5.1 The idea of enhancing cotton
Gives advantages in finer counts which are produced from specific grades of cotton ( Pima).
Yarn Tenacity (Strength and Softness) increases as Modal blending ratio increases.
It improves the processing performance of cotton.
It improves the consistency and quality of cotton yarns.
Overall spinning performance is enhanced by blending Modal with cotton.
This creates a new group of fabrics with new aesthetic properties and functionality compared to cotton fabrics
5.2 Lenzing Modal Card
... Produced from beech wood
... The Lenzing Modal production process is environmentally-friendly due to the exceptionally high recovery rate
... Low utilization of land and water during production – cotton requires up to 100 times more water than Lenzing Modal
... Lenzing Modal makes everything soft and coz
... Perfect for blends with cotton: mercerizability, alkali resistance, tone-in-tone dyeing
... Can be blended with all other fibers without any difficulty
... Lenzing Modal is a globally protected trademark
... Lenzing is the Modal specialist and has produced the fiber for fifty years
... Lenzing Modal is used by leading brand collections With special technical & commercial support from Lenzing fibers of Austria, Modal is tried and used in 5 to 50% blend with cotton for fine yarn counts ( 200s, 30s, 40s Ne )and this not only gives increase in yarn strength (CSP) but also reduces imperfections with smooth and shine on yarn. Overall quality and life of
Fibre Properties
Chapter 5
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end product made is much better, no combing process is required, productivity is increased_ With continuous increase in demand of supima, DCH, giza and other ELS cottons, using this special viscose fiber not only saves cost but also gives very good and consistent yarn quality. Good quality and high end cotton prices will be continuously increasing in coming years and availability will reduce. This is already observed in supima where prices are doubled in last one year. Use of Modal fiber gives us various benefits, since this is manmade cellulosic fiber only and one kind of viscose only, it has to considered like viscose with no import duties.
5.3 Modal fibre Characteristics:
o Soft, strong, absorbent
o Fibrillated during wet processing to produce special textures
o Excellent wet strength
o Wrinkle resistant
o Very versatile fabric dyable to vibrant colors, with a variety ofeffects and textures.
o Can be hand washable
o Simulates silky, suede, or leather touch
o Good drapability
o Biodegradable.
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ROCESSING GUIDELINE
SPINNING OF LENZING MODAL AND COTTON ACCORDING TO
THE THREE-CYLINDER AND OE-ROTOR SPINNING PROCESS
Recommendations for processing short staple MODAL fiber
The cellulose textile fibers Lenzing Modal are available in different types of machines, which are generally suitable for the processing of man-made fibers.
Procedure
Chapter 6
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The following processing recommendations and machine setting data apply equally to Lenzing Modal. They are based on our total experience to date and are valid for the processing techniques and machine types in general use at present.
6.1 Flock material and air conditioning
Lenzing Modal fibers are treated with a special spin finish which includes an antistatic agent to ensure good spinning properties. There is no need for any further additives in the spinning process.
However, if these fibers are subsequently dyed, a suitable secondary finish must be applied, because the flock loses the original preparation during the dyeing process.
Trouble-free running properties can be expected if the room air conditioning is within the following limits:
Room temperature: 24 – 26 degrees Celsius
Relative humidity: 50 – 60 %
As is the case all man-made fibers, it is advisable to allow the unpacked and opened bales time to acclimatize before processing. This should be a longer period in the cold winter months.
6.2 Bale laydown
MODAL bales weigh approximately 350 kg each and should be used, where possible, sequentially according to lot number and fiber production date. As with all man made fibers, adequate stock rotation of fiber, material in process and yarn should be carried out in order to optimize process continuity, avoid the build up of old stock and in order to minimize the risk of longer term process variations due to excessive storage intervals between materials in use.
Whilst MODAL fiber has significantly less bale to bale variation than cotton, as with other man made fibers, as many bales as possible should be used in each laydown. This will ensure that fibers are thoroughly blended. Where continuous use of MODAL fiber is anticipated, programmed use of bales from a range of deliveries is recommended. It is normally recommended to use a minimum of 15 bales in each laydown.
