Manufacturing Worsted Yarns | Manufacturing Woolen Yarns

Manufacturing Worsted Yarns: Now, we would learn the steps involved in manufacturing worsted yarns. In the manufacturer of worsted yarns, the Different steps involved are:

• Carding


• Gilling and combing


• Drawing


• Roving


• Spinning

Carding: The carding process for worsted yarn production is intended to disentangle and lay them as parallel as possible. The fibres are passed between rollers covered with fine wire teeth. Since worsted yarns, however, should be smooth, the fibers are made to lie as parallel as this process will permit. Following this operation, the wool goes to the gilling and combing processes.

Gilling and Combing: Gilling is carried out before (preparative gilling) and after (finisher gilling) combing. The preparative gilling is mainly to align the fibers in a parallel direction, further blend the wool through doubling and to add moisture and lubricants. Whereas finisher gilling is mainly aimed to remove the mild entanglement introduced to the combed sliver. The carded wool, which is to be made into worsted yarn, is put through gilling and combing operations. The gilling process removes the shorter staple and straightens the longer fibers. This process is continued in the combing operation, which removes the shorter fibers of 1 to 4 inch (25 – 100 mm) lengths (called combing noils), places the longer fibers (called tops) as parallel as possible, and further cleans the fibers by removing any remaining loose impurities.

Drawing : Drawing is an advanced operation which doubles and redoubles slivers of wool fibers. The process draws, drafts, twists, and winds the stock, making the slivers more compact and thinning them into slubbers. Drawing is done only for worsted process.

Roving : This is the final stage before spinning. Roving is actually a light twisting operation to hold the thin slubbers intact.

Spinning : The type of spinning explained here is applicable both for woolen and worsted yarns. In the spinning operation, the wool roving is drawn out and twisted into yarn. There are two main methods used to produce woolen-spun yarns. These are:

• Ring spinning


• Mule spinning

Mule-spun yarns generally are superior to ring-spun yarns but they tend to be much more expensive due to the slow production rates and high labor input.

Worsted yarns are spun on any kind of spinning machine – mule, ring, cap, or flyer. The two principle systems of spinning worsted yarns are the English system and the French system.

· In the English system (Bradford), the fiber is oiled before combing, and a tight twist is inserted. This produces smoother and finer yarns. The more tightly twisted yarn makes stronger, more durable fabrics.

· In the French system, no oil is used. The yarn is given no twist; it is fuzzier, and therefore suitable for soft worsted yarns.

Manufacturing Woolen Yarns: In the manufacture of woolen yarns, the fibers are passed through two stages such as:

• Carding


• Spinning

The objective of carding process is to disentangle the fibers. In this process the wool fibers are passed between rollers covered with thousands of fine wire teeth. The wool fibers are disentangled by the action of the wires and are arranged in parallel fashion. This makes the woolen yarns smooth. Since the production of woolen yarns is intended to be rough or fuzzy, it is not desirable to have the fibers too parallel. By use of an oscillating device, one thin film, or sliver, of wool is placed diagonally and overlapping another sliver to give a crisscross effect to the fibers. This process helps in obtaining a fuzzy surface on the yarn.

The next stage is spinning which is similar to that of worsted production process. We would learn the spinning process is the next section.

Manufacturing Processes for Wool Based Yarns | Production Processes for Wool Yarns

Wool is the fiber derived from
the hair of domesticated animals, usually sheep. Wool is classified
according to the source from which it is obtained. The fleece or the
wool which is collected is kept to the different stages of manufacturing
process which starts with the preparation of the fiber. The different
stage through which it is taken depends upon whether the fiber is intended for worsted or woolen yarns. The flow chart for the manufacturing process is as follows:

Preparation Wool

Fleeces
vary from 6 to 18 pounds (3-8 kg) in weight. The best quality wool is
obtained from the sides and shoulders and is treated as one fleece.
Similarly, the wool obtained from the head, chest, belly, and shanks is
treated as a second fleece.

Preparation Wool

The
raw wool or newly sheared fleece is called grease wool because it
contains the natural oil of the sheep. When grease wool is washed, it
loses from 20 to 80 percent of its original weight. The wool obtained
should be carefully sorted into different grades.

Sorting and Grading: In
sorting, the wool is broken up into sections of different quality
fibers, from different parts of the body. The best quality of wool or
one fleece is used for clothing; the lesser quality or second fleece is
used to make rugs. Each grade is determined by type, length, fineness,
elasticity, and strength. The wool may be graded according to the type
of merino sheep or according to fineness or diameter which is otherwise
called as United States System and British System.

