**An Overview of Yarn Tension Generators**

**Bhavdip Paldiya**

Dept. of Textile Technology

Sarvajanik College of Engineering & Technology, Surat, India

**Cell:**+91 9662020909

**Email:**bhavdipk9009@gmail.com

**Yarn Tension Generators**

Tension in the yarn is measured using of the tension devices, the operator sets the tension in the yarn to the required level by using means that are known as tension generators or compensators or simply

**tensioning devices.**

**Classification of tension generators under four different categories.**- Spring type,
- Ball type,
- Disc type,
- Gate

**And roller type tensioners fall under these categories.**- Additive type
- Multiplicative type
- Additive cum multiplicative type
- Self compensating type

**Additive type tension generators**

Additive type tension generators |

- Additive type tension devices add a constant tension to the input tension.
- A good example of this category is a disk-tension device. To calculate the added tension due to a disk-tension device, the formula, To = Ti + 2 μW, can be applied.
- Where W is the applied force and μ is the coefficient of friction between the yarn and the tension-device.

**Multiplicative type tension generators**

Multiplicative type tension generators |

- Multiplying type tension devices operate by multiplying the incoming tension.
- The formula used for calculating the output tension in this case, is called the “belt-formula”.
- These
**tensioning devices**is better than the common disk-tension devices. - The general equation for calculating the output tension in this case is given by To = Ti x eμθ.

**Additive cum multiplicative type tension generators**

Additive cum multiplicative type tension generators |

- Additive cum multiplicative type
**tensioning devices**comprise of both additive and multiplicative elements. - The general equation for calculating the output tension in this case is given by To= [{(Ti + 2μW1) x eμθ1 + μW2} x eμθ2+ μW3] x eμθ3.
- A typical example for this kind of
**tensioning device**is shown in Figure.

**Self-adjusting type devices**

Different types of tensioning devices |

- Self-adjusting type devices change their settings depending on the output tension.
- An example of this type of tension device is a Disc -type.
- Here the yarn passed between the two discs.
- The yarn is subjected to frictional force with both the disc.
- 2 μW will be the total frictional force of disc.
- Output tension To=Ti+ 2μW. Thus the input tension Ti is added by the factor μW.
- An example of this type of tension device is a lever-type.
- The upper arm is spring loaded in a clockwise direction. With low output tension, the lever is in the up position (dotted).
- In this position, the yarn has to run around the guides for an increased wrap angle, which increases the yarn tension.
- With high output tension, the upper arm moves closer to the lower arm, thereby adding less tension.
- The ball-tension device also changes the applied tension, to some degree when the output tension changes.
- Higher yarn tension lifts the ball higher, for less wrapping, or reduces the pinching force between the ball and the guide.
- In general, these devices are simple and “low cost”.
- Their major drawbacks include scuffing of the yarn, tension variations depending on the friction coefficient, and tension spikes with irregular yarns and knots.
- (In the general formula given above, To and Ti are the output and input tensions respectively, μ, W, and θ are the coefficient of friction between surfaces, force or pressure applied on the yarn and the angle of wrap over the surface respectively).
- (In the general formulae given above, To and Ti are the output and input tensions respectively, μ, W, and θ are the coefficient of friction between surfaces, force or pressure applied on the yarn and the angle of wrap over the surface respectively).