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Figure 1
6.3 Batch Spinning
This technique is based on the assumption that the customer is using only a limited quantity of fibers which he blends together, but which are spun as a separate entity. Where are large number of bales are involved, it is advisable to use the continuous spinning technique described overleaf.
6.4 Continuous Spinning
This technique is understood to mean the continuous and uninterrupted spinning of material supplied at different times over a prolonged period. In order to ensure uniformity of shade, the overlapping processing of three to four deliveries is necessary.
Furthermore it is recommended to work with a laydown consisting of minimum 10 to 12 bales (better are 20 to 24 bales). The fiber quantities taken from different bales should be comparable in weight.
Figure 2 illustrates the diagonal processing of a stock of 12 bales from a number of consecutive deliveries.
Figure 2
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6.5 Blending and Opening Machines
For the opening-up of Cotton and Lenzing Modal fibers the opener combinations normally used in today’s fiber processing industry will be found suitable. In the main, these combinations comprise a bale opener or a mixer bale opener and an on-line opening machine. The opener subsequently takes over the role of feeding the cards. The following points should be borne in mind in connexion with the achieving of a good degree of opening:
a) The beater speed of the Kirschner cylinder should be set at between 600 and 800 rpm.
b) The distance between the beating area and the mould or the draw-in roller should be set at between 8 and 11 mm.
6.6 Carding
The processing of Cotton and Lenzing Modal is usually on modern, flock fed units. In order to ensure efficient fiber opening, it is extremely important that the cards are highly ground and in a good condition, and further that they have been set in accordance with the manufacturers’ instructions. It has also been found to bee of
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Figure 3
advantage when processing these fibers, if the lickerin has a wire with a negative top rake of 5 – 10 degrees.
When processing only Lenzing Modal we recommend the following card clothings, settings and speeds:
1.) Card clothings
Licker-in 32 to 40 points / inch² / 5° positive
Main cylinder 600 to 720 points / inch² - 15° to 25°
Flats 300 to 420 points / inch² - flexible wire
Doffer about 360 points / inch² 30°
Fix flats under licker-in 90 p. / inch²
Fix flats above licker-in 90 and 160 p. / inch² or 160 and 240 p. /
inch²
Fix flats above doffer 550 to 600 p. / inch²
2.) Card settings (1/1000")
Feed table / licker-in 28
Licker-in / knife 18
Licker-in / fix flats under licker-in 18
Licker-in / main cylinder 8
Fix flats above licker-in / main cylinder 28 to 20 declining
Flats / main cylinder 12/12/10/10/9
Fix flats above doffer / main cylinder 10
Main cylinder / doffer 4
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Gap between both squeeze rolls 12
Total draft 80 to 120
3.) Rpm, sliver count and others
Licker-in (rpm) 800 to 1000
Main cylinder (rpm) 350 to 400
Sliver count Ne 0,10 to 0,13
Flat speed (mm / min) 80 to 140
Production rate (kg/h) 25 to 60 (Depends on the yarn spinning technology, yarn quality and on the type of card)
6.7 Drawing
When processing either Lenzing Modal fibers alone, two passes on the drawing rollers will generally be found sufficient. Basically, all conventional-type draw frame systems should be found suitable – provided they can be adjusted to the length of the staple. The doubling can be selected 6 or 8 times, and also the total drafting. Generally speaking, it will be found that cylinder loading commonly used for man-made fibers are also sufficient for Cotton and Lenzing Modal fibers.
The weight applied to the drawing frame – depending on the cylinder loading – should be so selected that the clamping of the slivers to be drawn is always sufficient to give fiber control.
Most of the synthetic material covers on the market today ( 80° - 84° Shore Hardness) will be found suitable for the pressure cylinders. A precondition for trouble-free running properties is the room temperature and the good condition of the cylinder covers, which should not show any signs
of damage or contamination. Roller lapping – which can occur at very high processing speeds, and where the air conditioning is not optimal, may make it necessary to lacquer the rubber roller with a suitable cylinder lacquer.
