Fiber Fineness Measurement By Projection Microscope

The projection microscope is the standard method for measuring wool fibre diameter, and all other methods have to be checked for accuracy against it. The method is also applicable to any other fibres with a circular cross-section. The method involves preparing a microscope slide of short lengths of fibre which is then viewed using a microscope that projects an image of the fibres onto a horizontal screen for ease of measurement. The apparatus is shown diagrammatically in Fig. Techniques are followed that avoid bias and ensure a truly random sample. 

Method of Test:A suitable random and representative sample is conditioned for 24 h in a standard testing atmosphere. Using a modified Hardy microtome the fibres are cut to a suitable length (0.4mm for fibres below 27 (im) and a slide is prepared by carefully mixing the fibres into the mountant. The use of short fibres gives a length-biased sample so that proportionally more of the longer fibres will have their diameter measured. The mounting agent should be non-swelling and have a suitable refractive index (for example liquid paraffin). The mixture of fibres and mountant is spread thinly on the slide and covered with a cover glass, carefully avoiding air bubbles and finger prints.

The projection microscope

The slide is placed on the stage, coverglass down (microscope inverted) and fibres are selected for measurement in the following way. The slide is traversed in a zigzag fashion, measuring every fibre that complies with the following requirements: 1 has more than half its length visible in the 7.5cm circle which is drawn in the centre of the field of view; 2 is not in contact with any other fibre at the point of measurement. The traverse of the slide is continued until the required number of fibres has been measured. The magnification of the microscope is adjusted to be 50Ox so that on the scale used to measure the fibres each millimetre represents 2 um.

For accurate tests three slides should be measured from randomly selected areas of the material and not less than 150 fibres per slide should be measured. The coefficient of variation of diameter for unblended wool lies between 20% and 28%. From this value the number of tests to give certain confidence limits has been calculated . 

  

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Posted in: Weaving

What Is Micronair Value Relationships Between Micronaire, Fineness, And Maturity

Micronaire is one of the two most important fiber characteristics for international cotton classers and spinners. Micronaire is an indicator of air permeability. It is regarded as an indication of both fineness (linear density) and maturity (degree of cell-wall development). For a given type of cotton, a relatively low micronaire has been used as a predictor of problems in processing, but a low micronaire may also indicate fine fibers with adequate maturity. Similarly, growers may be discounted for high micronaire when, in fact, the fibers have adequate fineness and good maturity, because high micronaire fibers are normally coarse, which is undesirable from the point of view of spinning and yarn evenness.

Fineness is generally expressed as gravimetric fineness or linear density (wall area times a constant), and maturity is generally expressed as maturity ratio (wall area divided by perimeter squared). One of the first practical tools to measure fineness and maturity was the determination of linear density and maturity ratio on the Shirley Developments Limited Fineness and Maturity Tester (FMT).

Although linear density, maturity ratio, and micronaire are useful to spinners, all three properties can be viewed for any given cotton in terms of wall thickness and perimeter. Wall area is a function of wall thickness and perimeter . Wall thickness and perimeter are fundamental cross-sectional characteristics of the fiber with respect to wall area, because the function cannot be decomposed further into other geometric measures. If one examines the fiber crosssection, the wall thickness is not constant but varies around the fiber, so that points must be sampled to get an averaged value. As a consequence, an averaged wall thickness and perimeter are fundamental with respect to an averaged wall area. Exploring the relationships on a fundamental level can be beneficial by demonstrating how a unique wall thickness and perimeter value together give an equivalent micronaire- fineness-maturity combination.

Cottons with a much greater genetic diversity are being developed, and a greater range of both fiber perimeter and wall thickness, and their combinations, is probable. Consequently, the relationships between micronaire, fineness, and maturity are being modified . This is because the original set of U.S. cottons that were used to calibrate the micronaire instrument had perimeters with a smaller range compared to current cultivars. The original relationships apply best to those cottons having perimeters similar to the calibration samples. For other cottons, these relationships do not apply as well, which results in modified expressions. 

