Mihaela Dochia

Monica Lungu

Monica Szabo

CiteSeerX

 
 
RESEARCH STUDY ON THE DIMENSIONAL STABILITY OF 
INTERLOCK 1:1 KNITTED FABRICS MADE OF  
COTTON YARNS 
 
 
Monica SZABO,  Mihaela DOCHIA, Monica LUNGU  
 
“Aurel Vlaicu” University of Arad, Romania 
 (szabomonica@yahoo.com, dochiamihaela@yahoo.com, lungu_monica@yahoo.com) 
 
DOI: 10.19062/2247-3173.2016.18.1.50 
 
Abstract: The study concerns the dimensional changes resulted during the relaxation process 
after knitting,  for tubular fabrics with interlock 1:1 structure, made of cotton yarn, with 50/1 
metric count of yarn. 
For the study of the dimensional changes on both directions of the fabric, on the direction of 
stitches courses and on the direction of stitches courses in vertical direction, can be used a 
mathematical model with two variables.  
The interlock 1:1 structures were obtained through the combined process of knitting, resulting 
a maximum uniformity of the structural parametres. The parameter’s uniformity on entire kittng 
process is a determinant factor of the dimensional stability. The corelation between the yarn’s 
characteristics, knitting machine’s technical characteristics and technological parameters of the 
kntting process, leads to the achieving of knitted fabrics with minimum dimensional changes. 
The interlock 1:1 stuctures which were analyzed in this study, were designed and produced so 
the final dimensional changes, after chemical finishing, this representing the last phase of the 
technological process from the knitting department, to be enclosed in the limits of  ± 2%, both on 
the direction of stitches courses and on the direction of stitches courses in vertical direction. 
 
Keywords: knitted fabric, interlock 1:1 structure, dimensional stability, relaxation shrinkage. 
 
1. INTRODUCTION 
 
The knitted fabrics are textile structures made of elastic interconnected stitches and 
characterized by two perpendicular directions, the direction of stitches courses on the 
direction of stitches courses in vertical direction. 
The dimensional stability of the knitted fabrics is reflected in the capability of the 
products made from these, of maintaining the shape and dimensions in the predetermined 
limits, after several cicles of washing-wearing process.  
The dimensional stability of the knitted fabrics made of cotton is a complex and 
widely studied issue worldwide. Due to the fact that these are elastic structures, the 
dimensional stabilization is obtained through the corelation of multiple paramenters, 
starting with the techological parameters of spinning operation of manufacturig the yarn, 
the knitting parameters, finishing parameters and finally by studying the washing-wearing 
behaviour of the clothing products made of these type of fabrics. 
For this study,100%  cotton yarns were chosen, with 50/1 metric count of yarn and 
with Z twist sense. Tubular knitted fabrics will be obtained. In this case, the tilt angles of 
the stitches courses in vertical direction, will become minimal for the tubular fabrics 
resulted. 
     SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE-AFASES 2016
367
 
The knitting process will be made with uniform alimentation supply for all yarns and 
on entire process, in order to avoid possible irregularities of the knitted stiches. 
The knitted fabrics will be deposited in folded condition for relaxation, for 72 hours in 
a enclosure that complies with standard parameters (temperature=200C, relative 
humidity=60%, atmosperic pressure=760 mmHg). During this relaxation period, the 
stitches modify their shape without respecting a predetermined rule, and the final knitted 
fabrics balancing the internal tensions cumulated during knitting process. In knitting 
structures situation, the dimensional changes are influenced by the number of the yarn-
yarn contat points of the structure’s elements, this fact leading to a superior dimensional 
stability compared to similar knitting structures, in wich the yarn-yarn contact point is 
smaller.  
In table no.1 there are mentioned the technical characteristics of the knitting machines 
on which the structures were designed, the type and and metric count of the yarn which 
were used for knitting process and the structure of the fabric. 
 