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In fig. 4 you can see the appropriate settings for different drawing systems.
Figure 4
6.8 Speed Frame
For the processing of Cotton and Lenzing Modal, high load drawing rollers such as three cylinder double apron drawing equipment are used.
As far as rubber rollers for the cylinders are concerned, the same remarks apply as under >>Drawing<<.
The sliver count should be between 0,20 and 0,30 Nm. The total draft should be between 6 and 12. The break draft serves to align the slivers in the pre-drafting
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zone. Experience has shown that breaks drafts between 1,1 – 1,3 times are advantageous.
For the selection of the roving twist, there are following criteria to be taken into account:
• Weight of the roving (a finer roving count is more sensitive in terms of fault tension)
• Weight of the roving bobbin (bobbin load and size)
• Fiber length
• Fiber fineness (finer titres needs less twist)
• Fiber type (Modal needs less twist than Viscose)
• Type of pendulum arm and cradle length on the ring spinning frame
As a guideline for roving, we recommend 1,0 – 3,0 Nm, whereby the roving twist should be between αm 23 – 28 for 1,3 dtex Viscose and αm 20 to 25 for 1,3 dtex Modal. You can determine the most favourable twist by conducting preliminary trials.
Fig. 5 shows a drawing roller arrangement for a three-cylinder double apron drawing system.
Figure 5
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6.9 Ring Spinning Machine
All modern types of double apron drawing equipments are suitable for the spinning of Cotton and Lenzing Modal fibers. The staple length of 40 mm can be produced with cradles for short staple and medium staple. All drawing equipment manufacturers give exact details regarding the basic settings for their machines so that only a few complementary remarks are necessary here.
For the processing of fiber types 1,3 and 1,7 dtex we recommend:
Total draft approx. 20 - max. 50 times
Break draft 1,15 - 1,4 times
The distance between the top and the bottom aprons should be adapted to the fiber mass to be drafted. Thus, the coarser the roving or the yarn, the wider the mouth opening should be. You can determine the most favourable setting by conducting preliminary trials.
Fig. 6 shows the drawing roller arrangement in a three-cylinder double apron drawing system.
Figure 6
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This is why Lenzing have determined the yarn twist range for Cotton and Lenzing Modal which optimises the machine performance and also the yarn tensile strength. The diagram 7 shows the upper and lower limits for the yarn twist which we recommend. The best tensile strengths are obtained with a α m 95 – 100. Beyond the recommended twist range the yarn tensile strength deteriorates increasingly and there is a higher tendency to yarn breaks. The spinning limit determined by the fiber titre and should not be allowed to fall below 70 fibers in a yarn cross section.
Figure 7
6.10 OE-Rotor Spinning Machine
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It is advisable to process only bright fibers by this method, because the deeply engrained dulling agent leads to heavy wear on the spinning organs of rotor machines.
6.11 Sliver pattern
The usual sliver count after 2 passages should be between 0,17 and 0,30 Nm. It is advantageous to have a finisher sliver from an auto-levelled drawing frame.
For coarse and medium counts it is possible to process with one drawing frame passage, provided the slivers are auto-levelled.
The condition of the rings and the travellers also has a major influence on the yarn quality and running properties. The travellers should have a low thread resistance and thus, ensure the maximum possible sparing. Worn-out rings lead to yarn damage. The speed of the ring travelers should not exceed 34 m/second. Selecting the best yarn twist is of decisive importance regarding both the spinning performance
6.12 Opening rollers
Cotton and Lenzing Modal fibers can be produced with cotton like types (OB20) or with synthetic like types (OS21) and the usual coating is a diamond and nickel (for instance DN). The speed of the opening roller should be in a range between 7500 to 9000 rpm (depends also on the diameter of the opening roller).