Even though micronaire is of great practical value for trade and industry, a literature review indicated no theoretical or experimental studies have been reported that model the three fiber characteristics in terms of the fundamental measures of thickness and perimeter. The specific objectives of this research were to use fineness and maturity components – wall thickness and perimeter to develop models for fineness, maturity, and micronaire; to simulate the interaction of fineness and maturity and the resultant micronaire; to quantify the relative sensitivity of the models to changes in thickness and perimeter; and to demonstrate variability in the coefficients of determination between micronaire and the other variables. 

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Posted in: Weaving

Calculation of Draft Constant

Name of the experiment: 

                                           Calculation of draft, draft constant and draft in each zone of the ring frame.

Objects: 1) To find out draft, draft constant of the ring frame.
2) To find out draft of each zone of the ring frame.

M/C specifications: 

• RPM of the motor =1440
• Dia of the motor pulley = 5”
• Dia of the tin cylinder pulley = 10.5”
• Dia of the tin cylinder = 10”
• Dia of the wharve = 1.125”
• No of teeth of fibre wheel = 42T
• No of teeth of front roller driving wheel = 98T
• Dia of the front roller = 1”

Gearing diagram:

Figure :- Gearing Diagram of Drafting Zone of Speed Frame Machine 

Calculation of draft, draft constant and draft of each zone of the ring frame: 

 

Conclusion: Ring frame is the final and very important machine for build the yarn onto bobbin in a form suitable for storage, transportation and processing. It is used to twist the drafted strand to form yarn of required count and strength.

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Posted in: Spinning

Defects In Blow Room Causes For Defects

Blow room is the first steps in spinning. Opening, cleaning, blending or mixing is done here. As a result different defects occur in different operation. Major defects or faults in blow room are mentioned below:

Defects in Blow Room:

1. Uneven lap
2. Irregular lap
3. Soft lap
4. Conical lap
5. Barrel shaped lap
6. Licking lap
7. Defective selvedge
8. Split lap
9. Dirty lap

Causes for Defects in Blow Room:
Important causes for defects in blow room are given below: 

Causes for Nep formation in Blow room:

• Cotton with too high or low moisture.
• Extremely fine cottons with high trash content.
• Reprocessing of laps and mixing of soft waste.
• Rough or blunt blades and bent pins on beaters.
• Narrow settings between the feed roller or pedal and beater.
• Long curved and U-bends in conveyor pipe lines.  
• Inappropriate ratio of fan to beater speed.
• Wider setting between stripping rail and beater blade. 

Causes for Curly Cotton: 

• Grid bars setting too close to beater.
• Hooked or bent pins on kirschner beater.
• Too wide a setting of stripping rail.
• Long and bent conveyor ducts with low fan speed.  

Causes for lap Licking : 

• Use of too much soft waste in mixing
• Too high fan speed, excessive beating.
• Cotton is damp or departmental humidity is high.
• Sticky nature of material

Causes for Conical Lap:

• Improper functioning of pedals on one side due to pedals being choked with dirt.
• Air entering at one side from under the grid bar of beater.
• Defective beater blade at one side.
• Uneven suction at the cages leaving to deposition of more material on one side than another.
• Lap roller racks, calander roller not exerting even pressure across the lap width. *Cages may not be properly levelled.

Causes for Soft Lap:

• Calender pressure inadequate due to wear and tear of weighting mechanism. 

Preventive Action or Remedies of Faults in Blow Room:

Preventive Action for Neps Formation:

For avoiding neps formation it is necessary to select the cotton according to moisture content in the cotton. In both cases if moisture content is less or more, our process will become critical.

As quality of our end product depends upon raw material. If cotton having more trash content then it is necessary to increase beating point. And this beating will directly affect our neps formation and neps formation will be more.

Cotton mixing supervisor should take action that during mixing soft waste and process lap not to be mix with fresh mixing. This step is necessary to avoid neps formation. As neps formation affect the quality of our yarn.

Preventive Action for Curly Cotton:
For getting good quality product it is necessary to keep trained staff for maintenance point of view. There is a need of technical person who have full grip on their work. They should check the setting of machine and to keep machine update to avoid the problems. Machine setting must not be wide not so close to avoid curly cotton problem.

