Non-woven fabric

Non-woven fabric:

Non-woven’s are a sheet, web or bat of natural and or man made fibres or filaments, excluding paper, that have not been covered into yarns, and that are bonded to each other by any of several means.

Non wovens are flexible porous product consisting of one or more fibre layers. The separate fibres may either be preferentially oriented in one direction or may be deposited in a random manner. They are bonded by chemical, thermal or mechanical processes into textile products. Non woven are mainly planner structures.

This relatively young branch of textile industry has expanded enormously after the Second World War, because of the high production rates & the resulting cost savings.

Characteristics of non woven fabrics:

The particular set of properties that a non-woven fabric may have is dependent upon the combination of factors in its production.

The range of characteristics is wide. Some characteristic is given below:

- The appearance of non woven fabric may be paper like, felt like or similar to that of woven fabrics.

- They may have a soft, resilient hand or they may hard stiff or boardy with the little pliability.

- They may be as thin as tissue paper or many times thicker.

- Non wovens may be translucent or opaque.

- Their porosity may range from high, free air flow to minute to impermeable.

- Their strength may range from low tear & burst strength to very high tensile strength.

- They may be fabricated by gluing, heat bonding or sewing (punching).

- The drapability of non-wovens varies from good to none at all.

- Some non-wovens have excellent launder ability, others have none. Some may be dry-cleaned.

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Structure of reactive dyes

Structure of reactive dyes:

The four characteristics feature of a typical reactive dyes are:

- The chromophoric grouping, contributing the color and much of the substantivity for cellulose;

- The reactive system, enabling the dye to react with the hydroxy group with water and cellulose;

- A bridge group that links the reactive system to the chromophore;

- One or more solubilizing groups, usually sulphonic acid substituents attached to the chromophoric grouping.

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Garment Printing

Recent trends in printing is not just designing, preparing screens and printing to get designs on the garment, but the combination of different designs with difference types of printing to make it more and more attractive.

Garments’ printing is a field which is given a less attention among various fields in manufacturing of garments. Earlier days printing was primarily done on kids garments in order to make it more attractive. But now as trend changes lot of adults garments is also being printed with various designs which add value to the garments.

Garment printing is one of most important fields where various techniques can be adopted for value addition of the garment. Puff printing, metallic printing, khadi printing and plastizol printing are some important garment printing effects.

Puff printing: In this method when the paste is printed and dries it look like normal printing garments but once it is cured the prints gets raised from the surface of fabric. Thereby the print will have the embroidered effect.

Metallic printing: Metallic printing consists of a mixture of binder with gold, copper bronze or aluminum powder and other auxiliaries. Here the fine powders of the above varieties will give different kinds of shades, silver tone. This is used mainly on ladies garments to give a rich look.

Khadi printing: This is done on light or dark colored grounds. It consists of titanium dioxide with other auxiliaries. The important factor in printing of this is right combination of titanium dioxide and proper choice of binder will give better fastness and soft handle.

Plastizol printing: Plastizol printing is the latest printing technique for last 5-6 years in India. The inks contain polyvinyl. Chlorides mixed with resins and pigments these inks have got a property by which the prints get dried only with the application of that. They have soft handle and resist cracking when stretched. Main thing is curing process in plastizol printing.

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Lay in spinning

Lay is the measure of the closeness of the spacing of the coils of yarn in any one layer on the bobbin. It is normally given as the number of coils per inch measured parallel with the axis of the bobbin.

Factor does the closeness of lay depends

The closeness of the lay depends upon
(a) the rate of delivery by the front roll
(b) the rate at which the ring rail is traversed
(c) the diameter on which the yarn is wound

In as much as the rate at which the front roll revolves depends upon such factors as the size of the yarn being spun, the spindle speed and the twist per inch, the proper lay is obtained by changing the rate at which the ring rail is traversed up and down. 

The diameter of the package being wound varies, depending upon the type of package being wound and the position in the package.

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Method to designate the size of traveler

There may be a question from the Yarn manufacturing section or spinning section. Like

Define the method to designate the size of traveler with examples.

So I am going to answer this question as below:

Travelers are designated by a numerial or combination of numerals which are called their “size” or “number”. This system is based on the weight of 10 travelers. 

Ten number “1” travelers weight 10 grains. As the weight of ten travelers increases, the number is larger. The increase is not unifoem but average two grains per number. 

