my academy assignment

1. PROCESSING OF MAN-MADE FIBRES AND BLENDED TEXTILES
BLENDING
 There is no perfect fiber. All fibers have good, fair and poor characteristics. Blending enables the
technician to combine fibers so that the good qualities are emphasized and poor qualities are minimized.
Usually different natural and synthetic fibers are blended together to achieve better qualities of both
natural and synthetic materials.
 A blend is an intimate mixture of fibers of different composition, length, diameter and color spun
together into a yarn. The accepted definition of a blend, as stated by ASTM, is a single yarn spun from a
blend or Mixture of different fiber species.
 Blending is a complicated and expensive process, but it makes it possible to build in a combination of
properties that are permanent.
Blending:
Neither natural or manmade fibres are optimally suited to certain fields of use, but a blend of these two
fibres types can give the required characteristics
Objectives:
1. Improvement in Functional Properties
 A 100% single fibre yarn cannot impart all the desired properties to a fabric.
 For example 100% viscose rayon suffer from low tensile strength, poor crease resistance and low
abrasion resistance.
 Similarly 100% polyester fabrics are not desirable as they are prone to static accumulation,
whole,melting and pilling. They are moisture resistant, difficult and expensive to dye and have a poor
hand.
 These negative attributes of polyester and viscose can be reasonably neutralized by addition of a certain
percentage of each fibre.
 In the blend of cotton and polyester, cotton provides the absorbency and polyester provides the
strength.
 Blending also helps to provide the fabric’s light weight with all desirable characteristics. Improving
spinning, weaving and finishing efficiency and the uniformity of product.
2. Improved Process performance
 Some fibres like polyester at times are quite troublesome to work in 100% form especially at cards.
Addition of fibres like cotton or viscose rayon in the previous process has been seen to facilitate the
smooth carding of such fibres.
 The blending of manmade which are longer and finer to cotton which is shorter influences the
spinnability as well as productivity.
3. Economy
 The price of manmade is much more stable than that of natural fibres like cotton. Price stability can
enable the mills to pursue optimization of their fibre purchase Programme.
 Blending could also be used for reducing the mixing cost. For example, a fibre like viscose can be
blended with cotton for producing specific yarns with reduced raw material costs.
4. Fancy Effect
Fibres with a variety of colour mixture or shades can be produced by blending different dyed fibres at the
blow room, draw frame or roving stage.

2. 5. Aesthetics
The aesthetics of a fabric can be developed by selecting specific blend components and their properties
How to select Blend Constituents
Selection of Blend Constituents depends upon the following factors:
1. Type of Fibre
 Depending upon the end use of the fabric, blend constituents are chosen.
For example, it is well known hat a polyester-cotton yarn looks fuller as compared to the lean look of
polyester-viscose yarn.
 Therefore for light constructions like shirtings, polyester-cotton blend is used.
However polyester-viscose blend is preferred for medium and heavy construcitons such as suitings.
2. Compatibility of blend fibres
Compatibility must be there in terms of the following properties:
a. Length and Denier of Fibres:
 The two most important properties which need to be matched for satisfactory processing of blends are
the staple length and the fineness (denier) of fibres.
 For blending of polyester with combed cotton which may have staple length in the region of 34 mm.
 The polyester staple normally employed is 38 mm.
 The denier of cotton component is generally in the range of 1.3-1.5(3.6-4.2 µg/inch) and so is the denier
of the polyester which generally 1.5 denier.
 Similarly in a viscose rayon cotton blend, the rayon staple of 1.5 denier and 29-32 mm length is
generally used since the cotton component used has a denier of around 1.5 and a length of 28mm.
 The length difference in the blend components may not always be detrimental to yarn quality. Repeated
trial have shown that blends of Indian cotton with polyester fibre of 38,44 and 51mm shows
improvement in strength , irregularity, thick and thin places as the fibre length of polyester is increased.
The neps may, however show a slight increase with 51mm fibre blend.
 The improvement may be attributed to the longer fibres acting as carrier fibres for shorter cotton fibres.
The increased in nep count is perhaps solely due to the higher nepping potential of longer fibres of
polyester.
 The denier difference on other hand seems to be really harmful to yarn quality as it affects the migratory
behaviour of the fibre during yarn formation.
 Excessive difference in the deniers of the blend fibres, say 1.5 denierviscose blended with 3 denier
polyester fibres will produce a very weak yarn.
b. Extensibility

