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Analysis of Fiber-Particle-Airflow Interaction and Its Application to the Development of a
Novel Card-Spinning System
Investigators: Youjiang Wang (leader), Mary Lynn Realff, Wallace W. Carr, Radhakrishnaiah
Parachuru, J. Lewis Dorrity, Fred L. Cook, Xi Chen (Georgia Tech)
Bhuvenesh C. Goswami, David A. Zumbrunnen (Clemson)
Students:
Jimmy Chowdhury, Jen-te Yu, Mandy Kratus, Shumin Zheng (Georgia Tech)
Kai Liu (Clemson)
PROJECT GOAL
The goal of this project is to create the fundamental knowledge needed to develop more efficient
machines and novel processes that can potentially decrease the number of process steps by a
factor of 2 to 3 in short staple yarn manufacturing.
ABSTRACT
Currently, the process sequence for short staple yarn manufacturing involves about ten individual
steps. To develop more efficient machines and novel processes that can significantly shorten the
processing line, we are currently conducting research in the following two interrelated areas: (1)
To analyze the motion dynamics of fiber clumps and particles in an airflow field, especially the
effect of flow pattern and barrier arrangements on fiber opening, trash removal, self-leveling, nep
formation, and fiber loss in opening, cleaning and carding; and (2) To develop a single-step
process (Card-Spinning) to incorporate multiple spinning heads into a carding unit. This will
require a fundamental analysis and understanding of web uniformity monitoring, measurement,
and regulation, web division, and feeding of web ribbons into yarn spinning heads positioned at
the front end of the card.
Since the start of the project in May 1998, we have conducted a state-of-the-art literature survey
on airflow in yarn processing, card web uniformity monitoring and control, fiber web transport,
and high speed yarn spinning. Literature on current processing machinery has also been studied.
We have met with industrial partners to discuss the interactions necessary to make the project
successful. Studies are underway on experimental and theoretical analysis of air flow, web
uniformity detection, and spinning head design.
INTRODUCTION
In the past decades, yarn manufacturing has transformed from a labor intensive operation to a
capital intensive one. Within this century, the operator productivity has increased by three orders
of magnitude, as a result of a series of innovations, as illustrated in Figure 1. The new
technologies also bring products that have different characteristics from the traditional process,
one example being the different yarn structures obtained from ring, rotor, and airjet spinning
technologies.
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Productivity, g/spindle-hour
filament texturing
1000
open-end spinning
100
ring spinning
10
mule spinning
1
1700
hand spinning
1800
1900
2000
Year
Figure 1. Illustration of Technological Innovations in Yarn Spinning
Some generic approaches toward technological development include:
1. Extrapolation of process speeds in traditional manufacturing methods (e.g., increasing
speeds)
2. Innovative modification of current processes (e.g., decoupling or coupling of
processes)
3. Development of radically different methods of manufacturing traditional products
(e.g., friction spinning)
4. Development of radically different products to replace conventional fabrics (e.g.,
nonwovens)
In this project, we are exploiting the first three approaches to make individual processes better, to
couple carding and spinning processes, and to explore new designs for making staple yarns.
Staple yarn manufacturing involves four essential operations: fiber separation, parallelization,
attenuation, and consolidation. The manufacturing process must produce quality products
consistently and economically. Currently, several machines (about 10) in sequence are needed for
these tasks. We have obtained descriptions of machinery from the leading manufacturers.
Although the systems differ, they typically include the following machines in sequence for a
carded yarn:
Bale opener
Coarse opener/cleaner
Blender
Intermediate opener/cleaner
Fine opener/cleaner
Card
Draw frame (breaker drawing)
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Draw frame (finisher drawing)
Yarn formation (e.g., roving and ring spinning, rotor spinning, airjet spinning, etc.)
The need for such a long processing sequence is due to the four essential operations involved. If
a machine can be improved so as to accomplish multitasks, this may eliminate the need for one or
more machines in the sequence. For example, the drawing process is to enhance fiber blending,
parallelization, and sliver uniformity. In some rotor spun yarn processes drawing has been
eliminated through the use of cards equipped with effective autolevelers.
Although the productivity of current manufacturing systems continues to increase, further
developments require a better understanding of the fundamental principles of the processes. This
includes analyzing the motion dynamics of fiber clumps and other particles in an airflow field, and
developing a single-step process (Card-Spinning) to convert fiber batt directly into yarns.
