Warping: definition, requirements and parts of warping machine

Warping is the parallel winding of yarn from cone or cheese package on to a warp beam.

Why warping is done.

1. To wound up fixed length of yarn to a warp beam
2. To increase the weavability of yarn
3. To make the next process dynamic
4. To increase production
5. To increase the quality of fabric
6. To make small package reusable
7. To make a convenient yarn sheet for sizing

Requirements of Warping

1. The tension of the wound ends must be uniform and constant during all times of withdrawal from supply package
2. Warping should not impair the physical and mechanical properties of yarn
3. The tension should be moderate to enable the yarn to retain its elastic property completely
4. Predetermined length of the yarn should be observed
5. The production rate of warping should be high
6. The surface of warping package must be cylindrical

Components of a Warping Machine

The warping machine is mainly divided into two major components

1. Creel
2. Headstock

Components of creel

1. yarn clearer
2. stop device
3. indicator
4. tensioners
5. yarn guide
6. package base
7. blower or suction fan

Components of Headstock

1. adjustable V-wraith
2. measuring and marking device
3. yarn speed controlling device
4. pneumatic or hydraulic pressure unit
5. break assembly
6. driving drum
7. stop motion
8. building drum
9. beam bracket
10. lease  rod

Five-Wheel Take-Up

The five-wheel take-up mechanism uses five gears for carrying out the take-up action. The five gears are as follows

1.     Ratchet Wheel- 50-60T

2.     Change Wheel- xT

3.     Compound Wheel- 100-120T

4.     Compound Pinion- 12-18T

5.     Beam Wheel or Take up roller wheel- 60-100T

Here T= teeth and circumference of take up wheel may be 6-16 inches.

                                                             ^{(75T) 1}|----------||||||||||||||||||||||| ^{(take-up roller 15inch)}

                                           ^{(120T) 3}|------------|_{2 (15T)}

                           ^{(50T) 5}|------------|_{4 (x T)}

The above is a representation of a 5 wheel take-up mechanism.

For 1 tooth revolution of the ratchet wheel 1 pick is taken up.

Therefore the number of picks taken up for one revolution of the take-up roller can be found out by doing gearing calculation-taking rpm of take-up roller to be 1.

For 1 revolution of take-up roller the number of picks taken up is

1* (75/15)* (120/x)* 50

= 30000/x

So by dividing with the circumference we can find out the PPI (Picks per inch)

PPI= (30000/x)/ 15

PPI ^{(loom state)} = 2000/x

This is the PPI at loom state.

At grey state, the fabric relaxes and so contracts. So the PPI increase. The contraction is about 1.5 t0 3%. Suppose the contraction is 1.5 % then the PPI of the fabric will be as follows

PPI ^{(grey state)} = (2000/x)* 1.015

PPI ^{(grey state)} = 2030/x

Here the “2030” is called the dividend. If we know the dividend for a certain loom we can easily calculate x, the teeth of change wheel, required to obtain our desired PPI.

In the finished state of fabric further shrinkage. The PPI further increases. The shrinkage is about 5-6%. Suppose the shrinkage is 5% the PPI at finished state will be

PPI ^{(finished state)} = (2030/x)* 1.05

PPI ^{(finished state)} = 2131.5/x

So to summarize, the five wheel take-up mechanism uses one ratchet and 4 spur gears. The change wheel is in driver position. To obtain different PPI we can just use different change wheels in the loom. PPI= dividend/change wheel teeth number.

Usually the five wheel take-up mechanism is used for coarser and heavier fabrics.

Size, its effects on yarn and its properties

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.

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

Technical changes that occur in yarn due to sizing

• Increase the abrasion resistance of yarn
• Increases the yarn breaking strength
• Increases the smoothness of yarn
• Makes the yarn stiff
• Increase yarn elasticity
• Decreases the hairiness of yarn
• Reduces static electricity formation
• Increases the diameter of yarn

The composition of size depends on the following factors

1. the type of fibre
2. the type of yarn
3. yarn quality
4. quality particulars of the fabric to be woven
5. machinery condition and the ambient condition of the loom shed
6. cost of size ingredients

Ingredients used in the size should have the following properties

• 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

Winding efficiency and Faults

Winding Efficiency

Winding efficiency depends on the following factors

1. Spindle or drum speed: the higher the speed the more is the winding efficiency
2. Yarn Count: yarn count is proportional to winding efficiency
3. Yarn quality: if yarn quality increases then winding efficiency increases
4. Worker efficiency: the more efficient the work is the more efficient the winding will be.
5. Humidity: humidity is reciprocal or inversely proportional to winding efficiency.
6. Work load per worker: If the work load on each worker is less then efficiency of winding will be more.
7. Maintenance and over hauling: if the maintenance and over hauling of the machine is not correct then efficiency of winding will decrease.
8. Power failure: if power failure rate increases the winding efficiency will decrease.
9. Creeling time: the more the creeling time the less is the efficiency.
10. Doffing time: the more the doffing time the less is the efficiency.
11. Capacity utilization: when capacity utilization decreases then efficiency increases.