The
classification according to the United States System or according to the
type of merino sheep from which it is obtained is as follows:

• First quality wool is identified as fine and is equivalent to the
  quality of wool that could be obtained from a full-to
  three-quarter-blood Merino sheep.


• Second quality is equivalent to the kind of wool that could be obtained from a half blood Merino.


• The
  poorest qualities are identified as common and braid; they are coarse,
  have little crimp, relatively few scales and are somewhat hair like in
  appearance.


• The grading system on the world market is based upon
  the British numbering system, which relates the fineness, or diameter,
  of the wool fiber to the kind of combed, or worsted, yarn that could be
  spun from 1 pound of scoured wool.


• The first in quality would be
  that wool which is fine enough for and capable of being spun into the
  highest wool yarn counts of 80s, 70s, and 64s (No. of 560 yards in 1 
  pound).


•  The second quality is fine enough to be capable of being spun into yarn counts of 62s, 60s, and 58s.
  
  


• The poorest grade is capable of being spun into yarn counts of only 40s and 30s.

TableComparative Wool Grading Table

United States System	British System
Fine (full-to-three-quarter-blood)	80S, 70S, 64S
Half – blood	62S, 60S, 58S
Three – eights – blood	56S
Quarter – blood	50S, 48S
Low – quarter – blood	46S
Common	44S
Braid	40S, 36S

Scouring: Wool taken
directly from the sheep is called “raw” or “grease wool.” It contains
sand, dirt, grease, and dried sweat. The weight of these contaminants
accounts for about 30 to 70 percent of the fleece’s total weight.
Wool
scouring is the first step in the conversion of greasy wool into a
textile product. It is the process of washing wool in hot water and
detergent to remove the non-wool contaminants and then drying it. The
scouring machine contains warm water, soap and a mild solution of soda
ash or other alkali. They are equipped with automatic rakes, which stir
the wool. Rollers between the vats squeeze out the water. If the raw
wool is not sufficiently clear of vegetable substance after scoring, it
is put through the carbonizing bath of dilute sulfuric acid or
hydrochloric acid to burn out the foreign matter.

Drying: Wool
after scouring should not be allowed to become absolutely dry. About,
12 to16 percent of the moisture is left in the wool which would enable
handling of the fibers in further processing.

Oiling: Wool
is unmanageable after scouring and hence the fiber requires to be
treated with various oils to keep it from becoming brittle. Oiling of
the fibers also helps to lubricate it for the spinning operation.

Carding:
From this stage, further processing depends on whether woolen or
worsted yarns are to be produced. The main objective of carding is to
disentangle and to open the scoured wool. Carding also forms a web of
disentangled fibers that are formed into sliver.

Wool Fiber | Properties of Wool Fiber | Classification of Wool

Wool Fiber

Wool fiber is the natural hair grown on sheep and is composed of protein substance called as keratin. Wool is composed of carbon, hydrogen, nitrogen and this is the only animal fiber, which contains sulfur in addition. The wool fibers have crimps or curls, which create pockets and give the wool a spongy feel and create insulation for the wearer. The outside surface of the fiber consists of a series of serrated scales, which overlap each other much like the scales of a fish. Wool is the only fiber with such serration’s which make it possible for the fibers to cling together and produce felt.

Wool fiber

Properties of Wool Fiber
The characteristics of Wool fiber or protein fibers are as follows:

• They are composed of amino acids.
• They have excellent absorbency.
• Moisture regain is high.
• They tend to be warmer than others.
• They have poor resistance to alkalis but good resistance to acids.
• They have good elasticity and resiliency.

Classification of Wool
The quality of wool fibers produced is based on the breeding conditions, the weather, food, general care etc. For example, excessive moisture dries out natural grease. Similarly the cold weather produces harder and heavier fibers. The wool could be classified in two different ways:

1. By sheep from which it is obtained
2. By fleece

Classification by Sheep
The wool is classified according to the sheep from which it is sheared as given below:

Merino Wool: Merino sheep originated in Spain yields the best quality wool.

• These fibers are strong, fine and elastic fiber which is relatively short, ranging from 1 to 5 inches (25 – 125 mm).
• Among the different wool fibers, merino wool has the greatest amount of crimp and has maximum number of scales. These two factors contribute to its superior warmth and spinning qualities.
• Merino is used for the best types of wool clothing.

