Indian Journal of Fibre & Textile Research
Vol. 20, December 1995, pp. 176-180
A study on measures to reduce infrequent yarn faults attachment
Development of an
A Kanthimathinathan;
M Kathirvel, K Gnanasekar, R Hariharan & K P Chellamani
The South India Textile Research Association, Coimbatore 641 014, India
Received 14 February
1995; revised- received and accepted 1 June 1995
A device has been designed and fabricated to be used at the back zone of ring frame to control the high
incidence ofiong thin faults, particularly at wider back zone settings. Trials conducted with this device show a
significant reduction (about 70%) in long thin and thick faults. Use of this device at the back zone of ring frame
does not affect the yarn evenness. However, Uster thin and thick places show a significant reduction. Mill level
trials also confirm the above findings.
Keywords:
Back zone setting, Classirnat faults, Fault control bar, Roving twist multiplier
1 Introduction
Detailed surveys of the mixing and yarn quality in
more than I()()mills exporting yarns and fabrics have
been done! by CfRAs during 1991-92.As per SITRA
survey, the overall quality of export yarns
corresponds to Uster 57% rating in coarse counts,
70% rating in medium and fine counts and 84% rating
in superfine counts. The various infrequent yarn
faults measured by the Uster Classimat System are
also very high. In coarse and medium counts, the
infrequent faults on an average meet Uster 70%
standards and in fine counts, the fault level
corresponds to as high as Uster 85% standards".
Shah- has shown that long thin faults (H + I) are
manyfolds higher than Uster 50% levels. Best values
of long thick faults (E + F + G) compare well with
Uster 25% levels in most of the cases but the average
values of these faults are worse than even 50% Uster
levels.
Substantial reduction in Classimat faults is
reported to occur" by using a narrow bottom front
zone setting in speed frame. In ring frame, wider top
front zone setting results in excessive Classimat yarn
faults. But, in this study, no mention is made about the
effect of wider back zone setting in ring frame. The
survey" by SITRA on "Measures to produce yarns
meeting international quality standards for export"
has shown that use of wider back zone setting in ring
frame (60-65 mm) and lesser breakdraft (1.14-1.3) is
prevalent in most of the mills covered in the survey. It
has also been observed that wider back zone setting
with lesser break draft improves yarn quality in terms
ofUster imperfections. However, the effect of wider
back zone setting in ring frame on Classimat long
length faults has not been covered in this survey.
Hence, the present study has been undertaken to
study the effect of wider back zone setting in ring
frame on long length Classimat faults, and to suggest
measures to control long length Classimat faults at
wider back zone settings in ring frames.
2 Preliminary Study on the Influence of Back Zone
Setting in Ring Frame on Frequent and Infrequent
Yarn Faults
To reconfirm the influence of wider back zone
settings in ring frame on Uster imperfections and long
length Classimat faults, this study was conducted for
three counts, viz. 30s K, 40s K and 60s K. Evenness
and imperfections at three different back zone
settings in ring frame (Table I) clearly show that there
Table I-Evenness
Count
30s K
40s K
60sK
Back zone
setting
mm
51
55
60
51
55
60
51
55
60
and imperfections
settings
Evenness
at different back zone
Uster imperfections/Itxn)
m
U%
15.6
15.8
15.2
16.1
15.7
15.·2
17.6
17.2
17.1
Thin & thick places
Neps
1218
1262
1034
1272
1138
924
2119
1876
1895
1590
1612
1490
1026
1152
909
2119
2291
2393
KANTHIMATHINATHAN
et af ..
is a distinct trend for the evenness and imperfections
to improve with wider back zone settings in ring
frame. Even though the difference in evenness and
imperfections
at 51 mm and 60 mm of ring frame
setting is not statistically
significant in individual
cases, the difference
becomes highly significant
taking all the counts together. This means that the
improvement
in evenness and imperfections
with
wider ring frame back zone setting is real and
consistent.
