1. No category

Development of Multi-Layer Fabric on a Flat Knitting
Machine
P. Kanakaraj1, R. Ramachandran R1, B.S. Dasaradan2
1
PSG College of Technology, Coimbatore, Tamil Nadu, INDIA
2
Angel College of Engineering and Technology, Tirupur, INDIA
Correspondence to:
P. Kanakaraj email: pkr@fas.psgtech.ac.in
ABSTRACT
The loop transfer technique was used to develop the a
splitable multi layer knit fabric on a computerized
multi gauge flat knitting machine. The fabric consists
of three layers: inner-single jersey, middle-1X1 purl
and, outer-single jersey. By varying the loop length
the multi layer knit fabric samples were produced,
namely CCC-1, CCC-2 and CCC-3. The above multi
layer fabrics were knitted using 24s Ne cotton of
combined yarn feed in feeders 3, 4, and 4
respectively. The influence of loop length on wpc,
cpc and tightness factor was studied using linear
regression. The water vapor and air permeability
properties of the produced multi layer knit fabrics
were studied using ANOVA. The change of raw
material in three individual layers could be useful for
the production of fabric for functional, technical, and
industrial applications.
Garments made of plant branch structured knit
fabrics facilitate the transport of sweat from the skin
to the outer layer of the fabric very fast and make the
wearer more comfortable. Qing Chen et al [3].
reported that the branching knitted fabrics made from
different combinations of polyester/cotton yarns with
varying linear density and various knitted structure
produced in rib machine improved water transport
properties. The Moisture comfort characteristics of
plated knitted fabric was good, reported by the
authors findings from three layer plated fabric of
cotton (40s), lycra (20 D) and superfine
polypropylene (55 dtex/72 f) was used as a raw
material in face, middle and ground layers
respectively [2]. The applications in wearable
electronics for the multilayer fabric are wider. Novel
multi-functional fibers structure include three layered
knit fabric embedded with electronics for health
monitoring. The knit fabric consists of 5% spandex
and 95% polypropylene in – 1stlayer, -2nd layer
composed of metal fibers to conduct electric current
to embedded electronics + PCM and the 3rd layer is
composed of highly hydrophilic cotton [1]. In flat
knitting, two surface (U-,V-,M-,X- and Y-shaped)
and three surface layers (U-face to face, U- zigzag
and X-shaped) spacer fabric were developed from
hybrid glass filament and polypropylene for light
weight composite applications [5]. H Cebulla et al [7]
produced three dimensional performs like open
cuboid and spherical shell using the needle parking
method. The focus was in the area of individual
needle selection in the machine for the production of
near net-shape performs. The multi layered sandwich
knit fabric of rectangular core structure (connecting
layer: rib), triangular core structure (connecting layer:
interlock), honeycomb core structure (connecting
layer: jersey combined with rib), triple face structure
1 (connecting layers are not alternated), Triple face
structure 2 (connecting layers are alternated) were
developed on a flat-knitting machine for technical
applications [1].
Keywords: Multi layer fabric, loop length, loop
transfer, permeability property, flat knitting machine
INTRODUCTION
New developments in flat knitting machinery are
capable of manufacturing engineered fabric in two
dimensional, three dimensional of bi-layer, and
multilayer knit fabrics. The feature includes
individual needle selection, the presences of holding
down sinkers, racking, transfer, and adapted feeding
devices combined with CAD. The layered fabrics are
more suitable for functional and technical
applications than single layer fabrics. These fabrics
may be non-splitable (branching knit structure, plated
fabric, spacer fabric) and splitable (bilayer,
multilayer). The functional knitted structure of two
different fabric layers based on different textile
components (hydrophobic and hydrophilic textile
material) is used to produce leisure wear, sportswear
and protective clothing to improve the comfort. The
separation layer is polypropylene in contact with
skin, and the absorption layer will be the outside
layer when cotton is used for the knit fabric [8].