Table  1 
Crt.
No. 
Knitting 
machine 
Technical characteristics of the knitting 
machine 
Yarn 
type 
Metric 
count 
of yarn 
 
 
[Nm] 
Structure 
of the 
fabric Needle 
bar 
diameter 
[in] 
Fineness 
 
 
[E] 
Number 
of 
systems 
Number 
of 
needles 
1 MULTIPIQUE 
TIP 5622-2 
30 20 72 2x1872 100% 
cotton 
50/1 interlock 
1:1 
 
2. MATERIALS AND METHODS  
 
To determine the influence of techological parameters of knitting process on the 
dimensional stability, a mathematical model was established in order to define the 
connection between the relaxation shrinkage, which is considered a dependent variable, 
and as independent variables, the wale density and the turn of the needle bar. 
The results of the practical determination were statistically processed. For the 
statistically process of the results, for all the knitting structures it was proposed an 
experimental program with 2 variables x1 (x of ecuation) and x2 (y of ecuation) which 
represent the entry data enclosed.  x1real represents the wale density on the knitting 
machine expressed in stitches/cm, and x2real represents the turn of the needle bar 
expressed in rotations/minut. The values z1 and z2 are the answers. 
For the study of the dimensional changes, made on the both directions of the knitted 
fabric, it is proposed a mathematical model as a rotatable central compound, with two 
variables. The coefficient's significance was tested with the T test and the adequacy with 
the Student test. 
The experimental program concieved offers information regarding the behaviour of 
the knitted fabrics from entire variation domain of wale density and turn of the needle bar, 
proposed. 
In table no.2 are represented the encoded and real values for the independent 
variables, and also the responses for the interlock 1:1 structure made of 100% cotton 
yarns, with metric count of yarn 50/1. 
 
 
 
 
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MECHANICAL ENGINEERING.  MATERIALS AND TECHNOLOGY
 
 
 
Table 2 
Crt. 
 No. 
x1 
 enclosed 
 
 
 
 
 
(x) 
x2 
enclosed 
 
 
 
 
 
(y) 
Wale density 
[stitches/cm] 
 
 
 
 
 
(x1 real) 
Turn of 
needle bar 
[rot/min] 
 
 
 
 
(x2 real) 
Dimensional 
changes 
during 
relaxation on 
stitch course 
direction [%] 
 
(z1) 
Dimensional 
changes during 
relaxation on 
stitch course in 
vertical 
direction [%] 
 
(z2) 
1 -1 -1 9,45 10,90 -2,00 -2,30 
2 1 -1 11,60 10,90 -0,50 -1,50 
3 -1 1 9,45 15,10 -2,50 -2,75 
4 1 1 11,60 15,10 -0,75 -1,80 
5 -1,414 0 9,00 13,00 -3,00 -3,20 
6 1,414 0 12,00 13,00 -0,20 -0,40 
7 -1 -1,414 10,50 10,00 -0,90 -1,40 
8 1 1,414 10,50 16,00 -0,75 -1,30 
9 0 0 10,50 13,00 -0,90 -1,20 
10 0 0 10,50 13,00 -0,80 -1,40 
11 0 0 10,50 13,00 -0,75 -1,50 
12 0 0 10,50 13,00 -0,60 -1,30 
13 0 0 10,50 13,00 -0,80 -1,25 
 
Dimensional changes study on stitch course direction (horizontal direction): 
 
The regression ecuation which describes the relaxation process of interlock 1:1 knitted 
fabrics made of 100% cotton, 50/1 metric count of yarn, stitch course direction is based 
on following relation (1): 
 
f x y,( ) 0.77 0.901 x. 0.471 y. 0.067 x2. 0.084 y2. 0.062 x. y.  
(1) 
 
Where: x and y are encoded values 
In fig.1 is presented the dependence U=(f,y), in the case of relaxation shrinkage on the 
stich course direction of the interlock 1:1 fabrics studied. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
     SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE-AFASES 2016
369
 
FIG. 1. Response surface in the relaxation shrinkage, on stitch course direction, for the 
interlock 1:1 knitted fabric  
The response surface represented in fig.1 has an elongated saddle shape, and the curve 
which generates it are hyperbolas.  
In fig. 2 there are presented sections through response surface, for the relaxation 
shrinkage on stitch course direction for interlock 1:1 knitted fabrics studied. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
FIG. 2.  Sections through response surface in the relaxation shrinkage, on stitch course direction, 
for the interlock 1:1 knitted fabric  
 
From the graphic representation from fig.2, the level curves can be noticed; these are 
portions of hyperbolas. 
While the wale density increases, the relaxation shrinkage decreases. For the entire 
field variation of wale density and of the turn of the needle bar, relaxation shrinkage 
appears (represented by negative values), but in elongation does not appear in any other 
situations (represented through positive values). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
FIG. 3. Variation of Z = f(y) for x = constant in case of dimensional changes after relaxation, on stitch 
course direction in horizontal direction 
 