In the case of wider back zone setting with optimum
break draft, twist in roving is broken up in a more
gradual
manner which, in turn, helps to avoid
undrafted ends and short slubs in the yarn. If the slub
is of a very high magnitude, it results in end breaks. On
the other hand, if the slub is of a smaller magnitude, it
is incorporated
in the yarn and counted as Uster
imperfections.
However, the large scale adoption of wider back
zone setting in ring frame critically depends on its
influence
in infrequent
yarn faults which are
important from the point of view of the performance
of the yarn in weaving preparatory
as well as during
the weaving
and knitting
processes
and the
appearance and appeal characteristics
of the fabrics.
The long thin and thick faults in yarn at different
back zone settings are given in Table 2. Both long
thick and thin faults increase with wider back zone
setting in ring frame. Between 51 mm and 60 mm of
back zone settings, the increase is rather statistically
significant. The probable reason for the increase in
long thin and thick faults at wider back zone setting
could be the relatively high level of short fibre content
in Indian cottons. The high short fibre content in
Indian
cottons
is supposed
to result in some
uncontrolled
fibre movement in the back zone. This
uncontrolled fibre movement creates mass variations
at the back zone which are extended in length by the
amount of draft in the main zone of the ring frame.
Hence,
these mass variations
are counted
as
infrequent long thick and thin faults.
Therefore,
unless some mechanism/method
is
devised to control the movement of short fibres in the
back zone .and thereby to control the tendency of
Classimat faults to increase with wider back zone
setting, the benefit of using wider back zone setting
towards producing yarns with less imperfections can
not be fully realized.
similar concept may help to control fibre movement
at the back zone of ring frame and thereby to control
the tendency of Classimat faults to increase at the
wider back zone setting. Accordingly, a fault control
bar has been designed and fabricated.
However,
towards optimizing
the configuration
of FCB, 4
different designs were made and their effect on
Classimat faults evaluated. The 4 designs made are
shown in Fig.l.
Exhaustive studies made using 4 different bars
showed that FCB of the type shown in Fig.1 c gives
better results. The results are given in Appendix I.
FCB-I C was used for further large-scale trials. The
positioning of FCB in the drafting zone of ring frame
is schematically-shown in Fig.2. The device consists of
a holder (I) which is clamped to the arm bar of the
drafting system in the ring frame. The holder holds
the long bar (2) which is projected
towards the
drafting system between top arms. The fault control
bar (3) is connected to this long bar with the help of a
setting unit (4). The FCB could be positioned
in
between the middle and back bottom rollers at a
raised level to the line offlow of material. The FCB
extends over the length between the roller stands.
3.] Effect of FCD on Classimat Faults
Using FCB, two counts, viz. 40s K and 40s C, were
produced. 40s Combed yarn was produced with 18%
noil extraction. The major process parameters
are
Table 2-Long
thick and thin faults-at different back zone
settings
Count
Back zone
setting
mm
Long thick faults
(E+ F+G)/Iakh m
30s K
51
55
41
61
511
624
60
88
700
51
55
41
73
60
86
699
794
1180
51
55
61
1450
80
99
2090
2379
40s K
60s K
60
Long thin faults
(HI + II)/Iakhm
3 Design and Development of a Fault Control Bar
(FeD)
In almost all the modern drawframes,an
attachment
movement
177
MEASURES TO REDUCE INFREQUENT YARN FAULTS
is provided at the front zone to control the
of fibres during drafting. Adoption of a
Fig. I-Designs
of fault control bar
178
INDIAN J. FIBRE TEXT. RES., DECEMBER
given in the Appendix II. Classimat long thick and thin
faults for the two counts while using FCB in ring
frame are given in Table 3. In this experiment, ring
frame back zone setting was maintained at 60 mm.
For comparative purposes, Classimat faults without
using FCB in ring frame are also given in Table 3.
At 60 mm setting, while using FCB the long thin
faults decreased by about 80% and the long thick
faults by'about 60% as compared to that obtainable
without using FCB in 40s K yarn. It may be seen from
Table 2 that in medium and fine counts, Classimat
long thick and thin faults, on an average, increase by
about 70% when the back zone setting in ring frame is
increased from 51 mm to 60 mm. Hence, the broad
indication is that the level ofClassimat faults (long
thin and long thick) at 60 mm back zone setting with
FCB is more or less equivalent to that obtained at 51
mm back zone setting without FCB.
