Original article
Impact of the ginning method on fiber
quality and textile processing
performance of Long Staple Upland
cotton
Textile Research Journal
2015, Vol. 85(15) 1579–1589
! The Author(s) 2015
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DOI: 10.1177/0040517515569524
trj.sagepub.com
Marinus HJ van der Sluijs1,2
Abstract
With the increased demand for quality and the production of finer, longer and stronger Upland cottons, an increasing
proportion of these cottons are ginned on roller gins to preserve and improve fiber quality. However, although the
benefits of roller ginning on lint turn out and fiber quality are fairly well understood, it is still unclear whether these
improvements translate into improved yarn quality and processing performance. The aim of this research was to compare the impact of saw and roller ginning on Long Staple Upland cotton in a high-production and commercial environment and to evaluate quality and textile processing performance in a commercial textile mill. One field located within the
central cotton growing area of Australia was planted with a Long Staple Upland variety, with a number of round modules
selected at random from the field and processed by a saw and a rotary knife roller gin. There was a significant difference
between the two ginning methods in some of the average fiber results, with the roller ginned fiber longer and more
uniform with fewer short fibers and fibrous neps, as well as stronger with higher elongation. These improved fiber
properties resulted in significant differences in the fine count combed hosiery ring spun yarn produced. On average the
yarn spun from roller ginned cotton was significantly more even with fewer total imperfections, although there was no
significant difference in yarn count, strength, elongation and hairiness. There were also no significant differences in terms
of processing performance, fabric handle, appearance and strength.
Keywords
cotton, ginning, yarn, fabric, quality, fabrication
The purpose of ginning is to convert seed cotton into
cotton fiber, which is a saleable and processable commodity. The process of ginning involves separating the
fiber from the seed, which was historically done by
hand. As this was laborious and slow the process has
since been replaced by machines, with the modern ginning process a combination of thermal, pneumatic and
mechanical processes.1 The layout, size, type and technology of the gin may take on a number of forms,
which depends mainly on the type of cotton grown,
the production and harvesting conditions and economic
factors, as well as consumer requirements.2 There are
essentially two ginning methods, namely saw and
roller.2–7
Saw gins are generally used to process Upland
cotton (Gossypium hirsutum L.) with short to medium
staple length (<1 inch to 1 7/32 inch), whereas roller
gins are used to process Extra Long Staple (ELS) cottons (Gossypium barbadence L.) with longer staple
length (1 3/8 inch).2,5 The production of ELS cotton
as compared to Upland cotton is relatively small,
making up just 3% of the world supply8 and, consequently, saw ginning is the most prevalent gin technology in the world.2–7,9 As the production of ELS cotton
is eratic, decreasing and expensive, substituting ELS
1
2
CSIRO Manufacturing Flagship, Australia
Deakin University, Australia
Corresponding author:
Marinus HJ van der Sluijs, CMF, Pigdons Road, Waurn Ponds, Geelong
Victoria 3216 Australia.
Email: [email protected]
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with less expensive Long Staple Upland (LS) cotton to
reduce manufacturing costs is a growing trend in yarn
manufacturing.10 This trend has been boosted with the
advent of compact spinning, which has allowed mills to
spin finer yarn counts with LS cotton that are normally
associated exclusively with ELS cotton.10–13
With the increased demand for quality and the production of these finer, longer and stronger Upland cottons, an increasing proportion of these cottons are
ginned on roller gins.8 As a general rule roller ginning,
when compared to saw ginning, results in a higher lint
turn out (percentage of weight of lint in bales per
weight of seed cotton in modules) of 1–2%2,7,14 and
as the process is gentler this results in longer and
more uniform staple length, with fewer short fibers
and neps.2–4,6,7,15 However, roller ginned fiber contains
more trash and dust as it is subject to less cleaning than
saw ginned fiber and has a rougher appearance,15 which
can lead to inferior color grades. Also, traditional roller
gins are slower than saw gins, resulting in lower ginning
rates and consequently higher ginning costs.2,14
Nevertheless, it has been estimated that up to 20% of
LS cottons (>1 1/16 inch) are ginned on roller gins,2
with producers receiving up to 2 US cent/lb premium
for the roller ginned LS cotton.2 It has been speculated
that this trend will continue with several producers in
the USA and Africa replacing their saw gins with roller
gins,2,5,6 although it has also been noted that this will in
all likelihood remain a novelty.16
A number of earlier studies17–19 have been conducted in the USA comparing the quality and lint
turn out of saw and roller ginned LS cotton.