Preventive Action for Lap Licking:
In order to prevent from lap licking it is necessary not to mix soft waste during mixing process. Avoid sticky nature cotton as in case sticky nature cotton then as a preventive action inside temperature of department is to be controlled. In this case low relative humidity and high temperature is needed.

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Posted in: Spinning

Problems Causes And Way of Remedies

Blow Room:

Blow room is the initial stage in spinning process. The name blow room is given because of the “air flow” And all process is done in blow room because of air flow. Blow room is consisting of different machines to carry out the objectives of blow room. In blow room the tuft size of cotton becomes smaller and smaller. In a word we can say, a section in which the supplied compressed bales are opened, cleaned & blending or mixing to form uniform lap of specific length is called Blow room section. During the opening, cleaning, blending or mixing different faults or defects occur in blow room. Now I will discuss about faults/defects, causes and way to remedies in blow room section.

Blow room

Problems/Faults/Defects in Blow Room:

1. Low cleaning efficiency
2. High nep generation and fibre rupture
3. High variability in the delivered hank
4. Formation of cat’s tail
5. Conical lap
6. Lap licking
7. Patchy lap
8. Holes in lap
9. Soft laps
10. Ragged lap selvedge

Causes and Remedies are discussed below: Low cleaning efficiency:

Lower extraction of wastes than required for that mixing considering the trash content is one of the main reasons for low cleaning efficiency. Increase the wastes if the lint in the wastes is normal or nil. If the beater speeds are lesser than required, we get lower cleaning. Check the beater settings and correct them if needed. Increase the space between the grid bars. Close slightly the air-inlets under the grid bars towards the cotton entry side, and open those on the delivery side. Reduce the fan speed following the beaters by 100 to 200 RPM. If the grip of the feed roller is less, we shall get low cleaning efficiency. Therefore check for the grip. Also check the sharpness of the beaters. Check the synchronisation of the machine working. The blending bale openers should work for 80 to 85% of the time of working of the final machine. If there is a back draught because of not cleaning the wastes under the machines, the cleaning efficiency shall come down.

High nep generation and fibre rupture:

The main reasons are blunt beaters, burrs in grid bars, bent pins on beaters, higher beater speed, lower fan speed and excessive feed. A higher beater speed shall give more neps, if the material is not moved out of the beating area effectively. If materials return back to beaters, neps shall generate, hence check the setting of leather flaps, stripper knife etc. Excessive of soft wastes fed, and cottons with more immature fibres are major reasons for neps in opened material. Therefore have a control on the issue of soft wastes to mixing and spread them uniformly throughout the mixing.

High variability in the delivered hank:

Improper levels in the hoppers, improper action of feed regulators viz, cone drums, pedals, photocells, direct driving gear motors, etc are the normal reasons for variability in delivered hanks.

Formation of cat’s tail:

If material movement is less and cottons are over beaten, we get this defect. By sharpening beater edges, increasing fan speeds, increasing the air in-let below the grid bar area of cotton entry, closing the striping knife and beater setting shall avoid cat’s tail. The very important step in avoiding cat’s tail is to avoid chocking of materials in beaters. Excessive use of cotton-spray oil, water etc., also causes cat’s tails.

Conical lap:

Conical laps are due to, either higher quantity of cottons coming on one side of the lap, or due to unequal calendar and rack pressures in scutchers. Ensure equal opening of air-inlets under grid bars, replace torn leather lining at the cage, clean the cage thoroughly with emery paper, make pressure on lap spindle uniform on both the sides, remove the pedals and clean thoroughly, and check the pedals where it rests on fulcrum and also pedal fulcrum bar.

Lap licking:

Lap licking can be due to excessive addition of soft wastes in mixing, higher rack pressures, lower compacting of laps and excessive dampness in cotton. In case of polyesters, this problem shall be mainly due to static charges and higher bulk of fibres. The problem of lap licking can be reduced by increasing the pressure on calendar rollers, reducing the pressure on racks, increasing the quantity of antistatic, use of roving ends or lap fingers behind the calendar roller nip, blocking of top cage and by reducing the lap length.