1995
In the case of 40s carded yarn, while using FCB the
long thick faults decreased by 75% and the long thin
faults by 40%. The extent of decrease in faults here is
rather low as compared to that in 40s K. This is due to
the fact that the basic level oflong thin faults itselfis
lower in 40s C. This is again attributed to the relatively
lower level of short fibre content in 40s C mixing.
3.2 Effect of FCB on Evenness and Uster Imperfections
It has been established beyond doubt from the
above studies that the introduction of FCB helps to
decrease the Classimat long thin and thick faults
substantially. However, to find out the effect of FCB
on evenness and imperfections, a controlled study
was conducted for two counts and the results are
presented in Table 3. It is evident from this table that
the use of FCB decreases the Uster imperfections
(thin and thick), on an average, by about 50% in
addition to decreasing the Classimat long thick and
thin faults. The effect of FCB on evenness is not
significant.
3.3 Effect ofFCB on Long Leogtb Faults While Using Roving with
Higher Twist Multiplier
Fig. 2-A device for the reduction of long length faults in ring
frame [l-holder, 2-long bar, 3-fault control bar, and
4-setting unit)
Table 3-Effect
Count
Back zone
setting
rom
40s C
1.40
Long thin faults
(HI + lJ)j1akh m
Evenness
(U%)
Imperfections/IOOO m
Thin & thick places
With
FCB
Wihtout
FCB
With
FCB
Without
FCB
With
FCB
5
446
93
13.6
11.6
13.4
11.5
12
60
6
25
60
13
Without
FCB
With
FCB
Without
FCB
With
FCB
1112
428
485
298
668
222
632
208
Uster imperfections/lOOO m
Classimat faultsl1akh m
Back zone
setting
rom
60
23
Neps
of FCB while using roving with higher twist multiplier for 40s K count
Table 4-Effect
Roving
TM
of FCB on classimat faults, evenness and Uster imperfections
Long thick faults
(E + F + G)/Iakh IT.
Wihtout
FCB
40s K
Shah" has shown that the frequency of long thin
and thick faults decreases by about 30% with the use
of higher roving twist multiplier. No draft problems
were observed on the ring spinning machine in the
case of roving material having higher twist levels. It
was, therefore, considered of interest to see the
influence of FCB on yarn faults while using roving
with higher TM. Accordingly, a study was conducted
with a higher roving TM of 1.4 (Count, 40s K,
Thin & thick places
Long thin
Long thick
Neps
WOB
WB
WOB
WB
WOB
WB
WOB
WB
17
15
171
68
1143
453
614
630
WOB- Wihtout bar; and WB-With
bar
KANTHIMATHINATHAN
Table 5-Mill
Mill
No.
Count
Ring frame
back zone
setting
mm
38s
Hosiery
2
3
50s
Carded
warp
60s
Combed
WOB-Without
et aI.. MEASURES
level trials using FCB
Long thick fault: Long thin faults
(Hl+ II)!
(E+ F+G)/
lakh m
lakhm
WOB
WB
WOB
WB
51
24.2
12.5
36.0
12,3
60
45.0
27.0
800
390
60
61.0
10.0
5503
3089
bar; and W~With
bar
Nominal TM, 1.25) and the results are given in Table
4. It is observed that by using FeB, long thin and thick
faults decreased by about 60% in 40s K yarn even
when roving with higher TM is used. It may, however,
be noted that the extent of decrease (60%) in
Classimat faults due to FCB (for roving of higher
TM) is slightly on the lower side as compared to that
obtained while using roving of nominal TM (70%).
However;further studies are required to confirm this
trend.
While using roving of higher TM the imperfections
also decrease (about 60%) due to the incorporation of
FeB in the back zone of ring frame. It is of interest to
note that the extent of decrease in imperfections at
higher level of rovingTM is more or less same as that
obtained in the case of normal roving TM while using
FeB. Hence, irrespective of roving TM (within the
range covered), FCB helps to control long length
faults as well as Uster imperfections.
