The effect of stitch length on abrasion resistance of grey knitted fabric.

1. The effect of stitch length on abrasion
resistance of grey knitted fabric
Md.Azmeri Latif Beg
MSc.Engr (Textile)

2. INTRODUCTION
Knitting is a method by which thread or yarn is turned into cloth
or other fine crafts. Knitted fabric consists of consecutive rows of
loops, called stitches. As each row progresses, a new loop is
pulled through an existing loop. The active stitches are held on a
needle until another loop can be passed through them. This
process eventually results in a final product, often a garment. The
art of knitting has been rapidly progressing in the world. In our
country knit sector already holds the highest position if compared
with weaving or other small sectors related to textile. Knit RMG is
the highest foreign currency earning sector of Bangladesh. The
industry is also growing very fast due to strong backward linkage,
less capital investment requirement and higher profitable.
Abrasion is just one aspect of wear and is the rubbing away of the
component fibers and yarns of the fabric.

3. Knitted loop is a knit of yarn that is intermeshed at its base i.e. when
intermeshed two kink of yarn is called a knitted loop. A knitted loop is a
basic part of knitted fabric. Technically a knitted loop consists of a needle
loop & a sinker loop. The length of yarn knitted into one stitch in a weft
knitted fabric. Stitch length is theoretically a single length of yarn which
includes one needle loop & half the length if yarn (half a sinker loop)
between that needle loop & the adjacent needle loops on either side of it.
Generally larger the stitch length more elastic & lighter the fabric also it’s
poorer its cover opacity & bursting strength. Generally stitch length is
expressed in mm (millimeter). In the fabrics, loop lengths combine in the
form of course lengths & it is there that influences fabric dimensions &
other properties like weight, density, shrinkage, spirality etc. Variations in
course length between one garment & another can produce horizontal
bareness & impair the appearance of the fabric. In the modern knitting
machine, it needs to maintain a constant loop length at one feed & another
on same machine is mandatory for continuing the constant loop length.
Although a machine may be set to knit a specific stitch length, fluctuations
in yarn or machine variable can affect yarn surface friction or yarn tension at
the knitting point. As a result, the ratio of ‘robbed back’ to newly-drown yarn
changes & alters the size of the knitted loop.

4. So abrasion resistance is the resistance against the wear to
rubbing.Now-a-days abrasion resistance is an important
quality parameter of knit fabric. The measurement of the
resistance to abrasion of textile and other materials is very
complex. The abrasion resistance best measure the
serviceability of any fabric or garment during end use. Though
pilling test is preferred for knit fabric, abrasion resistance is
also important for knit fabric which is made from combed or
compact yarn.

5. ORGANIZATION OF THE RESEARCH:
 Testing lab- The experiments were executed at the Fabric
Manufacturing Lab of DIU with the Hand Driven Hosiery Knitting
Machine & HATRA Course Length Tester as well as the Textile
Testing and Quality Control Lab of DIU with the Martindale
Abrasion and Pilling Tester – M235 and also with the help of
BENGAL NFK for providing the required yarn packages.
 Test method- In this research work it was used the ASTM D 4966
-- 98 Standard Test Method for Abrasion Resistance of Textile
Fabrics (Martindale Abrasion Tester Method) with the help of DIU
lab facilities.

6. The M235- Martindale Abrasion and Pilling Tester is also
known as M235 Abrasion and pilling Tester. Samples are
rubbed against abradant at a certain pressure and the
amount of weight loss is determined or rubbed samples are
compared against standard swatch for calculating abrasion
resistance.

7. METHODOLOGY:
At first the yarns of three different counts (24 Ne, 32 Ne and 34
Ne) of same lot number were collected from the BENGAL NFK
spinning mill, Dewhata, Tangail. Because of the same lot
number it can be said that the raw materials have constant
effect on bursting as changing the count of yarn. The each yarn
was fed into the hosiery machine and cam was set to three
position- bottom, mid and upper. Take down tension was similar
for each case. After production courses were unrobed from the
fabric and were set to HATRA course length tester with
mentioned tension thus determined stitch length.
.

