Bobbin | Structure of the Bobbin

Bobbin is a cylindrical or slightly tapered barrel, with or without flanges, for holding slubbings, rovings, or yarns.

The Structure of the Bobbin
The shape of the bobbin The tube is usually made of paperboard, plastics and has a conical shape similar to the spindle tip; the yarn is wound on the tube leaving a free space (10 ÷ 13 mm) at both ends. A full bobbin (Figure) consists of three different parts:

1.  The “H2” tapered base (kernel),
2.  The “H1”cylindrical part at the centre (yarn package or buildup),
3.  The “H” cone-shape upper end A bobbin is wound starting from the base to the tip by overlapping the various yarn layers frustrum-like; except for the kernel, this gives a conical shape to the material from the edge of the kernel to the tip of the bobbin. 

Each step of the bobbin formation consists essentially of the overlapping of a main yarn layer with a cross-wound tying layer. The main layer is wound during the slow upward travel of the ring rail; the yarn coils laid one next to the other provide the bobbin build-up. The cross layer, made of distant coils inclined downwards, is formed during the quick downward travel of the rail. This system keeps the main layers separated, in order to prevent them from being pressed one inside the other (thus resulting in a quite difficult or almost impossible unwinding of the yarn). 

Bobbin structure

The ratio between the number of yarn coils wound on the bobbin during the upward travel of the rail and the number of yarn coils wound during the downward travel usually range between 2:1 and 2.5:1 ; for this reason the rail must raise slowly (A) and lower quite quickly (B). When unwinding the bobbin at high speed (D) the simultaneous unwinding of many coils could lead to entanglements of the yarn (this does not occur in .C. case).

The yarn wound on the bobbin during each upward and downward travel of the ring rail is called run-out.; to facilitate successive unwinding, the length of the run-out ranges from 3 to 5 m and is smaller for coarse yarns and greater for finer ones. The travel of the rail is considered sufficient when it is 15÷18% larger than the 

ring spinning diameter.

The structure of the bobbin is the result of the continuous motion of the winding point of the yarn on the bobbin affected by the ring rail. The rail travels up and down along the vertical axis to form the main layers, and on the cross axis (with an upward progressive increment) to homogeneously distribute the yarn on the bobbin .

The increment value, i.e. the space between the two subsequent upward travels of the ring rail (winding cycles), determines the forming bobbin diameter with respect to two different parameters: the run-out and the yarn count.

To obtain bobbins of a given diameter it is necessary to consider that the increment is inversely proportional to the yarn count (Nm) and directly proportional to the length of the run-out; in other words, after establishing the diameter of the bobbin, with the same yarn count, when doubling the run-out length, the increment must also be doubled or, with the same run-out length, when doubling the yarn count (Nm) the increment value must be halved.

Definition and Classification of Textile Neps | Count of Neps

Any small entanglement of textile fibers that can not be unraveled, formed during carding or ginning.

Classification of Neps
For cotton fiber; there are five types of Neps. These are –

Process Neps: Commonly produced by faulty carding or up to spinning yarn.

Mixed Neps: Fibres tangle around a foreign materials. For instance – Grit.

Immature Neps: Generally form by processing immature fibre.

Homogeneous Dead Neps: A tangle of nearly all dead fibres.

Fuzz Neps: A fault of short fuzz fibers .

Count of Neps
Nep count is the no. of neps per 100 square inches of card web forming ( a standerd hank of sliver of 12 NE on a 40 inch wide card).

How To Measure the Count of Neps?
At first a web is collected from the card placed on a 10 inch × 10 inch black board. Then the neps are counted and the no. of neps found is corrected fro any difference in hank or card width.
Mathematically, Nep Count, n = m × 100 [ m = no. of neps per inch square card web].

Process Flow Chart of Textile Finishing Process

Textile finishing usually includes treatments such as scouring, bleaching, dyeing and/or printing, the final mechanical or chemical finishing operations, that during this stage are carried out on textile products (staple, sliver or top, yarns or filaments, woven or knitted fabrics) to enhance their basic characteristics like dye penetration, printability, wettability, colour, hand, and appearance.

