Opening

To carrying out the basic operation of spinning, Opening is needed. The raw materials enter the spinning mill in highly pressed from to enable optimum transport and storage condition to be used. Thus Opening must precede the basic operation. 
Opening is two types. They are:

1.      Opening to flocks. (In the blow room).

2.      Opening to fiber (In the carding machine).

There is the intensity of opening or factors conditioned for opening:

1.      Raw materials.

2.      Machines or devices.

3.      Speed.

4.      Ambient condition.

5.      Position of the machine.

3D Fabrics An Overview

INTRODUCTION:
Three-dimensional woven, braided or stitched fibrous assemblies are textile architectures having fibers oriented so that both the in-plane and transverse tows are interlocked to form an integrated structure that has a unit cell with comparable dimensions in the all three orthogonal directions. This integrated architecture provides improved stiffness and strength in the transverse direction and impedes the separation of in-plane layers in comparison to traditional two-dimensional fabrics. Recent automated manufacturing techniques have substantially reduced costs and significantly improved the potential for large-scale production. Optimal orientations, fiber combinations and distributions of yarns have yet to be fully developed and perfected for 3D fabrics subjected to impact loading conditions.

The term �three-dimensional� is applied in the sense of having three axes in a system of coordinates. If no yarn system penetrating the depth is present, we are confronted with a simple textile flat (2-D) fabric. Simple flat fabrics have very good stiffness and strength in two directions i.e. in warp-way and weft-way, but they have problem in thickness direction. In thickness direction they have very low stiffness and strength.

This limitation restricts the use of simple 2-D fabrics in the field of space engineering, automotive engineering and sports goods. One way to get added strength in thickness direction is by the use of fibre reinforced composites. Composites using long fibres for reinforcement purposes have long been popular in aviation and space engineering as well as for sports goods. But according to market projections, the annual increase for the raw materials used in such products, i.e. carbon fibres and polyaramide fibres are in the range of 15 to 20% only. The reasons for the comparatively limited proliferation of high performance composites (HPC) are found to be:-

� High cost for raw material, and
� High manufacturing cost.

Above mentioned limitations led the researcher to think in the direction of new concept, which led the discovery of 3-D fabrics.

HISTORY OF 3-D FABRICS:
The history of three-dimensional textiles reaches back to the 19th century. Already in 1898 it was recognized that the interlaminar shearing properties of rubber drive belts could be improved by adding reinforcements made of multi-layer fabrics, thus effectively eliminating the lateral displacement of layers. Subsequently, multi-layer fabrics which feature additional reinforcement by yarns arranged vertically to the fabric layers have been applied in a wide range of sectors:-

1. Conveyor belting
2. Straps
3. Carpets
4. Dry felts for papermaking
5. Interlinings for shirt collars

At the end of the sixties, the aerospace industry began to demand fibre- based composite structures which could withstand multi-directional stress at extreme thermal conditions. In France and later on in the United States and Japan, carbon fibre composites were developed whose yarn systems were arranged multi-dimensionally.

NEED FOR 3D FABRICS:
Traditional 2D weaving has been around for thousands of years. 2D weaving is a relatively high-speed economical process. However, woven fabrics have an inherent crimp or waviness in the interlaced yarns, and this is undesirable for maximum composite properties. Most of the marine and wind blade industry currently use glass non-crimp stitch-bonded or knitted fabrics, more properly known as multi-axial-warp-knits. These materials are cost-competitive. However, they do not conform well to complex forms and often have significant fiber distortion in the final composite. A fully automated 3D weaving process with simultaneous multiple filling insertions, has been developed at the NC State University College of Textiles [1]. This process is inherently 3D from the onset, and does not involve the building up of layers one layer at a time. Rather, a single unit of thick fabric is formed during each weaving cycle. The essence of the innovation/patent centers around this simultaneous multiple insertion from one or both sides of the fabric.

MANUFACTURING OF 3-D FABRICS:
Manufacturing method involves special peddles which are designed to sort the warps into three sections that form the mainframe and flanges of the 3D woven preforms. The preforms are woven into a plane construction and then unfolded to form a near-net-shape construction.

