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

textile warping

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.

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

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
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.






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