Although of interest, these studies are no longer of relevance as they were conducted with cotton varieties
that are no longer commercially available, were
mainly harvested by hand or by first-generation mechanical pickers, ginned by low production gins and
with the fiber quality assessed by obsolete or outdated
classing methods. Later studies15,16,20–25 found that
roller ginned LS fiber was significantly longer, more
uniform and contained fewer neps and obtained
higher lint turn out than saw ginned LS fiber. There
was, however, no difference in short fiber content
with saw ginned LS fiber being stronger and containing
less trash with lower ginning costs than the roller
ginned LS fiber. Surprisingly, despite the improvements
in the fiber quality that was roller ginned, studies20–25
found that generally the yarns produced (16, 22 and 50
Ne carded and 40 and 50 Ne combed ring spun yarns)
by saw ginning were generally more even (lower Uster
U%) with fewer imperfections (thick/thin places and
neps) and stronger than the yarn produced by roller
ginning.
As the production rate of conventional roller gins is
about 20% the rate of saw ginning, more recent
studies26–35 conducted by the United States Department
of Agriculture (USDA) have focused on improving
this production rate. This has resulted in the development of high-speed roller gins, with production rates
(5 bales per hour) almost equal to the production
rate (7 bales per hour) of high-capacity saw gins.2,36
This improvement in the production rate did not
compromise the fiber quality with high-speed roller
gins when compared to saw ginning, producing fiber
with improved length and uniformity, fewer short
fibers and neps, as well as higher lint turn out, but
contained more trash and consequently a lower color
grade. Incredibly, due to inferior color grades, roller
ginned fiber did not generate a higher bale value
under the US loan value, but there are expectations
that spinners would be prepared to pay a premium of
6–12 US cents/lb for high-speed roller ginned fiber
due to its improved fiber properties.28,32 This seems
somewhat unrealistic, taking into account the fact
that previous studies15,20–25,33,34 achieved mixed yarn
results, which makes it therefore still unclear what the
benefits are to the textile industry.
There is considerable interest within the Australian
cotton industry to produce finer, longer and stronger
fibers to keep abreast of new technology and processing
speeds in yarn and fabric manufacture, and to increase
the usage of Australian cotton in the premium yarn
(40–60 Ne)10,13,37,38 market. Although Australia produces predominately Upland cotton, which is ginned
by super high-capacity saw gins,36 at times small
amounts of ELS cotton is produced that is ginned by
traditional rotary knife roller gins.
Although there have been a number of studies conducted to compare roller with saw ginned fiber, the
consequence of this on yarn and fabric quality and processing performance is still unclear. A number of these
studies used nonstandard equipment and processing
stages during ginning, but more importantly there
have been contradicting findings in terms of yarn quality, with the majority of the yarns produced during
these studies not in the premium range. This study is
a more in-depth version of that reported by van der
Sluijs,39 and aims to rigorously compare the impacts
of these two ginning methods in a high-production
system on LS cotton, in terms of fiber quality, and textile processing in terms of yarn and fabric quality and
processing performance. The research was undertaken
using the current commercial LS variety available in
Australia with the ginning performance evaluated on
a commercial scale and the textile processing performance evaluated in a commercial textile mill. The results
of this trial will help assess and quantify the impact of
the ginning method on fiber quality produced in a highproduction system and the consequence on textile processing performance.
