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TM values for various staples:
If the staple length of fibre is 7/8” than TM value would be 4.75 and if staple length increases by 1/16” than TM value goes down by 0.1.
|M/c and its production capacity in terms of speed|
1. Blow room
3. Draw frame
4. Lap former and super lap former
Delivery speed-50-70 mpm
Feed per nip- 3.5 to 7mm
6. Speed frame
7. Ring frame
|TM values for speed frame|
8. Winding machine specification
Delivery rate 1000-2000 mpm
No. Of spindle- 60
9. Rotor specification
Rotor rpm 80000-100000 rpm
By : Noopur Shalini
THE HISTORY OF DENIMS
A popular conception of the etymology of the word denim is that it is a contraction or derivative of the French term, serge de Nmes. Denim was traditionally colored blue with indigo dye to make blue “jeans,” though “jean” then denoted a different, lighter cotton textile; the contemporary use of jean comes from the French word for Genoa, Italy (Gnes), from which the first denim trousers were made.
A similarly woven traditional American cotton textile is the diagonal warp-striped hickory cloth that was once associated with railroad mens overalls, in which blue or black contrasting with undyed white threads form the woven pattern. Hickory cloth was characterized as being as rugged as hickory woodnot to mention the fact that it was deemed to be worn mainly by “hicks”although neither may be the origin of that term [from a nickname for “Richard”]. Records of a group of New Yorkers headed for the California gold fields in 1849 show that they took along four “hickory shirts” apiece. Hickory cloth would later furnish the material for some “fatigue” pantaloons and shirts in the American Civil War.
Denim is a rugged cotton twill textile, in which the weft passes under two (twi- “double”) or more warp fibers, producing the familiar diagonal ribbing identifiable on the reverse of the fabric.
Denim washing is the aesthetic finish given to the denim fabric to enhance the appeal and to provide strength.
Dry denim, as opposed to washed denim, is a denim fabric that is not washed after being dyed during its production.
Much of the appeal of dry denim lies in the fact that with time the fabric will fade in a manner similar to that which artificially distressed denim attempts to replicate. With dry denim, however, such fading is affected by the body of the person who wears the jeans and the activities of their daily life. This creates what many feel to be a more natural, unique look than pre-distressed denim.
DENIM WASHES ARE OF TWO TYPES:
- Stone wash
2. Chemical washes
- Denim bleaching
- Enzyme wash
- Acid wash
In this process a strong oxidative bleaching agent such as sodium hypochlorite or KMnO4 is added during the washing with or without stone addition.
Discoloration produced is usually more apparent depending on strength of the bleach liquor quantity, temperature and treatment time.
It is preferable to have strong bleach with short treatment time.
Care should be taken for the bleached goods so that they should be adequately antichlored or after washed with peroxide to minimize yellowing. Materials should be carefully sorted before processing for color uniformity.
– Process is difficult to control i.e. difficult to reach the same level of bleaching in repeated runs.
- When desired level of bleaching reached the time span available to stop the bleaching is very narrow. Due to harshness of chemical, it may cause damage to cellulose resulting in severe strength losses and/or breaks or pinholes at the seam, pocket, etc.
- Harmful to human health and causes corrosion to stainless steel.
- Required antichlor treatment.
Problem of yellowing is very frequent due to residual chlorine.
Chlorinated organic substances occur as abundant products in bleaching, and pass into the effluent where they cause severe environmental pollution.
It is environmentally friendly wash. It involves the Application of organic enzymes that eat away at the fabric, i.e. the cellulose.
When the desired color is achieved, the enzymes can be stopped by changing the alkalinity of the bath or its temperature. Post treatment includes final rinsing and softening cycle. The effects produced by the cellulose enzyme are—
- Use of cellulase making the seams, hems, and pockets more noticeable
- Salt pepper effect is color contrast effect.
- Faded garment with acid cellulase enzyme provides less color contrast in proportion to garment washed with neutral cellulase enzymes.
Garment load size of the machine is 35-40 jeans per machine and it cannot be overloaded.
It is done by tumbling the garments with pumice stones presoaked in a solution of sodium hypochlorite or potassium permanganate for localized bleaching resulting in a non uniform sharp blue/white contrast.
In this wash the color contrast of the denim fabric can be enhanced by optical brightening. The advantage of this process is that it saves water as addition of water is not required.
