Denim Spinning Manufacturing Methods and Technologies

Process for ring-spun yarn

Speed Frames

Objects/ Functions of Speed Frame:

1. Attenuation of drawn sliver to form roving of required count by drafting.
2. Insert a small amount of twist to give the required strength of roving.
3. Wind the twisted roving on to the bobbin.
4. Build the roving in bobbin such a form which will facilitate handling, withdrawing & transfer to the next process

Operations Involved in Simplex Machine:

1. Creeling
2. Drafting
3. Twisting Open-end machines
4. Winding
5. Building
6. Doffing

Ring spinning

Ring spinning is a method of spinning fibres, such as cotton, flax or wool, to make yarn. The ring frame developed from the throstle frame, which in its turn was a descendant of Arkwright’s water frame. Ring spinning is a continuous process, unlike mule spinning which uses an intermittent action.

In ring-spinning, the roving is first attenuated by using drawing rollers, then spun and wound around a rotating spindle which in its turn is contained within an independently rotating ring flyer. Traditionally ring frames could only be used for the coarser counts, but they could be attended by semi-skilled labour.

The core objectives of ring spinning is to draft the roving fed to the ring-spinning frame i.e., to convert roving into a very fine strand called yarn

Ring Spinning: Merits and Limitations:

Ring spinning had remained unchallenged for almost 150 years, since its inception. However, its limitation in regard to production speeds was well realized which made its position quite vulnerable to new spinning technologies like rotor spinning. Subsequent to this realization, renewed attempts made the maximum production speed has increased to 25000 rpm by

• by extending the maximum traveller speed to 45m/sec and using
• smaller ring diameter and bobbin lift.

However, this has not prevented rotor spinning applications in coarse denim yarns as these yarns demand higher ring diameter and bobbin lift. Today the problem of excessive knots due to smaller ring package is of little consequence due to efficient splicing systems available at winding.

Another serious problem of excessive initial end breaks due to the greater number of doffs has been solved by the employment of efficient automatic piecing devices. Additionally, there are support systems such as automatic roving transport to the ring frame, automatic roving rupture if the yarn is not pieced in three successive attempts in order to reduce the incidence of roller lapping.

The merits which make it unique ever are

1. It produces the strongest yarn, it is the benchmark among all 100% staple fibre spinning systems for various types of fibres and their blends.
2. It can produce yarns with a large range of twist, density from very low to very high. No other spinning system can match this unique capability of catering from knitting to voile yarns.
3. It can be used for all types of fibres and can spin from very coarse to extremely fine yarns.
4. The desired hand, crisp or soft as per requirements can be imparted using the ring yarns.

Comparison of Ring Spun and Rotor Spun Yarns

There are many differences between ring and rotor/open-end spun yarns. The abrasion resistance of rotor yarn fabrics is better, and colourfastness is slightly higher for ring-spun yarn fabrics whereas shrinkages is the same for the fabrics made from ring and rotor spun yarns. Two of the important differences are the degree of fibre hookiness and fibre migration. In the below table, there are given many differences between ring and rotor spun yarns.

Quality Assurance:

Quality affirmation alludes to the designing exercises executed in a quality framework with the goal that necessities for an item or administration will be satisfied. It is the deliberate estimation, correlation with a standard, checking of procedures and a related criticism circle that gives blunder counteractive action. This can appear differently in relation to quality control, which is centred on procedure yields.

Quality assurance steps:

Quality assurance system can be divided into the following steps:

1. On line Quality assurance system and
2. Offline Quality assurance system.

Again on line Quality affirmation framework can be separated into the accompanying advances:

1. Raw material control.
2. Process control.

Yarn quality requirements:

For the best sewing, we need to pick the best yarn or perfect yarn for weaving to blame free texture or quality full texture. So we need to cautious about the yarn properties or for the perfect yarn. The accompanying yarn properties ought to must be said material yarn as a perfect yarn-

1. The yarn is round in a cross-area and is uniform along its length.
2. Yarn is made out of concentric layers of various outspread.
3. Every fibre pursues a uniform helical way around one of the concentric chamber with the goal that its good ways from yarn pivot stay consistent.
4. The fibre in the middle will pursue a straight line of the hub.
5. The hub of roundabout chambers coir sides with yarn hub.
6. The quantity of fibres or fibres crossing the unit region is consistent; that is the thickness of pressing.
7. Fibres in the yarn are consistent all through the model.
8. Each fibre in the yarn will have a similar measure of turn per unit length.
9. The yarn comprises an exceptionally enormous number of fibres.

In the event that the previously mentioned yarn properties are missing on any yarn then the yarn ought not to be permitted on weaving to make the texture. Since it won’t almost certainly give you immaculate sewing where the yarn’s parameter is obligatory to be kept up.

Yarn quality parameters, for example,

• Evenness,
• Count
• Breaking strength,
• Elongation,
• Twist,
• Moisture contents,
• Yarn winding,
• Yarn lubrication,
• Yarn hairiness.