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van der Sluijs
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Materials and methods
Seed cotton for this trial was obtained from a prominent grower in Australia who has successfully grown LS
cotton for a number of years and during the 2011/2012
season produced a total of 3731 bales of the current
smooth leaf LS variety, Sicala 340 BRF.40
One field was used in this study as it has grown the
current LS variety two years in succession, which would
ensure that the quality from this field was not diluted by
volunteers. The cotton was produced during the 2011/
2012 growing season (planted in 2011; defoliated, harvested and ginned in 2012) in St George (28 2’3’S,148
34’54’E) in Queensland, Australia. The weather experienced during the season was cold, overcast and wet
(day degrees 10% lower than the long-term average
and 256 mm of rain during boll opening), resulting in
an average fiber yield of 1929.5 kg/hectare (4253.8 lb/
acre). A summary of the field operations employed is
presented in Table 1.
The field was subjected to standard management
practices for irrigated Upland cotton in Australia.
The field was harvested using a grower-owned and
operated John Deere 7760 round module harvester,
according to normal industry practice and manufacturer’s recommendations. A total of 174 round modules were harvested from the field, of which 59
modules were selected at random from the field for
this study. The modules were ginned under standard
commercial conditions at Brighann Ginning in Moree,
New South Wales (NSW) and North Bourke Ginning
in Bourke, NSW. The Brighann gin is a modern Lummus
(Savannah, GA) super high-capacity saw gin. The gin is
equipped with standard drying and seed cotton cleaning equipment, which includes a tower dryer, inclined
hot air cleaner, stick machine, universal Collider dryer,
gravity-fed spiked cylinder cleaner and conveyor distributor, which feeds 4 170 saw gin stands, with
each gin stand followed by one Super Jet and two
SentinelTM lint cleaners (it is standard practice to
have at least three lint cleaning stages after the saw
gin stand), with each gin stand producing 15 (6.15
bales/h-m) high-density bales per hour. The North
Bourke gin is equipped with Consolidated (Lubbock,
TX) rotary knife roller gin stands. The gin is equipped
with standard drying and seed cotton cleaning equipment, which includes a universal Collider dryer,
inclined hot air cleaner, stick machine, gravity-fed
spiked cylinder and conveyor distributor that feeds
the seven roller gin stands, followed by an inclined
cylinder cleaner, equipped with seven spiked cylinders
and one Super Jet cleaner (no standard machinery
sequence after the roller gin stand), with each gin
stand producing 2 (1.64 bales/h-m) universal density
bales per hour. As the seed cotton was harvested
according to normal industry practice and manufacturers’ recommendations, only minimal heat (40–
60 C) was used to dry the seed cotton. Lint turn out
was calculated by the gins as per standard practice
using module and ginned bale weights. Table 2 summarizes the details of modules and ginned bales of fiber
produced by the two ginning methods. The number of
modules processed by the roller gin was less than that
processed by the saw gin due to the distance and cost of
transporting the modules to Bourke.
Classing samples were collected at the gin after bale
formation. Two classing samples, from two opposite
sides of each bale, were collected per bale. Fiber samples from each bale were subjected to manual visual
classing and testing by the High Volume Instrument
at Auscott Limited Classing (Sydney, NSW). Visual
classing assessed the color (color grade), visible trash
(leaf grade) and preparation (degree of smoothness or
roughness of the cotton sample) according to the 2012
grades as established by the USDA.41 Fiber quality
testing was conducted on a High Volume Instrument
model 1000 (Uster Technologies Inc., Knoxville, TN),
which determined fiber upper half mean length (inch),
uniformity, short fiber index, bundle strength (g tex1)
and micronaire (a combined measure of fiber fineness
Table 1. Details of the field size, planting date, harvest aid application dates and ginning date.
Field size (ha)
Planting date
1st harvest aid date
2nd harvest aid date
Harvesting date
Ginning date
83.24
12 Oct
25 Mar
05 Apr
12 Apr
3 May & 21 Sep
Table 2. Breakdown of number and weight of modules, number of bales produced and the gin out turn.