Limitations of acid wash:
– Acid washed, indigo dyed denim has a tendency to yellow after wet processing.
– The major cause is residual manganese due to incomplete neutralization, washing or rinsing.
- Manganese is effectively removed during laundering with addition of ethelene-diamine-tetra-acetic acid as chelating agent.
- Acid washing jeans avoided some of problems of stone wash, but came with added dangers, expenses, and pollution.
In the process of stone washing, freshly dyed jeans are loaded into large washing machines and tumbled with pumice stones to achieve a soft hand and desirable look.
Variations in composition, hardness, size shape and porosity make these stones multifunctional. The process is quite expensive and requires high capital investment.
Pumice stones give the additional effect of a faded or worn look as it abrades the surface of the jeans like sandpaper, removing some dye particles from the surfaces of the yarn.
Selection of stone
Stone should be selected of the proper hardness, shape, and size for the particular end product. It should be noted that large, hard stones last longer and may be suited for heavy weight fabrics only.
Smaller, softer stones would be used for light weight fabrics and more delicate items.
Stone wt. /fabric wt. = 0.5 to 3 /1
It depends on the degree of abrasion needed to achieve the desired result. Stones can be reused until they completely disintegrate or washed down the drain.
Problems caused by stones:
- Damage to wash machineries and garment due to stone to machine and machine to stone abrasion
- Increase in labor to remove dust from finished garments.
- Water pollution during disposal of used liquor.
- Back staining and re deposition.
Back staining or Re-deposition:
The dye removed from denim material after the treatment with cellulose or by a conventional washing process may cause “back staining or “redeposition. Re-coloration of blue threads and blue coloration of white threads, resulting in less contrast between blue and white threads.
Remedy of back staining —
- Adding dispersion/suspension agent to wash cycle.
- Intermediate replacement of wash liquor.
- Using alkaline detergent like sodium per borate with optical brightener as after wash.
Limitations of stone washing:
- Quality of the abrasion process is difficult to control Outcome of a load of jeans is never uniform, little percentage always getting ruined by too much abrasion.
- The process is non-selective.
- Metal buttons and rivets on the jeans in the washing machines get abraded.
- This reduces quality of the products and life of equipment, and increases production costs.
- Stones may turn into powder during the process of making the garment grayish in color and rough too
- Provides rougher feel than enzyme wash
- Stone may lead the harm to the machine parts
There are 3 ways for this technique:
- Machine sanding
- Hand sanding or hand brushing
Used in various ways:
- Flat surfaces (tables, ironing boards)
- On the dummy (inflatable dummies, sometimes standing, sometimes flat, sometimes ‘seated’)
- Various templates can be used to create a 3D effect.
Sand blasting technique is based on blasting an abrasive material in granular, powdered or other form through a nozzle at very high speed and pressure onto specific areas of the garment surface to be treated to give the desired distressed/ abraded/used look.
- It is purely mechanical process, not using any chemicals.
- It is a water free process therefore no drying required.
- Variety of distressed or abraded looks possible.
- Any number of designs could be created by special techniques.
- Also known as Cat’s Whiskers
- Crease lines around the crotch.
- Industrially done with laser, sandblasting, machine sanding, hand sanding and abrasive rods.
- Also used for ‘knee whiskers’ (whiskers on the sides of knees) and ‘honeycombs’ (crease marks on the back of the knee)
Other chemical washes:
- Rinse wash
- Cellulase wash
- Ozone fading
- Snow wash
- Salt water denim
- Flat finish
- Over dye
- Sun washing
- Super dark stone
– Chemically bleaching jeans so that the color fades away
- Breaks down the fibers of jeans and creates white streaks or spots on denim
- Gives a unique rugged look, also called snow wash
- Earlier involved the use of pumice stone
- Presently process involves spraying chemical and removing it immediately
- Come in colors like blue, black, green, brown, grey etc.
- This is done to achieve a wash down appearance without the use of stones or with reduced quantities of stones.
- Cellulase enzymes are selective only to the cellulose and will not degrade starch.
- Under certain conditions, their ability to react with cellulose (cotton) will result in surface fiber removal (weight loss).
- This will give the garments a washed appearance and soft hand.
Factors influencing cellulase performance
- Mechanical action
- By using this technique, the garment can be bleached.
- Bleaching of denim garment is done in washing machine with ozone dissolved in water.