Since reinforcements play a major role in dominating the mechanical properties of composites, the continuity and integrity of the architecture of fiber preforms becomes a main concern in 3-d composites. Textile reinforcements have received widespread use in composites based on their flexibility to accommodate various reinforcing requirements. From a textile constructional perspective, there are four reinforcing constructions, including chopped fibers, filament yams, simple fabrics, and 3-d fabrics. There are four basic textile techniques-weaving, knitting, braiding, and stitching-that are capable of fabricating 3D textile reinforcements .

These 3D woven preforms with various architectures can be fabricated using different weaving methods. Multi-warp weaving methods are used for weaving orthogonal and/or angle interlocked multi-layer woven fabrics. On the other hand, preforms with cylindrical profiles can be constructed using specialized looms developed by different methods, such as reciprocative loom and conical take-up device.

The warp/weft knitting technique has been widely used to produce non-crimped fabrics (NCFS) in which tows all lay flat, straight, and fully extended and are subsequently knitted by fine filaments to fix them in place. NCFS can be produced with single-layer or multi-layer constructions where each layer has a specific fiber direction. Stitching is a fairly convenient and cheap method for fabricating 3D textile preforms, which simply bind the fabrics, forming a 3D construction (thick plate, T-shaped, and so on) by chain or interlock stitching of a thread structure.

Since a 3D construction, especially for complex shapes, is difficult to fabricate at a reasonable production rate, very few automatic manufacturing systems available have been developed commercially. Two of the most successful automatic manufacturing systems for 3D textiles are the multi-axial warp knit (MWK) by Liba.

The applications include:
1. Textile applications
2. Reinforcement of composites

The various textile applications include:

a) Automotive application
 Seat coverings
 Carpets
 Airbags

b) Garment application
 Hats
 Outer wear
 Inner wears

c) Medical application
 Artificial blood vessels
 Orthopedist fabrics

d) Architecture & Construction
Membrane fabrics
 Canalization: tubes, fittings etc.

The various applications of reinforcements of composites are:
a) Automotive application
 Wheel rims
 Bumpers
 Crash elements
 Instrument panels
 Seat shells
 Armour platings

b) Motorbike application
 Helmets
 Monocoques
 Frame parts
 Mudguards, Fenders

c) Mechanical & Process Engineering
 Pressure vessels
 Fittings

d) Medical applications
Artificial joints & Limbs
Prothesis

e) Architecture & Construction
Conical pillars
Light weight panels

f) Aerospace Industry
Radomes
 Seat shells
 Pipes

ADVANTAGES OF 3-D FABRICS:
1.) Although these materials are typically more expensive than 2D fabrics and mats, reduction of labor, higher performance and improved process efficiency result in overall cost savings in a variety of applications.

2.) The absence of interlacing between warp and filling yarns allow the fabric to bend and internally shear rather easily, without buckling within the in-plane reinforcement as in case of 2-d fabrics.

3.) The 3D preforms are seamless and directly shaped on the loom, with each part taking three minutes to weave. Moulding is said to have proven easier and more efficient using the new 3D preforms, since, because the textile is already shaped, there are no forces to affect fibre placing during the moulding process.

4.) Less conformable fabrics would require extensive cutting and darting to avoid wrinkles and/or buckling in the laminate. The conformability of 3-d preforms can result in reduced labor and faster cycle times, regardless of the composite fabrication process.

Knitted Fabrics For Industrial Application

The production of various types of industrial fabrics for industrial application is almost as old as the mechanical weaving operation itself, and these end uses are important today. Whatare new and extremely attractive to the manufacturer are the growth in industrial textiles and

its application in the sectors such as agriculture, construction, geotextiles, automotive,

protective apparel, electronics etc. This rapid increase in market potential has led these high

profile manufacturers to develop specialized fabric for knitting and serving the end purpose

efficiently. In this paper focused various knitted fabrics used for manufacturing of industrial

textiles have been reviewed.

1. INTRODUTION:

Knitting is one of several ways to turn thread or yarn into cloth (compare to weaving, crochet).