Patchy lap:

Patchy lap is a result of unopened tufts. Ensure that the mixing is opened thoroughly, and increase opening points if feasible. Check tuft size at the delivery of each beater, and adjust the setting between feed roller and beaters, reduce the gauge between evener roller and inclined lattice, clean the cages, and increase effective suction at cages.

Holes in lap:

Holes in the lap can be due to different reasons. Check the cages for damage, and reduce tension draft.

Soft lap:

Lower calendar pressure makes the laps soft. Increase the calendar roller pressure.

Ragged lap selvedge:

Ragged lap selvedges are mainly due to uneven spots at the edges. Check for the rough spots on the sides of the feed plates, leather linings for the cages, and keep the edges of the scutcher clean.

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Posted in: Spinning

Physical Properties of Nylon

Nylon:

Nylon was the first synthetic fibre to go into full-scale production and the only one to do so prior to World War II. Nylon fibres are made up of linear macromolecules whose structural units are linked by the –NH–CO– group. Nylon is one of the most commonly used polymers.

Nylon fiber

Nylon polymers can be formed in many ways. The four most important for industrial polymers are:

1. The condensation of diamines with diacids;
2. The self-condensation of amino acids;
3. The hydrolytic polymerisation of lactams, which involves partial hydrolysis of the lactam to an amino acid; and
4. The anhydrous addition polymerisation of lactams.

Characteristics of Nylon Fiber :

1. Expetionally strong
2. Elastic.
3. Abration resistance
4. Luster
5. Easy to wash
6. Dyed in wide range of colour
7. Low in moisture absorbancy
8. Filamert yarn provides smooth, soft, long fabric
9. Spun yarn fabric give light weight and warmth
10. Resilient
11. Resistance to damage oil and many ressitance ( acid & alkali)

Physical Properties of Nylon 6 & Nylon 6,6: 1. Melting point : 

• Nylon6 : 215-218c
• Nylon 6,6: 250c

2. Sticking point : 

• Nylon 6: 217c
• Nylon 6,6 : 229c

3. Heat setting : 

• Nylon6: 205c
• Nylon 6,6: 150c

4. Safe ironing temp. : 

• Nylon 6 : 149c
• Nylon 6,6 :190c

5. Action of water : 
In standerd condiation Nylon 65% RH in 25c+2 temarature.

6. Action of light: 
Light wave length is 300-700mm of the nylon fibre.

7. Action of Acid: 
In conc. H2SO4 nylon6 & nylon66 is unstable and dilute is unstable.

8. Action of alkali: 
In alkali highly resistance 10% NaOH in 85% at 10 hr treatment. 

 
Comparison between Nylon 6 & Nylon 6,6:

Topics	Nylon 6	Nylon 6,6
1. Chemical composition
2. Crystallinity	less crystalline than nylon66	More crystalline than nylon 6
3. Melting point	215c	250c
4. Tg	40	47-57
5. Molecular mobility	high	low
6. Colour fastness	high	low
7. Stain cleanability	low	high
8. Temprature resistance	lower	higher
9. Regilience	low	high
10. Moisture regain	4.5	4-4.5

   

Different between Nylon 6 & Nylon 6,6: 
Nylon 6 is made from one component namely Caprolactum, which has six carbon atom , while Nylon 66 is made from two component s namely adipic acid and hexamethylene diamine each monomer has six carbon atoms.

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Posted in: Weaving

Chlorofibre Properties Characteristics

Chlorofibre:

Any synthetic fiber made from the polymerization of a chlorinated monomer (especially from forms of polyvinyl chloride) is Called chlorofiber. Chlorofibres are made from PVC which is derived from salt and petrochemicals. The term refers to all textile fibers from PVC. They do not support combustion and emit no droplets during combustion but emit toxic gases (HCl and CO) when burnt. They dry quickly, is waterproof, crease-resistant and have a high coefficient of thermal insulation, electric and acoustic. Commercialized in 1949 by the Society Rhovyl, they are mainly used in the manufacture of clothing or linen. Chlorofibres are flammable and emit no droplets during combustion but emit toxic gases. They dry quickly, waterproof, crease-resistant and have a highco-efficient of thermal, electric and acoustic. Chlorofibre came to be noticed because of its special properties. With high performance products and fibre of innovative characteristics, it becamean established material. Rhovyl is the leading manufacturer of synthetic PVC based fibres.