Commonly used numbers range from 1 upward to 50 as the weight of ten travelers less than 10 grains, the size is written with a number followed by a diagonal line and a zero. 

These are called “ought treavelers” or “naught traveler”. The size ranges 1/0 to around 25/0. These sizes decrease in weight in a varying range of staple of “1 grain per number, ½ a grain per number, and, finally ¼ of a grain per number, until the finest commonly used size weighs about 1 grain per ten travelers.

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What is the function of spinning ring? Define its essential parts clearly

The function of spinning ring is to serve as a track upon which the travelers may revolve. In this way, it assists in twisting the yarn and, in addition, helps in guiding the yarn on to the bobbin in the proper pattern to give the desired “wind”.

 A spinning ring is a narrow, vertical, cylindrical, steel band with a horizontal flange which projects at right angles from both sides of the top edge.

 The cylindrical band or vertical part of the ring, is called the “web”. It is quite thin so that the ends of the traveler may be close together, still clear the web and revolve freely.

 The horizontal part at the top of the ring is called the “flange”. This is broad enough to keep the traveler from lifting away from the web. The traveler must be related to fit the flange of the ring on which it runs.

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Which functions influence the amount of twist to use? How?

The amount of twist to use in any given yarn depends on several items:

1. the count to be spun

2. the use for which the yarn is intended

3. the staple of the cotton used

For coarse count, the twist per inch is low. As the count increases, the twist necessary increases.
The uses for which yarns are intended vary greatly and require quite different yarn characteristics.

These characteristics are very largely controlled by the amount of twist used. When soft and supply yarn is desired, these characteristics are obtained by the use of a relatively low twist. A low twist is used where a lustra yarn is desired.

For fabrics like   , where uneven or hard surface is desired, the yarn used has an exceptionally high or hard twist.

 For short stable cottons, it is necessary to use considerable twist to bind the fibres sufficiently to get a satisfactory commercial yarn. As the staple is longer, low twist is necessary to obtain the necessary strength.

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Objective of reversing mechanism in Spinning

When one complete layer has been wound on the bobbin, it is necessary to reverse the direction of the rail for the next layer. 

This is done automatically through the control of the “builder”. The more common mechanical means used for this purpose is a grasp of three bevel gears in the lay gearing train. 

Two large bevel gears are mounted on the same shaft in such a manner that with a short travel movement either of the two may be driven by the third, a small bevel gear. 

As one large bevel gear is driven from the left sideof the small bevel gear, one will cause the rail to descend.

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What is Twist Per Inch or TPI or Turns Per Inch?

Twists per inch are the number of times the strand has been twisted in a one inch length. This is the method of designating twist in a roving.

Twists per inch are often called “turns per inch”. It is difficult to measure twist per inch in a roving, because it is generally quite low and the untwisted strand is weak.

The amount of twist to use varies with the staple of the cotton and the size of the roving into which it is being made.

Longer cotton requires less twist because individual fibres extend further in the strand and so help to bind themselves together more securely than do short fibres.

Finer roving needs more twist than coarse roving. As the strand becomes finer, the strength due to bulk alone decreases.

Also, as the fibres are drawn to be more nearly straight and parallel, there is less strength due to entangling with one another.  

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How is the twist inserted in the roving?

Twisting is accomplished by the ‘flyer’ which is carried on the spindle. As the strand is delivered at the front rolls, it is led downward and forward to the top of the flyer, through the flier and on to the bobbin.

The flyer revolves rapidly and carries the roving around with it. The result is that the front roll is delivering a narrow ribbon of fibres in a fixed plane; the flyer, holding the other end of the exposed strand, turns rapidly and twists it.

The twist runs quickly up to the front roll as there is nothing to prevent. As rapidly as the front roll delivers a new length of ribbon, the flyer makes additional turns and they run back to the front roll.

For any given condition, the flyer speed and the front roll speed are fixed, which gives a constant ratio between the turns of twist and the inches delivered at the front roll. This is the “twist per inch”.

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Purpose of using twist in roving

As a Textile student/teacher and learner you must know what the roving is? Now I will try to mention the Purpose of using twist in roving or why twist is required in roving?

I will answer this topic very simply mentioning the basics in this one. See below

The purpose of using twist in roving is

- to give the strand sufficient strength to withstand the strain of turning the bobbin on which it is wound, in the creel of the next operation.

Hope, you got the answer in one sentence and this is helpful.

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