Unlike woven fabric, knitted fabric consists entirely of horizontal parallel courses of yarn. The

courses are joined to each other by interlocking loops in which a short loop of one course of

yarn is wrapped over the bight of another course. Knitting can be done either by hand,

described below, or by knitting machine. In practice, hand knitting is usually begun (or "cast

on") by forming a base series of twisted loops of yarn on a knitting needle. A second knitting

needle is then used to reach through each loop (or stitch) in succession in order to snag a

bight of yarn and pull a length back through the loop. This forms a new stitch. Work can

proceed in the round (circular knitting) or by going back and forth in rows. Knitting can also be

done by machines, which use a different mechanical system to produce nearly identical

results.

The knitting process consists of interconnecting loops of yarn on powered automated

machines. The machines are equipped with rows of small, hooked needles to draw formed

yarn loops through previously formed loops. The fabric is designed to take force in two

directions (0° and 90°). For this can be used roving of glass, high tenacity polyester, armid or

carbon as pillar threads and weft threads. These fabrics are used for reinforced composites.

Considering though orientation of the force taking yarns (0°, 90°) this fabric is comparable to a

woven fabric. However, there is the advantage that yarns are directly oriented and lie

absolutely straight in the fabric. This means that there is no loss of tenacity as in the woven

due to its crimp effect. Furthermore, the yarn-protective inlay system prevents all fiber

damage.

Warp knitted Woven fabric:

1.1. Innovation:

3D-Glass-textiles, manufactured on double needle bar high speed Raschel machines of LIBA

find ever more fields of application within the area of composite materials, technical textiles.

1.2. Manufacturing properties:

Made of 100% e-glass, one uses the capillary function of the glass, i.e. when absorbing the

resin, the commodity sets up itself automatically to the desired height.

1.3. Variety:

Whether as isolation layer in the boat- and container construction or as double-walled tanks,

these so-called spacer fabrics perform particularly well. Caused by the fabric construction,

after laminating, a more stable, lightweight and ductile composite develops.

1.4. Flexibility:

Depending on the final product, the thickness of the fabric can be adjusted between 3mm to

15mm directly at the machine. By using a special design technique, a thickness of even 25

mm can be achieved.

1.5. Applications:

Composite reinforcements (Sandwich-constructions)

Container

Tanks

Boats

Aircraft

Sport shoes

Medical textiles and Mattress

2. Geotextiles Application:

Geotextiles are permeable textile materials which are designed for use in civil engineering

applications such as erosion control, soil reinforcement, separation, filtration and drainage

etc. Geotextiles are forecast to be the fastest growing sector within the market for technical

textiles. At least 70% of all geotextile fabrics fall into the category of nonwoven geotextiles

and at least 25% are woven both warp knitted and weft knitted structures are used in the

manufacture of geotextiles.

Warp knitting is well established in this area and an extremely wide range of structures

spanning from nets and grids to monoaxial, biaxial, triaxial, multiaxial as well as composite

and three-dimensional spacer materials are all used as geotextiles. Grid shape structures

grip the soil more effectively than plain smooth fabrics. Also, for extremely high performance

and critical applications – such as land reclamation, construction of high walls and water

reservoir embankments – high strength (up to 1000 k N m-1) biaxial raschel structures are

more suitable. These fabrics have high strength, low extensibility, and high modulus, above

all, high tear strength.

A new and novel technology has been developed and commercialised at Bolton Institute,

which enables the manufacture of monoaxial and biaxial specialist natural fibre geotextile

structures for soil reinforcement. The technology is based on flat knitting, in which high

strength coarse and hairy natural fibre yarns such as sisal, coir etc can be inlaid in the

machine or cross, or both directions and incorporated within a knitted structure made from

jute, flax and other natural fibre yarns, such as cotton, viscose, Tencal, wool etc.

It is possible to manufacture designer natural fibre geotextile structures for specific short-term

solutions. These Directionally Structured Textile Fabrics have been patented, and are

currently being commercialised for mass production. Figures 1 and 2 illustrate the novel weft

knitted structures and Figures 3, 4 and 5 shows the modified mechanically operated flat

machine which enables either warp or weft or both threads to be incorporated within the fabric

structure.