Gin method
Number of modules
Total weight of modules (kg)
Number of 227 kg bales of ginned fiber
Lint turn out (%)
Saw
Roller
36
23
83,740
56,783
146
102
40.2
41.1
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and maturity).42 The above-mentioned quality attributes, with the exception of the short fiber index, are
used by merchants in Australia to value and trade
cotton bales. Fiber samples were also subjected to analysis at CSIRO Manufacturing Flagship (Geelong,
VIC) by the Advanced Fiber Information System
(AFIS) (Uster Technologies Inc., Knoxville, TN) to
determine total neps, fiber neps and seed coat neps
(total neps ¼ fiber neps + seed coat neps), short fiber
content and visible foreign matter.43 The maturity
ratio was determined by the CSIRO Cottonscan instrument44 and Lord’s calculation.45
One 40-foot container containing 51 saw ginned
bales and 46 roller ginned bales was selected at
random from the 248 bales produced and shipped to
India for commercial processing trials. The spinning
trials were conducted at a modern spinning mill situated in the Virudhunagar district in the Indian state of
Tamil Nadu. This mill was chosen as the mill is very
familiar with Australian cotton and is renowned for the
production of high-quality yarns for both the domestic
and international markets. All the bales from the two
ginning methods were processed separately into 50 Ne
combed hosiery ring spun yarns. For this trial the opening, cleaning, carding, combing, drawing, roving and
spinning processes were conducted with the equipment
set initially to the mill’s standard specifications. These
were then optimized to achieve the required quality, as
is accepted practice in high-quality spinning mills.
Production speeds were kept constant throughout the
trial. The combers were set to extract 18% noil.
See Figure 1 for details of the production route and
machine set up.
Fiber samples were collected from all processing
points in the blowroom and at each process through
to roving for AFIS testing. Irregularity (U%) of the
sliver produced by the carding, drawing and combing
machines, as well as that of roving, was monitored.
Yarn evenness and imperfections (thin and thick
places and neps), as well as hairiness, was measured
with a Premier iQ2 LX (Coimbatore, India) evenness
and hairiness tester,46 yarn strength was measured with
a MAG (Coimbatore, India) lea strength tester47 and
with a Uster Technologies AG Tensorapid 3 (Uster,
Switzerland) single yarn end strength tester.48 By multiplying the results from the lea strength tester with the
yarn count, the count strength product (CSP) is determined. To determine whether production levels and
quality standards could be achieved, end breakages
were monitored and recorded during the roving and
spinning process with the yarn cuts during winding
also recorded. Figure 1 summarizes the processing
steps, production speeds and other production-related
details used to convert the cotton into yarn. Eight kilograms of yarn from each gin treatment was knitted on a
24-gauge circular knitting machine into a single jersey
fabric, using a cover factor of 1.24 mm.tex, producing a
fabric weight of 85 g/m2. The fabric was scoured,
bleached and dyed in a winch machine into navy
blue. The dyed fabric produced from the two ginning
methods was tested after conditioning for mass per unit
area,49 bursting strength and bursting distension
(Testex AG, Zurich).50
Average fiber quality was calculated from all the
bales produced by each ginning method. To test for
statistical differences between the two ginning methods,
analysis of variance (ANOVA) in terms of fiber and
yarn properties, as well as processing performance, of
all the fiber and yarn properties was conducted using
Genstat 16.0 (Lawes Agricultural Trust, IACR
Rothamsted, UK). Least significant difference (LSD)
values (5%) were used to separate means.
Results and discussion
Lint turn out
The lint turn out achieved for the roller ginned fiber
was on average 0.9% higher (41.1 as opposed to 40.2)
than that achieved by the saw ginned fiber (Table 2).
Although lower than the average of 2% obtained from
previous studies,16,22,23,26,30 the results from this study
follow the general rule that roller ginning, when compared to saw ginning, results in a higher lint turn out.
Although the lint turn out obtained during this study
was somewhat lower than the expected lint turn out of
42%,40 it was on average 7% higher than that achieved
in previous studies.16,22,23,26,30,33
Fiber quality
By any measure, the quality of the fiber produced by
both ginning methods can be considered as good quality
with all the cotton fiber produced above (i.e. better than)
the Australian base grade. The fiber was visually classified on average as color 11 (Good Middling) or 21 (Strict
Middling) with a leaf grade of 2, which is better than the
Australian base grade of 31-3. Base grade refers to the
grade of cotton that is used by cotton merchants as a
basis for contracts, premiums and discounts. The average results for the upper half mean length of bales
ranged from 1.21 to 1.34 inch (30.81 to 32.13 mm), uniformity ranged from 80% to 87%, short fiber index
ranged from 5.3% to 9.9%, bundle strength ranged
from 28.7 to 34.4 g tex1, elongation from 5.3% to
7.5% and micronaire ranged from 4.37 to 4.84. These
results were all, with the exception of bundle strength,
within the expected ranges for this variety.40
There was a significant difference between the two
ginning methods in terms of the manually determined
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van der Sluijs
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Figure 1. Textile processing route for the production of fiber from the two ginning methods.