6.13 The rotor
When processing Cotton and Lenzing Modal fibers, different rotors are used depending on the desired yarn quality. Distinctions are drawn on the basis of the rotor diameter, the shape of the grooves, and the coating of the rotor.
Fig. 7 indicates the relation between fineness of fiber, fineness of yarn, rotor diameter and rotor speed.
Figure 7
Fineness of fiber 6.7 - 3.3 dtex 1.7 dtex 1.3 dtex 1.0 dtex
Rotor Ø in mm 56 and more 48/46/45/40/38 33/32/30 30 max.
Rotor rpm 60.000 60.000 - 80.000 90.000 - 120.000 110.000 - 120.000
Count range Nm 18 and coarser Nm 8 - 40 Nm 28 - 60 Nm 40 - 80
6.14 Take-off nozzles
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Most of the navels used today are made of sinter ceramic. Different type and shapes are available, depending on the desired yarn quality.
Indented nozzles (nozzle with notches) tend to produce rougher yarns, but these in turn have superior spinning stability. Indented nozzles have been found suitable at both low and high rotor speeds.
6.15 Yarn twist
For the processing of Lenzing Viscose it has been noted that an average α m of 90 – 120 is advantageous whereby the yarn mechanical properties are some 20 – 30 % inferior to those of ring yarns.
For Lenzing Modal fibers α m of 100 – 130 should be used.
6.16 Spinning limit
The spinning limit is dictated by the fineness of fiber. The yarn cross-section should show not less than 120 fibers. Fig. 8 shows the relation between fiber fineness and spinning limit.
Figure 8
6.17 Spooling and winding
Yarns of Cotton and Lenzing Modal fibers can be processed on all types of winders. In this context speeds of up to 1200 m/min are quite feasible. Whilst both viscose and Modal yarns have a low yarn-on-yarn coefficient of sliding friction, they have a high coefficient of sliding friction for yarn-to-reel. Because of this,
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there may be a slight loosening of the crossed yarn layers which may in turn lead to a damaging of the yarn in those critical zones i.e. around the edges.
In order to ensure trouble-free spooling and winding, therefore, the following points should be borne in mind:
1) Keep friction between the reel and the spool to a minimum. Adjust frame pressure to as low as possible so that a good knot zone is assured and no more.
2) Ribbon breaking in comparison to cotton spooling should be intensified.
3) Keep thread tension, thread speed and air-conditioning under control
6.18 Overall Procedure:
1) At first we have to select the Modal and cotton way of the fibre. Then we should select the mixing percentage of the fibre. Here it is 50% cotton and 50% modal / 45% cotton and 55% modal /60% cotton and 40% modal etc.
2) Now fibre will mixed with hand by. Mixing place is Blowroom in the spinning mill.
3) Then start the machine.
4) Then fibre following the mixing chamber.
5) This process is same to cotton process. Then mixed fibre is arrived in carding chamber.
6) Next stap is drawing then Roving and Ring fram.
7) Then produce 40 count, 38 count, 36 count, 34 count, 30 count, 28 count & 26 count yarn.
8) According to test CSP we will take the yarn
9) One end of the yarn is gripped in the fixed gripper of the m/c and the other end is gripped in the other setting the test length.
10) After that we will apply tension along the yarn length with Measuring machine by taking away the other end of yarn far from the first end.
11) As soon as the yarn is break by the tension.
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12) The strength of the yarn after applying tension is taking from the scale.
13) In this way at least 10 data for yarn is taken and average strength is calculated from them.