3.  The elongation ‘balance’ of the constituent fibres is equally important especially in regard to yarn
quality.
 A large difference in breaking elongation of fibres in a blend adversely affects the yarn tenacity; the
lowering of yarn tenacity being attributed to the unequal sharing of the tensile load at the rupture point.
 During shed formation in weaving, the breaking extension could significantly influences the weavability
of the warp yarn. It is sometimes preferable to consider the work of rupture in this connection.
 The change in the breaking extension of a blend yarn with change in blend ratio very much dependent on
the fibres extensibility of the blend components and the structure of yarn.
 In case of two blend fibres have very different breaking extension like cotton-polyester or viscose-
polyester then there is an abrupt transition from a lower extension level to a higher extension level.
 Normalcy breaking extension of two different fibres in a yarn lies between mean of two.
 A large difference in the breaking elongation of the fibres in a blend adversely affects the yarn tenacity.
c. Density
 The blend fibres should preferably have the same density. Any large differences on this account will lead
to selective separation while conveying the blended stock through ducts under the influence of air
suction in the blow rooms.
 The heavier fibers tend to fall in the lower section of the duct and move at a lower speed.
 Any large differential in fibre densities of the blend components works against the objective of achieving
a uniform blend
d. Dispersion Properties
 This property describes the ability of an individual fibre to separate from its group and disperse
thoroughly within the fibre matrix of the blend to produce an intimate and homogeneous blend.
 Poor dispersion may be caused due to factors such as too much or too little crimp, large fibre aggregates
with coterminous ends, excessive static accumulation
 Deficiency in proper dispersion of individual blend components is particularly undesirable for blends of
fibres having different dyeing properties.
e. Drafting Properties
Some fibres like viscose are outstanding it terms of draft ability. These fibres, when blended with other
fibres act as good carriers to obviate the trouble relating to drafting.
f. Dyeing Properties
In case the blend yarn or fabric is to be dyed subsequently, due consideration should be given to the dyeing
properties of individual fibre components.
Methods of Blending:
Blending can be done at the opening stage, drawing etc.

4. 1. In the initial opening stage of the blow room operation, the fibres are spread one on top of the other
and fed into the blending feeder.
2. The blending can also be done in the carding stage.
3. Similarly the blending can be done at drawing or roving stage.
4. A filament yarn blended contains yarns of different deniers (denier is the yarn numbering system used
for filament yarns) blended together.
.
Example of Blended Fabrics:
Some of the most common blended fabrics are:
 Polyester/Cotton – The tough crease-resistance of polyester combines with the cool comfort of cotton.
It is easily laundered, dries quickly and is ironed with lower temperature than pure cotton.
 Nylon/Wool – The blending of nylon with wool makes the fabric more absorbent and softer. It becomes
more strong and durable.
 Nylon/Acetate – This combination makes the fabric more absorbent than nylon alone.
 Ramie/Polyester or Ramie/Acrylic – These two blends help the fabric to be easily taken care of and it
is less stiff than pure ramie fabrics.
 Wool/Cotton – These two fabrics benefit from the inherent qualities of each other after blending. It
gives better comfort, better aesthetics and better performance.
 Linen/Silk or Linen/Rayon – This blend helps the fabric to retain the characteristics of linen and makes
the fabric drape better and wrinkleless.
 Silk/Wool – The blending of silk with wool provides subtle texture to the fabric. It is generally used for
ties.
 Rayon/Cotton – This fabric of rayon and cotton blend wears well and is washable. It is soft and has
fuzzy surface. Dresses, suits, sportswear, men’s shirts, etc. are made out of this fabric.
 Wool/Synthetics or Rayon/Synthetics – This blend has a very clear finish and it drapes better and
tailors easily. It has exceptional wearing qualities. The fabric is used for men’s and women’s suits and
coats. Ski slacks are also made out of these blends.
1. Blending at blow room
Man-made fibres are used extensively in blends, where the length of the man-made fibre has to be matched
to that of the natural fibre.
There are three methods of blending at blow room:
a. Feeder blending
In this method the blends are prepared by feeding different fibres to different hopper feeders with feeds
adjusted to the required blend ratio.
The blend components from the bale or bale breakers(preopened) are weighed and laid down
a separate blender can be allotted for feeding the recovered fibre waste if desied.The amount of material
taken from each bale for feeding these blenders should not exceed 2-3 kg.
This method is generally employed when more than two components are required to be blended.
b. Stack Blending

5. In this method the blend components from the bale or bale breakers (preopened) are weighed and laid down
in alternate layers, each about 15cm thick and covering about 40 sq. Meter.
If required, an antistatic solution may be sprayed onto each layer of static prone fibre. The stack is normally
laid up to a height of 3 m. This stack which laid horizontally is then withdrawn vertically for feeding.
Advantage of Feeder and Stack Blending
a. More intimate and homogeneous blend achieved.
b. Only one opening line needed.
c. Provides simplest control on the use of recovered fibre waste.
d. Requires minimum man hours for blending
Disadvantages
a. Difficult to attain uniform blend ratio
b. Demands greater skill on the part of the operator.
c. Labour intensive and somewhat slow.
c. Lap blending
This type of blending cannot be affected in a single process blow room as it involves the use of a breaker
and a finisher scutcher.
In this the laps of the components fibers made at the breaker scutcher generally 3 to 4 are blended by feeding
them together to the finisher scutcher in the desired ratio.
Advantages of Lap Blending
a. Ensures good blend homogeneity
b. Easy to work.
c. Good control on the use of recovered fibre waste.
d. Uniform blend ratio is achieved
Disadvantages
a. Opening line has to be modified to provide for both breaker and finisher scutcher.
b. Need for proper control on lap weights.
2. Card Blending
Blending by doubling with laps at the card is sometimes used in high production cards. The procedure
involves use of a double lap roll attachment whose feed rolls are positively driven by a link chain by the
regular lap roll gear.
Modification of carding of processing of manmade fibre:
Feed rollers:
 For a firm grip on the lap feed rollers the normal fluted rollers are replaced with serrated rollers.
 The weighting on the rollers is generally increased by 50% as otherwise the lap tends to be drawn into
the licker-in causing plucking of fibre tufts.