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visual color grade, with the saw ginned fiber visually
classified on average as color grade of 11, whereas the
roller ginned fiber was classified as color grade 21, both
with a leaf grade of 2. The saw gin thus produced fiber
that was on average one grade higher (i.e. better) than
the roller gin, and is in all likelihood due to the more
aggressive cleaning equipment (although in this case
SentinelTM lint cleaners were used, which are gentler
than the controlled batt saw-type lint cleaners4) post
saw gin stand, which removes more trash. These results
are similar to those in previous studies24,25,26,30,33 that
concluded that saw ginned fiber were on average one
half to one and a half grades higher than those produced by roller ginning.
There was a significant difference between the two
ginning methods in terms of length, uniformity, short
fiber index, strength and elongation (Table 3).
With an average length of 1.27 inches (31.71 mm) the
fiber produced by roller ginning was on average 0.03
inches (0.40 mm) or one 32nd longer, with better
length uniformity (1.4%) and lower short fiber content
as measured by both the High Volume Instrument and
AFIS (as shown in Table 4). These results are similar to
previous studies that concluded that roller ginned fiber
was on average one 32nd or 0.03 inch longer than saw
ginned fiber with a better length uniformity24–28,30,31,33–35
and better short fiber content,26,30,31,33–35 although
another study concluded that roller ginned fiber contained more short fibers than saw ginned cotton.22,23
There was a significant difference between the two ginning methods in terms of fiber strength and elongation,
with the roller ginned fiber on average 0.7 g tex1
stronger with 0.2% more extension than saw ginned
fiber. The strength results are similar to another
study,35 but are at odds with previous studies that
concluded that there was either no difference between
the two ginning methods28,32 or that the saw ginned
fiber was on average stronger than roller ginned
fiber.24–26,31,34 There was no significant difference
between the two ginning methods in terms of micronaire;
similarly, there was no significant difference in the
maturity and fineness (data not shown) of the fiber
processed by the two ginning methods. These results
were similar to results from a recent study,34 but are at
odds with other studies16,22–26,28,30,31,35 that concluded
that the micronaire values for roller ginned fiber were
on average higher, and with the fiber slightly more
mature35 than saw ginned cotton. It is possible that
the micronaire values of the roller ginned fiber in the
above-mentioned studies were affected by the presence
of trash and dust, as speculated by Wanjura et al.30 and
concluded in a study by Cheng and Cheng.51 The visible foreign matter % (VFM%) of the fiber produced
during this study was significantly lower than previous
studies and thus did in all likelihood not affect the
micronaire readings.
There was a significant difference between the two ginning methods in terms of total and fibrous neps (Table 4).
At an average of 148 neps g1, the roller ginned fiber
had significantly fewer fibrous neps (46 neps g1 or
23%) than the saw ginned fiber, which is in all likelihood due to the fact that the roller ginned fiber was not
subjected to multiple stages of lint cleaning, as is the
case with standard saw ginning. Although the
Table 3. Mean values for upper half mean length, uniformity, short fiber index, bundle strength, elongation and micronaire as
measured by the High Volume Instrument. Relevant probability values from analysis of variance (ANOVA) testing indicate the degree
of significance between the two ginning methods (n.s.: not significant).
Gin method
Length inch
Length mm
Uniformity %
Short fiber index %
Strength g tex–1
Elongation%
Micronaire
Saw
Roller
P-value
1.24
1.27
<0.01
31.50
32.26
<0.01
83.1
84.5
<0.01
8.17
6.75
<0.01
30.9
31.6
<0.01
6.42
6.60
0.006
(n.s.)