2.1. Knitted Spacer Fabrics:

Warp and weft knitted spacer fabrics continue to find new and novel product applications and

it is generally recognized that spacer fabrics will be extensively used in the future in a wide

range of products, mainly due to the fact that an extremely wide range of possibilities are

available to tailor make their aesthetical, functional and technical properties for applications.

2.1.1. Warp Knitted Spacer Fabrics:

Warp knitted spacer fabrics are structures that consist of two separately-produced fabric

layers which are joined back to back. The two layers can be produced from different

materials and can have completely different structures. The yarns which join the two face

fabrics can either fix the layers directly or space them apart. It is this three-dimensional space

which is the special feature of these structures. Typically, spacer fabrics can be from 1 to 15

mm thick, with the two faces being from 0.4 to 1 mm thick. The major single feature of warp

knitted spacer fabrics is that virtually any thickness can be obtained, depending upon the type

of machinery used and the type of yarns and structures used. The warp knitted spacer fabric

with a thickness of over 100 mm (4 inches) for use as a seating fabric for sports cars.

Spacer structure manufactured in one process:

· Up to 15 mm spacer distance

· Up to 3, 3 m full fabric width

· Large pattern variety for outside cover fabric and

spacer structure

3. Karl Mayer spacer machine RD6N:

In which guide bars 1 and 2 knit the front base fabric on the front needle bar only and

guide bars 5 and 6 knit the other separate base fabric on the back needle bar only. Guide

bars 3 and 4, which carry the spacer threads knit on both needle bars in succession. The

thickness of the spacer depends upon the distance between the two needle bars and can be

varied between 1 and 15 mm. In theory the material used in guide bars 1 and 2; 3 and 4; and

5 and 6 can be different, as well as the structure of the two base fabrics can be completely

different. It is possible to vary the structure from an inelastic, elastic, solid, net or a specific

textured surface independently in each face fabric. Furthermore, the compression and

resilience properties of the spacer can be altered at will, depending upon the material and the

pattern chains of the threads in guide bars 3 and 4.

The major benefit of using spacer material is to replace polyurethane, neoprene and other

types of foams which are laminated to textile fabrics for creating bulk, softness, flexibility,

resilience etc. These foams, however, have some serious drawbacks. For instance, foams

are generally flammable; they are extremely uncomfortable due to extremely small cavities.

Their thermo physiological properties are poor, their compression and resilience properties

deteriorate with time and their mouldability, delamination, maintenance of original thickness

when moulded into complex three-dimensional shapes, washing and drying properties are

often poor and not up to the standard required. Relatively stiff monofilaments generally used

as spacer material, more or less overcome the above-mentioned drawbacks associated with

laminated structures

The major product applications for warp knitted spacer materials are: car seat covers (both

solid or net structures in the face or back or both surfaces); automotive interiors (lining for

doors, roofs, convertible hoods etc); seat heating systems for cars; mud flaps for lorries and

buses; insoles and face fabric for sports and other shoes; lining for rubber and other boots;

protective inner lining; mattress underlays and mattress covers for prevention and

management of incontinence, pressure sores as well as for children’s beds; diving and surfing

suits; sports equipment; high-performance sportswear; reinforcement for composite

structures; bras; underwear; swimwear; shoulder pads; fluid filters; geotextiles; bandages;

plaster casts; braces; controlled release of drugs, antimicrobials, cosmetics etc; and finally

heat and moisture regulation fabrics.

3.1. SPACER FABRIC KNITTING:

Machine details:

High speed knitting process

• 6 Guide bars

• Gauge E6 – E14

• Working width 84” (213 mm) and 130” (330

mm)

• New linear system for easy variation of

spacer fabric thickness

• Easy access to knitting elements

3.1.1. Weft Knitted Spacer Fabrics:

Weft knitted spacer fabrics can be produced on circular double jersey machines as well as

electronically controlled flat machines. The major advantages of these structures are:

a) plain as well as colour and design and surface texture effects can be produced on the

face of the fabric knitted by the cylinder needles; and

b) Shaped and true three-dimensional structures can be produced on electronically

controlled flat machines.

