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Fasciated yarns - A revolutionary development?

Article · January 2001

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William Oxenham
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 Volume 1, Issue 2, Winter 2001

FASCIATED YARNS – A REVOLUTIONARY DEVELOPMENT?

William Oxenham, Ph.D.

North Carolina State University

ABSTRACT

While Vortex Spinning is hailed as a revolutionary new technology it can also be viewed
as a natural development in the technology of fasciated yarn production. From the
earliest inception of fasciated yarns it was evident that there were limitations, which
precluded its wide acceptance. From an understanding of the factors behind these
limitations it has been possible to institute developments that have ultimately resulted in
the present MVS system, which is being predicted to have profound impact on the cotton
spinning industry.

KEYWORDS: spinning, vortex spinning, jet spinning, fasciated yarns, MJS, MVS

INTRODUCTION

The idealized structure of a fasciated yarn,

which is shown above, consists of a core of
parallel fibers held together by wrapper
fibers [8]. The wrapper fibers and the core
are composed of the same staple fiber
material. If the structure of the yarn is the
method adopted for characterizing this
spinning system, then several different
spinning machines, which have had varying
levels of industrial acceptance, can be
included in this group. These are:
• DuPont Rotofil
• Toray AJS
• Toyoda TYS
• Howa FS
• Murata MJS, MTS, RJS, Vortex
• Suessen PLYfil
• Fehrer DREF 3?
Figure 1
1 JTATM
Volume 1, Issue 2, Winter 2001
This yarn structure offers many potential and a take up unit. Automation, in the form
advantages, one of the most important being of stop motions, automatic piecing,
that since no real twist is present in the final automatic doffing, yarn clearing and
yarn it should be possible to achieve high monitoring of process and product quality,
production rates. The potential of using twist enhance the commercial application of the
transference (see Figure 1) to create this spinning system. However, the most
“new” yarn structure was first promoted by important factor determining the success of
Du Pont in their early patent (Figure 2), a fasciated spinning system is the ability to
which utilized an air-jet to false twist the afford some control over the quantity and
yarn [5]. While there were several distribution of wrapper fibers created on the
publications concerning possible merits of yarn surface, since this ultimately controls
the yarns produced, this system achieved yarn quality [2,3].
little commercial success.
JET SPINNING

The introduction of Murata Jet Spinning

(Figure 3) seemed to address the issue of
wrapper fiber distribution, since the use of
two contra-rotating jets promotes better
wrapping by ensuring later capture of the
edge fibers. This effect is clearly shown in
Figure 4 [6], which compares single jet, two
jets twisting in the same direction (dual jets)
and two contra-rotating jets (twin jets - as
with MJS). While this appeared to offer a
Figure 2 [5] solution to the control of wrapper fibers and
DUPONT SYSTEM thus yield stronger yarns it is evident from
Figure 5 that there are still problems
associated with jet spinning [12].

Figure 3
MURATA MJS Figure 4 [6]
The basic requirements of a successful
spinning machine for fasciated yarn include
good drafting system, false twisting device
2 JTATM
Volume 1, Issue 2, Winter 2001
 Figure 5 [12] Figure 6 [10]

It is clear that the tenacity of the yarns

appear to be influenced by both the yarn
count (coarser yarns are much weaker) and
by the fiber type (polyester and polyester
blends are stronger than cotton).

An obvious suggestion may be that

improvements in the quality of cotton may
lead to improvements in the strength of jet
spun. Research in this area using a wide
range of combed cotton fibers yielded
surprising results as can be seen in Figures 6
and 7 [9,10]. These are samples of many
such results that appear to indicate that Figure 7 [10]
strong, long, fine cotton fibers give weaker
jet spun yarns. The explanation to this
seeming paradox is that the properties of the
cotton fibers used showed very strong Explanations to this behavior can be seen in
correlation between the individual fiber Figures 8 and 9. Edge fibers ultimately
properties and thus the finest fiber also produce wrapper fibers, which in turn
happened to be the longest and exhibit the promote yarn strength. However the number
highest tenacity. of edge fibers is obviously restricted to those
fibers at the outside and this is independent
If the results of Figures 5 and 7 are of the total number of fibers (Figure 8).
considered together it is clear that they hold
some of the same information, which is that Thus, as the number of fibers in the yarn
jet spinning seems to be sensitive to the increases the percentage of wrapper fibers
number of fibers in the yarns cross section decreases and thus yarn tenacity declines.
(this obviously increases both for coarser An additional feature, which is deliberately
yarns and for finer fibers). exaggerated in Figure 9, is that the wrapper
fibers' wrapping length declines, as the yarn
becomes coarser.
3 JTATM
Volume 1, Issue 2, Winter 2001
 Figure 8

Figure 10 [7]