8. Total needle was 132. Then fabrics were cut with the cutter of
the machine; weight was taken and set to M235. After applying
proper load machine was run for 100 cycles because of more
loop length. After completing required cycles specimen were
observed for any hole or breakage and in all cases that was
discovered. Again weight of rubbed fabric was taken and
weight loss ratio was calculated which refers the abrasion
resistance. More weight loss ratio indicates less abrasion
resistance.

9. Properties of yarns used in the research. Specimen
and abradant

10.  Stitch length determination:
When cam is in the bottom position for 24Ne when cam is in
the mid position for 24 Ne

11. When cam is in the upper position for 24 Ne When cam is in the
bottom position for 32 Ne

12. When cam is in the mid position for 32Ne When cam is in the
upper position for 32 Ne


13. When cam is in the bottom position for 34 Ne When cam is in the
mid position for 34 Ne

14. When cam is in the upper position for 34 Ne

15. Graph 1

16. Obs no.
Weight (a)
(before abrasion)
Weight (b)
(after
abrasion)
Weight loss% Average weight
loss%
1 0.1139 0.1117 1.93%
1.572 0.0733 0.0722 1.50%
3 0.0853 0.0841 1.41%
4 0.0895 0.0882 1.45%
When cam is in the mid position for 24 Ne
1 0.1250 0.1230 1.60%
1.762 0.1123 0.1104 1.69%
3 0.1190 0.1168 1.85%
4 0.1173 0.1151 1.88%
:
Results of the abrasion test:
When cam is in the bottom position for 24 Ne

17. When cam is in the bottom position for 32 Ne
0.0834 0.0821 1.56%
1.660.0964 0.0945 1.97%
0.0945 0.0933 1.26%
0.0912 0.0895 1.86%
When cam is in the mid position for 32 Ne
0.0712 0.0693 2.66%
2.650.0770 0.0750 2.59%
0.0766 0.0743 3.00%
0.0854 0.0834 2.34%

18. When cam is in the upper position for 32 Ne
0.0544 0.0520 4.41%
4.600.0483 0.0459 4.96%
0.0448 0.0427 4.69%
0.0507 0.0485 4.33%
When cam is in the bottom position for 34 Ne
0.0820 0.080 2.40%
2.190.0828 0.0810 2.17%
0.0862 0.0844 2.08%
0.0940 0.0920 2.12%

19. When cam is in the mid position for 34 Ne
0.0728 0.0701 3.70%
3.710.0756 0.0726 3.96%
0.0801 0.0772 3.62%
0.0783 0.0755 3.57%
When cam is in the upper position for 34 Ne
0.0526 0.050 4.94%
4.760.0493 0.0469 4.87%
0.0524 0.0501 4.38%

23. Change in Abrasion Resistance
The abrasive wear of a material depends on the construction
of the yarn & the structure of the fabric. It was established
that abrasion was less for higher density fabrics. This was
because of the fact, when the density was more, more loops
contributed to the wear & so its abrasion resistance
increased.

24. Discussion:
From figure 5 it is seen that, Single jersey fabric showed
higher abrasion loss% due to its soft nature on the surface.
Graph 1 shows that abrasion resistance decreases slightly
as stitch length increases but after few interval it
decreases rapidly for 24 Ne. According to graph no. 2 and 3
abrasion resistance also decreases as stitch length
increases but these are not also linear and show opposite
curves. The bubble graph (graph4) indicates the variable
fluctuation of abrasion at different cam position.

25. Following the linear regression obtained regression equation for
the fabric made from 24 Ne yarn is y=0.475256x - 1.06543 and
coefficient of determination R2= 0.989127.
Regression equation for the fabric made from 32 Ne yarn is y=
0.270613x + 0.527763 and R2= 0.661096
Regression equation for the fabric made from 32 Ne yarn is y=
0.552834x -0.39372 and R2= 0.795248

26. Conclusion:
Though hand driven small diameter hosiery machines (socks
machines) are not in use in export oriented factory in Bangladesh
but in cottage industries and in local factories these machines
are used. So this research is helpful for that concerning people
because in most cases they have no abrasion testing machine.
Abrasion resistance can be predicted by using different
regression equation for different type of yarns.

27. MSC. TTQC AZMIR PRESENTATION