Picking || Types of picking mechanism




Picking:

It is defined as the process of inserting weft yarn through the shed. It is the second Primary motion in weaving.

The objective of picking:

The objective of picking is to propel the weft carrying element or the weft yarn along the correct trajectory maintaining requisite velocity through the shed in order to provide lateral sets of yarn in the fabric.

Type of picking mechanism:

  1. Negative/conventional Picking mechanism.

  2. Semi-Positive Picking mechanism.

  3. Positive / Unconventional picking mechanism.


Negative/conventional Picking Mechanism:

In this mechanism, the shuttle is used as a carrier and the weft yarn placed in it is called pirn.

Functions of Negative picking:

  • To deliver the shuttle along the correct flight path.

  • To project the shuttle at a Predetermined velocity.

Types of Negative picking:

  • Over picking

  • Under picking


Semi-Positive Picking Mechanism:

In this mechanism, the weft carrier travels into the shed through a weft carrier guide. Projectile loom is an example of a semi-positive picking mechanism.

Positive Picking:

In this type of picking the weft carrier is controlled mechanically i.e., air, water, needle, or rapier.

Over Pick:

In this type of picking mechanism, the picking arm position is situated above the shuttle box then it is known as over pick.

Under Pick:

In this type of picking mechanism, the picking arm position is situated Under the shuttle box then it is known as Under pick.


Difference between Over pick and Under Pick

S. No

Over Pick

Under Pick

1

The Picking arm is situated above the shuttle box

The Picking arm is situated below the shuttle box

2

Looms with Over pick has higher speed

Looms with Under pick mechanisms has Low speed

3

Looms with Over pick will consume less power

Looms with Under pick mechanism will consume high power

4

Looms with Over pick mechanism runs smoothly

Looms with Under pick mechanism runs less smoothly compared to Over pick looms

5

It is the less clean mechanism

It is the more clean mechanism

6

Looms with Over pick mechanism has less wear and tear

Looms with Under pick mechanism will have more wear and tear

7

This mechanism possesses gentle picking action

This mechanism possesses Harsh picking action

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