Figure 9

While the above offers an explanation

concerning the fibers in the cross section it
fails to address the issue of fiber type and in Figure 11 [1]
particular "why can polyester be spun and
not cotton?" responsible for the yarn strength [7].
Analysis of different yarns indicate that
A possible reason was thought to be while there are differences in the incidence
associated with the yarn structure and that of different classes of wrapper fiber, one of
there may be differences between cotton and the most significant differences between
polyester in the number and type of wrapper polyester yarns and cotton yarns is the
fibers. While the idealized structure of jet length of the class 1 wrappers. It is clearly
spun yarns is a core of staple fibers shown in Figure 11 that the stronger
reinforced by wrapper fibers, examination of polyester yarns have much longer wraps
actual yarns show that the structure is much than the significantly weaker cotton yarns
more complex. Although there is no single [1].
structure associated with these yarns four
different categories of structure can be From the above analysis of jet spinning it is
identified and these are shown in Figure 10. clear that there are shortcomings in the
It is believed that “class 1” structure (tightly system. Indeed it can be inferred from the
wound wrapper fibers) is primarily above, that in order to spin acceptable
4 JTATM
Volume 1, Issue 2, Winter 2001
quality yarns from cotton, two
improvements are required. These are:
more wrapper fibers;
longer extent of wrapper fibers;
both of which should result in higher yarn
tenacity. Efforts have been made to modify
jet design in order to increase the tension on
the wrapper fibers during yarn formation,
which should yield longer and tighter wraps.
These have met with limited success with
greater benefits being achieved for finer
yarns.

VORTEX SPINNING Figure 12

Increasing the number of wrapper fibers
requires a re-examination of the original
concept shown in Figure 1 and the problem
identified in Figure 8. Simplistically it is
evident that the only way to increase
wrapper fibers is to increase edge fibers, but
this is not possible in the set up shown, since
only the outside fibers in the plane of the
drafted strand are “edge fibers”. However it
is also logical to assume that changing the
system from ”two dimensional” to “three Figure 13
dimensional” offers the possibility of
dramatically increasing the number of edge
fibers and hence the number of wrapper seen if small sections of the yarn are
fibers. This scenario is shown schematically untwisted. The results to date have shown
in Figure 12 [11]. that the amount of “untwisting” required to
reveal the yarn structure, varies considerably
Examination of literature associated with along the length of the yarn. Figure 14
Murata Vortex Spinning reveal that the three shows a typical photograph of a cotton
dimensional approach is being pursued. vortex spun yarn and Figure 15 shows an
While the components shown in Figure 13 is example of an untwisted sample. In the latter
only part of a much more complex set up, it is easy to differentiate the core (which is
there are obvious similarities between the now twisted due to the untwisting action to
schematic in Figure 12, and Figure 13 which prepare the samples) and the wrapper fibers
is from a US Patent concerning Vortex (parallel strand unwound from the yarn
spinning. If the system functions as core).
illustrated it should yield not only many
more wrapper fibers, but these fibers should
also have greater wrapping lengths.

Recent analysis of the general structure of

Vortex yarns, indicate that they are quite
different from Jet Spun yarn in respect of the
proportion of wrapper fibers. While there is
no unified structure, there is evidence of a
definite two-part structure, which is clearly
5 JTATM
Volume 1, Issue 2, Winter 2001
 are the primarily the product of parallel core
fibers [13].

TENACITY AND ELONGATION OF MVS & MJS YARNS

25
MVS (CN/tex)
MJS (CN/tex)
20
MVS (E%)
MJS (E%)
15

10

Figure 14 5

0
0 10 20 30 40 50 60 70 80 90 100
PERCENTAGE OF POLYESTER IN BLEND

Figure 16

CONCLUSIONS

It thus seems that from the original concept

of twist transference to produce a fasciated
yarn, there has been a gradual development
Figure 15 in the technology up to the current time
where we are on the threshold of a major
launch of Vortex Spinning. The road from
There is little independent data on the the original DuPont set up to the Vortex
properties of the yarn due to the proprietary system has been viewed as an evolution
nature of most of the research carried out to since, at each stage, sources of problems and
date. Figure 16 is an extract of data obtained limitations have been determined and
from a comparative study of vortex and jet elegant solutions have been found. While jet
spinning using different polyester cotton spinning was a major improvement over
blends but with the same raw material feed other fasciated systems it still was limited in
to each machine. The same yarn count was areas of application. Vortex spinning
spun on both machines (20 tex) at represents the next logical development and
production speeds of 200 m/min for Jet, and there is no doubt that experience gained with
350m/min for Vortex. It is apparent that the the system and ongoing refinements in
Vortex yields greater tenacity advantage as component design, will lead to potential
the cotton content increases. While data was improvements in both yarn quality and
not available for 100% cotton this was due productivity. Indeed if it realizes the
to problems in material preparation and potential being claimed, it will represent a
there are many reports that acceptable major breakthrough in spinning technology
quality yarns can be produced from cotton as we enter the new millennium.
fibers using Vortex spinning [4]. It is also
evident from the data that the extension at ACKNOWLEDGEMENTS
break for the Vortex yarn is lower than the
Jet spun yarn and this would be expected The author is grateful to the many graduate
from a structure where the tensile properties students who have worked with him in the
6 JTATM
Volume 1, Issue 2, Winter 2001
 area of yarn technology and upon whose 10. Oxenham W., "The Influence of Fibre
research the above discussion is based on. Properties in Air Jet Spinning", Indian
Significant contributions were made in this Journal of Fibre and Textile Research,
respect by: M. Miao; S. Puttachaiyong; A.P. vol. 17, Dec., pp. 194-200, 1992
Tembo; A.H. Noor; A. Basu; O. Ersoy; G. 11. Oxenham W., "Vortex Spinning - A
Basal. Natural Evolution", Proceedings of EFS
Conference, Spartanburg, pp. 1-8, [CD-
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7 JTATM
Volume 1, Issue 2, Winter 2001

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