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

 

Yarn Winding process | Precision Winding | Non Precision Winding

Winding is the process of transferring yarn or thread from one type of package to another to facilitate subsequent processing. The rehandling of yarn is an integral part of the fiber and textile industries. Not only must the package and the yarn itself be suitable for processing on the next machine in the production process,

but also other factors such as packing cases, pressure due to windingtension, etc., must be considered. Basically, there are two types of winding machines: precision winders and drum winders. Precision widers, used primarily for filament yarn, have a traverse driven by acam that is synchronized with the spindle and produce packages with a diamond-patterned wind. Drum winders are used principally for spun yarns; the package is driven by frictional contact between the surface of the package and the drum.

Types of Winding

A.Precision Winding

B.Non Precision Winding 

A.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

B.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 Efficiency | Factors of Winding Efficiency | Reasons for Lower Efficiency

Winding Efficiency :   The ratio of actual production and calculated production is called winding efficiency. It is expressed  as percentage. The efficiency of a highly automated winding operation is calculated by modification of the mathematical model developed for a similar problem.

Winding efficiency depends on the following factors 

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

Reasons for lower efficiency 

• power failure
• improper maintenance and over hauling
• natural disasters
• less skilled labor
• labor unrest
• shortage of machine parts and raw materials
• strike
• maintenance problems

Winding Packages | Types of Winding Packages | Parallel Winding | Non Parallel Winding | Cross Winding

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. The suitable package is used for proper winding are called winding package. 

Types of Winding Packages 

• Parallel Winding 
• Non Parallel Winding 
• 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

Sewing Thread Winding System | Different Types Winding | Precision winding | Parallel winding

A transformer winding in which all the turns are arranged on a bobbin instead of in the form of a disk. Generally used for the high-voltage windings of small transformers.

Different types of Sewing Thread winding system

Precision winding: 

• Constant winding ratio

• Winding angle reduces with increasing diameter

• No pattern areas

• Good off-winding characteristics

• High package density

Step precision or digicone winding:

• Almost constant winding angle

• The wind ratio is reduced in steps

• Combines the advantage of random and precision winding

• No pattern areas

• Higher consistent package density

• Perfect unwinding characteristics

• Straight sided packages

Random winding: 

• Winding angle is kept constant since the winding ratio reduces with increasing diameter

• Stable packages

• Even density

Pineapple winding:

• Winding traverse reduces to produce packages with tapered edges

• Required for filament winding operations

• All three types of winding applicable

Parallel winding:

• Very high package density

• Thread vertical to package axis

• Relatively short lengths of thread

• Suitable for side unwinding

• No pattern areas 5,6

Ball winding:

• Very easy unwinding 

• Winding takes place in 4 stages:

1. Rough base winding

2. Form winding

3. Surface layer winding

4. Circumferencial winding

Skein winding:

• Easy unwinding

• Very small parallel strand of soft twisted thread.

Winding | Objects of Winding | Importance of Winding in Weaving