Reasons for lower efficiency

1. power failure
2. improper maintenance and over hauling
3. natural disasters
4. less skilled labor
5. labor unrest
6. shortage of machine parts and raw materials
7. strike
8. maintenance problems

Faults and defects of Winding

1. formation of patches on the yarn
2. incorrect winding speed
3. package is too loss or tight due to tension variations
4. dirty package
5. incorrect shape of package
6. too many knots in yarn
7. excess yarn in bobbin
8. over lapping
9. two end winding
10. mixing of yarn of different linear density
11. unintentional pattern formation during winding
12. dirty yarn
13. poor yarn clearing and snarling

Methods of Winding

There are three methods of winding

1. Parallel Winding
2. Non Parallel Winding
3. Cross Winding

Parallel Winding Package

In this type of winding the yarn is wound parallel to each other on package containing flanges on both sides. This type of winding does not require traversing guide.

Advantages of parallel winding

·      many yarns can be wound at the same time

·      no need of traversing guide

·      no change in yarn twist occurs

·      the package is stable

·      side withdrawal is possible

Disadvantages of parallel winding

• flanges are required
• separate mechanism is required to unwind the yarn
• over withdrawal is not possible

example: beam, flange

Non parallel Winding Package

This package contains one or more threads which are laid very nearly parallel to the layers already existing on the package.

Advantage of non parallel winding

• flanges are not required
• over withdrawal is possible
• no change in yarn twist occurs

Disadvantages of non parallel winding

• side withdrawal is not possible
• the package is not stable
• traversing machine is required

example: cop

Cross Winding Package

This type of package contains a single thread which is laid on the package at an appreciable helix angle so that the layers cross one another to give stability.

Advantages of cross winding

• flange is not required
• yarn package is very stable
• over withdrawal is possible

Disadvantage of cross winding

• the yarn twist is changed during this winding
• traversing mechanism is required

Precision Winding

By precision winding successive coils of yarn are laid close together in a parallel or near parallel manner. By this process it is possible to produce very dense package with maximum amount of yarn stored in a given volume.

Features

• Package are wound with a reciprocating traverse
• Patterning and rubbing causes damage of packages
• Package contains more yarn
• Package is less stable
• The package is hard and compact
• The package is dense
• Rate of unwinding of package is low and the process of unwinding is hard
• The unwound coil is arranged in a  parallel or near parallel manner

Non Precision Winding

By this type of winding the package is formed by a single thread which is laid on the package at appreciable helix angle so that the layers cross one another and give stability to the package. The packages formed by this type of winding are less dense but is more stable.

Features

• Only one coil is used to make this packages
• Cross winding technique is used
• The package density is low
• Minimum number of yarn is wound
• The package formed is soft and less compact
• The stability is high
• Flanges are not required
• The rate of unwinding is high and the process is easy
• The packages formed have low density

Winding

Definition

            The process of transferring yarn from small packages like hank, bobbing etc to a large package such as cones, pirns, cheese etc, containing considerable length of yarn is called winding.

Objects of Winding

1. Bobbin emptying operation
2. Make a continuous supply of yarn
3. Remove thick and thin places from the ring yarn
4. Remove weak places from the yarn
5. remove neps
6. remove knots
7. remove slabs

Requirements of a Winding Machine

1.     the faults should be reduced to an acceptable level

2.     the yarn must not be damaged during winding

3.     Winding should be carried out at high speed for higher productivity

4.     The knots and splices should have sufficient strength and stability

5.     The process should be economical

6.     Winding package should not be too loose or tight.

Winding Parameter

1. winding plate speed (meter per minutes)
2. winding diameter (cm)
3. Traversing velocity (meter per minutes)
4. angle of winding (degree)
5. package velocity (meter per minutes)
6. net winding velocity (meter per minutes)