1.5− 1.2− 0.9− 0.6− 0.3− 0 0.3 0.6 0.9 1.2 1.5
3.5−
3.05−
2.6−
2.15−
1.7−
1.25−
0.8−
0.35−
0.1
0.55
1
y=0
y1=-1.414
y2=-1
y3=1
y4=1.414.
Z=f(y) for x=constant
Wale density [stitches/cm]
R
el
ax
at
io
n 
sh
rin
ka
ge
 [%
] f x y,  ( )
f x y1,  ( )
f x y2,  ( )
f x y3,  ( )
f x y4,  ( )
x
 
 
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MECHANICAL ENGINEERING.  MATERIALS AND TECHNOLOGY
 
 
FIG. 4. Variation T=f(x) for y=constant in case of dimensional changes to relaxation, 
on stitch course direction in horizontal direction 
 
In fig. 3 is represented the dependence of Z = f (y) for x = constant  on stich course 
direction. 
From the graphic analyze from fig.3 results that together with the increase of vertical 
density, the shrinkage to relaxation in the direction of vertical stitches courses decreases, 
approaching to the 0 value (ideal value). The curves present the same trend for the entire 
variation domain of vertical density. The switch from one level to another is done with 
the same effort for the entire variation domain of vertical density. 
In fig. 4 is represented the dependence T=f(x) for y=constant. 
From the graphic analyze from fig.4, it results that together with the increase of turn 
of the needle bar, shrinkage to relaxation increases in the direction of vertical stitches 
courses. The curves present the same trend for the entire variation domain of vertical 
density. The switch from one level to another is done with the same effort for the entire 
variation domain of vertical density. 
Dimensional changes study on stitch course in vertical direction: 
The regression ecuation which describes the relaxation process of the intrelock fabrics 
made of 100% cotton, 50/1 metric count of yarn, on stich course in vertical direction is 
given by the following relation (2): 
 
f x y,( ) 1.33 0.714 x. 0.363 y. 0.076 x2. 0.138 y2. 0.037 x. y.  
(2) 
 
In fig. 5 is presented the response surface, which means the dependence U=f(x,y), in 
the relaxation shrinkage on stitch course in vertical direction of interlock 1:1 fabrics 
which were studied. 
 
1.5− 1.2− 0.9− 0.6− 0.3− 0 0.3 0.6 0.9 1.2 1.5
3.5−
3.05−
2.6−
2.15−
1.7−
1.25−
0.8−
0.35−
0.1
0.55
1
x=0
x1=-1.414
x2=-1
x3=1
x4=1.414
T=f(x) for y=constant
Turn of needle bar [rot/min]
R
el
ax
at
io
n 
sh
rin
ka
ge
 [%
] f x y,  ( )
f x1 y,  ( )
f x2 y,  ( )
f x3 y,  ( )
f x4 y,  ( )
y
 
     SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE-AFASES 2016
371
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
FIG.  5. Response surface in the case of relaxation shrinkage, on stitch course in vertical 
direction, for interlock 1:1 structures  
 
The response surface has a elongated saddle shape. The curves which generates is are 
hyperbolas. 
In fig. 6 are represented the sections through response surface, in the relaxation 
shrinkage case, on stitch course in vertical direction, for the interlock 1:1 fabrics studied. 
 
 
FIG. 6. Sections through response surface in relaxation shrinkage, on stitch course in vertical  
direction, for interlock 1:1 structures  
 
From the graphic representation from fig.6, the level curves are evidenced, which are 
portions of hyperbolas. 
Together with the increase of the wale density, the relaxation shrinkage decreases. For 
entire domain of variation of wale density and of turn of the needle bar, the relaxation 
shrinkage appears on the stitch course in vertical direction (represented by negative 
values), and in any case does not appear elongation (represented by positive values). 
 
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MECHANICAL ENGINEERING.  MATERIALS AND TECHNOLOGY
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
FIG.7. Variation Z=f(y) for x=constant in case of dimensional changes during relaxation, on stitch 
course in vertical direction  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
FIG. 8. Variation T=f(x) for y=constant in case of dimensional changes after relaxation on stitch course in 
vertical direction 
In fig.7 is represented the dependence Z=f(y) for x=constant. 
 