By textile finishing, we also mean all the processing operations that, though included in the socalled finishing stage, are generally applied to the fabrics to improve their appearance, hand and properties, at times in accordance with their field of application.

The finishing stage plays a fundamental role in the excellency of the commercial results of textiles, which strictly depend on market requirements that are becoming increasingly stringent and unpredictable, permitting very short response times for textile manufacturers.

The latest machines on the market used for finishing operations generally offer multi-purpose applications; the flexibility and versatility features of these machines are uninterruptedly evolving to grant excellent consistency of the results.

Finishing operations can be carried out by means of discontinuous, continuous and semicontinuous systems.
 

Discontinuous or Batch-type Systems: 

All the operations are carried out on a single machine; it is therefore necessary to load the machine, carry out the treatments following a predetermined cycle, unload the machine and finally wash it thoroughly before starting a new cycle. This working process is extremely flexible and is suitable for processing small lots: for example, it is possible to a carry out a scouring treatment on a single machine, then a bleaching one followed by a dyeing process. For the production of large lots, the discontinuous process is labour-intensive, i.e. it requires many operators to load and unload the material; it also entails long processing times and results that can vary from one batch to another.

Continuous Systems: 

The operations are carried out by means of a series of machines; every machine carries out always and solely the same process. Every machine is assembled according to specific production requirements. A system like this entails high start-up costs and a complex setup but once the system has started, it requires a smaller staff and grants excellent repeatability and high output rates; continuous systems are therefore suitable for manufacturing large lots of products with the highest cost-efficiency.

Semi-continuous Systems: 

In these mixed systems several operations are carried out with both continuous and discontinuous machines. For example, a continuous pad-batch machine is used to wet the fabric and a discontinuous system is then used for other treatments. These mixed systems are suitable for processing small and medium lots; they require reasonable start-up costs and grant quite good reproducibility. 

The Textile Finishing Stage:

What is ERP Software? | Functions of ERP Software’s in Textile |Application of ERP Software in Textiles

ERP Software:
ERP(Enterprise Resource Planning) is revolutionary concept in the contemporary world. All the information of an enterprise under one roof for assisting planning and implementing decisions having complete visibility that is the main objective of ERP.

ERP Software’s in Textiles:
ERP Software’s are available in different sectors in textiles. Such as:

1. ERP-Software for Home Textiles
2. ERP-Software for Spinning Mills
3. ERP-Software for Weaving Mills
4. ERP-Software for Textile Processing Mills

What are the Benefits of ERP ?

1. Easily monitoring of an industry
2. Compiling report within a very short time
3. No chance for data manipulation
4. Saving of time
5. Easy access anywhere from the world

Functions of ERP Software’s in Textiles
ERP Software allows the following functions :

1. Sales order entry
2. Procurement
3. Inventory
4. Production
5. Costing
6. Managing Dye house

1. Sales Order Entry:
Considering color size combinations , creation of preformed invoice,shipping document, sales invoice, picking of finished goods, packing list generation, handling letter of credit facilities.

2. Procurement:
Requisition, approvals, purchase order creation, receiving goods through receiving documents.

3. Inventory:
Availability of raw materials/work-in progress/finished goods per lot, container, batch wise, order wise.

4. Production:
Production steps with consumption breakdown, starting and end dates, waste calculation, production progress tracking.

5. Costing:
Pre-costing by merchandisers and actual costing from raw materials in reality utilized in production floor.

6. Managing Dye House:
A lot of waste come from dyeing industry that certainly increases the fabric price. ERP software facilities dye house management providing chemical inventory, batch management system, daily production report with waste calcularion, recipe creation, lab-management, actual cost calculation, reprocess dyeing etc. in their recognized ERP system. 

Ring Traveller | Features of a Ring Traveller | Types of Traveller |Factors for Ring Traveller Selection

Traveller

Traveller is a tiny element which is used in ring spinning system , acts as the main of twist imparter during yarn production. On the other word , it is also called the twisting element merely responsible for twist impartion.It is a C-shaped, metal clip that revolves around the ring on a ring spinning frame. It guides the yarn onto the bobbin as twist is inserted into the yarn.

