Yarn Tensioning Device: Functions, Requirements and Types

Last Updated on 25/02/2023

What is Yarn Tensioning Device?
A yarn tensioning device or yarn tensioner is a mechanism that helps regulate the amount of tension on a yarn as it is being used in various textile processes, such as winding, spinning, weaving, knitting and crocheting. Yarn tensioner ensures a constant yarn tension over the entire length and width of the yarn, just from the first to the last meter.

The principle task of a tensioning device is to detect thick spots or slubs in the yarn and a stop motion which causes the winding to stop in the case of a yarn break or the depletion of a supply package. The yarn is directed into this zone by a guide.

Besides, in order to suit the different types of yarn, speed of operation and requirements and different types of tensioner or tension devices are employed. Irrespective of the type, the yarn tensioner should be reliable in operation, cleaned and could be adjusted easily, so designed that the yarn can be threaded easily through it and should not affect the twist of the yarn. The yarn tensioner should also not induce or increase tension fluctuations of the yarn passing through it.

Some tension is already generated during over end unwinding. However, if this tension is inadequate, it becomes necessary to employ a yarn tensioning device that raises mean thread tension to required level. The most common method of adding tension to a running yarn is to apply frictional retarding force to running yarn. Principle of applying tension to running yarn by applying frictional retarding force is shown in below Fig. A frictional retarding force applied to a running yarn is in the direction opposite to yarn movement, and therefore tension is applied to yarn.

Tensioning devices applying frictional retarding force work on any one of the following two principles or their combination:

1. Multiplicative type of yarn tensioner
2. Additive type of yarn tensioner

Functions of Tensioning Device:

1. To allow the maintenance of proper tension in the yarn in order to achieve a uniform package density.
2. The tensioning device also serves as a detector for excessively weak spots in the yarn which break under the added tension induced by the tension device.

Effects of Tension Variation:

• Too high tension may damage the yarn whereas too low tension can lead a unstable packages which will not unwind cleanly.
• In case of man made fiber high tension can cause molecular change which affects the dye ability, so that variations in tension ultimately show as apparently random variation in color shading.
• In case of winding staple yarns, yarn tension may break thin place of yarn.

Requirements Which Influence the Choice of Tensioning Device:

1. The device must be reliable.
2. It must be easily threaded.
3. It must neither introduce nor magnify tension variations.
4. It must not introduce difference in twist.
5. It must not be affected by wear.
6. It must be easily adjustable.
7. It must not be affected by presence of oil or dirt.
8. It must not encourage the collection of dirt and lint.
9. It must be capable of easy cleaning.
10. The operating surfaces must be smooth.
11. It must be inexpensive.

Types of Yarn Tensioner Device:
Tensioning device can be classified in 2 ways as follows-

1. Depending on the type of the working member acting on the yarn.
2. According to the working principle.

A. Depending on the type of the working member acting on the yarn the tensioning devices are the following types:

1. Ball type.
2. Washer type.
3. Disc type.
4. Roller type.
5. Comb type.
6. Two zone type.

B. According to the working principle the tensioning devices are the following types:

1. Capstan (multiplicative) tensioner.
2. Additive tensioner.
3. Combined tensioner.
4. Automatic tensioner.

References:

1. Fundamentals of Spun Yarn Technology by Carl A. Lawrence
2. Fundamentals of Yarn Winding By Milind Koranne
3. Role of Yarn Tension in Weaving by Samir Kumar Neogi

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Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.

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