Wed formation on nonwovens. A group research based on web formation and end uses.

1. Kwame Nkrumah University of
Science & Technology, Kumasi, Ghana
Topic: WEB PREPARATION
Name GROUP 3
Department: Industrial Art
Faculty & College: Art Faculty

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GROUP MEMBERS
Yeboah Oforiwaa
Yaa Ladzaglah Millicent - Leader
Serwaa Bonsu Afram
Sintim-Aboagye Akosua Serwaa
Boateng Edmund
Tawiah Gyanea Forkuo
EdnaFirdaus Ezomah Musah
Babangida Ilhaam
Frimpong Lilian Korantemaa
Berko Benedicta
Elizabeth OtooKessey
FrancisAntwi Boahemaa
Eunice Kyei-Baffour Kerfa

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Introduction
Nonwoven fabrics are one type of textile fabrics or a manufactured sheet
made of a fibrous layer, which may be a carded web, a fiber web,
or any system of randomly laid or oriented fibers or threads, possibly
combined with textile or non-textile materials such as conventional
woven fabrics, plastic films, foam layers, metal foils, etc., & forming
them with a mechanically bound or chemically bonded textile product

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There are three basic methods of web formation:
• Dry Laid
• Wet Laid
• Polymer Laid
Introduction
• Nonwoven manufacturing techniques is basically a continuous process
in which the web laying and web bonding are performed by two
consecutive machines.
• In general, the nonwoven formation processes consists of two basic
steps, web formation followed by bonding.
• The web formation in nonwoven production is a critical contributor of
the end-use product performance.

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Introduction
• The latter one classified as spun laid and melt blown web formations
which are particularly applicable for synthetic polymers.
In web formation the characteristics of the fibrous web are a key
determinant of the physical properties of the final product.
In web formation, methods for forming webs is determined by fibre
length.
• Staple Fibres uses Dry-laid and Wet-laid Methods.
• Filament fibres uses Spun laid and melt blown

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Introduction
• There are three basic types of bonding: chemical, thermal, and
mechanical. The natural fiber webs can be successfully bonded by
mechanical process without any additives.
• Additional binder polymer or synthetic fiber is required for the
chemical or thermal bonding.

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Introduction
WEB FORMATION TECHNIQUES
DRY LAID
1.CARDING
PARALLEL
LAID
CROSSLAID
2.AIR
LAID
WET LAID
1.HYDROFORMER 3.RADFOAM
PROCESS
2.CYLINDE
R MOULD
MACHINE
POLYMER LAID
1.SPUN BOND
2.MELT BLOWN

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DRY LAID
• Dry laid is the staple fiber based web laying process involves three
major steps.
• They are fiber preparation (by opening and mixing processes), web
formation (by carding) and finally web stacking (by parallel-lay, cross-
lay, and perpendicular-lay processes).

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DRY LAID
DRYLAID
CARDING
PARALLEL LAID CROSSLAID
OPENING &
MIXING

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OPENING, CLEANING, MIXING
AND BLENDING
Machines used could be;
✓ Bale opener
✓ Cleaning machine
✓ Blending machine
• The bale are dispersed on a conveyor belt.
• At this stage there is Opening, Cleaning, Mixing and blending
• The correct choice of fibre opening, cleaning and system is therefore
of utmost importance to ensure a profitable nonwoven manufacturing
operation

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This involves taking raw fibers and aligning them into a thin
web. The fibers are fed into a carding machine, which combs
and separates them before laying them down in a thin layer.
CARDING

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CARDING
• Purpose of carding: Carding is done to disentangle and mix fibres to
form a homogeneous web of uniform weight per unit area.
✓ Cylinder: Heart of carding machine and is the central distributor of
fibres during the process.
✓ The worker-stripper pairings: Have both carding and mixing function.
✓ Doffer rollers: Condense and remove fibre from cylinder in the form of
continuous web and a proportion of circulating fibre is recycled to
combined with fresh fibre.

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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 conveyor which runs
along the full length of the production line underneath the card.
• As the web from the first card passes from the second card, the web from
the 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.
• This system mostly used for light weight nonwoven.

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PARALLEL – LAID WEB

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CROSS – LAID WEB
• Cross laying - web is deposited on an inclined lattice or conveyor
• As it leaves the card and is laid in cross manner
• Which moving in a direction at right angle to the original direction of
laying.
• Area of weight of resulting layer depend on feeding velocity
• Area weight of carded web depend on the width of layer and velocity of
output belt.

