NONWOVEN WEB FORMATION

Prepared by:

S.RAJESH KUMAR

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CONTENTS

• Introduction

• Fiber properties

• Fabric production stages

• Fibrous web formation

• Tasks of web laying machine

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INTRODUCTION

• The term „nonwoven‟ arose from more than half a century ago when nonwovens were

often regarded as low-price fibrous materials.

• In the carding system, basically opens up the randomly tufted feed stock fibers,

Uni- directionally individualizes and parallelizes them in the machine direction and

finally delivers in a continuous web of light weight, 10 to 15 grams per square meter.

• This fibrous web then may either be assembled with other similar webs and produced

as a web of desired weight density for fabric formation. This is the most important

factor for deciding nonwoven fabric properties.

• The ultimate nonwoven properties such as overall nonwoven strength and porosity

also play an equally important role in end-use applications.

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Polymers

Fibers

Yarns

Woven Knitted Braided Non-woven

Fabrics

Application

Woven structure Knitted structure Braided structure

Fabric Development process

• Fibers are the basic element of Nonwovens. The selection of raw fibers, determines the

properties of the final nonwoven products.

• The fibers can be in the form of stable form (or) filament form. Any natural or synthetic

fiber could be used in the production of non woven.

• Synthetic fibers provide specialized properties, uniformity, and consistency of supply

which cannot be achieved by natural fibers.

• Bi component fibers are a manufactured fiber having two

distinct polymers components may also used in nonwoven

manufacturing.

• Nano fibers, Glass micro fibers also used in nonwoven

Industry

Brief about Nonwoven

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FIBER PROPERTIES

• The choice of fibre depends on the required profile of the fabric and the cost

effectiveness.

• To produce nonwoven bonded fabrics chemical fibres of both cellulosic and synthetic

origin as well as natural fibres and inorganic fibres are mainly used. Hence, the most

important properties required for nonwoven web formations are provided below,

• Length - The length of the preferred fiber is directly related to the diameter. This is

referred to as the aspect ratio. Aspect ratio is found by dividing the length of the fiber

by the diameter (using the same unit of measure for each). The ideal aspect ratio is

500:1.

• When the correct aspect ratio is used, you receive an optimum amount of strength,

as well as good dispersion. As the aspect ratio increases, the fiber becomes more

difficult to disperse; as it decreases, there is a loss of strength resulting from poor

binding capability.

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Generic TypeDiameter

Density Denier Microns Decitex

Acrylic 1.18

1.5 13.40 1.65

3.0 18.95 3.3

15.0 42.39 16.5

Nylon 1.14

1.8 14.95 1.98

3.0 19.29 3-3

15.0 43.13 16.5

Polyester 1.38

0.5 7.16 0.55

3.0 17.53 3.3

12.0 35.06 13.2

Polypropylene 0.9

3.0 21.71 3.3

7.0 33.16 7.7

15.0 48.55 16.5

Rayon 1.5

0.5 6.86 0.55

3.0 16.81 3.3

20.0 43.41 22.0

Fiber Type and its Diameter in different units

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Denier - Denier is a property that varies depending on the fiber type. It is defined as the

weight in grams of 9,000 meters of fiber. The current std. of denier is 0.05 grams /450 mts.

FABRIC PRODUCTION STAGES

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The production of nonwovens can be described in three stages, although modern

technology allows an overlapping of some stages, and in some cases all three stages

can take place at the same. That three unavoidable main stages are:

1) Web formation

a) Fiber to Fabric (Ex: Carded, Air Laid, Wet Laid)

b) Polymer to fabric (Ex: Spun Bond, Melt Blown, SMS)

2) Web bonding

3) Finishing Treatments

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Types of web formation techniques

• The ready-made bales of nonwoven are mostly finished in discontinuous processes.

The process-related differences concern raw material supply and the ways into web

formation.

• Fig.1 shows the possible manufacturing processes of nonwoven fabric formations in

fiber form to fabric stage, it‟s taking into consideration of the base processes of

nonwoven production and also in Fig.2 shows the various other techniques which is

related to granules to nonwoven fabric formations.