6. Sliver weight:
 The sliver weight is generally adjusted between 35-45 gr/yd. for fine denier and 40-50 gr/yd. for coarse
denier polyester and acrylic fibers. The sliver weight for viscose rayon could be higher and should lie
between 55-65 gr/yd.
 In case of blends, the linear density of the sliver made from manmade should be nearly the same as that
used for the component to be blended at the Drawframe.
Web and sliver tension:
 Some manmade fibres like viscose rayon have a tendency to have a sagging web due to the slickness of
fibre. This is usually set right by a slight increase in the web tension by increase the speed of the
calendar rollers.
 However any excessive tension on the web has to be carefully avoided as this can lead to undue
stretching of the web.
Trumpet bore:
 The trumpet size for the manmade depends upon the type of fibre. The viscose rayon which condenses
much more needs a smaller bore whereas bulkier fibres like polyester, polypropylene and acrylic require
a larger bore.
 The bore size varies from 3.8-4.6mm for 55-75gr/yd. sliver.
Coiler tube:
 For bulky fibres like polyester, acrylic and polypropylene a coiler tube of larger bore should be used.
Increasing the pressure of the can spring so that sliver presses harder against the coiler disc helps to
eliminate coiler tube choking. Increase in calendar roller pressure also helps in avoiding choking.
 Brass tubes are particularly prone to choking and should be replaced by steel or chromium plated matt
finished tube wherever possible.
Atmospheric condition:
 It is essential to maintain proper atmospheric conditions in the card room.
 A lower relative humidity may cause broken web, excessive fly liberation and lapping on doffer. Too
high a humidity should also be avoided as it leads to sagging of web and loading of the licker-in and the
cylinder.
Scouring of metal clothing:
 The scouring of metal clothing particularly the licker-in with petrol or carbon tetra-chloride solution may
become necessary when tinted fibres are being processed.
Autolevelling:
 Most modern card have electronic autolevellers as an integral part. It makes it possible to achieve very
low count C.V. and asignificant reduction in end breaks both in ring and rotor spinning.
 The autolevelling system is generally based on the principle of correction in the feed roller speed.
 For high quality yarns produced from manmade fibres it is advantageous to have autolevelling done at
the card than Drawframe because the short term irregularity introduced in the sliver due to the
autolevelling action is largely neutralized by doubling at post-card doublings.

7. Advantages of Card Blending
 Most intimate blend is obtained.
 This method is used to randomly mix two laps differing in color.
Disadvantages of Card Blending
1. It can’t be obtained from wide range.
2. Controlled metered blending can’t be carried out.
3. Only make a previously proceeded blend more intimate
3. Blending modification at Draw Frame
This method is normally used for binary blends only. The required blend proportion is adjusted by the
number of slivers of each component and the hank of respective slivers.
The fleece blending is done on the blending Drawframes specifically designed for this purpose. They are
fed with 16-20 slivers at the back and therefore provide a much greater flexibility as regards the blend
ratios.
Advantage
 Easier to obtain uniform blend ratio.
 During opening and carding, optimum settings for each blend component can be used
for better quality of output with less damage to the fibres.
 Easy working.
Disadvantages
 Difficult to attain random arrangement of fibres in the yarn cross section.
 Additional drawing capacity needed.
 Separate opening lines needed for each component.
Drawframe
Passages
Number of Doublings Blowroom Blend Drawframe Blend
Degree of Mixing IBI Degree of Mixing IBI
1 1 0.68 1.48 0.47 1.92
2 36 0.76 1.42 0.63 1.50
3 216 0.81 1.38 0.75 1.36
4 1296 0.83 1.38 0.78 1.32
Table: The results clearly show that the index of blending irregularity goes down with increase in the number of Drawframe
passages.
 One of the serious problem of blending on a normal Drawframe is the difficulty of achieving random
distribution of fibres in the yarn cross-section i.e. the index of blend irregularity is higher for this form of
blending than the Blowroom blending.