- Denim garments can also be bleached or faded by using ozone gas in closed chamber.
- In the presence of UV light, there is an interaction between the hydrocarbons, oxides of nitrogen and oxygen that causes release of ozone.
- Indigo dyestuff tends to fade or turn yellow due to ozone reaction.
The advantages associated with this process are:
- Color removal is possible without losing strength.
- This method is very simple and environmentally friendly because after laundering, ozonized water can easily be deozonized by UV radiation.
It is a special process done to impart fabric with an even wash down effect and very clean surface. Originally liquid ammonia was used, but now use mercerization plus calendering processes to achieve the flat surface.
Mercerization swells up the cotton fibers and allows the calendering to press flat the surface.
They consider this as an imitation process to the use of ammonia, which is toxic and not allowed in commercial use in most countries
- Dyeing over the fabric or jeans to add another tone of color
- Most often used is a ‘yellowy’ overdye to create a ‘dirty’ look
- Also can be applied with spray gun or paintbrush for local coloring
- A very light shade by bleaching and stoning
- Looks as if the sun faded the fabric
SUPER DARK STONE
- Commercial term for an extra dark indigo color
- Results from a double-dyeing technique
SNOW WASH DENIM
Denim treated with a variation of acid wash that imparts bright white highlights.
QUICK WASH DENIM
- Aims at minimizing wash cycle time
- Results in more economical washes and solving many other washing problems faced by launderes during fashion wash cycles
- The yarns are ring dyed using indigo giving 25 to 30% less fixed dye to obtain a given shade
- During wash cycle,indigo dye can be removed quickly,giving washed look
1. Streaks develop in garments after washing process due to differences in dye concentration of denim fabrics are avoided using a modified alkali-ph controlled system giving uniformity of shade.
2. Amount of indigo dye required is less thus making it an economical process
3. Time required for washing is 20-30% less than that required for conventional denim.
4. Lesser enzymes and oxidising agent used
5. Environment friendly process
6. Back staining is minimised due to less concentration of of indigo dye in the wash liqour.
Other Mechanical washing
- Shot gun denim
- Water jet fading
- Super stone wash
- Ice wash
- Thermo denim
- Laser technology finish
- Hydrojet treatment is used for enhancing the surface finish, texture, durability of denim garment.
- Hydroject treatment involves exposing one or both surfaces of the garment through hydrojet nozzles.
- The degree of colour washout, clarity of patterns, and softness of the resulting fabric are related to the type of dye in the fabric and the amount and manner of fluid impact energy applied to the fabric.
- As this process is not involved with any chemical, it is pollution free.
- It is a computer controlled process for denim fading.
- This technique enables patterns to be created such as lines and/or dots, images, text or even pictures.
- It is water free fading of denim.
- Being an automatic system, chances of human error are slim.
- Also called spray painting in denims.
- This technique has relatively high cost.
- Prolonged stonewashing, up to six hours or more.
- Ice washing in denim fabrics is done to remove more than half the dye during washing
- Also called double denim. A lightweight fabric (either plain, fancy or colored) is glued to the denim. The glue comes off after washing and the trousers look like they’ve been lined
- Applies heavy stonewashing or a cellulose enzyme wash, with or without bleach
- Gives an old and worn look
CHEMICALS ON DENIMS
1. Bleach fast Indigo
- Value addition to denim
- Retains indigo on certain parts
- Kind of resist effect
- Chemical applied by brush, cured at 150C
- Ex. Indigofix AXN
2. Anti-depositing agent
- Prevents back staining of fabric by loose indigo during washing
- Improves contrast in denim
- Used in stone wash step
3. Dye stuffs with softener
- – To carry dyeing and softening in one step
- – Soft and supple hand
- – Saves time, money and energy as added to final rinse
- – Gives used and worn out effect
4. Anti creasing agent
- Provides fabric to fabric lubrication
- Prevents formation of crack marks and streaks
- Minimizes abrasion and gives strength
5. Wrinkle formation
- Creating smooth and permanent wrinkle
- Cross linking concept
- Ex. DMDHEU
- White pigment
- Can be applied by brush, spray or screen
- Then cured at 150C
- Washed and treated with softener
6. White pigment
- Can be applied by brush, spray or screen
- Then cured at 150C
- Washed and treated with softener
Denim is unique in its singular connection with one colour. The warp yarn is traditionally dyed with the blue pigment obtained from indigo dye. Until the introduction of synthetic dyes, at the end of the 19th century, indigo was the most significant natural dye known to mankind, linked with practical fabrics and work clothing. The durability of indigo as a color and it’s darkness of tone made it a good choice, when frequent washing was not possible.
