Investigating the Relationship between Yarn Structure and Mechanical Properties in Ring and Rotor Spun Yarns
MD Rakib Hassan Gazi1*, Hasan Mazharul Haq1 and Mushfiqur Rahman2
1Department Name of Yarn Engineering, Bangladesh University of Textiles, Bangladesh
2AGM, Mahmood Spinning Ltd, Mahmood Group, Shafipur, Gazipur
Submitted: June 17, 2023; Published: July 20, 2023
*Corresponding author: MD Rakib Hassan Gazi, Department Name of Yarn Engineering, Bangladesh University of Textiles, Bangladesh
How to cite this article: MD Rakib H G, Hasan Mazharul H, Mushfiqur R. Investigating the Relationship between Yarn Structure and Mechanical Properties in Ring and Rotor Spun Yarns. JOJ Material Sci. 2023; 8(1): 555726. DOI:10.19080/JOJMS.2023.08.555726
Abstract
Ring and rotor spinning systems have their own yarn manufacturing principle. It was our interest to study the impact of yarn manufacturing principle of ring- and rotor spinning on their corresponding yarn properties. In this context, 7 Ne and 12 Ne ring- and rotor yarns were produced from the same fiber and the structure and properties such as uneven-ness (Um%, CVm%), imperfections, hairiness, CSP and elongation%, were analyzed by Evenness tester and Lea Strength Tester. Unevenness and imperfections in both ring- and rotor yarns were found comparable. Hairiness value of rotor yarns was observed somewhat lower that may be attributed to the influences of wrapper fibers. Strength of ring yarns was higher compared to rotor yarns. The reason can be ascribed to the higher fiber migration caused in ring spinning in the spinning triangle.
Keywords: Ring Yarn; Rotor Yarn; Yarn; Spinning; Textile; Characteristics; Structure
Keywords: QC: Quality Control, CSP: Count Strength Product
Introduction
It is very difficult to ascertain the historical period precisely by which man first started spinning fibers into yarns. However, based on the archaeological evidence, we can understand that this particular skill was well practiced at least 8000 years ago. Certainly, the weaving of spun yarns was developed around 6000 BC. Among the various spinning systems available in the spinning technology, ring spinning is still dominant for more than 150 years [1]. It is due to the versatility of this spinning system to produce wide range of counts ranging from coarser to superfine counts in natural, manmade and blends. Today, yarn spinning or production is a highly advanced technology that enables the engineering of different yarn structures having specifically desired properties suited for particular end use applications. The basic difference between ring-spun yarns and rotor yarns is in the way they are formed. The former produces yarn by inserting twist into a continuous ribbon-like strand of cohesive fibers delivered by the front rollers, while the latter forms yarn from individual fibers directly by collecting them from the inside surface of a rotor by twist forces [2]. This project work was undertaken in order to compare the principle of yarn formation of ring and rotor spinning on their respective yarn characteristics. 7 Ne & 12 Ne ring and rotor yarns were produced from the same raw material and different yarn properties such as unevenness (U%), co-efficient of mass variation (CVm%), imperfections, hairiness and count strength product (CSP) were analyzed.
Materials & Methods
Materials
Raw material represents about 50 - 75% of the manufacturing cost of a short-staple yarn. This fact alone is sufficient to indicate the significance of the raw material for the yarn producer. Hardly any spinner can afford to use problem free raw material because it would normally be too expensive [3].
Fiber
For this project we are used 100 percent cotton fiber. Cotton is a cellulosic fiber. 80-90% cellulose is in cotton but oil, wax, protein, pectin and some coloring content are also present. The polymer chain of cotton cellulose is linear. It is a polymeric sugar of polysaccharide made of up to 4000 - 9000 repeating cellobiose unit, which consist of two glucose units connected to each other by 8- ether linkages [4].
In this experiment Brazilian 100% cotton fiber was used. The particulars of this cotton are given below (Table 1):
Yarn
Yarn may be defined as a linear assembly of fiber or filament that are twisted (Z and S twist) in order to make strong or laid together to form a continuous strand, which is suitable to manufacture fabric [5].
Yarn Evenness: Yarn evenness deals with the variation in yarn fineness. This is the property, commonly measured as the variation in mass per unit length along the yarn, is a basic and important one, since it can influence so many other properties of the yarn and of fabric made from it. Such variations are inevitable, because they arise from the fundamental nature of textile fibres and from their resulting arrangement. The spinner tries to produce a yarn with the highest possible degree of homogeneity. In this connection, the evenness of the yarn mass is of the greatest importance. In order to produce an absolutely regular yarn, all fibre characteristics would have to be uniformly distributed over the whole thread. However, that is ruled out by the inhomogeneity of the fibre material and by the mechanical constraints.