Journal of Engineered Fibers and Fabrics
Volume 9, Issue 2 – 2014
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In this direction the flat knitting machine was elected
to produce splittable multi layer knit fabric with
varying loop length and loop transfer techniques. The
influence of loop length on wpc, cpc and tightness
factor was studied for the three individual layers in
the fabric. The important breathability properties of
the fabric such as water vapor permeability and air
permeability were studied. The production technique
used for this fabric has wide applications such as in
functional wear, technical textiles, and wearable
textiles.
to move back from its closure. Finally, loop
transference is completed.
TABLE I. Machine & Fabric parameters.
MATERIALS AND METHODS
The production of multi-layer knit fabrics such as
CCC-1, CCC-2 and CCC-3 cotton yarn with the
linear density of 24s Ne was fed in the knit feeder.
For layered fabric development, a computerized multi
gauge flat knitting machine and combined yarn feed
was selected like 3, 4 and 4 respectively, shown in
the Table I. Q. M. Wang and H. Hu [9] was the
selected yarn feed in the range of 4 – 10 for the
production of glass fiber yarn composite
reinforcement on a flat knitting machine. The
intermediate between integral and fully fashioned
garment was produced using the “half gauging or
needle parking” technique. The use of only alternate
needles on each bed of the flat knitting machine was
used for stitch formation, The remaining needles did
not participate in stitch formation in the same course,
but the loops formed were kept in the needle head
until employed for stitch formation again, thus
freeing needles to be used as temporary parking
places for loop transfer [6]. For production of layered
fabric and fully fashioned garment, the loop transfer
stitch is essential part of the panel. The running-on
bars were used for transferring of loops either by
hand or automatically from one needle to another
needle depending on the machine. The principle of
the loop transfer is shown in the Figure 1.
Knitting machine
Flat knitting machine
Make
M/s STOOL Company
Model
CMS 822
Machine Gauge
7.2 – 14
Total Number of
Needles
1175
Working width
50”
Software used
STOLL M1.PLUS 5.1.034
Samples
Multi layer fabrics
s
CCC - 1
CCC - 2
CCC - 3
3X24 Ne Cotton/3X 24s Ne Cotton/3X 24s Ne
Cotton
4X 24s Ne Cotton/4X 24s Ne Cotton/4X 24s Ne
Cotton
4X 24s Ne Cotton/4X 24s Ne Cotton/4X 24s Ne
Cotton
Fabric Development
Using STOLL M1.PLUS 5.1.034 software the needle
selection pattern was simulated is shown in Figure 2.
In Figure 3, feeder 1, 2 and 3 are used for the
formation of three layer fabric (inner-single jersey,
middle-1X1
purl
and
outer-single
jersey)
respectively. With knit stitches the outer and inner
layer knit fabrics are formed by means of selecting
the alternate working needles in each bed. But the
middle layer fabric is formed by free needles in each
bed with the help of loop transfer and knit stitches.
FIGURE. 1. Principle of loop transfer.
(a)The delivering needle is raised by a cam in the
carriage. The loop is stretched over the transfer
spring. (b)The receiving needle is raised slightly from
its needle bed. The receiving needle enters the
transfer spring of delivering needle and penetrates the
loop that will be transferred. (c)The delivering needle
retreats leaving the loop on the receiving needle. The
transfer spring opens to permits the receiving needle
Journal of Engineered Fibers and Fabrics
Volume 9, Issue 2 – 2014
FIGURE 2. Selection of Machine & pattern parameters.
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Loop Length
In outer, middle and inner layers of various
combinations in multi layer fabric, 20 loops in a
course were unraveled and the length of yarn in cm
(LT) was measured. From the LT value the stitch
length/loop length was measured by using
Stitch length/loop length in cm (L) = (LT)/20
(1)
The average loop length (cm) was taken and reported
in Table II.
FIGURE 3. Needle diagram for the multi-layer knit fabric.
Tightness Factor (K)
The tightness of the knits was characterized by the
tightness factor (K). It is known that K is a ratio of
the area covered by the yarns in one loop to the area
occupied by the loop. It is also an indication of the
relative looseness or tightness of the knitted structure.