8.  This is due to the fact that during drafting there is little lateral movement of fibres. Further, when the
web is condensed into sliver there is very little improvement in fibre intermingling as each sliver in the
drafted web tends to retain its entity. It is only repeated doubling and drafting that blending really
improves and reach near the random state.
4. modification at roving frame:
Roller weighting:
The roller weighting considerations in speedframes are similar to those operating at the Drawframe.
The weighting is much higher than that used for cotton and should range between 10-15kgandspindle.
Use of condensers:
If excessive fly liberation is a problem it is advisable to use condensers in the front zone to restrict the
ribbon width at the front roller nip thus allowing the twist to run closer to the roller nip. This is not only
makes the material slightly more compact but also reduces the roving brakes.
Tensor or spacer:
In general the spacers used for a given hank of cotton roving is inadequate for that of manmade and blends.
Wider apron spacing is essential for smooth drafting.
The optimum spacer size depends on hank of material, the total draft and the fibre characteristics,
particularly the fibre bulk.
Surface finish of machine parts:
All the parts over which the fibre pass must be kept smooth and clean. The flyer surface, in particular,
should be absolutely smooth. Even a scratch on the flyer surface can cause the fibres to deposit around it
forming a lump and thus adversely affecting the operating conditions and the roving quality.
For fibres like polyester which are prone to static accumulation, it is preferable to use a flyer having a matt
chrome finish than a high polish chrome plating. The matt finish reduces the adhesion of the flyer leg and
thus avoids any build up fly.
Winding tension:
Due to the excellent elastic recovery of synthetic fibres like polyester, the hardness of the roving bobbin
would be much higher than that obtainable with cotton.
Therefore to prevent stretching of roving during winding on this hard surface the roving should be given
only ¼ wrap at the layer top and 1 turn around the presser to keep the winding tension at the minimum level.
Ratchet wheel:
The size of the ratchet wheel is determined by the fibre bulk.
For the viscose rayon staple which can pack more compactly than cotton, a bigger ratchet wheel or an
equivalent gear change in building motion is required. Similarly, for bulky fibres like polyester and acrylic a
smaller ratchet wheel or an equivalent gear change is essential.
Bobbin taper:
The taper of the bobbin should be more than that for 100% cotton to prevent sloughing off of outer layers.
Storage bobbin:
The roving bobbin should not be held up or stored for a long time since the inter-layer pressure which
increases the fibre coherence in roving may present problems during drafting at the ring-frame. This
precaution should be particularly taken when spinning 100% polyester or its blends.
Stop motions:

9. Many modern roving frames are equipped with suitable stop motions. Whenever there is a sliver breakage,
slivers run-out, or a roving breakage the machine immediately stops.
5. Blending of Combed Cotton Sliver and Polyester
Many Indian mills resort to this practice when the humidity control or conditions of machines is very
poor.
Advantages
- Produces very intimate blend
- Trouble free running and high productivity at card.
- Less yarn imperfections due to better fibre individualisation because of reprocessing of the cotton
component.
- Reduced number of d/f passages.
- Lower end breaks due to fewer slubs.
-better uniformity of dyeing due to more intimate blend.
Disadvantage
- Poor tenacity and evenness in blend yarn.
- High cotton nep content in blend due to reprocessing
- Need of additional b/r and card capacity
- Slightly higher waste in b/r and carding.
Optimum Blending Method of various Blends
1. For blends like P/V , blowroom blending is effective as they need similar b/r sequence.
2. For blending of manmade stack blending method is generally used.
3. The polyester /cotton or acrylic/cotton are generally blended at d/f because cotton component
needs a severe opening and cleaning action
4. Where there is a problem of running 100% polyester on card, stack
blending of polyester stock and combed cotton may be resorted to.
5. In case of v/c blend, they should be blended at the draw/frame as they need quite a different opening s
equence.
6. Blended Yarn
Blended yarn involves the constructive gelling together of two or more constituents. SHM Traders has a
comprehensive list of blended yarns to offer.
Modification in Ring spinning:
Feed:

10. Double end feed is not desirable especially for yarns of higher tensile strength like those spun from polyester
, acrylic and their blends because even if one roving breaks the other half of the yarn may be strong enough
to continue to run without breaking. This creates single in the yarn and is highly objectionable.
To ensure stretch – free unwinding of roving, umbrella creels should be preferred.
Roller lapping:
In spinning of manmade fibers, the problem of rollers lapping is always more serious because the laps are
more frequent and difficult to remove. This is particularly problem some when one spins long staple fibers
of 51mm and above. Lot of precious time is spent in removing them .In general, the lapping are more
frequent with longer and finer fibers because of their lower flexural rigidity.
Roller lapping at the ringframes not only causes loss in productivity but also loss of valuable raw material.
The following suggestions may be helpful while tackling the problem of excessive lapping:
a) It is important to maintain suitable conditions of temperature and relative humidity.
b) Proper cleaning and upkeep of drafting rollers and apron bands is essential.
c) The suction system should be properly maintained and checked for the suction pressure .The
pressure should not drop below 110mm of water.
d) Reduce the front top roller pressure within reasonable limits.
e) Application of varnish to the front top rollers brings down the incidence of lapping but only
temporarily. Some anti-lapping solution now available are claimed to resist lapping for much longer
periods. Like in drawframes, the process of irradiation or acid treatment applied to the newly buffed
rollers can also be extremely helpful.
f) Buff the cots at regular interval, say after every 8-10 weeks. Buffing removes the outer surface of the
top roller which has progressively been damaged due to ozone-cracking, chemical degradation and
mechanical damage
g) The top rollers should be regularly cleaned with solvents like carbon tetrachloride.
h) A damaged front roller surface is prone to lapping. Therefore, use of licker-in wire, knives or other
sharp tools to remove roller laps should not be allowed. Suitable cutters, designed by the research
associations, are available for removing such laps without any damage to the top roller surface.
Roller weighting:
The roller weighting has to be increased as one change from cotton to manmade and blends. Polyester and
its blends require higher weighting than viscose rayon. In general, a weighting of 1.5-1.7kg/cm at the nip is
adequate for most of the manmade and their blends.
New aprons:
Aprons, like travelers, give best performance after certain breaking-in period. The duration of these periods
depends on the quality of aprons and the material being processed. It is generally claimed that a combination
of leather apron below and synthetic on the top is more suitable than both being synthetic aprons.
Fiber lubricant film:
Like cotton fibers, the synthetic fibers such as polyester also form a very fine fibre film on the running track
of the ring during spinning due to the crushing action on bits of fibres by the ring and the traveler. The film
through a few microns thick, act as a very effective lubricant and allows a higher traveler speed to be
realized. However, when spinning certain fibre type like rayon, delustered fibres or when using certain
finishes, no effective fibre lubricant film is formed.
Balloon control rings:
The use of balloon control ring should be avoided. as far as possible, while spinning polyester and its blends.
These rings can cause filamentation (rupturing of fibres) and melt-spots at high spinning speeds as the yarn
rubs against the control rings at speed of 30-35m/sec under considerable contact pressure. In case it is
essential to use them, as in large packages and high speeds, the problem can be minimized by having a
suitable ring profile (cross-section of wire and ring diameter) and yarn lubrication.