Ring Traveller

The traveller allows the twisting and the correct delivery of the yarn on the bobbin. The take up speed of the yarn, which corresponds to the difference between the peripheral speed of the bobbin and the peripheral speed of the traveller, is equal to the peripheral speed of the delivery cylinders of the drafting unit. The difference between spindle rpm and the traveler rpm, within a specific unit of time, gives the number of coils deposited on the bobbin within a specific unit of time. Therefore, with the same spindle speed, the traveller rpm increases along with the bobbin diameter while the number of coils wound on the bobbin decreases.

When the traveller rotates the high contact pressure between the ring and the traveller creates huge friction forces that generate heat; the traveller can reach temperatures exceeding 200 ÷ 300 °C since its small mass does not allow a quick transfer of the heat to the air or to the ring. For this reason, significant improvements in ring spinning can be hardly achieved with the materials currently available, since the speed of the traveller has apparently reached its maximum limit (approx. 33 ÷ 35 m/sec for steel travellers and 45 ÷ 47 m/s for nylon-glass fibre travellers). This is why the traveller used for producing a specific type of yarn must feature the most suitable shape, mass, material, finish and cross section. To reach the highest speeds, the shape of the traveller must correspond to the shape of the ring.

This creates a very large contact surface, which facilitates heat transfer; the surface must also be very smooth to grant a low barycentre. The flat profile must allow space enough for the yarn since the friction between the yarn and the ring could increase the yarn hairiness and consequently the formation of flying fibres.

The mass of the traveller determines the friction force between the ring and the traveller, the balloon size and consequently the take up tension of the yarn. If the mass of the traveller is very small, the balloon will be sufficiently large, the take up tension will be limited and the bobbin will be soft; on the contrary, a heavy traveller will determine an increase in the take up tension and a greater number of breaks. In a few words, the mass of the traveller must be strictly proportional to the yarn mass (count and resistance) and to the speed of the spindle. 

Features of a Traveller:

1. Generate less heat
2. Dissipate heat fastly
3. Have sufficient elasticity for easy insertion and to retain its original shape after insertion
4. Friction between ring and traveller should be minimal
5. It should have excellent wear resistance for longer life
6. Hardness of the traveller should be less than the ring

Types of Traveller:

Traveller are normally three types. They are:

1. OS -Type
2. C-Type
3. G-Type

Factors for Ring Traveller Selection :

1. Count of yarn to be spun
2. Fiber used in the yarn
3. Ring cup diameter
4. Spindle speed

Basic Woven Structure | Classification of Basic Woven Structures

The form of interlacing of warp and weft yarns can be divided basically into three categories- plain, twill and satin/sateen weave. These three kinds of forms are called basic weaves.

1. Plain Weave: 

The simplest of all weaves is the plain weave. Each filling yarn passes alternately over and under one warp yarn. Each warp yarn passes alternately over and under each filling yarn. Some examples of plain-weave fabric are crepe, taffeta, organdy, and muslin. The plain weave may also have variations, which include the following:

Warp rib weave- Warp rib weaves may be described as plain weave in which two or more picks are inserted in the same shed. Warp rib weaves are normally used in warp faced constructions. The warp cover factor and the warp crimp are substantially higher than the weft cover factor and the weft crimp. The intention is to produce fabrics with prominent weft-way rib formed by the crowns of the warp threads.
 

Weft rib weave- Weft rib may be described as plain weave in which two or more ends weave together as one. It is difficult to achieve very high weft cover factors in weft faced plain-weave cloths. By using two finer ends weaving as one, it becomes possible to achieve higher weft cover factor. Such cloths are expensive to weave and not very common.
 

