Process control in warping
The
following are the process control parameters in a warping department:
1.
Minimising end breaks.
2.
Quality of warping beams
3.
Control of productivity
MINIMISING END BREAKS
Minimising
end breaks in warping involves four steps namely:
1.
Control of tension in the yarn
2.
Satisfactory maintenance of those machines
3.
Minimising the defects on packages produced at winding
4.
A regular cheek on the end breakage rate for comparison with the norms.
1. Control of tension in the yarn
On
the warping machine, there are two types of variation in yarn tension
A. Between different stages
of unwinding of a package. This can be detected after the first thread guide.
B. Between ends. It can be
detected at the head stock.
The tension variation that occurs during the unwinding of a package can be minimised if you design creel such that the distance between the package and the first thread guide is shortest, it will avoid yarn balloon rubbing the nose of the package The tension variation between the ends at the headstock is minimised if the groups of neighbouring on the beam are taken from the same column of packages in the creel.
The tension variation that occurs during the unwinding of a package can be minimised if you design creel such that the distance between the package and the first thread guide is shortest, it will avoid yarn balloon rubbing the nose of the package The tension variation between the ends at the headstock is minimised if the groups of neighbouring on the beam are taken from the same column of packages in the creel.
2. Condition of Machine
A.
Alignment of the package at the creel
Non alignment of the creel package with
respect to the first guide is often seen to be a cause of high end breakage
rate at warping. This alignment is done with the help of a gauge.
B.
Eccentric Guide rollers
On
machines with mechanical stop motions, there are several guide rollers at the
headstock which are positioned very near to one another. Eccentricity in those
rollers can introduce short term tension variations of high amplitude.
C.
Thread Guides
Deep
cuts in thread guides can significantly increase yarn tension and hence
deteriorate warping performance. If found dirty, the thread guides should be
cleaned with CCI4
D.
Relative humidity and temperature
For
satisfactory working at warping , about 60 % RH should be maintained .The dry
bulb temperature should be kept at about 29°C (84°F).Lower humidity may
increase yarn hairiness, end breaks and liberation of fluff. The fluff
ultimately passes to-the beam and given difficulty during sizing. Higher
humidity is unnecessary , in fact relative humidity higher than 70 % may
increase end breakage rate
Importance of Minimising End Breaks
The
stoppage of the machine due to an end break is likely to deteriorate the
quality of the beam due to three reasons
1. The rubbing of the beam by the drum which stops abruptly
1. The rubbing of the beam by the drum which stops abruptly
2. Owing to the difficulty
in finding the broken end, there is a possibility of incorrect mending. It may
lead to tappers during sizing
3. There is some loss in the
extensibility of broken end when the machine is stopped, it increases the
probability of breakage in weaving and sizing.
QUALITY OF WARPING BEAMS
The following
points should be noted to improve the quality of warping be
1. Condition
of beam flanges:
If the beam flanges are damaged, the unwinding
of yarn near the flanges will not be satisfactory. This will cause difficulties
in sizing and weaving.ges are damaged, the unwinding of yarn near the flanges
will not be satisfactory
2. Stop
Motions and Breaks:
Proper stopping of the warping machine after
an end break ensures that the broken end on the beam can be traced easily
3. Condition
of the driving drum:
On most
warping machines the beam is driven by frictional contact with the driving
drum. In to get a package of the correct density, the pressure between the drum
and the warper's beam has to be kept at
fairly high level
4. Barrel
Diameter of the Beam
Beams of small
barrel diameter give rise to high unwinding tension at sizing, particularly
when the beam is about to become empty.
5. Cuts in Accessories in the path of yarn
5. Cuts in Accessories in the path of yarn
Drop pins of
stop motion, guide rollers, recd denting etc. should be not have any grooves
6. Creel Fans
or Floor
Fluff
accumulated on the machine, particularly at thread guides, causes tension
variations yarn. This fluff can pass on to the beam.
7. Length
Measuring Motion
The length
measuring motion should be accurate, otherwise estimation of beam count would
be wrong and subsequently will give incorrect values of size percent which is
commonly determined from the weights of yarns on the warper's and the size
beams
8. Density of the
Beam
The beam
should be firm, inadequate pressure between the beam and the drum causes soft
beam Adequate pressure should be maintained by making suitable mechanical
adjustments trained by making suitable mechanical adjustments
CONTROL OF PRODUCTIVITY
The
productivity at warping depends upon the machine efficiency and machine speeds.
The speed is governed by the mechanical condition of the machine and its
design. Machine efficiency depends o several factors, such as the breakage
rate, the time taken to mend the machine stop of yarn on supply package etc.
Causes of Flow
Efficiency or Low Productivity
1. Increase in
End breakage rate,
The machine
efficiency at warping is highly sensitive to the end breakage rate
2. Improper
utilisation of magazine creel
If the creel boy does not keep the magazine
creel ready to be used by the time the package in the running creel are over,
the efficiency will fall.
