Rotor Spinning Performance Under Some Important Technical Variables with Special Reference to Winding Angle and Package Density

ROTOR SPINNING PERFORMANCE UNDER SOME IMPORTANT TECHNICAL VARIABLES WITH SPECIAL REFERENCE TO WINDING ANGLE AND PACKAGE DENSITY
Author: Iftikhar Ahmad, Nisar Ahmed Jamil and Kamran Saeed
Department of Fibre Technology,
Agriculture Engineering & Technology, Faisalabd, Pakistan 





Abstract
Open end spinning is popular for coarse and average yarn counts for minimum cost of production, better quality and some peculiar end uses. The present study was conducted on Schlafhorst autocoro machines by adjusting variables as rotor speed, twist multiplier and winding angle whereas rotor speed and twist multiplier effect was found significant on yarn characters whereas winding angle effect on package density was significant.

INTRODUCTION
In the process of open end rotor spinning, the loose fibers are fed to the conical inner wall of the rotor with the fibers transferring along the wall into the rotor groove from which they are withdrawn and twisted in a generally orderly manner to form the yarn. The fibers acting in this way form a main strand that can be made by controlling the processing parameters to have characteristics and qualities closely resembling those of ring spun yarn. However, due to the nature of open end rotor spinning all of the fibers do not follow this orderly formation. Rather, some fibers, particularly those that feed to the rotor groove as the revolving draw-off of the yarn formation passes the yarn feed location, do not intertwine orderly with the other fibers but wrap rather tightly around the yarn and have ends that project randomly.

Although rotor spinning is now a well-established manufacturing process, there are problems that must be solved if the full potential of this method of spinning is to be exploited. For example, rotor spun yarns have low tensile strengths due to their structure, which can be improved particularly for medium and coarse count range. In addition to the yarn values, running behavior is of great importance for very high speed rotor spinning, playing main role in its fibres interruption, by the process of fibre separation, but the fibres are recollected on the so-called collecting surface of the rotor as a ribbon, which is then converted into yarn by means of the rotating open end yarn end.

As the technology of rotor spinning has gained popularity because two-third of all the fibres is used in this technology. The latest rotor spinning technology is now being used to spun even low grade cotton for better quality yarn. This spinning technique has further enabled the reduction of handling cost because it is sliver to yarn system in which the yarn is wounded on large package. The capital cost is high and necessitates high-speed operation. Fortunately, the combined cost of power and labor per pound of yarn is lower than that of yarn from ring spinning. The latest generation of the machine allowed the implementation of computer-integrated manufacturing approaches in rotor spinning plants. Yarn manufactured on rotor spinning machines differs from ring-spun yarn in its winding build up and in its unwinding behavior as well. Rotor yarn is less hairy than ring-spun yarn and can be more easily unwounded. However, the rotor yarn has a greater tendency to roll than ring-spun yarn, causing the wound yarn in the edge area of the cheese to be pressed to the outside by the yarn layers above it.

The quality of a package of strand material is determined by several variables the most important being the angle at which the strand is wound onto the package. As a rule, the higher the winding angle, the better package, but there is a maximum angle that can be wound without slippage of the strand at the reversals. The yarn is produced on the package in a cross-wound fashion. The angle between changing the direction of the coils is the angle-of-wind (θ), a measure for the density of the package. The angle of wind mainly depends upon the fibre stock being processed and upon the subsequent manufacturing process of the delivery packages. With smaller angle of wind the individual winds are close to each other; the packages of high density. A large angle of wind produces packages with a low density.

The present study is planned to observe the yarn characteristics improvement on open-end system machines by adjusting some technical variables as machine speed, winding angle, twist multiplier and the effect of winding angle on the package density is also check during process.

Materials and methods
The present research entitled “Rotor spinning performance under some important technical variables with special reference to winding angle and package density ” was initiated in the Department of Fibre Technology, University of Agriculture, Faisalabad and conducted at Bhatti Textile Mills Ltd., Lahore during the year 2007. The details of materials used and methods applied to test the raw material and to measure various quality characteristics described here as under.