The major limitations of weft knitted spacer fabrics are:

a) The thickness of the spacer is normally limited to between 2 and 10 mm

b) The basic structure of the spacer fabric is limited to either knitting the spacer threads

on the dial and tucking on the cylinder, or tucking the spacer threads on the dial and

cylinder needles.

It is obviously more practical to use tuck stitches with spacer monofilament yarns in order to

ensure that the spacer yarns lie correctly inside the knitted fabric and prevent the face and

back of the fabric from having a rough or harsh feel.

Knitting Constructions:

The structure of a circular knitted monofilament spacer fabric is Produced on circular interlock

gaited machines are shown in Figures. Three different yarns are required for each course:

a) Yarn for the dial needles

b) Yarn for the cylinder needles

c) Spacer yarn, normally monofilament yarn.

CONCLUSION:

The future scope of fabric science is very broad. Only innovative products will be able to open

up new markets and new horizons for the textile industry. To achieve this, it is essential to

invest in future research and researches. In the coming years, knitted fabrics will increasingly

take on industrial functions. Fabric will combine the functions of medium, carrier and interface

for an extremely wide range of industrial applications. This new generation of industrial fabric

makes considerable new demands on the innovative ability within the clothing industry. What

is needed is not simply the conveyance of knowledge but the development of truly creative

researchers. The textile industry needs to shift its emphasis from ‘quantity, quality; to

‘functionality’ in the new millennium of Global Competition Era.

REFERENCE:

1. S. C. Anand, Developments in Technical Fabrics – Part 1, Knitting International, July

2000, page 32

2. M. Hard castle, In the Driving Seat, Knitting International, July 2001, page 52

3. 7. T. Shah and S. C. Anand, Geotextiles: A Growing Market for Technical

Textiles, Technical Textiles Markets, 2nd Quarter 2002, page 34

4. S. C. Anand, Developments in Technical Fabrics – Part 2, Knitting

International, August 2000, page 53

5. S. C. Anand et. al., Directionally Structured Textile Fabrics, UK patent

Number GB2339803, published on 27th November 2002

6. Double-Layer, Circular Weft Knitted Fabrics with Monofilaments (Spacer

Fabrics), Knitting Technique, 16, 5, 1994, page 306

7. J. Millington, Do We Have Lift Off, Knitting International, October 2002,

Knitting Faults

Here are some knitting faults:

1. Fabric barre or stripe.

2. Press off.

3. Miss stitch/ drop stitch.

4. Needle mark.

5. Sinker mark.

6. Oil stain.

7. Crease mark.

8. Hole.

9. Excessive slubs and entanglement in the fabric.

10. Spirility.

11. Pin hole.

12. Broken needle.

13. Tight course.

14. Missing yarn.

15. Fine yarn.

16. Coarse yarn.

17. Colored fly. Etc.

Industrial Garments Washing

Industrial Garments Washing is one of the major important parts for Textile sector. By industrial garments washing we can remove dust, dirt and infections material. For improving special look on garments as per fashion requirement.

There are many types of Industrial Wash. These are:

1.     Normal/Detergent Wash(Normal Detergent Wash)

2.     Bleach Wash

3.     Stone Wash

4.     Acid Wash

5.     Enzyme Wash

6.     Caustic Wash

7.     Super-White Wash

8.     Combined Wash.

There is some physical pretreatment related to industrial  garments washing. These are Hand Scraping, Sand Blasting, Whiskering, Tagging, Crinkle Effect, Grinding, and Destroying.

There is also some chemical pretreatment related to industrial garments washing. These are Potassium per Manganate spray, Color Spray. Color spray is also known as tinting.

For garment dyeing and washing plant some machines and equipments are necessary. These are:

1.     Dyeing and washing machine.

2.     Hydro extractor.

3.     Drying machine.

4.     Spray boote.

5.     Brushing mannequin.

6.     Sand blasting unit.

7.     Grinding machine.

8.     Hot pressing machine.

9.     Tag gun.

10.   Minor sewing facilities.

Identification of Cotton Fiber

1. Burn Test: 
The burn test is a quick way to determine the cotton fiber. A few threads from the fiber is moved slowly to the flame of the burner and then into it. Where it is watched carefully. Then the sample is removed from the flame still watching it. The fiber sample is evaluated considering the following point.

a.       Ability to ignition.

b.      Art of burn.

c.       Smell.

d.      Combustion residue.