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STYLE – 01
Price distribution to 100% Cotton Fiber for 36, 40 count- Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 CSI 75% 64 tk 15% 55.20 tk 02 MCU5 25% 60 tk 15% 17.25 tk Total- 72.45 tk
For 100% cotton yarn –
CSP = 2500
IPI = 300
36, 40 Ne 50/50 MODAL/ Cotton Yarn Comparisons-
Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 Modal 50% 90 tk - 45.00 tk 02 CIS 30% 64 tk 15% 22.08 tk
Data Collection
Chapter 7
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03 MCU5 20% 60 tk 15% 13.80 tk Total - 80.88 tk
For 50/50 Modal & cotton yarn –
CSP = 2700
IPI = 160 STYLE – 02
Price distribution to Fiber for 30 count- Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 MCU5 80% 60 tk 13% 54.24 tk 02 Sankar-6 20% 58 tk 15% 13.34 tk Total- 67.58 tk
For 100% cotton yarn –
CSP = 2350
IPI = 374
30 Ne 50/50 MODAL /ELS Carded Cotton Yarn Comparisons-
Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 MCU5 50% 60 tk 13% 33.90 tk 02 Modal 50% 90 tk - 45.00 tk
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Total - 78.90 tk
For 50/50 Modal & cotton yarn –
CSP = 2670
IPI = 200 STYLE – 03
Price distribution to Fiber for 30, 34, 38 count- Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 CSI 1-1/8 55% 64 tk 14% 40.12 tk 02 Sankar-6 20% 57 tk 15% 13.11 tk 03 MCU5 25% 60 tk 15% 17.25 tk Total- 70.48 tk
For 100% cotton yarn –
CSP = 2300
IPI = 400
30, 34, 38 Ne 40/60 MODAL /ELS Carded Cotton Yarn Comparisons-
Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 CIS 1-1/8 40% 64 tk 14% 29.18 tk 02 Modal 40% 90 tk - 36.00 tk
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03 Sankar-6 10% 57 tk 15% 6.56 tk 04 MCU5 10% 60 tk 15% 6.90 tk Total - 78.64 tk
For 40/60 Modal & cotton yarn –
CSP = 2650
IPI = 250 STYLE – 04
Price distribution to Fiber for 28, 30 count- Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 CIS 50% 64 tk 15% 36.80 tk 02 Turkey 25% 58 tk 15% 16.68 tk 03 MCU5 25% 55 tk 17% 15.81 tk Total- 69.29 tk
For 100% cotton yarn –
CSP = 2400
IPI = 323
28, 30 Ne 50/50 MODAL /ELS Carded Cotton Yarn Comparisons-
Serial no Fibre Name Mixing Price / Wastage Costing /
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Quantity Pound Pound 01 CIS 30% 64 tk 15% 22.08 tk 02 Modal 50% 90 tk - 45.00 tk 03 Turkey 20% 58 tk 15% 13.34 tk Total - 80.42 tk
For 50/50 Modal & cotton yarn –
CSP = 2700
IPI = 190 STYLE – 05
Price distribution to Fiber for 26, 28 count- Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 CIS 55% 64 tk 15% 40.48 tk 02 Sankar-6 45% 57 tk 16% 29.75 tk Total- 70.23 tk
For 100% cotton yarn –
CSP = 2360
IPI = 530
26, 28 Ne 55/45 Modal /ELS Carded Cotton Yarn Comparisons-
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Serial no Fibre Name Mixing Quantity Price / Pound wastage Costing / Pound 01 CIS 45% 64 tk 15% 33.12 tk 02 Modal 55% 90 tk - 49.50 tk Total- 82.62 tk
For 55/45 Modal & cotton yarn –
CSP = 2690
IPI = 224 STYLE – 06
Price distribution to Fiber for 30 count- Serial no Fibre Name Mixing Quantity Price / Pound Wastage Costing / Pound 01 MCU5 100% 58 tk 15% 66.70 tk Total- 66.70 tk
For 100% cotton yarn –
CSP = 2200
IPI = 400
30 Ne 100% Modal Yarn Comparisons-
Serial no Fibre Name Mixing Quantity Price / Pound wastage Costing / Pound
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01 Modal 100% 90 tk - 90.00 tk Total- 90.00 tk
For 100% Modal fibre yarn –
CSP = 2950
IPI = 43
Here, CSP = Count Strength Product &
IPI = Imperfection Index (Hairiness, Neps, Thick place, Thin place).