Basket, matt or hopsack weave- In matt, basket or hopsack weaves two or more ends and two or more picks weave as one. The simplest and commonest of these weave is 2/2 matt.
(Refer to Annex 2 for weave diagrams)

2. Twill Weave: 

A weave that repeats on 3 or more ends and picks & produces diagonal lines on the face of the fabric. A twill weave is characterized by diagonal rib (twill lines) on the face of the fabric. These twill lines are produced by letting all warp ends interlace in the same way but displacing the interlacing points of each end by one pick relative to that of the previous end. In twill weave line moves sinisterly (Right - Left, Z twill) and dextrally (Left - Right, S twill). Common derivatives of twill weave are as follows:
 

Zigzag Weave- If the direction of the diagonal in a twill fabric is reversed periodically across the width, a zigzag effect is produced. Zigzag weave is achieved by simply combining two S and Z twill weaves of equal repeat.

Diamond weave- Diamond weaves are achieved by combining two symmetrical zigzag weaves of equal repeat. Diamond designs are vertically and horizontally symmetrical.
 

Herringbone weave- In Herringbone weave also the twill direction is reversed periodically like zigzag weave but at the point of reversal the order of interlacement is also reversed and then twill line commence as usual.
 

Diaper weave- Diaper weaves are produced when we combine two Herringbone designs. Diaper designs are diagonally symmetrical. (Refer to Annex 2 for weave diagrams)

3. Satin/sateen Weave: 

The satin weave is characterized by floating yarns used to produce a high luster on one side of a fabric. Warp yarns of low twist float or pass over four or more filling yarns. The low twist and the floating of the warp yarns, together with the fiber content, give a high degree of light reflection. Weights of satin fabrics range from chiffon satin to heavy duchesse satin. The sateen weave is similar to a satin construction except that in the sateen weave, the filling yarns float and are visible on the surface of fabric. Examples: cotton sateen, and damask.

Textile Softening | Fabric Softening Process | Types ofSoftener/Softening Agents

Softening
As a general rule, each fibre has its specific softness value, which depends on its chemical composition and physical structure (less crystallinity = greater softness). The fineness of the fibre or of the filament directly affects the softness of the yarn (woollens, worsteds, microfibers etc.). The yarn twist ratio is inversely proportional to its softness.

The weave also contributes to reducing (closer weave = cloth) or increasing (looser weave = satin) the fabric softness. Furthermore, a greater number of yarns per centimetre increase the stiffness of the fabric, thus reducing its softness.

Softening is carried out when the softness characteristics of a certain fabric must be improved, always carefully considering the composition and properties of the substrate. It is also worth underlining that no standard methods have been developed and established to determine exactly what the softness of a fabric is. This evaluation is therefore almost personal and carried out on the basis of operator.s experience. It is anyway possible to distinguish between many types of softness:

a) surface softness,
b) surface smoothness,
c) elasticity (to compression and stretching).

Fabric Softening Process:
To change the hand properties of a fabric, we can apply mechanical, physical, chemical or combined techniques; some of these methods (sueding, raising) have already been explained in detail in previous sections of this handbook, while some others refers to machines that give different degrees of softness, by means of high-speed rope processing in wet or dry conditions, with the drying stage carried out during the treatment (with or without softeners or enzymes.)

The functional core of these machines are the two tunnels where the fabric is fed through two Venturi tubes. The energy applied for drawing the material is produced only by air and pressure. The fabric flowing through the Venturi tubes is pushed at high speed against a grid on the machine rear side; the fabric then slides on Teflon-coated chutes and reaches the machine front side to start the cycle again; the fabric can reach a speed of 1000 m/min., depending on the type and weight of the different textiles to be processed and according to the desired results. 

Schemes of fabric softening machines

This unit applies physical and mechanical principles on fundamental elements such as: 

• air, which is the fabric propeller and drawing element; 
• the mechanical stress exerted on the fabric inside the Venturi tubes and the stress due to the impact against the rear grid; 
•  the eventual action of heat.

It is also worth noticing that water is not a crucial element for the process; it is only a medium for carrying dissolved non biodegradable chemical additives (if required.) The combination of all these elements, almost free of polluting charge, cause the structural modification of the fibres making up the fabric.

They result in more or less marked surface modifications, which can radically change the appearance and the sensorial properties of the fabrics. The complexity of the finishing action starts inside the Venturi tube where the tail of the fabric is subjected simultaneously to a compressive action and to a subsequent series of vibrating pulses which tend to “random-modify” and compact the textile structures, eventually giving them different properties.