The old mass market has segmented, fragmented, shattered into a multitude of mini, micro and niche markets. The last generation has a vast quantity of brands to choose from, a different perception of the cult value of owning small insider labels and a fanatical loyalty only to what’s hot on a daily basis.
Freed of all social and creative restrictions, denim is assuming any number of disguises and contexts to be worn in and has broken through almost any limitation on price. It can also be found in home collections, appearing in cushions, bed spreads and furniture-coverings.
Knitting is fabric-or garment-making by forming a series of interlocking loops in a continuous yarn or a set of yarns. In production situations, the work is carried out through the movement of hooked needles. (Hand knitting is normally performed with straight needles.) Each row of loops is vertically interlocked with the preceding row. With a sufficient number of loops, the yarn becomes a fabric. Knitted fabrics have the advantage of stretchability, a property not possessed by woven fabrics. Stretching can be in any direction even if the yarn used has little elasticity. Fig. 10D illustrates two types of knitted fabric. Mechanized production knitting utilizes a series of needles commonly operated by cams.
Figure 1A: Two examples of knit fabrics made by interlocking continuous strands of yarn—a) a plain knit made on a weft or filler knitting machine. The path of each crosswise yarn is called a course. b) a single-warp tricot knit.
somewhat more common. In weft knitting, the courses (crosswise rows of loops) are composed of continuous yarns. Weft knitting can be done by hand or machine but production weft knitting is a machine operation. The individual yarn is fed to one or more needles at a time. In warp knitting, the wales (predominantly vertical columns of loops) are continuous.3 Separate yarns are fed to each needle. The warp knitting operation is always produced by machine.
Knitted fabrics can be either flat or tubular in form. Warp knits are usually flat; weft or filling knits are most often tubular.
1 Two types of hooked needles are used in production knitting machines, the bearded or spring needle and the latch needle. They are illustrated in Fig. 1B. With both designs, the needles draw new loops through the previous loops that they have retained. Once the needle head and new loop have gone through the old loop, the old loop is cast off. The latch needle is most often used. It operates more automatically than the bearded needle which requires other machine elements to present the loop and close the hook. Fig. 1A illustrates stitch formation with a latched needle in a circular machine.
Figure 1B Production knitting needles. a) the bearded spring needle used for fine knitted fabrics and b) the more common latch needle.
Figure 1C: Stitch formation in weft knitting with latch needles in a circular machine. (from Knitting Technology by David J. Spencer. Reprinted by permission of Elsevier Science.)
Weft or Filling Knitting
Can be produced on either flat or circular knitting machines. In weft knitting, one continuous yarn runs crosswise in the fabric and makes up all the loops in one course. The needles either act in succession or the yarn is fed in succession, so that loop formation and interlocking is not simultaneous. Fig. 1C, view (a), illustrates a basic weft knit jersey cloth. Fig. 1C illustrates weft knitting with latch needles and shows that the multiple, evenly-spaced, needles have hooks with latches at the end. The needles are moved upward or downward by cams. As each needle rises, the needle hook loops over the yarn which it hooks on the down stroke, and the yarn is held in place by the needle latch. At the bottom of the needle stroke, a previous loop slips off the needle, and the new loop is held in place with the latch. On the next cycle,the loop is released from the latch as the needle rises, another loop is formed and the process is repeated.3 Fig. 1D shows six stages of weft knitting with bearded needles.
Figure D: Six stages of stitch formation in weft knitting with bearded needles. In this example, all stitches in one row are formed at the same time. (from Knitting Technology by David J. Spencer. Reprinted by permission of Elsevier Science.)
Figure E: Warp knitting with bearded needles. Loop forming is performed simultaneously with separate yarns fed through warp guides.
