11/15/2022

Reference:
* 1. Technology of textile Processing by Dr VA. Shenai (chapter 3. py
42-51)
Course title: Textile Finishing + 2.Textile Finishing by Derek Heywood pg 432-437 & {32
Course code: WPE 403 * 3. Principles of Textile Finishing by AK. roy.P et 34-36)
“4
Chapter 3
Mechanical finishing
(Raising, napping, shearing, sueding)

Raising
* Raising is the process of lifting of layer of fib
the fabric whee stand out hare the surface in mar
;
Specially prepared surface from particular v ‘oven struthe body of
e
ctures.
* Or
* Plucking the fibre from a woven or knitted fabric to
effect on the surface. to g civ
Raising © sive a nap
* Raising is done after shearing and crop ping, dyeing and
drying.
* Application:
* A wide variety of fabrics including blankets, flannelettes and
industrial fabrics.
* The raising action is mainly confined to weft yarns. Hence the
fabric which require a high degree of raising Should have a strong
weft yarn. Generally, raising effect,is produced on cotton, wool,
polyester and viscose blended fabric and acrylic fabric.
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 Uses of raised fabric Uses of raised fabric
* 4. Dress fabric, costume, light weight suitings (cloths with
¢ 1. Blanket EA
asoft finish)

° 2.Rugs
¢ 5.Biliard Cloth

° 3.Shawls Pity
¢ 6.Velour

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° Effect Different factors affecting the raising effect (ref. 1, pg 42-43)

* Lofty handle * Raw materials.
* Woven fabric after raising- Flannel * The Cloth Structure
* Knit fabric after raising-Fleece
* The raising conditions such as moisture, presence of acids,
* Objectives
alkalis, neutral salts, lubricants etc.
* To produce nap or pile on the fabric.
* To obtain fleecy appearance. For example, coarser fibres of long staple are particularly for
* To soften the outline of the design. the production of rugs and blankets while finer materials are
* To improve the handle. best suited for the production of fabrics in which a short, dense
* To develop some structural features. pile is required. Plain .......... Wet cloths are easier to raise
* To give lofty handle of a fabric. than dry cloths.
* To create heavier surface on the fabric.
* To improve the cold protecting ability.
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 Raising machine 1.The gig or teasle machine
* Here, the fabric is passed over a revolving cylinder , which is
* Based on wire there are 2 types of raising machines. They covered with teasles. The teasels are obtained from thistle
are: plant and they are obtained by boiling seed pod of thistle.
* 1.The gig or teasle machine These teasels were nailed to wooden board or iron steel. Then
this iron sleet /wooden board placed on drum.
* 2.Card wire raising machine
* Teasels are 1.5” to 1.75” in length.
* i) Single acting raising machine
* The fabric and cylinder rotates in the same direction. But
* Ii) Double acting raising machine
surface speed of cylinder and fabric is different.
* Teasles wears out rapidly.
* Lower production than card wire raising machine.
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2.Card wire raising machine (refl, pg 44)

Figure of Teasle gig (V.A Shenai pg 44)
* It is modern type of raising machine. Here the rollers are
covered with card clothing. Card clothing is made of hooked
or bent steel wire to lift the fibre from the surface of the
fabric. and rollers are mounted on the surface of a large
cylinder, which rotates as a whole and is so fitted into the
machine that by rolling contact, the raising rollers also rotate
about their own axes.

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1.Single acting raising machine (ref 1, pg 44) Double acting raising machine (ref 3, pg 35-36)

gt
* Single-action raising machines utilize only pile rollers
whereas double-action machines normally have both pile and 5
counter-pile rollers mounted alternately.
C eo"

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so YY -
\ Coawnen
Figure 12.22 Scheensic ¢f doubio actos rating machine Fegrv tii Fie wd octetars

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BUY

Double acting raising machine

=) $2
_ Return drag roter

e\ Sa

So 4
LOD YW —
\ Praner rote

m ‘Oo :
Ineo? eroa Front drag —— =
otter rotler —
Fiz 2.5 Fabric path in a bothside mising machine.