Product of Chlorofiber

Poly (vinyl chloride) fibre used for textiles is manufactured from acetylene and hydrogen chloride which is dissolved in mixtures of carbon disulphide and acetone for dry-spinning of normal vinyl chloride (PVC) homopolymer. The fibers are co-polymer of vinylchloride / vinyledine chloride and vinyl cyanide or vinyl acetate. 

The fiber is stretched to varying degrees as it leaves the spinning jet to give different types of filaments. The repeat units of some of the chlorofibres are shown in Fig.A The water absorption of these fibres are extremely low, softening temperature is low with considerable shrinkage at 70~ and have poor dyeability at moderate temperatures. These fibres are mainly used in filter cloths, flying suits (in which their property of non-flammability is an asset), curtains (owing to their resistance to degradation of light) and fishing nets (owing to their resistance to water). These fibres have regular round, dogbone or dumbell shaped cross-section and transparent, even and smooth. They are highly lustrous and silky in hand.

Figure.A. Repeat units of some chlorofibres.

Properties/Characteristics of Chlorofibre: 
Like polyester, Chlorofibre is a synthetic polymer that is spun and turns into yarns and weaved to become fabric. Chlorofibre is a soft, dry and comfortable fabric. Chlorofibre fabrics are non-absorbent which is why it is easy to keep dry. Its construction gives the fabric a wicking effect, channeling perspiration from the skin and expelled through the fabric. This helps to keep the skin dry and increase level of comfort. The fabricis soft and has an excellent isothermic property, keeping away cold air and acting as an insulator.It also has the highest thermal efficiency of any fibre(natural or manmade) and, being totally non-absorbent, is easy to launder and does not retain dour. To make garments even more comfortable, itis recommended to brush the inner surface of the fabric to give a warm furry finish and use flat-locked seams to ensure comfort when carrying a ruck sack, golf clubs or fishing bag. Chlorofibre is likely to be PVC of low degree of polymerization, which accounts for its softness without the need for plasticizer. Like most synthetic polymers, it is likely to be protected against oxidative degradation with antioxidant. Another redeeming quality for Chlorofibre is that the fabric is surprisinglysoft and comfortable. As a good insulator, it has the property of keeping out the cold, which has traditionally relied on air (and perspiration) trapped in the air pockets of wool and other thick fabrics. 

Applications of Chloro Fiber: 
Hosiery: Technique and comfort are the key words for Chlorofibre used in hosiery. These characteristics blend happily with other fibres to respond most accurately to the requirements of the end-users. 

Casual Outerwear: Chlorofibre casual outerwear line gives the ability to really take pleasure in looking casual while also giving human body the added health benefits, like, the rapid moisture permeability and added warmth that these garments have to offer and feel protected all day long. 

Kids wear: Chlorofibre provides the excellent range of kids ‘garments to assist their bodies to breathe easier and fight those seasonal allergy attacks by surrounding them with a healthy an ionic atmosphere. 

Undergarments: Warmth, softness and comfort are among the qualities that make Chlorofibre such an essential part of the world of underclothes. Chlorofibre undergarments deliver premium health benefits protecting against harsh environments every day. They are light weight and breathable to keep person dry and comfortable in the areas where they need it the most. 

Sportswear: Comfort and performance are among the qualities that make Chlorofibre so essential to the sports world. It offers a range of products that meet the requirementsof sportsmen for technical clothes that arecomfortable, warm and breathable. 

Socks: Socks made out of this fibre are the perfect socks foractive wear, business wear, or even stay-at-home-wear. The negative ion technology repels moisture, protectingagainst infection, foot odour, and forming bacteria. 

Advantages of Chlorofibre:

• Thermal insulation
• Wicking of moisture
• Flame retardancy
• Resistance to mildew and fungi
• Resistance to acids, bases, reducing and oxidizing agent

Health Benefits Chlorofibre:

• Purify the blood, regulate its PH balance, and stimulate circulation
• Rejuvenate cells, stimulate cell metabolism
• Strengthen the immune system
• Regulate autonomic nerves

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Posted in: Weaving