Several different stitches can be formed in weft knitting. In the knit stitch, the loop is drawn from the back and passed through the front of the preceding loop to the front of the cloth. In the purl stitch, the loop is drawn from the front through the back of the preceding loop to the back of the cloth. In the miss stitch, no loop is formed. In the tuck stitch, two courses on one wale are looped over a third. The stitches, and various combinations of them, make all the patterns of knit and double knit cloth. Distinct patterns can be made from combinations of the knit and purl stitches since the knit tends to advance and the purl to recede.1 Double knits are made by machine only, using two yarns and two sets of needles. These knits use a variation of the rib and interlock stitches, drawing loops from both directions.1 Jersey is a common knitted
cloth, made from only knit or only purl stitches.
Circular weft knitting machines are used to make hosiery, underwear and simulated furs. They can knit shaped garments. Jacquard effects are possible, and are now generally controlled electronically. Flat knitting machines can also produce shapes by increasing or decreasing loops. Full-fashioned garments can be made on flat knitting machines.
The previous loop to slip off the hook while a new loop is held.3 If bearded needles are used, a yarn guide, called a sinker, positions the yarn across ascending needles and then retracts as the needles descend. Fig. E illustrates warp knitting.
Warp knitting is a versatile process, but standard warp knitting machines make just three basic stitch variations: open loop, closed loop or no loop. Various fabric patterns are created from different combinations of these stitches. One simple pattern produces tricot knit, which consists of a zigzag pattern of closed loops of parallel wales. Tricot fabrics are run-resistant. Other warp-knit patterns are simplex, milanese and raschel. Milanese knitting produces run resistant fabrics with a diagonal rib pattern. Several sets of yarn are used. The raschel knit is made with latched needles rather than the spring beard needles used for other knits. One or two sets of latch needles are used. Raschel knit fabrics are used frequently for underwear. Warp knitting is used to produce fabric for dresses, lingerie, upholstery and draperies. among other products.
These Designs, from the point of view of their construction, can be regarded as the further development of twill weave.
Those that are symmetrical about their diagonal axes, these are based on herringbone draft and vertical waved twilled peg-plan.
Ø Diamond is constructed on wavy twill while Diaper is constructed on herringbone twill.
Principle of Construction:
True diamond shapes converge into a vertex and for this reason most designs of this type can be constructed economically on the point draft basis. The structure may be developed in following two ways:
1. By employing a vertical waved twill or zigzag as the lifting plan in conjunction with the point draft.
By indicating a diamond base and building up the design symmetrically on each side of the centre thread.
· While this represents the same twill arrange to zigzag vertically.
· Two such repeats are given in each direction.
First method is most commonly employed to produce economical diamonds.
This class of weave will form cut effect or dice effect with the implementation of herringbone twill. This effect is used in ornamentation, shirting, etc.
Principle of Construction:
Ø The simplest weaves of this type are produced as a further development of the herringbone twill, in which the principle of opposing a warp float on the one side of the design by a weft float on the other is extended in both directions, i.e. horizontally and vertically.
Ø In this manner a design is formed in which the typical herringbone cut splits the design into four quarters, the diagonally opposite caters being similar.
Ø These structures are frequently employed as they are capable of forming large design repeats with considerable economy in the number of heald to be used.
v Diapers can also be constructed on the herringbone draft basis provided that the twills from which they were originated fall into a certain specific category the characteristic of such twills are:-
o They are even sided
o Their repeat splits in two halves each of which is symmetrical within itself.
o The lifts in each of the two halves are diametrically opposite
v Even sided twill containing more than two lines of float which do not split in the manner indicae than two lines of float which do not split in the mannner self.
v twills from which they were originated falll ted above cannot be woven with the economical herring bone draft.
v Warp and weft faced twills can also be used to produce diapers on the herring bone reversal but owing to the very prominent quartering of the repeat a distinct check effect is produced and for this reason, such effects are frequently termed as “dice checks”.
v In additional to the herring bone based diapers many other diaper forms can be constructed without a preconceived base.
|Diamond weave||Diaper weave|
|It looks like a diamond||It looks like a dice checks|
|It can be formed by two methods
o Wavy twill
|It can be formed by using herring bone twill|
|Diamond is asymmetrical on both vertically and horizontally.||It is only diagonally similar.|
|This is used for dress material and furnishing fabrics.||This is used for dress materials.|
|This weave is produced with point draft||It is not produced with point draft.|
|Diamond made from 3/3.1/2 Horizontal Waved Twill & Point Draft|
|Diamond made from 3/3.1/2 Horizontal Waved Twill & Point Draft|