In consequence, the thicker yarn region will tend to be deeper in shade than the thinner ones and if a visual fault appears in a pattern on the fabric, the pattern will tend to be emphasized by the presence of color or by some variation in a visible property, such as crease resistance controlled by a finish. Other fabric properties, such as abrasion or pill-resistance, soil retention, drape, absorbency, reflectance, or luster, may also be directly influenced by yarn evenness. Thus, the effects of irregularity are widespread throughout all areas of the production and use of textiles and the topic is an important one in any areas of the industry. [6].
Experimental Materials Blowroom
TRUTZCHLER blow room line was used in this project. The description of the blow room line is given below (Tables 2-7):
Properties of Yarn
Methods
Research methodology is the path through which researchers need to conduct their research. It shows the path through which these researchers formulate their problem and objective and present their result from the data ob-tained during the study period. This research design and methodology chapter also shows how the research outcome at the end will be obtained in line with meeting the objective of the study [7].
Sample Preparation
Steps of Sample Preparation in Ring & Rotor Frame
a) At first in blow room section opening, cleaning, mixing
operation were done.
b) Then cotton was passed to the carding section through
chute feed and eight large cans of card sliver from carding machine
no. 3 were produced.
c) Then card sliver cans were fed into the breaker
drawframe (machine no. 1) and sixteen breaker drawn sliver cans
were produced.
d) Then produced breaker drawn sliver cans were fed into
finisher drawframe (machine no. 6) and twelve cans of finisher
drawn sliver were manufactured.
e) After that six-finisher drawn sliver were fed into simplex
machine to produce ring yarns and another six finisher drawn
sliver cans were taken to autocoro machine to produce rotor yarn.
f) From simplex machine (machine no. 2) twelve roving
packages were produced and fed six roving in ring frame (machine
no.2) for producing count 7 Ne and an-other six were fed in ring
frame (machine no. 3) for producing 12 Ne carded yarn.
g) Other six finisher sliver cans were fed into autocoro
(machine no. 3) to produce 7 Ne rotor yarn. After this operation,
we took this sliver can and again fed into autocoro (machine no. 4)
to produce 12 Ne rotor yarn.
h) Finally, all produced yarn were taken to the QC
department for testing and analyzing.
Results
In this part, the various physical properties of ring carded and rotor yarns are evaluated comparatively. The mean differences of different properties are evaluated and explained through Uster Evenness Tester and Mesden Lea Strength Tester. Uster testing result of yarns for unevenness (U%), co-efficient of mass variation (CVm%), hairiness, tenacity, thick place, thin place, neps and Mesden strength tester result for CSP and Elongation values are shown below in different tables.In this case of experiment, the velocity is kept of material is 200m/min and duration of passing material is 1 min. The parameters and test results are shown in table below (Table 8):
Strength means the quality or state of being strong. In this experiment, Mesdan Lea Strength Tester is used to de-termine the breaking strength of the yarn in bundle form. A sample of yarn with 640 mm length is taken to test and attached to the clamp of the machine. The clamp speed is kept 500mm/min. The test result are show below (Table 9).
Discussion
The changes of value of given parameters are presented in graphical method. Then the result is discussed below the graphical representation:
The mass per unit length variation due to variation in fiber
assembly is general as yarn irregularity or unevenness. It is also
necessary to have a numerical value that represents the mass
variation [8]. The coefficient of variation is the ratio of standard
deviation of mass variation divided by average mass variation. The
higher CVm value is the more irregular the yarn [9].
a) In the present study as it is seen in figure1: here mass
variation (U% and CVm%) of ring and rotor yarns are similar to
each other.
b) In the previous similar work done by Sharif et al. [10], it
was observed that ring yarn has more unevenness than rotor yarn
for 20 Ne yarn.
c) Usually for finer yarn, unevenness of ring yarn is higher
than the rotor yarns. `Because in ring spinning, fibers are passed
through various drafting system (Simplex and Ring frame),
for where the more unevenness is produced. When, the roving
passing through the drafting arrangement, then there starts to
produce static charge for the friction between materials to roller.
Moreover, due to this static charge sometimes fibers are wrapping
on the cot roller.
d) which is called lapping. For this unwanted reason in ring
spinning the mass variation is more [11, 12].
e) On the other hand rotor yarn is produced by transforming
sliver into individual fibers. Here fiber to fiber doubling (back
doubling) is occurred and there are no drafting arrangement
present here, so the mass variation is much lower in rotor yarn
[13].
f) In the above figure: it is seen that mass variation is
similar for both ring and rotor yarns, it may be due to the number
of fibers are presented more in the cross section for coarser count.
Therefore, the fibers are equalized and reduced the mass variation.