OPENING AND CLEANING
The opening and cleaning process is the first part in a staple yarn manufacturing line. It opens
fiber bales into small tufts, removes most of the impurities, and blends fibers together. Airflow
plays a very important role in determining the efficiency and quality of the opening/cleaning
operations. Fiber opening, cleaning, and transport in the opening and cleaning processes are
achieved through interactions among airflow, inertia forces, gravity, fiber/particle configurations,
barrier arrangements (mote knives, grid bars, plates, etc.), beating actions, carding actions, among
others. Although some studies have been conducted in this area (e.g., [1] on opening and
cleaning and [2,3,4] on carding), the depth has been limited due to the complexity of the problem.
In our discussions with the machine manufacturers, we have tried to learn about the processes and
tools used to design the machines. Despite that few papers appear in recent literature on air flow
in opening and carding, effective use of airflow to assist fiber opening and cleaning can be found
in the latest machines such as the Trutzschler CLEANOMAT cleaners, Rieter cleaners, as well as
in devices like heavy particle extractor, deduster, condenser, and chute feeder. With the
availability of modern tools such as computational fluid dynamics (CFD), computational solid
mechanics, and fluid flow visualization using high-speed videography, a better understanding of
airflow in yarn processing is possible. We are building simulation models using the FLUENT
CFD software to analyze the fluid flow in cleaners and other devices. Figure 2 illustrates the
static pressure distribution and airflow streamlines in a heavy particle extractor. Airflow
acceleration, deceleration, and flow separation (vortices at A and B) were observed. The flow
pattern changes as fibers and particles are introduced in the flow, as the movement of solid
particles is affected by the air drag and their own inertia. Because air, fibers and trash particles do
not accelerate or decelerate at the same rate, these components may be separated in a properly
designed flow field. To complement the analytical studies, experiments on actual machines and on
laboratory models will be conducted to verify the results.
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Figure 2. Static pressure distribution and streamlines in a particle extractor
CARDING
In a traditional process, carding individualizes fibers, removes fine impurities and neps, and forms
a sliver. We are also developing a novel process (Card-Spinning) by incorporating multiple
spinning heads on the carding machine itself. This single machine will replace the card, two
drawframes and the yarn-spinning machine. The elimination of the drawing processes makes it
necessary for the card to assume additional responsibility in fiber alignment and straightening, and
in mass regulation. To achieve this, the airflow analysis will be extended to study the interaction
among fibers, airflow and cleaning/carding elements of the card. This along with improved card
clothing design, altered speeds and settings, and superior mass regulating devices in the card
should lead to better longitudinal and transverse web uniformity.
The research team has completed a literature survey, contacted several instrumentation vendors,
and conducted preliminary tests in an effort to identify instrumentation and techniques for
determining card web uniformity in the cross and machine directions for web produced by current
carding machines [5,6,7,8,9]. The technique for measuring card web uniformity must be capable
of determining card web uniformity in the cross and machine directions for webs produced by
current state of the art carding machines. The system should also be capable of measuring higher
areal densities than produced on today’s cards since the new process may require a heavier carded
web. We have evaluated several methods that have the potential for measuring card web areal
density. These include: beta gauge, gamma gauge, capacitance, laser scanning, image analysis,
fiber optics, ultrasound infrared absorption, and Video Image Analysis. These methods are
summarized in Table I.
Our study using Video Image Analysis indicates that this technique to measure the areal density in
light-weight webs has possibilities. Initial results show that using reflected light with proper
calibration may be sufficient to indirectly measure weight by analyzing the pixel values form the
card web. This will require careful calibration to correct for non-uniformity in illumination. Our
first step is to develop the correlation between pixel intensities and actual weight for a given
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TABLE I. Techniques with Potential for Measuring Card Web Uniformity
Method
Beta Gauge
Gamma
Gauge
Capacitance
Laser
Scanning
Image
Analysis
Fiber Optics
Ultrasound
Infrared
Absorption
Principle
Atomic
absorption and
scattering of
beta radiation
Atomic
absorption and
scattering of
gamma
radiation
Bulk dielectric
properties
Applicable
areal weight
Reflectance:
5-50 g/sm
Transmittence:
>50 g/sm
Advantages
•
Accurate and
repeatable
Disadvantages
•
•
•
•
Reflectance:
5-50 g/sm.
Transmittence: >
50 g/sm.
•
•
Accurate
measurements
for >50 g/sm.