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• Air laid aim to overcome the high degree of anisotropy of fiber
direction in non woven formed by carded web.
• The fibres are dispersed in air and deposited from a suspended
state onto a perforated screen to form a web.
Benefit:
• Deliver web with high isotropy
• High porosity
• Utilized short fibre which are not possible to be processed by
using carding technology.
CROSS – LAID WEB

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• The fibers are fed to opening roller by a pair of feed roller.
• The fibers are then gripped by feed roller and opened by the opening roller.
• They are then transported by hooking around the wire teeth on the roller and
removed by high velocity air stream directed over the wire teeth surface
• The fibers are mixed with air and transported to conveyor where air is
separated and fiber is deposited to form a web.
CROSS – LAID WEB

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WET LAID SYSTEM
Raw materials; Fibers (naturals and man-made) and water

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WET LAID SYSTEM
PROCESSING SEQUENCE
• Wetting and dispersing fibers in water.
• Transport fiber dispersion towards web forming device.
• Forming fiber web on the moving endless wire screen or perforated
drum.
• Removing water by suction, pressure and drying.

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WET LAYING PROCESS
• Fibers are dispersed in water and laid on wire mesh to filter the liquid
• Fibers then transferred to drying felt and being heat cured in continuous
process
• A web will be produced where fiber was random oriented
• It later will be superimposed on one another on parallel fashion
• Application: surgical gowns, gloves, mask, medical care bed sheet,
clothes liner, dust-proof clothing, protective clothing, vacuum filter bag,
sofa cloth

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WET LAYING PROCESS
• To increased volume flow onto the wire had to be drained, the
modification of wire section is needed.
• Early experimental work showed that inclination of the wire and the
use of vacuum boxes under the wire to increase drainage resulted in
a machine configuration that could handle these materials.

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POLYMER-LAID
• Manufacturing of non woven web directly from the
thermoplastic polymer
The two types of Polymer-laid non woven fabrics. They are;
➢ Spunbond
➢ Melt blown

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SPUNBOND
• Polymer granule are melted and then the molten polymer is extruded
throughout the spinnerets
• The continuous filaments are chilled and transported onto conveyor
belt to structure a uniform web
• In spunbond method, the raw material elasticity is more controlled
and gives non woven superior strength.
• Application: Surgical gowns, home furnishing, geotextile fabrics,
house wrap

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Basic stages in the process of spunbond fabrics
SPUNBOND

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MELT BLOWN
In melt blown process web formed by low viscosity polymer which
are extruded into a high velocity air stream.
This distributes the melt, solidifies it and break it up into a fibrous
web.
Applications: Insulation, face masks.

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• Needle punched nonwovens are created by mechanically orienting and
interlocking the fibers of a spunbonded or carded web.
• This mechanical interlocking is achieved with thousands of barbed
felting needles repeatedly passing into and out of the web.
NEEDLE PUNCHING

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• Needle punching is carried out passing a number of needles with barbs,
mounted in a board, through the batt at a high reciprocating speed.
• Needles are arranged in a number of rows (up to 23 -26) in a needle
board with about 1500 to 5000 needles per 1 m working width.
• The needles are usually triangular in cross-section with barbs at the
three edges.
• As the needle penetrates through the batt, the barbs carry fibres with
them thereby causing mechanical entanglement of fibres.
• This gives strength and dimensional stability to the batt.
PROCESS OF NEEDLE PUNCHING

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• Punch density is dependent upon the number of needles per board, number
of boards, stroke frequency and delivery rate.
• Stroke frequency is indicated by the number of up and down strokes made
by the needle board per min. This is usually 1000 in old machines and has
gone up progressively upto 3000 in latest models.
• Width of needle punching machine ranges from 2 to 10 m.
PROCESS OF NEEDLE PUNCHING

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PROCESS OF NEEDLE PUNCHING

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• Thus finer the needles, higher the punch density.
• Coarse fibers use the lower punch density, and fine fibers and
delicate fibers use the higher punch density.
• For example, a coarse fiber product may use a 12 to 16 punch
density and fine synthetics may use 25 to 40 punch density.
TYPES OF NEEDLES USED IN
NEEDLE PUNCHING