Yarn counts (tex) and twist (turns/cm):

The obligation regarding the precision of the yarn check and the resistance levels for variety in yarn tally and curve (turns/cm), just like the sort and level of grease/complete, lies with the spinner and are typically pronounced in the terms and states of the offer. For exceptionally basic end-uses, for example, military things and specialized materials, extraordinary yarn quality particulars and inconstancy points of confinement will be required and should be consulted with the spinner.

Yarn evenness:

Yarn uniformity is a proportion of the degree of variety in yarn direct thickness or mass per unit length of yarn. At the end of the day, it alludes to the variety in yarn tally along its length. It is the uniformity of staple spun yarn that is of worry here. Consistently fibre yarns have basically no variety in straight thickness so equity isn’t an issue for those yarns. A yarn with poor uniformity will have thick and meagre places along yarn length, while an even yarn will have little variety in mass or thickness along length. While a yarn may change in numerous properties, equity is the most significant quality part of the yarn, since varieties in other yarn properties are regularly an immediate aftereffect of yarn tally anomaly. We definitely realize that bend will in general collect in the slight places in yarn, so anomaly in yarn straight thickness will cause varieties in turn along yarn length. This particular centralization of turn in slender places along a yarn likewise compounds the varieties in yarn distance across or thickness, which regularly unfavourably influences the presence of the resultant textures. A sporadic yarn will likewise change in quality along the yarn.

Conclusions–The spinning process is one of the important production processes in the textile industry. Yarn is created using Cotton Fibre on a rotor or ring spinning machine. The quality of the resulting yarn is very important in determining their application possibilities. An important aspect of the production process is a selection of raw material, quality of resulting yarn and cost. The yarn should have Optimal Product Characteristics with minimum cost.

The proposed paper aims to study profitability and predictability by developing a computational model. ANN is used for the prediction of yarn properties from fibre properties. These fibre properties are optimized using a Genetic Algorithm (GA). GA also considers available stock into account. Linear Programming is used to decide the proportionality of fibres in cotton bled and cost optimization. The result shows that the accuracy of the proposed integrated approach is higher than the Industrial Standards.

Additional information on Genetic Potential, Genetic Control, and Environmental Variability

• Improvements in textile processing particularly advance in spinning technology, have led to increased emphasis on breeding cotton for both improved yield and improved fibre properties (Meredith and Bridge, 1972; Green and Culp, 1990; Patil and Singh, 1995).
• Studies of gene action suggest that within upland cotton genotypes there is little non-additive gene action in fibre length, strength, and fineness (Meredith and Bridge, 1972); that is, genes determine those fibre properties. However, large interactions between combined annual environmental factors (primarily weather) and fibre strength suggest that environmental variability can prevent the full realization of the fibre quality potential of a cotton genotype (Green and Culp, 1990).
• More recently, statistical comparisons of the relative genetic and environmental influences upon fibre strength suggest that fibre strength is determined by a few major genes, rather than by variations in the growth environment (May 1999). Indeed, spatial variations of single fertility factors in the edaphic environment were found to be unrelated to fibre strength and only weakly correlated with fibre length (Bradow et al., 1999b,c; Johnson et al., 1999).
• The genetic potential of a specific genotype is defined as the level of fibre yield or quality that could be attained under optimal growing conditions. The degree to which genetic potential is realized changes in response to environmental fluctuations such as application of water or fertilizer and the inevitable seasonal shifts such as temperature, day length, and insolation. Season-related shifts in cotton plant metabolism and fibre properties take the form of higher levels of fibre maturation in upland and Pima bolls from July flowers, compared with the maturity levels of fibres in bolls from August flowers on the same plants (Sassenrath-Cole and Hedin, 1996; Bradow et al., 1996c; Bradow et al., 1997a).
• Similar effects of the environment on genetic potential have been quantified in plant and field maps of micronaire and maturity (Bradow et al., 1996b, 1999b; Johnson et al., 1999).
• In addition to environment-related modulations of fibre quality at the crop and whole-plant levels, significant differences in fibre properties also can be traced to variations among the shapes and maturities of fibres on a single seed and, consequently, within a given boll. Comparisons of the fibre-length arrays from different regions on a single seed have revealed that markedly different patterns in fibre length can be found in the micropylar, middle, and chalazal regions of cottonseed – at either end and around the middle (Delanghe, 1986).
• Mean fibre lengths were shortest at the micropylar (upper, pointed end of the seed) in G. hirsutum, G. barbadense, and G. arboreum genotypes (Vincke et al., 1985). The most mature fibres and the fibres having the largest perimeters also were found in the micropylar region of the seed. After hand ginning, the percentage of short fibres less than 0.5 inches or 12.7 mm long on a cotton seed was extremely low.
• It has been reported that, in ginned and baled cotton, the short fibres with small perimeters did not originate in the micropylar region of the seed (Vincke et al., 1985; Delanghe, 1986). Further, AFIS-A21 (Advanced Fiber Information System, Model A-2, Zellweger, Knoxville, TN) measurements of fibres from micropylar and chalazal regions of seeds revealed that the location of a seed within the boll was related to the magnitude of the differences in the properties of fibres from the micropylar and chalazal regions (Davidonis and Hinojosa, 1994).