1.5− 1.2− 0.9− 0.6− 0.3− 0 0.3 0.6 0.9 1.2 1.5
3.5−
3.15−
2.8−
2.45−
2.1−
1.75−
1.4−
1.05−
0.7−
0.35−
0
y=0
y1=-1.414
y2=-1
y3=1
y4=1.414
Z=f(y) for x=constant
Wale density [stitches/cm]
R
el
ax
at
io
n 
sh
rin
ka
ge
 [%
] f x y,  ( )
f x y1,  ( )
f x y2,  ( )
f x y3,  ( )
f x y4,  ( )
x
  
1.5− 1.2− 0.9− 0.6− 0.3− 0 0.3 0.6 0.9 1.2 1.5
3.5−
3.15−
2.8−
2.45−
2.1−
1.75−
1.4−
1.05−
0.7−
0.35−
0
x=0
x1=-1.414
x2=-1
x3=1
x4=1.414
T=f(x) for y=constant
Turn of needle bar [rot/min]
R
el
ax
at
io
n 
sh
rin
ka
ge
 [%
] f x y,  ( )
f x1 y,  ( )
f x2 y,  ( )
f x3 y,  ( )
f x4 y,  ( )
y
 
     SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE-AFASES 2016
373
 
For the anlayze of graphic representation from fig.7 can be observed that together 
with the increase of the wale density, the relaxation shrinkage decreases on stitch course 
direction for the intrelock structures studied.  
In fig. 8 is represented the dependence T=f(x) for y=constant. 
From the graphic anlayze from fig. 8 results that together with the increase of the turn 
if the needle bar, the relaxation shrinkage increases. The curves have the same evolution 
for entire variation domain of wale density, the tranzit from one level to other is made 
with the same effort on entire variation domain of wale density. 
 
3. RESULTS AND DISCUSSION 
 
For real values of wale density between 10,5 -12 stitches/cm, the relaxation shrinkage 
decreases to  -0,8% la -0,2%, which are considered very good. 
Knitting with big wale densities, over 12 stitches/cm, elongations appear. These 
elongations appear due to increasing of yarn-yarn contact points,  resulting yarn-yarn 
contact surfaces which lead to modifications of the stitches shape during relaxation 
period. 
       The variation of the wale density together with the turn of the needle bar in order 
to maintain a constant contraction is needed because once with the increase of the turn of 
needle bar over a certain value, the remanent tensions from the knitted fabric increase 
also, and in order to maintain the fabric in the same stich shape and at the same values of 
the structural parameters, the contact surface betewwn the yarns must be increased also. 
A too high density does not allow the return through relaxation of the knitted fabric, to 
a minimum energy state and the remanent tensions manifest through contraction. Also, in 
the case of big wale densities, the knitted structures loose their elasticity and become. 
 
4. CONCLUSIONS 
 
1. The interlock 1:1 structures made of 100% cotton, 50/1 metric count of yarn 
studied, were designed so the dimensional chages during relaxation shrinkage to be 
minimum, this fact having a positive influence on previous procedures applied on knitted 
fabrics.  
2. In order to obtain structures with dimensional stability in the limits of ±2%, the 
wale density of the knitted fabric determined on the knitting machine, has a major 
influence. 
3. After establishing the optim wale density on the knitting machine, the turn of the 
needle bar must be set, the other technological parameters of the knitting process having 
less influence regarding the dimensional changes in un-finished state, of the knitted 
fabrics. 
4. After the relaxation of the knitted fabrics which were released from the knitting 
machine, minimum contractions are noticed, both on the stitch course direction and on 
stitch course vertical direction, which concludes to a structure with very good 
dimensional stability. 
5. The use of this method allows with a minimum effort, starting form initial data, 
which is the fineness of the yarns, technical characteristics of the knitting machine, the 
wale density, the turn of the needle bar, to predict the final data, more exactly the values 
of the dimensional changes after relaxation processes. 
 
 
 
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MECHANICAL ENGINEERING.  MATERIALS AND TECHNOLOGY
 
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[9]. Ahmed, M. E., Abdel, Z. M., The Effect of Machine Setting on Weft Knitted Fabric Properties, Journal 
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MECHANICAL ENGINEERING.  MATERIALS AND TECHNOLOGY


RESEARCH STUDY ON THE DIMENSIONAL STABILITY OF INTERLOCK 1:1 KNITTED FABRICS MADE OF COTTON YARNS

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RESEARCH STUDY ON THE DIMENSIONAL STABILITY OF INTERLOCK 1:1 KNITTED FABRICS MADE OF COTTON YARNS

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