Material Used
The raw material was the medium staple cotton collected from the running stocks of the mills. The raw cotton and sliver samples were conditioned in the laboratory at standard atmospheric conditions RH% (65±3%) and Temperature (20±2C°) before testing the physical characteristics.

3.2-Spinning Process
The samples of the raw material were processed in the blow room and carding section under running processing setup & then sliver will be fed to different autocoro machines where the following changes were made, to study their affects on the yarn quality.

The variables selected for their interaction effect on rotor yarn of nominal count Ne=20s were as under:

Rotor Speed
“S”
Twist Multiplier
“T”
Winding Angle
“θ”
S1=80,000
S2=90,000
S3=1,00,000
S4=1,10,000
S5=1,20,000
T1=4.75
T2=4.85
T3=4.95
θ1=30˚
θ2=31˚
θ3=32˚
θ4= 33˚

Yarn Characteristic
After spinning of yarn samples from each treatment combination, following yarn characteristics were tested according to the recommended methods of the committee of American Standards for Testing and Material (1997)

Yarn Count
The yarn count was estimated through “Skein Method”, according to ASTM standard (1997c) with the help of Uster autosorter.

Yarn Lea Strength
Breaking strength of yarn was also determined by “skein Method” recommended by ASTM Committee (1997c) according to standard method by using pendulum type lea strength tester.

Counts Lea Strength Product Value (CLSP)
Count Lea Strength Product value was calculated by multiplying average count with respective average lea strength value of yarn.

Analysis of Data
Completely Randomized Design was applied in the analysis of variance of data for testing the differences among various quality characteristics as suggested by Faqir (2000). Duncan’s Multiple Range test was also applied for individual comparison of means among various quality characters. The data were subjected to statistical manipulation on computer by employing M-Stat microcomputer program as devised by Freed (1992).

Package density (ρ=W/V)
Where W= net weight of package V= volume of package V= π h/12(D2-d2)

Results and discussion

Yarn Lea Strength
The analysis of variance and comparison of individual mean values for yarn lea strength as a result of trialed variables is presented in Table 1 and Table 1a respectively. The results show that the effect of Rotor Speed (S) and Twist Multiplier (T) is highly significant whereas winding angle (q) and all the possible interactions remain non-significant.

Duncans Multiple Range (DMR) test for the comparison of individual mean values at Rotor speed (S) elaborates the range for yarn lea strength from 99.08 to 107.17 lbs, ranking as 107.17, 105.11, 103.07, 101.06 and 99.08 lbs, for S1, S2, S3, S4 and S5 respectively while all the values differ significantly with one another. These results clearly show that there is remarkable effect of change in rotor speed on the yarn lea strength therefore each rotor speed responsible for different lea strength of the yarn. The results clearly reveal that when rotor speed increases the yarn lea strength decreases. The present results are supported by the findings of Haq (2003) who stated that with the increase in rotor speed, the lea strength of the yarn decreases. Likewise, Hanif (2002) claimed that by increasing rotor speed, the yarn lea strength decreases.

Table 1: Analysis of variance for Yarn Lea Strength

S.O.V.
D.F.
S.S.
M.S.
F. Value.
Prob.
S
4
2456.955
614.239
86.2904
0.0000**
T
2
2288.942
1144.471
160.7792
0.0000**
Ө
3
41.945
13.982
1.9642
0.1200N.S
S × T
8
1.181
0.148
0.0207
N.S
S × Ө
12
0.608
0.051
0.0071
N.S
T × Ө
6
0.397
0.066
0.0093
N.S
S × T × Ө
24
0.600
0.025
0.0035
N.S
Error
240
1708.386
7.118


Total
299
6499.016




CV% = 2.59 %       **= Highly significant     N.S = Non-significant

Table 1a: Comparison of individual treatment means for Yarn Lea Strength

Rotor Speed
(S)
Twist Multiplier         (T)
Winding Angle
(Ө)
S1 = 107.17a
T1 = 99.74c
Ө 1 = 102.63
S2 = 105.11b
 T2 = 103.06b
Ө 2 =  103.61
S3 = 103.07c
T3 = 106.5a
Ө 3 = 102.88
S4 = 101.06d

Ө 4 = 103.28
S5  = 99.08e



Any two mean values not sharing a letter in common differ significantly at α=0.05 level of probability.