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STYLE – 01
Here,
For 100% cotton yarn –
CSP = 2500
IPI = 300
For 50/50 Modal & cotton yarn –
CSP = 2700
IPI = 160
So, Increase CSP = ( 2700 – 2500 ) = 200 &
Reduced IPI = ( 300 – 160 ) = 140
STYLE – 02
Here,
For 100% cotton yarn –
CSP = 2350
IPI = 374
For 50/50 Modal & cotton yarn –
CSP = 2670
IPI = 200
So, Increase CSP = ( 2670 – 2350 ) = 320 &
Reduced IPI = ( 374 – 200 ) = 174
STYLE – 03
Here,
Calculation
Chapter 8
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For 100% cotton yarn –
CSP = 2300
IPI = 400
For 40/60 Modal & cotton yarn –
CSP = 2650
IPI = 250
So, Increase CSP = ( 2650 – 2300 ) = 350 &
Reduced IPI = ( 400 – 250 ) = 150
STYLE – 04
Here,
For 100% cotton yarn –
CSP = 2400
IPI = 323
For 50/50 Modal & cotton yarn –
CSP = 2700
IPI = 190
So, Increase CSP = ( 2700 – 2400 ) = 300 &
Reduced IPI = ( 323 – 190 ) = 133
STYLE – 05
Here,
For 100% cotton yarn –
CSP = 2360
IPI = 530
For 55/45 Modal & cotton yarn –
CSP = 2690
IPI = 224
So, Increase CSP = ( 2690 – 2360 ) = 338 &
Reduced IPI = ( 530 – 224 ) = 306
STYLE – 06
Here,
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For 100% cotton yarn –
CSP = 2200
IPI = 400
For 100% Modal yarn –
CSP = 2950
IPI = 43
So, Increase CSP = ( 2950 – 2200 ) = 750 &
Reduced IPI = ( 400 – 43 ) = 357 Following the total table data: Style Produce yarn count For 100% cotton CSP For Mixed Modal CSP Increase CSP For 100% cotton IPI For Mixed Modal IPI Reduce IPI 01 36s, 40s 2500 2700 200 300 160 140 02 30s 2350 2670 320 374 200 174 03 30s, 34s, 38s 2300 2650 350 400 250 150 04 28s, 30s 2450 2700 300 323 190 133 05 26s, 28s 2360 2690 338 530 224 306 06 30s 2200 2690 750 400 43 357 Average= 376.34 Average= 210
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Increase the yarn CSP
Reduce Yarn IPI
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Result: Average increase CSP for cotton & Modal mixed yarn = 376.34 And average decrease IPI for cotton & Modal mixed yarn = 210 So Modal fibre is better than Cotton fibre.
Result
Chapter 9
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Viscose fiber is used (5 -20%) in cotton yarns especially fine yarns to have better price as well as smooth appearance & shine to yarn, however basic viscose being weak fiber reduces the strength of final yarn and this becomes more problem in wet conditions as viscose loses more than 50% of its strength in wet condition. Lenzing site: largest integrated cellulose fiber production world-wide
Remark
Chapter 10
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11.1 Overview
1. BY our project work we get chance to introduce various types of materials, yarn properties (CSP & IPI ), different structure of different mills.
2. Our project work is a challenging job for us to do. Here we work in different favorable and adverse situation . But we have highly prepared for that . Our supervising teacher taught us how to face that situation .By this project work we learnt a lot of thing outside the curriculum study.
3. In our limited knowledge we tried our best and utilized the full facilities at our disposal to make the project work success .we did project work sincerely. After the work we analyzed collecting data discussed various terms and made reports.
4. We visited more mills in our project work we more fulfill. But this are a comparatively higher number that other department project works, for next year project work should be more no. of mills.
5. This project work has given us the chance to visit different mills and their head offices. We think that this knowledge will help us in every step of our life as a textile engineer.
6. Project work makes a student skillful to face the obstacles in different section of a dyeing mill.
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