For determination of TF the following formula was
used
TESTING
The produced multi layer knit fabric was given a
relaxation process and the following tests were
carried out. The knitted fabric properties are given in
Table II. and the cross sectional view of the fabrics is
shown in Figure 4.
Stitch Density
The courses and wale density of the samples in outer,
middle and inner layer were calculated individually
in the direction of the length and width of the fabric.
The average density per square centimeter was taken
for the discussion.
Tightness Factor (K) = √T/l
(2)
Where T= Yarn linear density in Tex, l = loop length
of fabric in cm. The TF of three layers (outer, middle,
and inner) were calculated separately is given in
Table II.
TABLE II. Multi-layer knitted fabric parameters.
Water Vapor Permeability (WVP)
The fabrics were conditioned for 24 hours in standard
testing condition. Seshadri S. Ramkumar et al. [13]
elected the best method to analyze Moisture Vapor
permeability. The evaporative dish method based on
British Standard, BS 7209 was used to determine the
water vapor permeability (MVTR) of the multi layer
knit fabrics. The MVTR in g/m2/day was calculated
from.
MVTR= 24 M/At
Air Permeability (AP)
Air permeability is the rate of air flow passing
perpendicularly through a known area under a
prescribed air pressure differential between the two
surfaces of a material of textile fabrics [12]. The air
resistance values of the multi layer knitted fabrics
were measured individually by using the Kawabata
evaluation system (KES-FB-AP1 Katotech Co, Ltd).
The air resistance value of KES was converted into
Frazier type tester values using the following
relationship:
(3)
Air permeability (ft3/ft2.min) = 24.58 / R
where,
M - Loss in mass of the assembly over the
time period t in grams
t - Time between successive weighing of the
assembly in hours and
A - Area of the exposed test fabric (0.0054
m2)
Journal of Engineered Fibers and Fabrics
Volume 9, Issue 2 – 2014
(4)
Where R is the air resistance value measures in KESFB-AP1 tester in cm3/cm2s.
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FIGURE 4. Cross Sectional view of Multi-layer knit fabric.
RESULTS AND DISCUSSION
Knitted fabric quality depends on its stitch length. If
the length of yarn in a loop increases, the fabric
become porous, and if it decreases the fabric become
tighter. The Figure 5 shows the CCC multi layer
fabric loop length (cm) measured in the relaxed
condition. In these fabrics, the mean loop length for
the inner and outer layer (single jersey) was found to
be equal, but the average loop length of the middle
layer and other layers (1X1 purl) was as shown in
Table II.
FIGURE 6. Variation of fabric densities with the loop length.
Influence of Loop Length on WPC and CPC
The dimensional properties of the knit fabrics are
based on the number of wales per unit length and the
number of courses per unit length. The multi layer
CCC fabrics’ wpc and cpc for the various loop length
are shown in Figure 6. It was observed that there is a
inverse relationship between multi layer fabrics
knitted with variations in loop length and loop
densities. When loop length increases the wpc and
cpc decreases. Regression analysis also confirmed
that the correlation of cpc with loop length is more
highly significant (R2 values 0.949, 0.926, and 0.971
for outer, middle, and inner layer respectively) than
that of wpc with loop length (R2 values 0.889, 0.675,
and 0.874 for outer, middle, and inner layer
respectively). The jamming occurs between yarns in
the direction of course and has more influence on
wpc. There is a significant influence of tightness
factor on wpi, as reported by Q.M. Wang et al [9]
from their work.
Influence of Loop Length on Tightness Factor
The tightness factor (K) is an important parameter
which influences loop density in the course direction.
So with respect to various loop lengths in the multi
layer fabrics, such as CCC-1, CCC-2, and CCC-3,
tightness factor was analyzed. From Figure 7 it was
observed that there is an increases of fabric tightness
factor with increasing loop length and combination
feed (between CCC-1 and CCC-2). And at constant
combination feed, increase of loop length will
decrease the tightness factor of the fabric (between
CCC-2 and CCC-3).