In case of twist multiplier (T) variation effect the range for yarn lea strength is noted from 99.74 to 106.5 lbs, ranking as 106.5 103.06 and 99.74 lbs for T3, T2 and T1 respectively therefore it is clear that all the values differ significantly with one another. The present results are supported by the findings of Haider (2000) who concluded that with the increase in twist multiplier, the average value of lea strength also increases. Likewise, Mahmood et al. (2004) stated that as the twist factor increases, the yarn lea strength also increases but after a certain optimum level the further increase the twist will cause fibre rupture and strength of yarn suddenly increases. Moreover, Sharma et al. (1987) observed that strength of the yarn increased by increased twist factor.

For winding angle (q), the range for yarn lea strength is found from 102.63 to 103.28 lbs, ranking as 103.61, 103.28, 102.88 and 102.63 lbs and lbs for q2, q4,q3, and q1 respectively and it is clear that winding angle has no effect on yarn lea strength. It is a matter of common fact that the objective of giving proper winding angle to the package forming device is just for a better package structure and appearance. Further more, there are not many stresses on the yarn by changing winding angle during package formation as during the weaving process on warp yarn as an example. Therefore it is quite clear that the winding angle does not affect the yarn lea strength except the package physical condition.

Yarn Evenness (U %)
The statistical analysis of variance and comparison of individual means for yarn evenness (U%) is presented in Table 2 and Table 2a respectively. The results show that the effect of Rotor Speed (S) and Twist Multiplier (T) is highly significant whereas winding angle (q) effect on yarn evenness (U%) and the possible interactions remain non-significant.

Duncans Multiple Range (DMR) test for the comparison of individual mean values for the variable Rotor speed (S) reveals the range for yarn evenness (U%) from 10.54 to 11.61 % , ranking as 11.61, 11.33, 11.06, 10.80 and 10.54 % or S5, S4, S3, S2 and S1 respectively and all values differ significantly with one another. These results clearly show that there is remarkable effect of change in rotor speed on the yarn evenness (U%) therefore each rotor speed responsible for different evenness (U%) of yarn. These results are supported by Khalid (1987) who stated that increase in rotor speed results increase in yarn irregularity. Likewise, Simpson and Louis (1983) who stated that with increasing rotor speed, tenacity at break and elongation deteriorate but irregularity improves.

Table 2: Analysis of variance for Yarn U%

S.O.V.
D.F.
S.S.
M.S.
F. Value.
Prob.
S
4
42.637
10.659
876.4844
0.0000**
T
2
14.281
7.140
587.1465
0.0000**
Ө
3
0.071
0.024
1.9427
0.1233N.S
S × T
8
0.035
0.004
0.3642
N.S
S × Ө
12
0.003
0.000
0.0196
N.S
T × Ө
6
0.001
0.000
0.0190
N.S
S × T × Ө
24
0.003
0.000
0.0089
N.S
Error
240
2.919
0.012


Total
299
59.950





















CV% =1.00 %  **= Highly-significant   N.S = Non-significant
 

Table 2a: Comparison of individual treatment means for Yarn U%

Rotor Speed
(S)
Twist Multiplier         (T)
Winding Angle
(Ө)
S1 = 10.54e
T1 = 10.80c
Ө 1 = 11.06
S2 = 10.80d
T2 = 11.06b
Ө 2 =  11.08
S3 = 11.06c
T3 = 11.34a
Ө 3 = 11.09
S4 =11.33b

Ө 4 =11.05
S5  = 11.61a



Any two mean values not sharing a letter in common differ significantly at α=0.05 level of probability.

Duncans Multiple Range (DMR) test for the comparison of individual treatment mean value under the effect of Twist Multiplier (T) shows the range for yarn evenness from 10.80 to 11.34 %, ranking with mean values recorded as 11.34, 11.08 and 10.80 % for T3, T2 and T1 respectively. These results clearly shows the effect of twist multiplier on yarn evenness (U%). These results are supported by Simpson and Fiori (1975) who expressed that yarn uniformity improves and imperfections decreases when the twist is increased. Also Khalid (1987) stated that increase of twist multiplier increases the U%.