TO REDUCE
INFREQUENT
yARN
FAULTS
179
ase, probably due to the gradual breaking up of twist in
the roving. However, the Oassimat long thin and thick
faults increase, probably due to the uncontrolled movement of short fibres during drafting.
5.2 The tendency of Classimat long thick and thin faults
to increase at wider back zone setting of ring frame is
controlled by the use of fault control bar (FeB) designed and fabricated at SITRA.
S.3 Use of FeB at ring frame decreased the long thin
faults by 60-80% and the long thick faults by about
70%.
FCB also decreased the Uster imperfections. While
using FCB at 60 mm back zone setting, the various yarn
imperfections, on an average, decreased by about
50%.
5.4
While using a roving of 1.40TM (normal TM, 1.25),
FCB decreased the Classimat long thin and thick faults by about 60%.
5.5
Mill level trials also, by and large, confirm the findings ofSITRA pilot mill studies. In mill level trials, by
incorporating FeB at the ring frame, long thin and
thick faults decreased by more than 50%.
5.6
Acknowledgement
The authors are thankful to MrT V Ratnam, Advisor, SITRA, for guidance throughout this work and to
Mr K Sellamuthu, General Manager, Sree Shanmughavel Mills, Dindigul, for permission to conduct the experiments in their mills and also to use the testing instruments at their R&D laboratories. They are also thankful to two other member mills for conducting trials using FeB at their units and to their colleagues, particularly Mr N Ramakrishnan, in Spinning and Textile Physics Division for help at various stages of this project.
4 Mill Level Trials
To supplement the finding at SITRA pilot mill,
trials were conducted in 3 member mills of SITRA
with and without using SITRA's FCB in ring frame.
References
The counts produced include 38s carded hosiery, 50s I Measures to improve the quality of export yams. A joint report of
carded and 60s combed. The results are given in Table
ATIRA, BTRA, SITRA and NITRA (BTRA, Bombay).
5. It is observed that 60s combed yarn shows substarnial
1992.
2 Seshadri S & Ramakrishnan N, A study on the quality of export
reduction in terms of long thin and thick faults on
yams, SITRA resea~ch report. 36(7) (1991).
incorporation of SITRA's FCB at the back zone of
3 Shah P H, Measures for reducing long thin faults in cotton yams
the ring frame. The extent of decrease is 50-65% in
through appropriate
actions at speed and ring frames.
long thin faults and4O-50o/~ in long thick faults in all .
Proceedings of the 34thjoint technological conference of A TI RA.
the three mills.
BTRA. SITRA and NITRA (ATIRA, Ahmedabad), 1993.
5 Conclusio~
5.1 At wider ring frame back zone settings, the Uster
imperfections, particularly thick and thin places, decre-
53-58.
4 Chellamani P, Kanthirnanthinathan
A & Karthikeyan S,
Measures to produce yarns meeting international quality
standards for export. Mill control report No.7 (SITRA,
Coimbatore), April 1991.
180
INDIAN J. FIBRE TF.XT. RES., DECEMBER 199'1
AppeDdix I-Putiealars
ofabe optimizatioil IriaI ofabe deslp of
FCB
[Count, 30sC; Drafting system- SKF PK 225;Backzone setting
at ring frame, 60 mm; and Break draft,l.3]
Classimat
fault type
Short thick
Long thick
Long thin
Without
bar
4769
64
423
With bar
A
B
C
D
4508
43
340
4495
39
318
4211
35
.247
4369
62
385
Appeadix II-Major
.pMCe18parameten
Process parameter
Card sliver hank, Ne
Comber noil extraction, %
Finisher drawing sliver hank, Ne
Roving hank, Ne
Roving TM
Ring frame back zonesetting"mm
Spindle speed, rpm
40s K
0.15
adopted
40s C
0.15
18.0
0.15
0.15
1.5
1.5
1.25 1.40 1.25 1.40
6Oand7~
---14000"----