•
Transmittence
and intensity
detection of
HeNe laser
beam
Reflected or
transmitted light
with a digitized
camera
Usage of
reflectance with
optical fibers to
determine
thickness
Areal density <
45 g/sm
•
Time dependant
thickness
measurement
with reflectance
of ultrasound.
Molecular
Absorption by
chemical bonds
at specific
wavelengths
•
•
Detectable range
is yet to be
determined
•
•
Detectable range
is yet to be
determined
•
Areal density >
5 g/sm.
More accurate
for thicker webs
(>50 g/sm).
Areal Density >
3 g/sm
•
•
•
•
Uses nuclear
radiation.
Scans rate may not
be sufficient.
Very expensive
Poor accuracy for
organic materials.
Very expensive.
Uses nuclear
radiation.
Ineffective for
lightweight (5-50
g/sm.) webs
Accurate readings
for slivers.
Inexpensive
•
Less then 2% error
for webs less then
45 g/sm.
Not as expensive as
beta/gamma gauges
Inexpensive
Simple setup.
•
Poor accuracy for
webs with areal
density > 45 g/sm
•
Attempted analysis
of basis weight has
been unsuccessful.
Relatively
inexpensive
($1500/unit)
•
Better accuracy then
fiber optics
Fairly inexpensive.
•
Material thickness
≥ 1.3 mm required.
Not accurate for
materials with high
transmissivity and
low reflectivity and
diffuse surface,
e.g., a carded web.
Results are affected
by surface angle,
surface roughness,
and temperature.
Accurate and
repeatable (within
5%) measurements.
Affordable testing
equipment.
•
•
Reflectivity tests
are not as reliable
as transmission
tests.
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Web Weight (grams /m 2)
20.00
15.00
10.00
5.00
0.00
10.00
12.00
14.00
16.00
18.00
20.00
Sum of Pixel values (thousand)
Figure 3. web weight versus camera pixel value
fiber. Since the color of the fiber would also affect the reflected light, an absolute measure is not
possible using this technique if visible light is used. It may however be an excellent means of
measuring relative densities, which could be used for control. Figure 3 illustrates the test result of
web weight versus camera pixel value with static samples and an array camera. Although a clear
correlation can be observed, the coefficient of correlation R2 (0.74) is not very high due to nonuniform illumination. Correcting for these non-uniformities should significantly improve the
correlation. On-line implementation on a card would require a line-scan camera and a line source
of light.
The video image analysis technique may possibly be applied using infrared (IR) radiation. We
have investigated the effects of web basis weight of on the IR transmissivity and reflectivity
properties of the web. The infrared range studied was from 0.66 to 20 micrometers. We tested
four pieces of polyester card webs, each with a different areal density, ranging from 4.8 to 21.8
g/sm. The results clearly showed that as the areal density of the web increased, reflectivity
increased and transmissivity decreased for almost all wavelengths. As would be expected, IR
absorbency of the web also went up as the areal density increased. The magnitude of variation in
transmissivity with areal density was larger than for reflectivity. While transmissivity varied from
30 to 70 percent, reflectivity changed from 5 to 15 percent. Transmissivity tests were also
repeatable with more precision than reflectivity tests.
Once a suitable web monitoring device is identified, it will be modified and installed on a card for
online operation. After testing for effectiveness, this will be coupled with a suitable mass
uniformity regulating device to control the web mass uniformity in both the machine and cross
directions.
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YARN FORMATION
In a traditional staple yarn spinning system, fibers are opened and or cleaned, carded, drawn and
reduced to a stand before spinning (twisting). One of the objectives of this project is to design a
system where the short staple fibers in the carded web can be spun directly into a yarn before the
web is consolidated into a sliver. Literature research shows that the only system where the short
staple (cotton type) fibers are converted into a yarn in a shortened process is the one where sliver
(carded and drawn) is processed into a ring spun, a rotor spun or an air-jet spun yarn, thus
eliminating the extra step of drawing and roving.
One of the short staple spinning systems that has achieved commercial success is the air jet
(vortex) spinning system. Most of the published literature on air jet or vortex spinning systems is
in the patent literature and deals with the design of the vortex nozzle [10,11,12,13].
In the design of the vortex nozzle, attention is directed at straightening the fibers, twisting the
bundle, and providing tension and forward motion to the twisted structure with a minimum of air
consumption. The yarns produced have relatively low strength; low compressive characters and
consequently hard feel than the corresponding ring spun yarns. The obvious reasons for such a
behavior are the arrangement of fibers in the yarn structure.