When cotton ignited it will not shrink from the flame will burn with a yellow flame. It continues to burn when the flame is removed and smell like burning paper. There is a little grey ash residue after combustion.

2. Chemical test:

i. Treatment with H₂SO₄: With concentrated H₂SO₄ the cotton fiber will be destroyed, i.e. the cellulose components will be dissolved.

ii. Iodine potassium iodide test: The iodine potassium iodide solution is prepared by dissolving 20gm iodine in 100ml solution of potassium iodine. The samples are treated some seconds with this solution followed by rinsing with water unmercerized cotton will not be colored, where as the mercerized cotton remain longer time dark blue to blue colored.

Difference Between Dyeing and Printing

The difference between dyeing and printing are given below:

Dyeing	Printing
There is no localized application.	This is localized application of dyes (pigments).
Color applied in form of solution.	Color applied in form of thick paste.
Fabric, yarn and fibers are dyed.	Only fabric is printed.
Thickener is not used.	Thickener is used.
Generally one color is used.	One or more color is used.
Steaming is not required.	Steaming is required.
Liquor ratio is high.	Less liquor ratio.
More time is required.	Less time is required.

Matt Rib Weave

The weaves are also variously known as ‘hopsack’ or ‘basket’ weaves. The hopsack weave a variation of the plain weave, uses two or more warp and/or two or more weft yarn side by side as one yarn.

Feature of Matt Rib Weave:

1. The Matt rib structures result from extending the plain weave in both directions.
2. In case of regular Matt rib the plain weave extended equally in the warp and weft direction.
3. In case of irregular Matt rib the plain weave is extended unevenly in the warp and weft direction.
4. The Matt rib weave cloth has a greater resistance to tearing.
5. Matt rib tends to give smooth surface fabric.
6. In the repeat size of the Matt weave the numbers of warp and weft yarns are equal.
7. There are four types of Matt weave, such as Regular, Irregular, Stitch and Fancy Matt.

Application of Polymer

The applications of polymer are given below:

Agriculture: Fertilizer.

1. Medicine: Heart value, blood vassels. These two medical equipment are made up from decron tollon and poly urethane.
2. Consumer products: Clothing, floor covering. Different types of plastic material which are home use different bags.
3. Industry: Automobile parts, tire (rubber), pipe, adhesive, different machine valve and different machine belt.
4. Sports: Football.

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. 

Manufacturing Process of Nylon 6,6

Nylon 6,6 is made from Hexamethylene diamine and adipic acid as shown in the figure below.

Spinning of Nylon 6,6:

The chips of nylon polymer are fed through a hopper A, into a spinning vessel B, on an electrically heated grid ( perforated plate) C. The perforations are so small that the chips do not pass through, but when melted, the liquid can pass.

The molten nylon collects as a pool D, at the bottom of the vessel. This liquid should not come into contact with oxygen or air and hence nitrogen is introduced into the vessel. The molten polymer is kept at a temperature of about 288 deg C and sucked by a pump F, into a spinnerette E. The molten polymer solidifies as soon as it emerges out of the spinnerette. The filament thus formed pass through a colloing zone, in which cold air G circulates directed towards the filaments. The filaments are then passed through a steam chamber H, to wet them before winding on the bobbin L.

Drawing:

Nylon filaments as obtained are not very strong. They have to tbe drawn 4-7 times their original length. This is done by cold drawing. The yarn in pulled off from bobbin L through guides M and N, between a pair of rollers O. The speed of rotation of these rollers determines the initial speed. The yarn then goes over a deflector P, and two to three times around roller Q, running at five times the speed than that of O. The yarn subsequently courses through another guide R, and wound on another bobbin which rotates at veryhigh speed, to impart twist in the yarn before being wound.