4.56
4.56
0.564
(n.s.)
Table 4. Mean values for Advanced Fiber Information System (AFIS) neps, short fiber content (SFC(w)) trash, dust and percent
visible foreign matter (VFM). Relevant probability values from analysis of variance (ANOVA) testing indicate the degree of significance
between the two ginning methods (n.s.: not significant).
Gin method
Total neps g1
Fiber neps g1
Seed coat neps g1
SFC(w) %
Trash g1
Dust g1
VFM %
Saw
Roller
P-value
223
178
<0.01
194
148
<0.01
29
30
0.058
(n.s.)
9.0
7.4
<0.01
38
44
<0.01
262
443
<0.01
0.88
1.07
<0.01
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van der Sluijs
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difference between the two ginning methods was only
23%, the results are similar to previous studies26,29,30,31,35
conducted with an AFIS instrument, which concluded
that roller ginned fiber contained on average 30% fewer
fibrous neps than saw ginned fiber. The lower percentage obtained in this study was in all likelihood due to
the fact that two SentinelTM lint cleaners were used,
which are less aggressive than the traditional controlled
batt saw lint cleaners.4 There was, however, no significant difference in terms of seed coat neps. There was a
significant difference between the two ginning methods
in terms of trash (>500 mm), dust (<500 mm) and visible
foreign matter. The fiber produced by the roller gin on
average contained slightly more trash (6 g1) and dust
(181 g1), which resulted in higher VFM (0.19%) than
the saw ginned fiber. This was expected as the lint
cleaner, irrespective of which type, was specifically
designed to remove any trash remaining in the fiber
after ginning.
In terms of size, there was no significant difference in
nep size between the two ginning methods, with the average nep size of the roller ginned fiber slightly larger
(4 mm) than that of the saw ginned fiber (Table 5).
There was, however, a slight but significant difference
between the two ginning methods in terms of seed coat
nep size, with the average seed coat nep size of the saw
ginned fiber 31 mm, or almost 3% larger than the roller
ginned fiber. There was also a slight but significant difference between the two ginning methods in terms of
trash size, with the trash size of the saw ginned fiber
averaging 42 mm or almost 14% larger than the roller
ginned fiber. It is currently unclear what the reasons
are for these slight but significant differences, with the
carding and combing process removing all seed coat
neps as well as all trash and dust particles.
Yarn quality
The performance and quality results obtained during
commercial textile processing will now be discussed.
Prior to processing, the bales produced by both ginning
methods were opened at least 24 hours prior to processing with bale wrap and straps removed, to allow the
bales to acclimatize. The bales from both ginning methods processed well through the preparation stages and
there was no significant difference in irregularity (U%)
of the sliver produced by the carding, drawing and
combing process and the roving produced (results not
shown). Figure 2 provides an overview of the total neps
for the two ginning methods at the various processing
stages. Although there was a significant difference in
the total nep count for the two ginning methods, the
number of neps in the roving was the same at
23 neps g1. Inevitably, the number of neps increased
during the blowroom stage, but at 40% can be considered to be low.52 As expected, there was a significant
decrease of 69% and 80%, respectively, for the roller
and saw ginned fiber during the carding process, which
can be considered to be average.52 There was no significant difference in seed coat nep results for the two ginning methods at the various processing stages, with no
seed coat neps present in the roving (results not shown).
It is accepted that the opening and cleaning processes,
as well as the carding process, have a considerable influence on product quality, processing performance, productivity and profitability. This study has shown that
modern blowroom and carding machines, which are
well maintained and set according to machinery manufacturer’s recommendations, are capable of intensified
cleaning with minimal fiber damage.
Textile mills are focused on realization (output
versus input) and, as a consequence, many mills install
elaborate systems to capture and accurately record
waste figures from the various processes. There was a
significant difference in the total waste (blowroom to
combing) extracted from the two ginning methods, with
the total trash extracted from the saw ginned fiber
almost 2% less than that extracted from the roller
ginned fiber. The increased waste of the roller ginned
cotton was extracted during the blowroom (0.34%) and
carding (1.51%) process, with the combers extracting
16.2% for both the roller and saw ginned fiber. This
was not unexpected, as the roller ginned fiber contained
more trash and dust as was determined earlier, but is
contrary to recent studies33,34 that concluded that there
was no difference in the amount of waste extracted in
Table 5. Mean values for Advanced Fiber Information System (AFIS) nep and trash size. Relevant probability values from analysis of
variance (ANOVA) testing indicate the degree of significance between the two ginning methods (n.s.: not significant).