11. Index of blending irregularity (IBI):
IBI used to assess the degree of randomness in the fiber distribution
This index was evolved by coplan and Klein for variation in the blend proportion against the theoretical
value for random mixing.The IBI for a given blend can be calculated from the following expression:
IBI=√
𝟏
𝑴
∑
( 𝑻 𝒊 𝑷−𝑾 𝒊) 𝟐
𝑻 𝟏 𝑷𝑸
Where Ti: total number of fibres in a given section
Wi: the number of fibres of component W at that section
P: the average fraction of component W for all section
Q: equal to (1-P)
M: number of section examined
This index is primarily a chi-square test. For complete randomness, IBI has a value equal to unity. values
greater than unity indicate less homogeneity than complete randomness would give. The index would be
zero for perfect blending.
According to bogdan et al. the basis of evaluation in this method is the longitudinal variation in the ratio of
the number of different fibres in the cross-section. Coplan and Bloch expanded on the longitudinal variation
method and developed two other methods of evaluation viz., radial distribution and rotational distribution of
fibres.
1. Radial distribution:
This describes the fibre motion across the cross-sections of the yarns. To estimate this, the yarn cross-section
is divided into a number, usually four, concentric circles of either equal area or thickness.
2. Rotational distribution:
For estimating the variation in the rotational distribution, the yarn cross-section is divided into four to six
segments. The blend ratio is calculated and plotted as a bar diagram. Ideally, the ratio should be the same for
all the segments.
FIBRE PROPERTIES & SPINNABILITIES
processing differ between, cotton spinning, wool spinning,semi worsted and worsted yarn spinning because
different fiber different characteristics discussed below.

12. SPINNABILITIES OF FIBRES:
 This is describes various properties of the fibres related to their spinnability in particular. The fiber
characteristics largely influence the processing and the spinnability of all staple fibres.
 Primary facture like staple length, denier, and strength not only affect spinning limit (the maximum
count that can be spun from a given fibre) but also the yarn quality.
 Whereas certain fibre characteristics like crimp, friction, static charge, and hygroscopicity are the factors
along with primary factors which largely influence the processing at various stages of yarn manufacture.
.
Staple length:
 This is one of the major fibre characteristics which influences not only the spinnability but also the
quality of yarn.
 A longer fiber can be spun to a finer count, needs a lower twist multiplier and gives a better spinning
performance.
 Too long fiber, however is liable to give processing problems especially in carding (also in drafting);
there is excessive nepping tendency, more so with finer fibers.
 Longer the fiber higher is the yarn tenacity. The yarn irregularity and imperfections may increase with
fibers longer than 44mm.
 The advantages of using longer fibers include higher yarn tenacity, higher spinning limit, reduced
hairiness and lower pilling tendency, the productivity also increases because the yarn spun from a longer
fiber needs a lower twist.
 Longer fiber tend to make a more compact yarn (small diameter) for a given twist level, breaking
extension is also higher for yarn spun from longer fibers.
 Manmade fibres generally cut to 32-61mm for processing on cotton system.
Fiber denier(fineness):
 Fiber finenes greatly influnces the yarn unevenness , yarn tenacity, spinning performance and varous
other yarn parameter.
 Denier of yarn related to number of fibres in the yarn cross-section .A finer fiber is expected to spin finer
yarns.
 Fiber denier and yarn dnier are related to each other ,so the quality of yarn and its spinning performance
influenced by number of fibres in yarn crossection(it should be around 85fibres for 38mm length and
68 fibres for 61mm length)
 A finer fiber means more number of fibres in the cross-section for a given yarn count.the yarn
unevenness is largely dependent on this number. A greater number of fibres in the yarn cross-section
result in a more even yarn.
 The yarn twist multiplier needed for optimum strength is also lower because finer fibres provide larger
area of inter-fiber contact
Fiber strength :
 A textile fibre should have adequate strength so that it can be converted into a useful product.
Minimum fiber strength for this purpose is lies between 0.6-0.7grams per denier.
 The tenacity of manmade fibres can be varied to a great extent during spinning and drawing.
 Stronger fibers gives a stronger yarn. However in case of blends the compatibility of blend
constituents is important to derive the maximum fiber strength utilization.
 New spinning system such as rotor spinning and friction spinning are highly influenced by fiber
strength. High tenacity fibres invariably used for sewing threads.
 Also high tenacity fibres are needed in cotton/viscose component is made equal to the polyester
component for greater comfort(50:50 blend).