Video – Nonwoven Production line:

https://www.youtube.com/watch?v=hhj9sVYeHP4

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Fig 1: Nonwoven

manufacturing from fibers

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Fig 2: Nonwoven

manufacturing from granules

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FIBROUS WEB FORMATION

1) Carded web: This method, commonly referred to as “Dry-Laid,” is utilized for staples

fibers, whether natural, synthetic or blends. Fibers are conventionally carded to form

a web, which then can be cross lapped to attain desired thickness and mass. It is a

relatively slow and more expensive method to convert fibers into a continuous web of

certain integrity. It is commonly under the term dry laid process.

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Carded fabric Applications:

• All fiber to fabric products

• Bandages

• Some pre-moistened wipes

• Apparel Interlinings

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2) Air laid system: In this air-laid technique, staples fibers, possibly along with certain

powders, resins, or thermally fusible, low-melting fibers, are pneumatically “gathered”

and laid to form a web of required density. This method does not involve carding.

3) Wet laid systems: In the wet-laid technique, fibers of relatively short length, say,

pulp, are passed through water or some other medium, which provides the required

inter and intra fiber cohesiveness or adhesion to form a continuous web of desired

structural integrity for down-stream processes. The method is not recommended for

long fibers, as they may clog the system.

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Dry laying process

• Fibre tufts are discretized to form single fibres, and the web is formed by a flat card

(Latin carduus=thistle) or roller card (OHG Krampe=hook).

• The function of the roller card can be defined as follows: the task of the roller card is

to produce an orderly fibre layer from the tangled fibre mass resulting from the fibre

opening or feed.

• This should result in individual fibres, i.e. in the disentangling of the fibre tufts and

bundles.

• The discretization or opening should be carried out in such a way that a parallel layer

of fibres or a tangled layer is produced. As a rule this occurs in the two-dimensional

plane in the machine direction (MD) and across (CD) the machine direction.

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Parallel-laid web:

• Several carding machines are placed one behind another in a long line.

• The web from the first card is allowed to fall on a conveyor which runs along the full

length of the production line underneath of the card.

• As the web from the first card passes from the second card, the web from second card

is superimposed upon it.

• This process is repeated along the line until a fleece of the correct mass per unit area is

achieved. (15-100 g/m²)

• This system is used extensively for relative light weight adhesive bonded nonwovens,

such as cleaning cloths.

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Web formation in parallel laid

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Cross-laid web:

• The cross laying, the web deposited on an inclined lattice or conveyor aprons as it

leaves the card and is subsequently laid in cross wise manner on a wider lattice which is

moving in a direction at right angle to the original direction of laying.

• The area of weight of the resulting layer depends on the feeding velocity and area

weight of carded web, on the width of layer and on the velocity of the output belt. These

are two types:

1. Horizontal laying

2. Vertical laying(or) camel back lay

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Web path through a cross-lapper

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Horizontal cross lapper :

• To minimises the introduction of web irregularities. The concept of a carriage has

changed from that of a heavily constructed unit within a distinctive framework, to a

lighter mechanism incorporating a relatively simple series of rollers in which the web

may be turned only once during its passage through the cross-lapper.

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Principle of a cross lapper

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• A cross-lapper apron is a consumable item that is expensive to replace. Early cross-

lappers suffered from tracking problems and variations in tension caused gradual

migration of the apron to one side leading to serious damage.

• Tracking control systems are used to prevent such events by ensuring that equal

tension is maintained at both sides of each apron to prevent distortion. Should a

deviation of the apron position occur, tension is applied to the appropriate side to force

the apron back onto the correct path.

• In some systems the apron edges are continuously monitored by optical sensors and

automatic adjustments are made by a tracking control system. Recent developments in

cross-lapping technology have primarily focused on increasing speeds.

Video – Cross lapper:

https://www.youtube.com/watch?v=j5VGEt31-kI

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Vertical laying:

• This technology was developed at the technical university of Liberec Czech Republic,

during 1988-1992.