For winding angle (q) the range for yarn evenness (U%) is found from 11.05 to 11.09 %, ranking as 11.09, 11.08, 11.06 and 11.05% for q3, q2, q1, and q4 respectively and it is clear that winding angle has no effect on yarn evenness (U%).

Yarn Hairiness
The statistical analysis of variance and comparison of individual means for yarn hairiness is presented in Table 3 and Table 3a respectively. The results show that the effect of Rotor Speed (S) and Twist Multiplier (T) is highly significant whereas winding angle (q) effect on yarn hairiness and the possible interactions remain non-significant.

Duncans Multiple Range (DMR) test for the comparison of individual mean values for Rotor speed (S) elaborates the range for hairiness from 5.36 to 6.22, ranking as 6.22, 6.00, 5.77, 5.57 and 5.36 for S5, S4, S3, S2 and S1 respectively and all values differ significantly with one another. These results clearly shows that there is remarkable effect of change in rotor speed on the yarn hairiness. These result shows that as the rotor speed increases the hairiness increases. These results are supported by Haq (2003) who stated that with the increase in rotor speed, the imperfections and hairiness increase Likewise, Shahbaz (2000) concluded that the imperfections and hairiness increases as the rotor speed increases.

Table 3: Analysis of variance for Yarn Hairiness

S.O.V.
D.F.
S.S.
M.S.
F. Value.
Prob.
S
4
27.897
6.970
609.9950
0.0000**
T
2
9.419
4.709
412.1632
0.0000**
Ө
3
0.071
0.024
2.0851
0.1028N.S
S × T
8
0.063
0.008
0.6930
N.S
S × Ө
12
0.017
0.001
0.1244
N.S
T × Ө
6
0.001
0.000
0.0124
N.S
S × T × Ө
24
0.076
0.003
0.2769
N.S
Error
240
2.742
0.011


Total
299
40.268






















CV% = 1.85 % **= Highly-significant N.S = Non-significant
 

Table 3a: Comparison of individual treatment means for Yarn Hairiness
Rotor Speed
(S)
Twist Multiplier         (T)
Winding Angle
(Ө)
S1 = 5.36e
T1 = 5.57c
Ө 1 = 5.79
S2 = 5.57d
T2 = 5.78b
Ө 2 = 5.79
S3 = 5.77c
T3 = 6.00a
Ө 3 = 5.81
S4 = 6.00b

Ө 4 =5.76
S5 = 6.22a


Any two mean values not sharing a letter in common differ significantly at α=0.05 level of probability.

Duncans Multiple Range (DMR) test for the comparison of individual treatment mean value under the effect of Twist Multiplier (T) shows the range for yarn hairiness from 5.57 to 6.00 , ranking with mean values recorded as 6.00, 5.78 and 5.57 for T3, T2 and T1 respectively. These results clearly show the effect of twist multiplier on yarn hairiness. These results are supported by Lin et al. (2004) who stated that the twist multiplier affects neither the tenacity nor the elongation but the increase in twist multiplier increases the hairiness. Moreover, Rust and Peykamian (1992) noted that yarn hairiness may be found in one, or of several forms, including fibre ends protruding from the body of yarn, fibres extending from the body of yarn and then returning into the body of the yarns, producing loops, and existence of wild fibres out side the body of the yarn.

For winding angle (q) the range for yarn hairiness is found from 5.76 to 5.81, ranking as 5.81, 5.79, 5.79 and 5.76 for q3, q1, q2 and q4 respectively and it is clear that winding angle has no effect on yarn hairiness.

Package density (ρ=W/V)
The package densities of the yarn package samples produced in the present studies at the trialed wing angles q1=30o, q2=31o, q3=32o, q4=33o were calculated after their representative packages diameter measurement i.e. Diameter of cheese or package D1=240mm, D2=245mm, D3=250mm and D4=255mm respectively.