13. PHYSICAL FIBRE PROPERTIES
The very importance thing in spinning is to have knowledge on the raw fibres properties tobe used and their
spinnability. Following properties are largely influence the processing at various stages of yarn manufacture
Hygroscopic properties:
 Cellulosic fibres like cotton and rayon have high hygroscopicity to atmospheric temperature and
humidity. On the other hand synthetic fibres like Polyester have generally low hygroscopicity.
 On the temperature 250C and 65% RH. The moisture regain on rayon is 12% to 13% and cotton 8%,
the polyester is as low as 0.4%.Hygroscopicity generates static charge during spinning process and
affects spinnability andbrings a degree of changes in moisture regain of the fibres at various
temperatureand Re. Humidity.
The graph shown below is the hygroscopicity curves of various fibre at 250C
Static charges:
 Friction among fibres or between fibre and metal during spinning sometimes generates and builds up
static electricity especially with the fibre of lowerhygroscopicity.
 Usually antistatic oil had been added during manufacturingPolyester and Rayon in order to have the
same spinnability as cotton fibre, bymaintaining the temperature between 20 – 28oC and 55 to 70% of
RH, will notgenerate much problems in spinning process.
Friction:
 As mentioned above that friction may cause troubles in spinning process and affectsthe spinnability
either. The higher coefficients of friction will produce problem incard action and draft effects but the
lower coefficient will cause less cohesion amongthe fibres and will affect yarn strength (lower or in
sufficient). Polyester fibres havehighest coefficients of friction followed by Rayon then cotton.

14.  Polyester and Rayon are given oiling treatment during process in order to get the sufficient coefficient
offriction.
Crimp:
 To increase of friction among the fibres and the cohesion, to improve bulkiness,elasticity and
spinnability, certain degree of crimps are applied to the man-madefibres.
 Polyester as well as Rayon, bright and semi dull are crimped.The rayon with smaller number of crimp is
called “Regular Rayon Staple” and“Crimp Rayon Staple” is the Rayon with higher degree of crimp.
PREDICTION OF BLENDED YARN STRENGTH
In comparison with 100% polyester, cotton/polyester blending has many advantages such as
 Less pilling,
 Less static electrification,
 Easier spinning,
 Better evenness for sliver, roving and yarn
 Prediction of the mechanical properties of blended yarns has also been studied by numerous authors.
Theoretical and mathematical models have been proposed in these studies.
 It is a critical problem in fibre blending technology to choose appropriate types of fibres and blend ratios
depending on the final product.
 This study aims to predict the strength of cotton/polyester blended rotor yarns using blend ratios and
yarn count as predictors
The regression equation of this model is as follows:
Design points (blend ratios) used in this study.
Design points Blend ratios, %
X1 (polyester) X2 (cotton)
a 0 100
b 25 75
c 50 50
d 75 25
e 100 0
Yarnstrength (cN/tex) =
[7.13 X1+ 16.91 X2- 7.39 X1X2 + 1.14 X1Z - 0.19 X2Z - 0.02 X1Z2+ 0.003 X2Z - 0.29 X1X2Z + 0.002 X1X2Z2] 0.98...........[1]
In this equation; X1and X2are the polyester and cotton ratios respectively, and Z is the yarn English cotton
count.
The strength of the cotton/polyester-blended rotor yarns can be predicted by this equation. Figure 3
illustrates the relationship between blend ratios and yarn strength.

15.  The blending of a relatively weak fibre (i.e., cotton) with a strong fibre (i.e., polyester) leads, as
expected, to some losses in yarn strength.
 The properties of the blended yarns cannot merely be explained in terms of the proportions of the
different constituent fibres in the blends. In fact, the overall properties of the blended yarns are related to
the blend ratios, the corresponding properties of each component and the interactions of the components
themselves.
 When the polyester ratio changes from 0 to 25%, the strength of the blended yarn decreases. However,
the yarn strength increases after 25% polyester. This trend is observed for all the yarns spun with five
different counts. The loss of strength in the blended yarn is attributed to the differences in the breaking
elongation of the constituent fibres.
 When the blended yarn with 0 to 25% polyester is subjected to increasing load, the cotton fibres with
smaller elongation break first, and then polyester fibres are exposed to entire load.
 If there are not enough polyester fibres in the yarn cross-section, they cannot carry the entire load,
resulting in a loss of strength in the blended yarn.
 When the polyester ratio is over 25% in the blended yarn, the yarn strength increases because there are
sufficient polyester fibres in the yarn cross-section. If the ratio of one of the components is insufficient,
the yarn’s properties will not meet our expectations.
 The correlation coefficient between the predicted and observed strength values is 0.986. Figure 4
illustrates this strong positive correlation