• Due to the position of fibres which are predominantly perpendicularly oriented to the

area of fabric, the textiles show high compression and excellent elastic recovery after

repeated loading

• Some properties of textiles such as filling and thermo-insulating properties are a

function of thickness. Thus, the perpendicular laid textiles are superior to cross-laid

when and after being compressed.

• Cushioned furniture, automotive industry, sleeping bags, thermo-insulating interlining

and blankets are typical end-uses of perpendicular laid textiles.

Video – Vertical lapper:

https://www.youtube.com/watch?v=zBakFyvyUSg

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• The perpendicular-laid batt can be obtained by reciprocating lapper (Struto technology)

or rotary lapper (Wave maker technology).

• The struto technology is illustrated in Figure (a) here; a reciprocating lapping device is

used to continuously consolidate the carded web into a vertically folded batt that is

bonded by through-air bonding. It has low rate of production.

• The resulting structure of the batt is displayed in Figure (b).

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• The wave maker technology is shown in Figure (a).

• Here, a rotary lapping device is used to continuously consolidate the carded web into a

vertically folded batt which is bonded by for through-air bonding.

• It has relatively high rate of production. The resulting structure of the batt is displayed

in Figure (b).

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Air laying process

• The air-lay process was invented during 1940s with an aim to overcome the high

degree of anisotropy of fibre direction in the nonwoven fabrics prepared from carded

webs.

• In this process, the fibres are dispersed in air and then deposited from a suspended

state onto a perforated screen to form a web. Fig. displays the schematic diagram of

air-lay system.

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1. Pre-made batt

2. Feed rolls

3. Main cylinder

4. Air blower

5. Suction

6. Conveyor belt

7. Airlaid web

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• The fibres are fed to an opening roller by a pair of feed rollers.

• The fibres are gripped by the feed rollers and opened by the opening roller.

• The fibres are then transported by hooking around the wire teeth on the roller and are

subsequently removed by a high-velocity airstream directed over the wire teeth

surface.

• In this way, the fibres are mixed with air and transported with it to a perforated

conveyor where the air is separated and fibres are deposited to form a web.

Benefits:

• It delivers webs with high isotropy, high loft (if required), and high porosity.

• It can utilize short fibres which are not possible to be processed by using carding

technology.

Video - Air laying m/c :

https://www.youtube.com/watch?v=nYd0Rdu53Rw&list=PLb3eEvVqFH4RVw4ii

Hax75V5qh8wuqR8v

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Wet laying process

• The wet-laid web forming technique is similar to paper making technique.

• In Papermaking uses pulp but in Wet laid uses longer fiber, perhaps blended with

wood pulp.

• If more than 70% of material is wood pulp, then that is a paper, 5-10 % of nonwoven

roll goods are produced using these methods.

• The fibres are dispersed in water and then laid on a wire mesh to filter the liquid and

form a web, which is transferred to a drying felt before finally being heat cured in a

continues process.

• This produces a web in which fibres are randomly oriented.

• These fibres are then superimposed on one another in a parallel fashion; hence it is

termed as wet laid webs.

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Processing sequence:

• Wetting and dispersing fibres in water

• Transport of fibre dispersion towards web-forming device

• Forming fibre web on the moving endless wire screen or perforated drum.

• Removing water by suction, pressure and drying

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Principle of wet laid web formation

• This webs accounts 15% of web production and are produced on modified paper

machines.

• This technique is only successful with short fibers and large scale production of a

particular quality in order to be economical

• The production of fabrics are low cost and limited durability

• A wide range of natural, mineral, synthetic and man-made fibres of varying lengths can

be used.

• Disposable end products include handkerchiefs, napkins, aprons, gloves, tea bags and

surgical gauzes.

Video - Spunlace m/c :

https://www.youtube.com/watch?v=Uv9U1ribwg0

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TASKS OF WEB LAYING MACHINE

• Increasing the web mass: Using multilayer web laying, the web mass can be

increased by a direct multiple of the card web mass to the required product weight.

