Dr. P.H. Ukey, Dr. R N Joshi
DKTE’s Textile & Engineering Institute, Ichalkaranji and
Department of Textile Technology SGGSIE&T Nanded
Winding faults will occur in the POY bobbins of melt spinning. These faults will be ribbon formation, jali, hard bobbins, crushed paper tubes, loops, broken filaments, yarn wrapping on the drum, winder vibrations etc. In this paper, an attempt has been to review the problems associated with the winding of POY bobbins and their remedial actions.
In the melt spinning, from the quench chamber filament falls through the duct and thread are wound on the bobbins of the take up unit. The winder may have 4 to 6 bobbins on the same bobbin chuck. The winder is having friction drum, grooved drum, bobbin chuck, reversing mechanism, reversing shaft, bobbin push off device, intermingling jets etc.
The pneumatic air operation system will start the winder automatically. With the help of suction gun, operator collects all the threads and will do the threading on the paper tubes. The rotation of bobbin chuck, traversing mechanism, grooved drum and friction drum will build the bobbin properly. While winding the yarns on the bobbins, there are chances to occur the package faults in the bobbins which lead to down grade the packages. It could be due to yarn wrapping on the drum, crushed paper tubes, winder vibrations, poor package build up, hard POY bobbins, broken filaments, loops etc. In this paper, the causes of faults and their remedies are presented.
2.0 Different problems and remedies
2.1 Ribbon formation
Ribbon formation is also called as patterning. Pattern will occur when winds per double traverse is a whole number for surface driven machines. In case of precision winders, when the ratio between rotational speed of package and traverse frequency are in an integral ratio which causes the subsequent to warp on the same point. When successive layers wrapped on the same point, it will lead to pattern formation. Even, there will be an abnormal sound at the time of ribboning, it can also be visualized with the help of Stroboscope by matching the frequency of light with the rotational speed of the package.
Pattern formation can be avoided by use of ant patterning mechanism. In this mechanism, the rotational speed of the drum shall be interrupted; package may be momentarily lifted from the drum.
2.2 Jali Formation
Jali or the net effect is also known a stitching. It is related to the improper tension in the yarn. It may occur due to low or high tension in the yarn. When the yarn falls out of the grooves of the drum, it may cause the slippage of winding layers and lead to jali formation. It is very difficult to unwind the thread from such type of packages. It will generate the winding waste since only choice is to cut the bobbins. Jali may occur in the single bobbin or all bobbins of the one winder or it may occur in all positions. Following actions may be taken to avoid jail formations
o Check the yarn guide for any accumulation
o Yarn path must be straight
o Check the yarn tension
o Change the TG
o Check the reversal point on the grooved drum
o Clean the surface of the grooved and friction drum
o Adjust the pig tail guide properly
o Check timing belt
o Spin finish oil level
2.2 Yarn wrapping on the drum
Two drums i.e. grooved drum and plain drum may get sticky deposits on their surfaces. It could be due to spin finish, monomers which cause yarn wraps on the drum. To avoid the yarn wrapping, both the drums should be regularly cleaned. Spin finish oil may also cause the deposits on the drum. It is suggested that silicon free water can be used while preparation of spin finish oil.
Yarn warps may also cause due to spin out, broken traverse guides, damaged paper tubes, improper spin finish oil preparation.
2.2.1 Crushed paper tubes
High tension in the yarn may leads to paper tube crushing. The reuse of paper can lead to also the same problem. Before reuse the condition of paper tube must be checked. The proper tension is to be adjusted in the yarn depending upon the winding speed and single yarn strength.
Winders must be checked for vibrations periodically and any excessive vibration should be removed and rebalanced by balancing machines.
2.2.3 Poor package build
The bad package build could be due to the tension variations in the all packages of the same winder. Equal tension must be adjusted by adjusting the pig tail guide.
2.2.4 Hardness of POY bobbins
When the winder pressures are not adequate, it may lead to hard packages. By the adjusting the over feed, it can be avoided.
2.2.5 Broken filament
BF may occur due to fault in the spinning. When few filaments present out of the spin finish applicator guide, would lead to BF. Also check the oil reaches properly to the tip of the guide. When any hole of spinneret blocked, spin out/BF will occur. In this case, change the pack. Scrapping of spinnerets will also reduce the chances of BF
2.3 Poor uster values
When spinning without godets, the grooved drum of winder imposes a shot term fluctuations on the POY. The frequency of this wave is that of the traverse frequency of the traverse mechanism. When the yarn runs out of the groove or at the reversal point may cause the variation in the uster value. The cv% of the Uster depends upon the over feed rate, spin finish type and OPU%.
The loop will occur in the POY bobbins. It could be due to grooved drum, spinneret, and traverse guide. To avoid loops in the packages, check the groves of the drum, fix TG properly, change pack etc.
The take up unit of the melt spinning is an important part of the entire melt spinning line for winding of good packages. The good buildup of bobbins will decide the smooth unwinding of the thread in the next processes like texturing and twisting. The package faults like ribbon and jali will downgrade the quality of package. Moreover, it leads to breaks and waste generations. Proper settings, maintenance and control can avoid the faults in the packages. Proper housekeeping and material handling will also avoid the incidence of package faults.
1. Authors work experiences in the Rajasthan Petro Synthetics Ltd Udaipur on Barmag POY line.