Gin method
Nep size mm
Seed coat nep size mm
Total trash size mm
Saw
Roller
P-value
707
711
0.094
(n.s.)
1118
1087
<0.01
292
250
<0.01
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Textile Research Journal 85(15)
Figure 2. Mean values for fibrous neps as tested by the Advanced Fiber Information System (AFIS) at the various processing stages
prior to yarn formation.
Table 6. Mean values for yarn count, strength and evenness. Relevant probability values from analysis of variance (ANOVA) testing
indicate the degree of significance between the two ginning methods (n.s.: not significant).
Gin method CV% count Lea strength CV% lea strength U%
Saw
Roller
P-value
1.7
1.4
0.033
(n.s.)
2550
2525
0.617
(n.s.)
4.7
4.6
0.772
(n.s.)
Thin (–50%) Thick (+50%) Neps (+200%) Hairiness (HI)
11.1 7.1
10.9 5.4
<0.01 0.118
(n.s.)
the blowroom and carding process from roller and saw
ginned fiber.
For average yarn results, yarn count CV% varied
from 2.12% to 1.07%, yarn strength ranged from 2724
to 2380, irregularity (U%) ranged from 11.3% to 10.7%,
in terms of imperfections; thin places ranged from 9 to 2
per 1000 meters, thick places ranged from 63 to 40 per
1000 meters and neps ranged from 68 to 46 per 1000
meters, while the yarn hairiness index ranged from 2.21
to 2.77. The average yarn results for the two ginning
methods are listed in Table 6.
There was no significant difference in the average
yarn count variation (CV%), as well as yarn lea
strength and CV% of lea strength, as determined, in
skein (hank/lea) form. From experience the mill has
identified that the minimum acceptable CSP is 2400.
Although only a limited number of tests were conducted on single yarns, the results (not shown) also
showed no significant difference in yarn strength and
elongation between the yarns produced from the two
53.4
43.1
<0.01
63.1
53.9
<0.01
2.6
2.5
0.604
(n.s.)
ginning methods. These results are at odds with the
results obtained by previous studies,15,33–35 which concluded that the average yarn strength and elongation
for roller ginned fiber was significantly higher than saw
ginned fiber, whereas other studies20,22,23,25 concluded
that the average yarn strength for saw ginned fiber was
significantly higher than for roller ginned fiber. It must
be borne in mind that the above-mentioned studies
were mainly conducted on coarser count carded yarns
that were ring spun and even rotor spun yarns, with
only a limited number of studies conducted on fine
count combed yarns in the premium 40–60 Ne range.
There was, however, a significant difference between
the irregularity and imperfection results for the two
ginning methods. The U% of the roller ginned yarn
was on average slightly but significantly lower, that is,
better, than the U% of the saw ginned yarn. Similarly,
the yarn produced from the roller ginned yarn contained on average 17.2% fewer total imperfections
(thin + thick + nep) than the saw ginned yarn. There
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van der Sluijs
1587
was no significant difference in the average number of
thin places per 1000 meters, whereas the average number
of thick places was 19.2% and the average number of
neps was 14.6% lower per 1000 meters for the roller
ginned yarn. There was no significant difference in the
hairiness values for the yarns produced from the two
ginning methods. These results are similar to the results
obtained by previous studies,15,33–35 which concluded
that the average yarn evenness and imperfections for
roller ginned yarn were significantly lower than for saw
ginned, but are at odds with other studies20–23 that concluded that the average evenness and imperfections for
saw ginned yarn was on average significantly lower than
for roller ginned yarn or that the two ginning methods
did not significantly affect the average yarn evenness and
imperfections, or that the results were mixed and hence
no conclusion could be drawn.24,25 As mentioned earlier,
it must be borne in mind that that the above-mentioned
studies were mainly conducted on coarser count carded
yarns that were ring spun and even rotor spun yarns,
with only a limited number of studies conducted on
fine count combed yarns in the premium 40–60 Ne range.