Class – Two Wool: This class of sheep originates from England, Scotland, Ireland and Wales.

• The fibers are comparatively strong, fine, and elastic and range from 2 to 8 inches (50 – 200mm) in length.
• They have a large number of scales per inch and have good crimp.

Class – Three Wool: This class of sheep originates from United Kingdom.

• The fibers are coarser and have fewer scales and less crimp when compared to earlier varieties of wool fibers and are about 4 to 18 inches long.
• They are smoother, and are more lustrous.
• These wool are less elastic and resilient.
• They are of good quality, used for clothing.

Class – Four Wool: This class is a group of mongrel sheep sometimes referred to as half-breeds.

• The fibers are abour 1 to 16 inches (25 – 400 mm) long, are coarse and hair like, and have relatively few scales and little crimp.
• The fibers are smoother and more lustrous.
• This wool is less desirable, with the least elasticity and strength. It is used mainly for carpets, rugs, and inexpensive low-grade clothing.

Classification by Fleece
Shearing, is the process by which the woolen fleece of a sheep is removed. Sheep are generally shorn of their fleeces in the spring, but the time of shearing varies in different parts of the world. Sheep are not washed before shearing. They are sometimes dipped into an antiseptic bath as prescribed by law. The classification by fleece is as follows:

Lamb’s Wool: The fleece obtained by shearing the lamb of six to eight months old for the first time is known as lamb’s wool. It is also referred to as fleece wool, or first clip. As the fiber has not been cut, it has a natural, tapered end that gives it a softer feel.

Hogget Wool: Hogget wool is the one obtained from sheep about twelve to fourteen months old that have not been previously shorn. The fiber is fine, soft, resilient, and mature, and has tapered ends. These are primarily used for warp yarns.

Wether Wool: Wether wool is the one obtained from the sheep older than fourteen months. The shearing is not done for the first time and in fact these fleeces are obtained after the first shearing. These fleeces contain much soil and dirt.

Pulled Wool: Pulled wool is taken from animals originally slaughtered for meat. The wool is pulled from the pelt of the slaughtered sheep using various chemicals. The fibers of pulled wool are of low quality and produce a low-grade cloth.

Dead Wool: This is the wool obtained from the sheep that have died of age or accidentally killed. This type of wool fiber known should not be confused for pulled wool. Dead wool fiber is decidedly inferior in grade; it is used in low-grade cloth.

Cotty Wool: This type of wool is obtained from the sheep that are exposed to severe weather. As discussed; the severe weather conditions hamper the qualities of the fleece obtained. The cotty wool is of a poor grade and is hard and brittle.

Tag locks: The torn, ragged, or discolored parts of a fleece are known as tag locks. These are usually sold separately as an inferior grade of wool.

Properties of Size Ingredients | Size Ingredients and Their Functions

Size ia a coating with a gelatinous or other substance to add strength or stiffness or to reduce absorbency.Sizing is the process of applying the size material on yarn.

Properties of Size Ingredients 

• Ease of preparation 
• Uniform viscosity 
• Absence of prolonged congealing and kenning at application temperature 
• pH control 
• absence of foaming properties 
• absence of prolonged tackiness 
• compatibility with other components of the size 
• stability towards decomposition 
• ease of desizing

Size Ingredients and their functions 

Adhesive: example: maize, wheat, corn, potato, ferina, sago, PVC, PVA, CMC

Function: it increases yarn strength and abrasion resistance

Lubricant: example: mineral oil, linseed oil, tallow, Japan was, cotton oil

Function: increases yarn smoothness and elasticity

Antiseptic agent: example: ZnCl2 , Phenol, carboxylic acid, synthetic acid

Function: it helps to store the yarn without being damaged and it also gives protection from bacteria or fungus.

Deliquescent agent: example: MgCl2, glycerin

Function: it prevents brittleness of size and helps to keep the standard moisture regain by not allowing water to enter or exit the fibre.

Weighting agent: example: china clay, French chalk

Function: it increases the weight of the yarn

Wetting agent: example: MgCl2

Function: helps to wet the yarn instantaneously

Tinting agent: example: Blue

Function: it helps o increase the brightness of yarn

Antifoaming agent: example: Benzene, Pyridine

Function: it prevents the formation of foam

Define Sizing | Objects of Sizing | Types of sizing | Properties of Size Ingredients | Disadvantages of Sizing

Sizing:

Size is a gelatinous film forming substance in solution or dispersion form, applied normally to warp yarns. It can sometimes be applied to weft yarns. Sizing is the process of applying the size material on yarn.A generic term for compounds that are applied to warp yarn to bind the fiber together and stiffen the yarn to provide abrasion resistance during weaving. Starch, gelatin, oil, wax, and manufactured polymers such as polyvinyl alcohol, polystyrene, polyacrylic acid, and polyacetates are employed. 2. The process of applying sizing compounds. 3. The process of weighing sample lengths of yarn to determine the count. Now automation is used in sizing operation.