16. Figure 4 Correlation between predicted and observed strength values
The developed multiple linear regression equations of yarn tenacity
Yarnstrength (cN/tex)= 21.77-3.04X1+.10X2-0.02X3+1.64X4…………………………….[2]
Where X1 is the PES/CO blend ratio, X2is the twist multiplier (TM), X3 is the back roller cot hardness in
degree shore, and X4is the break draft ratio
 Equation … [2] expresses that, by increasing cotton share and cot hardness yarn tenacity decreases,
while tenacity increases with increase in twist multiplier and break draft. This is due to inherent
characteristics of cotton fibres which are less strong as compared to polyester fibres and higher back
roller cot hardness may lead to improper fibre control in predrafting zone which causes irregularities in
yarn structure,
TINTING
Identification method in the spinning process for various materials generallytaken as follows:-
 Identification by color of cans and bobbins- Separation based on “one product on one mill principle”.
 Tinting is the easiest and most convenient way among the above method but it isnot recommended
because it may sometimes cause neps and fluffs and alsodyeing problem.
The following pointed are strictly to be followed it “tinting method” isunavoidable:-
 Tinting should be applied on polyester part in a blend because the drying of polyester isshortdyeing
affinity is comparatively low and easy to be stripped in finishingprocess.
 If tinting applied on rayon staple fibre since it willbecome the main causes of generating neps and fluffs
due to entangle fibre,processing problem in dyeing.-
 Use spray gun and not brushes- Tinting solution must be evenly sprayed on four sides of the bales
afterunpacked and must be left as it is for at least 24 hours.-

17.  The tinting is usually done with fugitive dyes so that they are easily removed in normal scouring.
 A dye whose color fades in a few days to neutral on exposure, usually to ultraviolet rays in
sunlight. Fugitive dye is often used to temporarily color.
 When fibres like polyester and acrylic are to be tinted, care to be taken to see that they retain the spin
finish applied during their manufacture. For this reason the tinting of these fibres should be carried out
on 15-20% fibres only which are then blended with the remaining non-tinted fibres after drying .
 The tinting is normally carried out by spraying tinting solution , generally the concentration of tinting
solution is to be around 0.03-0.1% sprayed on fiber preferably after passing through the bale opener.
 The spraying should be carried out with a spray gun which ensures fine spray without drip .in certaion
cases it might become necessary for synthetic like polyester to spray the tinted fibres with an anti static
agent before processing them further.
 The dye is sprayed onto the exposd faces of the bale which is then taken for opening in the normal way
.For the tinting of fibres like cotton or viscose rayon, the fibres are invariably pre-opened before
dipping them in a solution of the desired dye .After removing surplus water the stock is thoroughly
dried.
 Acid dye normally recommended except for cashmilon wool blend. These dye easily washable and have
remarkably good light fastness and tinctorial value and donot create problems like card loading and
roller lapping.
The tinting may carried out on either blend components.some people recommend the tinting of cellulosic
blend components like viscose rayon or cotton in preference to the synthetic component like polyester or
acrylic due to higroscopic nature of cellulosic fibre an the fact that the spin finish on synthetic thus remains
unaffected.
However the general practice is to tint the synthetic components .therfore in blends of P/C or P/V polyester
is normally tinted.there seems to be three main factors for such a practise.
a) First the tinting solution sprayed on polyester or acrylic dries up very fast due to their hidrophobic
nature.
b) Secondly these fibres are very sensitive to dyeing and any inter mixing of different lots would result
in serious dyeing defects which can cause great financial loss to the mills.
c) Thirdly , the viscose rayon or cotton if dyed would take much longer to dry completely and present
difficulties in their proper opening and carding.
 However in case super fine polyester it might be advisable not to tint polyester as this may prove to be
more difficult to be processd.
For a dye to be eligible for tinting purposes it should meet the following conditions:
 The tint should not stain other fibers in the blend or stain machine parts like drafting rollers, the
aprons, card cylinders, flats etc.
 It should be reasonable fast to light and easily identifiable both in day and night lighting
 It should be easily and completely removed in normal scouring process without associated
contamination or staining of the blend components.
 It should not have any adverse effect on drafting and dyeing processes.
 It should be water soluble or oil soluble for use with finishing oil incases moisture is detrimental to
the constituent fibres.
 It should not set at conditions of twist setting carried out after spinning.