Yarn hairiness is defined as fibers protruding from the main body of a yarn. The amount of hairiness is important to both the textile operations and the appearance of fabrics and garments [14].
In the above figure 2 for both count (7 Ne & 12 Ne) it is seen that hairiness of ring yarn more than rotor yarn. In ring spinning for roller lapping and frayed fibers in the spinning triangle are caused more hairiness. Besides that, the ballooning tension also here creates a great impact on hairiness of ring yarns [15]. But in rotor spinning there are back doubling occurred in the rotor groove. Where the fibers are laid down on each other and more wrapping fibers are presented in the structures of rotor yarns. So the hairiness of rotor yarns are less than ring yarns [16]. The product of the lea strength (pound force), and the actual count of cotton yarn (Ne) is known as Count Strength Product (CSP) [17].
In the above figure 3 for both count yarns, CSP is higher for
ring yarns than rotor yarns. Ring yarn has more strength than
rotor yarn because of (i) different twisting system and (ii) fiber
migration which are elaborated below:
a) In ring yarn twist is enveloped outside to inside of the
yarn. And all the fibers are contributed in twisting. So, the friction
between fiber to fiber is higher. So, the strength is also increased.
But in rotors yarn the twist is generated from inside to outwards.
So, the degree of parallelism of rotor yarn is low as well as CSP is
lower than ring yarns [18].
b) The ring spun yarn exhibits the highest fiber migration,
followed by rotor spun yarn. A higher migration factor corresponds
with a higher yarn breaking tenacity. The degree of fiber migration
in rotor yarn is much lower than that of ring-spun yarns, because
the fibers do not form a flat ribbon immediately before twist is
inserted [19].
The increase in length of a specimen during a tensile test, expressed in units of length or percentage value [17].
In the above figure 4 we show that the elongation property of both rotor and ring yarn is similar to each other. In the previous similar work done by Sonkusare Chetan R et al. [20], it was observed that rotor yarn has more elongation than ring yarns. Although rotor spun yarns are known to be somewhat more extensible, fuller, and softer than ring yarns. Elongation property of ring and rotor yarns is not a constant result, it depends on various parameters. If any parameter change then result can be reversible [21].
Neps may be considered as small tight balls of entangled fibers, which lead to the downgrading or yarn and fabric. The cross-sectional size of neps is + 140% to +400% of normal yarn and its fault length is 1mm. In the above figure 5: 4.2.7 it is seen that neps in of ring yarn is higher than the rotor yarns for both counts. Usually due to back doubling low fiber entanglements occur in rotor yarn [13]. Neps in rotor yarns tend to be spun into the solid yarn body rather than remaining on the yarn surface, which is typical for ring-spun yarns. It is embedded in the yarn core. So these neps shows a short mass defect, which is not exceeding the preset threshold value. Therefore, the neps of rotor yarn is less than ring yarn [22].
A place in the yarn having yarn diameter in excess of +50% of the average yarn diameter and the length 8-12 millimeters is considered as a thick place. A place in a yarn having yarn diameter -50% or more than average diameter and any length is considered as a thin place [23].
In the above figure 6, it is seen that the thick place (+50%) of ring yarn for 7 Ne is less than the rotor yarn. Nevertheless, for 12 Ne it is significantly higher than the rotor yarns. In the previous similar work done by Sharif et al. [12], it was observed that ring yarn has thicker place (+50%) than rotor yarn for 20 Ne yarns. In our observation it is also found that ring yarn has thicker place than rotor yarns for 12 Ne. But for 7 Ne the result is reversed. It may be due to more fibers present in the cross section of coarser yarns that enables the yarns to withstand higher spinning tensions. Thin places lie in the range of -50% with respect to the mean value of yarn cross-sectional size and their length ranges from 4-25mm. Thin place -40% means the x-section at the thin place is only 60% of the yarn x-section or less (Figure 7) [24-31].
Conclusion
In the current study, the reflection of yarn manufacturing principle of ring- and rotor spinning on the characteristics of yarns was studied. 7 Ne and 12 Ne ring- and rotor yarns were produced from the Brazilian cotton and the structure and properties were analyzed by Uster Evenness Tester and Mesdan Lea Strength Tester. After a thorough study, much differences were not found in the unevenness and imperfections of both ring- and rotor yarns. Hairiness value of rotor yarns was slightly lower due to the presence of wrapper fibres. Strength of ring yarns was higher in compare to rotor yarns. The reason of higher strength of ring yarns can be ascribed to the occurrence of higher fibre migration in the spinning triangle (Figures 8 & 9).
Acknowledgement
The authors are extremely thankful to the production and quality control department of Mahmood spinning Ltd. For their good co-operation & selfless support in conducting the work.
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