Yarn sizing

Objects of Sizing:

1. To protect the yarn from abrasion
2. To improve the breaking strength of the yarn
3. To increase smoothness of yarn
4. To increase yarn elasticity
5. To decrease hairiness
6. To decrease the generation of static electricity

Types of Sizing:

1. Pure sizing: when the size pick up % is about 3 – 10 % it is called pure sizing.
2. Light sizing: when the size pick up % is about 11 -16% it is called light sizing.
3. Medium sizing: when the size pick up % is about 17 – 40 % it is called medium sizing.
4. Heavy sizing: when the size pick up % is above 40 % then it is called heavy sizing.

Disadvantages of Sizing:

• Cost of land and machine is high
• Requires lot of labors
• Requires utility like gas, electricity etc and their cost is high
• Cost of ingredients
• The process is long and it takes time
• There is a risk of degradation of yarn
• The yarn diameter is increased
• Requires robust loom
• It increases yarn stiffness
• The fabric needs to be desized before use
• Need knowledge and information about the size ingredients
• There is a risk of pollution
• Sizing changes the shade of colored yarn
• 100% size material cannot be removed
• Size material presence leads to uneven dying

 

Warping Machine | Main Parts of Warping Machine | Components of Creel | Components of Headstock

Warping:

The operation of winding warp yarns onto a beam usually in preparation for slashing, weaving, or warp knitting. Also called warping. In a word, Warping is the parallel winding of yarn from cone or cheese package on to a warp beam. Warping Process are done by different types of Warping Machine. The main parts of warping machine are given below.

Warping Machine

Components of a Warping Machine
The warping machine is mainly divided into two major components

1. Creel
2. Headstock

Components of Creel

• yarn clearer
• stop device
• indicator
• tensioners
• yarn guide
• package base
• blower or suction fan

Components of Headstock

• adjustable V-wraith
• measuring and marking device
• yarn speed controlling device
• pneumatic or hydraulic pressure unit
• break assembly
• driving drum
• stop motion
• building drum
• beam bracket
• lease rod

 

Yarn Tensioners in Weaving | Types of Tensioning Device | Important Effects of Tensioning Device | Factors Influencing the Selection of Tensioners

Yarn Tensioners:

Yarn Tensioners are devices by the help of which tension is given to the yarn. This is an important device because it enables us to provide necessary tension to the yarn as it moves through the different parts of the mschine. It is specially used in spinning, weaving and knitting machine.

Yarn Tensioners

Types of tensioning device 

There are basically three types of method by which tension is applied to yarn. They are as follows:

• Capstan method 
• Additive method 
• Combined method

Capstan Method

This is the simplest form of yarn tensioning device where the yarn is passed around posts where the tension on the yarn is provided from the friction between the posts and yarns.

This follows the classic law of:

Output tension = Input tension x eµθ

Additive method

In this method the yarn is passed through the middle of two surfaces in contact. The force is applied from above to give suitable tension to the yarn.

Combined method

The combined system is a combination of capstan and additive method. This device is a complicated system which on allows the addition of tension. We cannot decrease the tension with this device. It is seldom used.

Important effects of tensioning device 

If the tension is too high then

• The yarn can be damaged 
• The rate of yarn breakage will be high 
• The elongation property of yarn will change

If the tension is too low then

• It can lead to unstable or loose package formation which will cause problems during unwinding
• Variation in yarn in different parts of a wound package will cause undesirable effects

For man made filament yarn improper tension will cause

• Change in molecular structure 
• Variation in colour shades

For staple or spun yarn too high tension will cause

• Yarn breakage at thin places

Factors influencing the selection of Tensioners 

• The device must be reliable to control uniform tension 
• The device must be easily thread able 
• It must not introduce or magnify tension variation 
• It must not introduce variation in twist 
• It must not be affected by wear 
• It must be easily adjustable 
• It must not be affected by oil and dirt 
• It must not encourage dirt collection 
• It must be easily cleanable 
• The operating surface must be smooth 
• It must be cheap