18. Processing of P/w blend:
Properties of wool:
● It is a luxury fibre with an excellent feel and touch.
● It is soft and natural hand feel.
● It is wrinkle-resistant.
● It is light weight and durable.
● It absorbs moisture.
● It retains shape.
● It has a good drape and fall
Dyeing wool / polyester and other fibres
It is the process of colouring fibres, yarns or fabrics from which we canget solid shades, mélange (mixture).
There are different ways of dyeing. Some of them are:
(a) Dope dyeing
(b) Top dyeing
(c) Piece dyeing
(d) Yarn dyeing
(a) Dope dyeing:
Mass coloration, spun-dyeing or dope dyeing may be defined as “a methodof colouring manufactured fibres
by incorporation of the colorant in thespinning composition before extrusion into filaments”.
(b) Top dyeing:
It is a method for dyeing combed wool yarn, before spinning, by placing it in large vats and circulating dye
liquor through the yarn at increased temperatures.
(c) Yarn dyeing:
We use this form of dyeing for decoration shades. In this process use of auto colour dispenser avoids any
lot-to-lot variation.
(d) Piece dyeing:
In this process, the woven white fabric is dyed in desired colours by complete immersion, contrasted with
yarn dyeing or raw stock dyeing.
● By this, it is possible to dye solid colours.
● It is possible to dye one component in the blend of different dyes taken up to get a mixture look.
● Quick dyeing method where the white fabric is ready and hence quick delivery.
● Desired quantity can be dyed.
● Finish of piece dyed fabric is smoother.
● Use of auto colour dispenser avoids any lot-to-lot variation.
Blending
It is a process of mixing two or more different fibres in desired percentage.
For example,
●60% wool / 40% polyester
●55% polyester / 45% wool
●75% polyester / 25% wool
●60% polyester / 20% wool / 20% linen
Types of basic blends:
● All wool
● Wool rich
● Poly / wool
● Poly / viscose
● Wool and poly / wool in combination with speciality fibres –

19. Polyester:
The first polyester fibre, Terylene, was produced in England. It was first introduced in the US by the DuPont
under the name Dacron.
Types of modified polyester fibres:
●Benzoate polyester
● Flame-retardant polyester
● POY polyester
 For apparel and furnishing. Polyester knits well and is used for making knitted shirts and blouses.
Polyester is used as a fiberfill (Polyfill) in pillows, quilts and padding.
 It is light in weight and more washable as compared to a cotton filling and had thus gained a lot of
popularity. Non woven polyester is used for making bandages and pads in the medical fields.
 Polyester is easy to care as it can be washed in the washing machine using warm water. Hot water (120–
140°F) causes wrinkling on the fabric.
 Polyester is oleophilic, i.e. it tends to attract oily soil making the fabric look dingy over a period of use.
Soil-release finishes can solve this problem.
 Cross-sectional view of polyester fibre. Polyester is a form of manmade fibre. It is available in various
deniers
 Finer the denier, more easy the handling and could be spun in finer yarncounts and could also be blended
with wool, viscose and cotton in desired percentage.
 Types of polyester
● Trilobal polyester
● Low pill polyester
● Normal polyester
Properties of polyester
● Strong, dimensionally stable material that absorbs very little water
● Improved wrinkle resistance
● Easy care and toughness
● Resistance to stretching
● It is procured from best sources
Virtually all goods made from polyester/wool blends are intended for outerwear, typically suiting’s, dresses
and skirts. Modified polyester fibres with improved resistance to pilling have been blended with wool in
knitted jersey dress wear. This can eliminate the need to singe polyester/wool fabrics, a treatment not usually
available in wool processing. Singeing may also introduce dyeability differences.
 Polyester/wool fabrics can often be dyed on the beam and these blends show better dimensional stability
on washing.
 The important 55:45 polyester/wool blend arose from the realization that this is the minimum polyester
content that allows durable pleating of the blend fabric.
 Reducing the wool content lowers the aesthetic appeal but decreasing the polyester proportion makes it
no longer possible to retain pleated effects after washing.
 The most important blend in the USA is an 80:20 fabric, composed of a textured filament polyester warp
and a 55:45 polyester/wool blended staple weft.
 In Western Europe another luxurious fabric is a 20:80 blend, containing a 55:45 blended staple warp and
a pure wool weft.
 Smaller market niches exist, e.g. a 40:60 polyester/wool blend for luxury automotive fabrics.
 This specific outlet puts high demands on both fabric and dye performance. To meet these demands the
two fibres are usually dyed separately as loose stock or tops and subsequently blended.
 Polyester fibres will withstand the normal processes used to prepare wool fabrics, such as carbonizing
and milling.
 The stentering temperature must not be too high when carbonizing polyester/wool fabrics, however,
because appreciable damage and yellowing of the polyester component may occur under such
conditions.

20.  Neutralised fabrics should have a slightly acidic pH to avoid possible damage to the wool. It is usual to
give a crabbing treatment to polyester/wool fabrics to minimize creasing during winch or jet scouring
and subsequent dyeing.
 Jet dyeing has a mild milling action on these goods and yields a softer handle compared with the
somewhat crisper feel characteristic of beam-dyed fabrics.
 Careful preparation of the fabric prior to beam dyeing is most important. Preshrinking is necessary to
prevent any moiré effect (water marking) that may arise from differential shrinkage on the beam .
 Presetting at 170–190°C protects against rope creasing or possible shrinkage in beam dyeing. Higher
setting temperatures cause yellowing of the wool.
 Heat setting improves the handle, resilience, crease resistance, dimensional stability, shrink resistance
and pilling performance of the goods. It does, however, reduce the dyeability of the polyester component
after setting. This may aggravate wool staining.
 Scouring with an anionic detergent and soda ash eliminates the risk of residual nonionic detergent being
carried out into the dye bath and adversely affecting the dispersion stability of disperse dyes.
 Polyester/wool knitted fabrics may be scoured in the jet machine with ammonia at 40°C before dyeing.
Bright shades may require a preliminary mild bleaching treatment. The wool may be given either
oxidative or reductive bleach, whereas the polyester only requires treatment with a fluorescent
brightening agent.