FIGURE 5. Variation of fabric loop lenth.
This may be due to the torsion and bending forces
involved in forming single jersey fabric being high,
but in double jersey fabric these forces are lower
[10]. Even though, there is a presence of dissimilar
structures in a layered fabric, t-test shows there no
significant difference between the loop lengths. At
alpha 0.05 the t-value is less than t-Critical for fabrics
CCC-1 (0.601<2.228), CCC-2 (1.342<2.262), and
CCC-3(2.236<2.262).
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Air Permeability (AP)
The air permeability of the multi layer knit fabrics
was analyzed and is shown in Figure 8. It can be
observed that the air permeability of the CCC-1,
CCC-2, and CCC-3 fabrics is linear with loop length.
FIGURE 7. Variation of tightness factor with the loop length.
A regression analysis was done between CCC-1 and
CCC-2; it shows R2 = 0.293 and 0.413 for middle and
other layers. So the tightness factor had obviously no
dependence on loop length alone. The value K is
dependent on the yarn linear density, and the
combination yarn feed in multi layer fabrics. And
between the fabrics CCC-2 and CCC-3, shows that
the correlation will be perfect R2 = 0.999 for all the
layers.
FIGURE 8. Water Vapor Permeability & Air Permeability of
fabric.
As loop length in the fabric increased, air
permeability also increased. The Anova- single factor
analysis also proves that there is a significant
difference at 5 % significance level between the air
permeability characteristics of multi layer fabrics
produced from various loop length [F (2, 15) > F crit]
shown in Table IV. To study the influence of the
combination yarn feed, the regression analysis was
done between CCC-1 and CCC-2 and CCC-2 and
CCC-3. It shows R2 =0.757. So, the air permeability
of the fabric is may not be dependent on the number
of yarns fed, but more influenced by the loop length.
Water Vapor Permeability (WVP)
The water vapor permeability of the multi layer knit
fabrics were analyzed and shown in Figure 8. It can
be observed that a linear trend is followed between
water vapor permeability and loop length. With
increases in loop length, there is less resistance per
unit area, so, the permeability property of the fabric
also increased. Anova data show increases in loop
length yield a significant difference in the water
vapor permeability of the multi fabrics [F (2, 15) > F
crit]. The regression analysis was done between
CCC-1and CCC-2 and CCC-2 and CCC-3 for
studying the influence of the number of yarn feeds.
R2 values shows 0.755 for both comparisons. The
water vapor permeability of the fabric is highly
influenced by the length of the loop in the fabric and
less by the number of yarn feed in the fabric.
Journal of Engineered Fibers and Fabrics
Volume 9, Issue 2 – 2014
CONCLUSIONS
In flat knitting machine using a loop transfer
technique, multi layer fabrics were developed with
varying loop length. With respect to loop length, the
loop density and tightness factor were analyzed.
Based on analysis the following conclusions were
made:
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TABLE III. Permeability Characteristics of Multi-layer knit fabrics.
TABLE IV. ANOVA single factor data analysis.
For multi-layer fabric produced with various basic
structures (single jersey and 1x1 purl), the change of
loop length between the layers has no significant
difference.
[3]
The wpc and cpc had an inverse relationship with the
loop length produced from CCC combination
multilayer fabrics.
[4]
The combination yarn feed is an important factor
affecting the tightness factor and loop lengths of the
individual layers in knitted fabrics.
[5]
The water vapor and air permeability properties of
the multi layer knit fabrics were highly influenced by
the change in loop length followed by the
combination yarn feed.
[6]
[7]
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AUTHORS’ ADDRESSES
Kanakaraj P
Ramachandran R
PSG College of Technology
Peelamedu
Coimbatore, Tamil Nadu 641 004
INDIA
Dasaradan B S
Angel College of Engineering and Technology
Tirupur 641 665
INDIA
Journal of Engineered Fibers and Fabrics
Volume 9, Issue 2 – 2014
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