Where d=60mm h=145mm W=6.25lb

For winding angle q1 the volume will be
V1=6831 cm3
Now ρ1=.416 g/cm3

For winding angle q2 the volume will be
V2=7020.75 cm3
Now ρ2=.404 g/cm3

For winding angle q3 the volume will be
V3=77210.5 cm3
Now ρ3=.394 g/cm3

For winding angle q4 the volume will be
V4=7400.25 cm3
Now ρ4=.384 g/cm3

As we see when winding angle increases the dia of the package increases but the package density decreases. These results are supported by the anonymous (1998) who states that with smaller angle of wind the individual winds are close to each other, the packages of high density. A large angle of wind produces packages with a low density. Likewise, Booth (1983) stated that as the winding angle increase, the density decreases but with decrease of angle of wind the package density increases. Therefore, the overall results about the package density analysis and visual examination revealed that the best one angle of wind q3 is the most suitable for the package structure and appearance. This situation elaborates the importance of the winding angle for an excellent marketable yarn package formation. So it is fact that the excellent quality of yarn may get good or bad influence from its marketable presentation point of view due to proper or improper winding process parameters including winding angle adjustment. Also an excellent yarn package is helpful in fetching the comparative good price in the market because it cause minimum ends down in weaving, knitting or any other proceeding process.

Package density calculation:

Θ=Angle of wind, D = dia of cheese, d = dia of the empty tube

h = width of the package

Package density ´ ρ ´= W/V where w = weight of package

V= volume of package

ρ = W/π h/12(D2-d2)

References:
  1. Anonymous. 1998. Rotor Spinning. The Autocoro Manual: 65-70.
  2. ASTM Committee. 1997c. Standard method for test yarn number (skein method). ASTM Designation. D: 1907-97. Amer. Soc. for Test and Materials, Philadelphia, USA.
  3. Booth, J.E. 1983. Textile progress. Principles of Textile Testing and Quality Control. Newness, Butter worths, London. 3rd Ed.: 427-527.
  4. Freed, R.D. 1992. M. Stat micro computer statistical program. Michigan State, University of Agriculture, Norway-324B. Agriculture Hall, East Lausing, Michigan Luasing, USA.
  5. Haider, M.N. 2000. Study of spindle speed and twist multiplier for different yarn counts with special reference to end-breakage analysis. M.Sc. Thesis, Deptt. of Fibre Tech., Univ. of Agri., Faisalabad.
  6. Hanif, M. 2002. Optimization of rotor speed for different yarn counts spun at BD-200 and RNK open-end system. An M.Sc. thesis Deptt. of Fib.Tech. Univ.of Agri. Faisalabad.
  7. Haq, U. Z. 2003. Interaction study of some rotor spinning machine variables by feeding combed sliver for optimum yarn quality. M.Sc. Thesis, Deptt. of Fib.Tech. Univ. of Agri., Faisalabad: 102.
  8. Khalid. A.S. 1987. Studies for optimum rotor speed on open-end for Pakistan cotton. An M.Sc. Thesis, Deptt. of Fib. Technology, University of Agriculture, Faisalabad: 30-63.
  9. Lin, J.H.,Chang, C.H.,Chen, H.C.,Lou, C.W.2004. Polyester textured yarn fabricated spun-like filament by rotor twister.Indian J. of Fib. and Text. Res.29(3):278-282.
  10. Mahmood, N., N.A Jamil, A.haq, and M.I. Javed 2004. Effect of some mechanical variables in condensed spinning of cotton yarn. . Pak. Text. J. 53(5): 54-55.
  11. Rust, H.P. and S. Peykamian. 1992. Yarn hairiness and the process of winding. Text. Res. J. 62(6): 685-688.
  12. Shahbaz, M. 2000. Influence of sliver weight, rotor speed and opening roller speed upon the quality of open-end yarn. M.Sc. Thesis, Deptt. of Fib.Tech. Univ. of Agri. Faisalabad: 55-62.
  13. Sharma, I.C., N.K. Gupta., B.R. Agarwal and N.R. Patnaik.1987. Effect of twist factor and stitch length of open-end spun cotton yarn on properties of rib knitted fabrics. Text. R. J. 57(2):73-81.
  14. Simpson, J. and L.A. Fiori. 1975. How yarn twist affects yarn Uniformity and Imperfections. Text. R. J. 45(2):136-137.
  15. Simpson, J. and G.L. Louis. 1983. Comparison of different open-end machines fed with slivers from different cottons and cards. Text. Res. J. 53(9): 551-556. 

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