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 * Modern Raising Machine:

* Construction:
* High Efficient Raising Machine
¢ Working principle:

* The card wires are bent so that at the point of contact they form an angle
of 45° with the surface of the fabric. The fuzzy surface is created by
pulling the fibre end out of the yarns bymeans of metal needles provided
with hooks shelled into the rollers that scrape the fabric surface. The ends
of the needles protruding from the rollers are 45 degrees hooks; their
thickness and length can vary and they are fitted inspecial rubber belt
that is spiral wound on the raising rollers Those rollers in which the card
wires point in the direction of the movement of the fabric are called ‘pile
rollers’. Conversely, those rollers in which the card wires point against
the direction of the movement of the fabric are called ‘counter-pile Valipabarcon
rollers’.
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MIC Type: High Efficient raising machine

Brand Name:Shanshan Problems/Disadvantages of Raising:
Origin :China
Main Technical Data:
Excessive friction or Mechanical stress can damage the
1.Normal width:2000-2800mm fabric.
2.Speed of the fabric:6-30m/min Low resiliency and hence premature flattening occur

nN pwn
3.Drum Speed:60-90rpm . Nap can be partially restored by frequent brushing.
4.Number of Raising Roller:36 . Subject to pilling.
5.Roller Dia:70 mm - Rapid wear at abrasive points (like sleeve ends, elbows,
6.Motor Speed:34.7 KW button holes etc.)
7.weight:6400-6950 KG - Not recommended for hard wear.
a + Lusture of the fabric surface reduces.
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 Napping
* Napping is the process by which pile or deep hairy surface is
produced by passing the fabric over revolving cylinders covered with
fine wires that lift the short, loose fibre to the surface forming a nap.
Thus aesthetics of fabrics is changed by developing a pile on the
. surface of the fabric.
Napping
* The depth of pile developed on a napper can be much greater than can
be obtained by sueding, assuming the fabric construction is correct.

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Application Napper
* Wire nappers, known as planetary nappers, are the most
commonly used machines in the industry. The basic design of
* For example fleeces, velours, high-pile fur-like effects, flannels and a wire napper is 24 to 36 small pile wire clad rolls (worker
bed blanket finishes are produced by napping. Proper fabric ;
construction is a prerequisite to napping. Napping is done by napper. rolls) mounted on the periphery of a large main cylinder.
* Generally woolen, cotton, spun silk, spun rayon are napped.

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 Napping process
The process involves passing the fabric over revolving cylinders covered with
fine wires with small hooks on the ends. The large napper cylinder rotates in the
same direction as the flow of the fabric at a constant speed while the worker
rolls rotate on their own axis in a direction opposite to the rotation of the main
cylinder. Cleaning rolls or brushes below the main cylinder remove lint and
entangled pile to keep the wires at high efficiency. The speed of the worker rolls,
the type of wire, the angled direction of the wire all influence the degree of nap.
There are many arrangement of these components each designed for their
individual specialty.
* The hooks scrape the surface of the fabric pulling up the fiber ends and thus
lift the short, loose fibres, usually from the weft yarns, forming a nap.
* Resulting fabric is warmer, more comfortable, and softer. Eg, Flannelette and
wool flannel.

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Shearing
Shearing * This involves cutting the surface fibre from the fabric to give a smooth
appearance, often used on woolen fabric & worsted fabric where the
¢ Reference removal of surface hair by singeing process is not possible.
* 1. Technology of textile Processing by Dr. V. A. Shenai (chapter 3, pg * Shearing is an alternative to singeing. More often however, shearing
42-51) follows napping. Knitted and woven fabrics with loops on the face or
back are not necessarily napped first - they can be sheared directly to
* 2. Chemistry & Technology of fabric preparation & Finishing by Dr.
cut off the tops of the loop and produce plushy velours such as knit
Charles Tomasino (chapter 13,pg 239-240) velours and plush towels. Terry looped bath towels can be sheared on
one or both faces to produce a plush pile surface.
* The depth of the cut may be varied by raising or lowering the height of
the cutting bed.

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 Objectives of shearing (ref 1, pg 48) Use of sheared fabric:
* 1. To clear out the random length fibres and produce a uniform and * Use: -- looped terry fabric (sheared the top of the loops of the terry
level pile.
fabric are cut off and a velvet like appearance is produced)
* 2.To reduce the height of the wild fibres and prevent pilling. + -- knitted velour (knitted loop pile fabrics are sheared) that is use in
¢ 3.To produce a certain hand. upholstery fabric.
* 4.To improve the color and appearance of the fabric. * Most napped fabrics (except napped sleepwear print cloth, flannel
¢ 5.To produce sculptured effect. and some industrial fabrics) are sheared.

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Shearing machine

* |.Shearing machine with a single head. They have one cutting head
per unit.
* Woven fabric is sheared by multiple head. One set of shearing frame
contains two three or four shearing unit.