The smallest unit is a so-called double layer, i.e. a web formed by the traversing of

the plaiting-down carriage. For quality reasons, however, at least two double layers

are used in practice.

• Increasing the web width: Web laying machines can produce webs in widths of

upto 7meter widths of up to 16meter are reached in special designs for papermakers

felts. Thus the web laying machine determines the maximum end product width.

However, the web laying machine can also be used to product webs in infinitely

variably smaller widths.

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• Improving the end product quality: Distortions during web consolidation

(mechanical, thermal, chemical) result in web width contractions which viewed over

the overall web width are not equal, but are concentrated more strongly at the edges.

The result is that the areal density in the edge regions of the end product is higher

than in the rest of it.

• This phenomenon of textile technology is also known in specialist technology as the

„bathtub‟ or „smile‟ effect. Modern drive and control elements in the web laying

machine permit irregular profiling to counteract this bathtub effect.

• Nonwoven webs are playing the vital role of application in a new method of

entangling fibres to create lace-like nonwoven fabrics uses fine, precisely controlled.

• When the jets pass through the web of fibres, they form a small vortex at each point

of contact. This creates sufficient fibre movement to entangle the fibres. In the aspect

of fiber properties and it‟s web forming methods makes variety of changes in the

product application area.

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REFERENCES

1. Singh J P ,“Nonwoven: A Versatile Fabric”, J Textile Sci Eng 2014, 4:5

2. Ingo Bernt1 and Rene Eckhart , “Design of Viscose Fibres for Wetlaid Nonwovens”, Len zinger Berichte 91

(2013) 71–76.

3. Paul Sawhney, Brian Condon and D.V. Parikh, “Nonwovens Manufacturing Technologies And Cotton‟s

Realistic Scope In Nonwovens”, Beltwide Cotton Conferences, San Antonio, Texas, January 5-8, 2009.

4. Sakthivel S., Ezhil Anban J, Ramachandran T, “Development of Needle-Punched nonwoven Fabrics from

Reclaimed Fibers for Air Filtration Applications”, Journal of Engineered Fibers and Fabrics, Volume 9, Issue

1 – 2014

5. Mr. S. Sakthivel, Dr. T. Ramachandran, Ms.G.Archana, Mr.Ezhilanban.J.J and Mr.V.M.S.Sivajith Kumar,

”Sustainable Non Woven Fabric Composites for Automotive Textiles Using Reclaimed FIBRES,

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Volume 4, Issue 7 (November 2012), PP. 11-13.

6. T. Weigert and K. Pöhler, “Paper and Nonwoven Webforming with Wetlaid Spunlace (WLS)”, Volume 2,

PP.21-24.

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8. Kunal singha, subhankar maity, mrinal singha, palash pauland debi prasad gon, ”Effects of fiber diameter

distribution of nonwoven fabrics on its properties”, International Journal of Textile Science 2012, 1(1): 7-14

9. Paul Sawhney, Hiram Allen, Michael Reynolds, Ryan Slopek, Brian Condon, David Hui and Suhad Woj

kowski, “Effect of web formation on properties of hydroentangled nonwoven fabrics”, World Journal of

Engineering 9(5) (2012) 407-416.

10. N.C. State University, College of Textiles, Professional Education & Development Program, “Nonwoven

Products and Processes.” Raleigh, NC. (2008).

11. Smith, Johnson & Associates. Cotton Opportunities in Nonwovens and the US Nonwoven Industry. A

consulting study for the U. S. Department of Agriculture, Agricultural Research Service, Southern Regional

Research Center, New Orleans, Louisiana. (March 2008).

12. S. J. Russell, Handbook of nonwovens, Wood head publishing limited, Cambridge, Page no 1-143.

13. www.minifibers.com

14. www.youtube.com

15. www.inda.org

16. www.autefa.com

17. www.espintechnologies.com

18. www.ijerd.com

19. www.fleissner-ansbach.de

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Thank you

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