The one-way thrusting force is transformed into a impact force against the grid on which the fabric is pushed when emerging from the Venturi tube; this causes other modifications of the fabric and add structural and surface effects.

This simple treatment that combines physical and mechanical principles, carried out at a precise temperature set by the operator, is sufficient to create particular effects on the morphology of fibres and the weave. The modifications produced by this treatment are very different and not only affect the colour, appearance and hand properties of the fabric, but also add new properties, e.g. modifying the refraction and diffraction of light on the fabric surface.

The most notable effects in terms of style and added value are obtained on linen, a precious delicate fibre, particularly difficult to process without using chemicals.

The combination of a chemical product or an enzyme liquor with the mechanical treatment can be carried out not only on linen but also on many other widely used fibres such as Tencel and polynosic fibres, imparting a draping, full and lively hand.

All these effects are obtained thanks to the air thrust and to the following impact against the grid, or to the pressure of rollers on the fabric rope. Comparing the effects of this treatment on a Tencel fabric and on a similar treatment carried out on a dyeing machine, we can see that, as previously explained, this finishing process not only affects the appearance of the fabric, but also .cleans up. the fabric surface homogeneously, as a result providing good anti-pilling properties.

The best softness results can be obtained by carrying out the above mentioned physical mechanical processes and by applying a special chemical softening agent.

As a general rule, the softening agents applied are hygroscopic or lubricating agents, which facilitate the fibre sliding within the fabric structure, thus granting easier deformation and creasing of the fabric. In most cases, the duration of the effect is limited since the products applied during the treatment are eliminated by subsequent washing; for this reason they must be applied in the final stage of the treatment. The most common softeners are below:

1. Non-ionic Softener
2. Anionic Softener
3. Cationic Surfactants
4. Silicone-Based Softeners
5. Reactive Softeners

Non-ionic Softeners: 

Generally ethers and polyglycol esters, oxiethylates products, paraffins and fats. These softening agents are generally less efficient than anionic and cationic ones but they withstand the effects of hard waters, acid or basic environment and also in presence of cations and anions, therefore the normal fabric care conditions.

Anionic Softeners: 

Sulphoricinates, anionic surfactants produced by the condensation of fatty acids. They have good characteristics as lubricating softening agents and give the fabric a full hand; they are unstable in hard water and acid environment. In addition, they must not cause yellowing at condensation temperatures.

Cationic Surfactants: 

Usually they are quaternary ammonium salts, amino-esters and amino amides; they are recommended for all types of fibre, and can be also applied with exhaustion process in acid environment (pH 4-5). These are the best softening agents and are also called molecular velveting. Agents because they form bonds with the cationic group on the surface of the fibre generally with negative electric potential. They can give some problem in presence of large anions, and they can cause dye toning, or a reduction in fastness to light values in the presence of direct and reactive dyes; they also have a high polluting charge as waste water (bactericides).

Silicone-Based Softeners: 

These are generally polysiloxane derivatives of low molecular weight. They are insoluble in water, and therefore must be applied on fabrics after dissolution in organic solvents, or in the form of disperse products. They feature quite good fastness to washing. They create a lubricating and moderately waterproof film on the surface and give fabrics a velvetysilky hand (desirable for velvets, upholstery fabrics and emerised fabrics)

Reactive Softeners: 

N-methylol derivatives of superior fatty amides or urea compounds replaced with fatty acids. The products have to be cross-linked and provide permanent softness and water repellency.

As explained previously, even though some softeners can be applied with exhaustion processes on yarns, when softening fabrics, the best technique is the continuous pad-wetting process followed by a drying stage in a stenter. This treatment must be carried out at the end of the finishing process; for this reason, softening is usually performed simultaneously with other dimensional stability processes (width stabilisation, weft and warp straightening). It is worth remembering that the use of softeners can reduce the fastness to rubbing of synthetic fibres dyed with disperse dyes, as the fatty surface layer tend to attract the dye molecules after hot treatments.