There was no statistically significant difference
between the two ginning methods in terms of yarn processing performance. The end breaks per 100 spindle
hours during the roving process and spinning were
monitored, with no statistically significant difference
between the two ginning methods (results not shown).
This is similar to the results obtained by a recent
study.34 There was also no significant difference in the
yarn cuts during the winding process, although the
roller ginned yarn recorded on average 17% fewer
cuts per 100 km than the saw ginned yarn.
Fabric quality
For average dyed fabric results, the fabric weight
ranged from 83 to 88 g/m2 and the bursting strength
ranged from 280 to 294 kPa. There were no statistically
significant differences in fabric appearance and handle,
and although the fabric produced from the roller
ginned yarn required nearly 5% more pressure to
burst than the fabric produced from the saw ginned
yarn, the difference was not statistically significant.
Conclusion
There have been a number of studies conducted to compare roller with saw ginned fiber and, although the
benefits of roller ginning on fiber quality are fairly
well understood, the consequence of this on yarn and
fabric quality and processing performance is still
unclear. The aim of this study was to compare the
impacts of these two ginning methods, in a highproduction and commercial environment, on the fiber
quality of LS cotton and to evaluate textile processing
performance in the production of fine count yarns in a
commercial textile mill. Results from this study show
that the lint turn out of roller ginned fiber was on average higher than for saw ginned fiber, and that there
were significant differences between the two ginning
methods in some of the average fiber results. Fiber
that was roller ginned was longer, more uniform, stronger with higher elongation, fewer short fibers and
fibrous neps, and with slight but significantly smaller
seed coat nep and total trash size when compared to
saw ginned fiber. There was no significant difference in
the average results for micronaire, maturity, fineness,
seed coat neps and total nep size. However, the roller
ginned fiber contained on average significantly more
trash and dust and an inferior visual color grade. The
improved fiber properties of the roller ginned fiber
resulted in significant differences between the fine
count combed hosiery ring spun yarns produced by
the two ginning methods. On average, the yarn spun
from the roller ginned fiber was significantly more even
with fewer total imperfections, containing significantly
fewer thick places and neps than the saw ginned fiber.
There was, however, no significant difference in count
variation, lea and single yarn strength, elongation, thin
places and hairiness values of the yarns produced from
the roller and saw ginned cotton. There was also no
significant difference between the two ginning methods
in terms of yarn processing performance, and in fabric
appearance and strength.
The results from this study show that the improvements, due to roller ginning, in fiber quality of LS
cotton do in fact translate into significant improvements in yarn evenness, which is of paramount importance in the production of fine yarns.38 There is,
however, no doubt that the production of traditional
and high-speed roller gins are substantially lower than
super high-capacity saw gins, resulting in higher ginning costs. This, in combination with the penalty associated with lower grades, means that roller ginned
cotton must be sold at a premium. This study will
give textile mills confidence that premiums paid
for this type of fiber will result in the production of
high-quality fine count yarns, which can be used for
the production of high-quality fabrics and garments.
Indeed, private discussions with a number of international textile mills confirm that they would be prepared to pay premiums of up to 6 US cent/lb for roller
ginned LS cotton, if the cotton was slightly finer
(4.2 micronaire) to be able to produce yarns in the 60
Ne count range.
Funding
This work was supported by the Australian Cotton Research
and Development Corporation and CSIRO.
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1588
Textile Research Journal 85(15)
Acknowledgments
The author acknowledges the generous cooperation of Glenn
Rogan for facilitating the experiment on his farm, to
Brighann and North Bourke Ginning for ginning the
cotton, to the Auscott Classing facility for fiber quality testing, to John Lupton from Plexus Cotton Australia for facilitating the trade and shipment of the cotton and to the
management and staff of S.A. Aanandan Spinning Mill.
Thanks also to Robert Long for assistance with statistical
analysis and to Jeff Church for his valuable input and to
Susan Miller for technical assistance.
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