinner as well as the
end-user is the winding of a constant length of yarn on each
cone which, after conditioning weighs 4.1666 Lbs (1890 Gms).
On packing 24 such cones, a bag or carton with net yarn weight
of 100 Lbs will be produced. Sales of any number of such bags
or cartons will safeguard the interest of the spinner as well
as the end-user.
Whereas it is possible to wind a constant length of yarn on
each cone on modern winding machines by means of setting of
the length measuring monitor, variations in the weights of cones
wound are introduced by the following factors.
1. Variations in the yarn count
Variations in the count of material are minimised at each processing
stage in the spinning process by the application of on-line
and off-line quality control techniques. However, variations
in the count of yarn below and above the actual count are unavoidable
and give rise to the variations in the net weight of yarn of
constant length, wound on each cone. Usually the actual yarn
count is kept lighter than the nominal count.
2. Variations in paper cone weight
4-ply paper cones are used for winding yarn for the local market
and 5-ply paper cones for the export. During the process of
manufacture variations in the weight of paper cones are introduced
which give rise to the variations in the gross weight of wound
cones of yarn.
3. Tolerance limits for gross weight of cones
Tolerance limits for gross weight of cones are calculated and
enforced by all spinning mills. The object is to pass cones
with gross weights within the tolerance limits to the conditioning
room so that after conditioning and packing of 24 such cones
the net weight of yarn in each bag is as closely as possible
equal to 100 Lbs.
The procedure of calculating the tolerance limits for four different
counts of yarn is given in Annexure No.1 and explained as follows.
In each case actual count required is generally kept 0.2 count
lighter than the nominal count so that a longer length of yarn
per lb, is wound on the cone which makes the consignment of
yarn attractive to the weaver.
The range of variations in each count is kept at ± 0.5
count which is the usual range in most of the spinning mills
operating in the textile industry of Pakistan.
Variations in the weight of paper cones used for local market
are generally from 43 to 47 gms, average being 45 gms. Based
on both these types of variations, range of gross weights of
cones produced is calculated. Tolerance limits are finalised
on the basis of gross weights so that excessively light and
heavy cones are detected by the weight clerks and returned to
the winding department for re-winding. It is necessary that
the tolerance limits are realistic so that the percentage of
cones returned for rewinding is not high and at the same time
excessive number of light and heavy cones is not passed onto
the conditioning room.
The tolerance limits of -35 gms to + 20 gms have been used in
the calculations reported in Annexure No.1.
4. Setting of the length measuring monitor
The calculations, given in Annexure No.1, also show the range
of net weights and lengths of yarn on cones after application
of tolerance limits. On the basis of the average length of yarn
wound on cones in metres i.e. average of length for lowest and
highest counts of yarn in each case settings for the measuring
monitor has been calculated and shown respectively. On the basis
of this setting the length of yarn which would be wound count-wise
is given and also the length per cone to be guaranteed to the
weaver suggested in each case.
5. Average net weight of yarn per cone
With the suggested settings of the measuring monitor the average
net weight of yarn wound on cones would be 4.11 Lbs in each
case. These cones will in general have a moisture content level
of 6.5% which corresponds to a moisture regain of approximately
7%. The cones of yarn which are passed for conditioning in the
packing room are either stacked on the floor in such a manner
that the cones at the bottom are also exposed to the humidified
air produced either by the Humidifiers or by a mini-humidification
plant called the Saturation Duct. The best practice mills creel
yarn cones on pegs in the packing room ensuring more effective
all round exposure.
The duration of conditioning for shift-wise production of cones
is generally as follows:
5.1 Morning shift from 8 am to 2 pm packing time 12 pm
(next day) = 22 to 28 hours.
5.2 Evening shift from 2 pm to 10 pm - packing time 8
am (Day after next day) = 34 to 40 hours
5.3 Night shift from 10 pm to 6 am - packing time 10
am (Day after next day) = 28 to 34 hours
With exposure of yarn cones to humidified atmosphere with prevailing
conditions of 93ºF temperature and 88% R.H. the moisture
uptake of cones will be in general in the range of 1.5% to 1.75%.
Thus, the final net weight of yarn on cones packed into bags
or cartons for delivery to the end-user will be as follows.
5.4 Average net weight of yarn on cones passed for conditioning
= 4.11 Lbs
Net weight of yarn on cones after conditioning and just before
start of packing into bags or cartons = 4.17 to 4.18
Weight of bag/carton containing 24 conditioned cones
Minimum = 100.08 Lbs
Maximum = 100.32 Lbs
The delivery of consignments containing bags of net yarn weights
specified above consistently will lead to satisfaction of the
end-user who will place repeat orders and thus the spinner will
achieve market success at the same time preventing any loss
of yield in winding, conditioning and packing.
Acknowledgement
Useful technical information received from M/s. Iftikhar Iqbal
Khan, Arfat Tahir Siddique, Moeed Ikhlaq Khan, Rauf Tahir during
the preparation of this report is gratefully acknowledged.
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