Two shear head machine

2
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 Basic principle of shearer (Ref 2, pg 239)

* The principles used is that a spiral cutter rotates against a stationary

blade and cuts off any material protruding from the fabric surface.
* The shearer head consists of a spiral blade revolving on its own axis in
contact with a ledger blade. This creates a shearing action similar to
that produced by a pair of scissors. When fibers aré presented to this
cutting head, they will contact the ledger blade and be cut off by the
rotating blade. The fabric travels over a cloth rest(bed) in front of the
ledger blade and the design is such that an acute angle is formed by the
fabric. This sharp angle causes the pile to stand erect and be more
easily cut. The distance between the bed and the ledger blade is
adjustable so the height of the pile can be regulated.
* Very often the fabric is brushed prior to shearing. The object of
brushing is to lay the fibers in one direction and thus facilitate the
cutting process.
Single head machine
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3)

deme cl
— SS
Problems in Shearing

> Defects caused by folds, creases, and heavy

edges
> Uneven shearing caused by misaligned blades
> Destruction of sewn seams
> Blade damage by foreign metallic objects

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i Sueding Sueding/Emerising
* Sueding is a mechanical finishing process in which a fabric is
¢ Reference: abraded with sand paper or emery cloth on one or both sides to raise or
. ag : 3 create a very low pile on a fibric surface. This operation is often
" Technology ofitexttle Processing iy Dr. V.#&. Shenat carried out before the raising process to reduce the friction between
(chapter 3, pg 45) the fibres making up the cloth and consequently to facilitate the
* 2. Chemistry & Technology of fabric preparation & Finishing extraction of the fibre end.
by Dr. Charles Tomasino (chapter 13, pg 232-234) * The sueding process is carried out on both sides of the fabric and
* 3. Textile Finishing Edited by Derek Heywood (chapter 4, pg modifies the appearance and the final hand of the cloth; when touched
126-131) ~ it gives a soft and smooth sensation similar to the one given by a
oo. . _.. peach-grain surface. TE rer
* 4.Principle of textile finishing by A.K roy. . Z

Objectives of sueding Sueding machine

¢ Asueder is sometimes referred to as a sander since the machine
1. .To cut surface fibers and produce sude or fuzzy surface on consists of one or more rolls covered with sand paper or emery board
the fabric. as the abrasive. The abrasive material is wrapped around rotating
2. To recreate the natural suede feel using other materials, rollers over which the fabric passess.
making them ideal for certain clothing applications such as
shoes and children wear. + Fabrics traveling over these rolls develop a very low pile and the
To make upholstery, table and wall coverings with a suede material's surface can be made to feel like suede leather with softer
U2

feel to create a really luxurious effect for selected home hand.

ware. * There are two types of sueding machine.
4. To appeal to consumers who prefer a non-animal product. ¢ 1. The single cylinder sueder
¢ 2. The multi cylinder Sueder

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i 1. Multi-Cylinder Sueders (ref 1, pg 45 2. Single Cylinder Sueder(ref 2, pg 45 )

Pigure 79. Multi- Cylinder Sueder ‘ i

Fabric Let-off

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Abrasive covered rolls (ref 2 pg 234)

* The abrasive roll is made from diamond chips embedded in a

Kevlar paper base. The quality of the nap will depend on the
fabric construction and selection of abrasive grit. Fabric
construction will determine the abrasive grit size, the wrong
grit may over sand the fabric and either weaken woven
fabrics or perforate knit fabrics. Since the abrasive material
deteriorates with use, it must be changed on a regular basis to
guarantee a uniform suede throughout a production run.

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 TANG “SUEDING 77 a7
re3-3h0,
Er . i
Advantages & disadvantages (ref 2 pg 234) Fibers are raised from the The raised fibers are cut to”
fabric surface by using wire- smooth out the fabric y paper covered rolls fone
covered rolls to“dig out”. Y loth, ete) j
individual fibre ends tothe :
surece)

Speed, tension of rollers i Ber revolver , blade, cloth Grit of sandpaper, speed of
play an important role rest design and raising brush roll, speed of fabric.
equipment should be
considered.

Produce warmth and soft

Pile height greater than that Uniform pile height Produces low pile on fabric.
obtained from sueding.

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Brushing Brushing
« Amechanical process that gently raises the fibers from
This process, applied to a wide variety of fabrics, is usually
Surface.
accomplished by bristle- covered rollers.
« Used to remove loose threads, short fibre ends from smooth-
surfaced fabrics and is also used to raise a nap on knits and
woven fabrics.
* Brushing is frequently applied to fabrics after shearing,
removing the cut fibres that have fallen into the nap
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Brushed Fabric

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