Currently we are concentrating on designing a system where a ribbon from the carded web will be
doffed and delivered to a vortex nozzle where the fibers will be twisted in to a yarn structure and
subsequently delivered through delivery rolls to a winding unit.
The primary effort is being directed at designing a "complex nozzle" where the carded fibers when
fed into the nozzle will be straightened to the maximum achievable extent before being twisted (in
the second part of the nozzle) into a yarn. The design of the nozzle will be such that is will
minimize turbulence in the vortex to achieve maximum twisting efficiency. To accomplish this,
computational fluid dynamics modeling will be use to guide the design process, and a large scale
model sized using scaling laws will be built to enable the observation of fiber movement using a
video camera and a still camera with a stroboscope. A prototype yarn spinning unit will then be
designed, fabricated, and tested in the laboratory.
SYSTEM INTEGRATION
We have analyzed the effect of card web areal density and speed on card-spinning parameters.
The calculations show the effects of changing the card web areal density on card web speed,
required draft, and final yarn speed for three yarn counts of 2’s, 4’s, 10’s and for card web
divisions of 2, 4, 8 and 16. We have varied the mass flow rate of the card from 25 to 150 lb./hr.
Table II shows the analysis for a 50 lbs./hr flow rate with different numbers of web slits and final
yarn count. Web speed for a card producing a one-yard wide web at a mass flow-rate of 50
lbs./hr is approximately 100 yd./min. Depending on the number of splits and draft required to
produce a yarn of specified count, the final yarn delivery speed can vary greatly and may exceed
the exit speed of currently available spinning systems, which is approximately 200 to 450 yd./min.,
as illustrated in Figure 4. It also shows that the web weight has no effect on the yarn delivery
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Yarn Speed vs. # of Web Splits
(for 50lbs/hr mass flowrate)
4,000
120 grains/yd web
3,500
240 grains/yd web
480 grains/yd web
Yarn Exit Speed (yd/min)
3,000
2,500
2,000
1,500
1,000
500
2
4
8
16
# of Web Splits
Figure 4. Effect of number of web splits and web weight on the delivery speed of a 10’s
yarn
speed, although it affects the draft ratio required. This analysis provides a guideline for the
section of processing variables, and possibly points to a need for developing faster yarn spinning
systems that can extend the range of yarns to be produced on the system.
Additional effort is needed to develop technologies to split the web into ribbon strips and to
transport them to the spinning units.
SUMMARY
To develop more efficient machines and novel processes that can significantly shorten the
processing line, we are currently conducting research on the motion dynamics of fiber clumps and
particles in an airflow field and on the development of a single-step process (Card-Spinning) to
incorporate multiple spinning heads into a carding unit. We have conducted a state-of-the-art
literature survey on airflow in yarn processing, card web uniformity monitoring and control, fiber
web transport, and high speed yarn spinning. The project has received significant interest from
the textile and the machinery industries, and we have interacted with industrial partners for
collaborative approaches to make the project successful. Progress has been made in the various
fronts of the project, and the results to date are very encouraging. Continuing effort is underway
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on experimental and theoretical analysis of air flow, web uniformity detection, and spinning head
design.
Table II. Relationship among Web Weight, Number of Splits, Yarn Count, Draft Ratio,
and Yarn Delivery Speed for a 100 lb./hr Flow Rate
Web Weight
grains/yd
Web Linear
Speed
yd/min
60
97.25
120
48.63
No. of Web Ribbon
Splits
Count
Ne
Yarn
Count
Ne
Required
Draft
Yarn Delivery
Speed
yd/min
2
0.276
2
4
10
7.2
14.5
36.2
705
1,409
3,524
4
0.552
2
4
10
3.6
7.2
18.1
352
705
1,762
8
1.104
2
4
10
1.8
3.6
9.1
176
352
881
16
2.208
2
4
10
0.9
1.8
4.5
88
176
440
2
0.138
2
4
10
14.5
29.0
72.5
705
1,409
3,524
4
0.276
2
4
10
7.2
14.5
36.2
352
705
1,762
8
0.552
2
4
10
3.6
7.2
18.1
176
352
881
16
1.104
2
4
10
1.8
3.6
9.1
88
176
440
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1
2
3
4
5
6
7
8
9
10
11
12
13
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