Group members:

Md. Al Amin

Bsc in textile engineering

Daffodil International University

Welcome To

Our Presentation Topic: Picking & its Classification

Pick:Pick is a single weft thread in fabric as woven.

Picking:The process of passing through warp shed during weaving is called picking. It is the 2nd primary motion in weaving.

Objective of picking:

To insert the weft through the shed.

The shuttle must travel in the correct flight path.

To maintain pick spacing/PPI

CLASSIFICATION OF PICKING:

Negative picking

Positive picking

1. over picking2. Under picking

Over pick mechanism - Cone over pick mechanism

Under pick mechanisms – a) Side-lever under pick mechanismb) Side-shaft under pick mechanismc) Cone under pick mechanism.

NEGATIVE PICKINGIn this mechanism, a carrier known as shuttle carries the weft yarn in a package called the “pirn”.

CONE OVER PICK MECHANISMA picking tappet, driven by the bottom shaft and carrying a nose bit, hits a cone, which in turn drives a vertical shaft. From here, the motion is transmitted to the picker through a picking stick and picker. The picker pushes the shuttle into the shed.

Overpick mechanism

FLOWCHART OF CONE OVER PICKING MECHANISM

bottom shaft ↓ 

picking lever ↓ 

The picking arm ↓ 

shuttle moves   ↓ 

Picking is done  ↓ 

move back after the delivery of a pick.

SIDE-LEVER UNDERPICK MECHANISM

In this mechanism, a circular disc carrying a bowl is driven by the bottom shaft. The bowl hits a shoe, which in turn depresses a side lever, and the picking stick is driven. So the picker is pushed and the shuttle is pushed out of its box into the shed.

Under pick mechanisms

SIDE-SHAFT UNDER PICK MECHANISM

A disc carrying a bowl is driven by the bottom shaft. The bowl hits a shoe, which in turn drives the picking stick though a side-shaft lever and connecting lever. The picker is pushed and the shuttle is shot out of the shuttle box into the shed.

Under pick mechanisms

CONE UNDER PICK MECHANISM

The nose of a picking tappet, driven by the bottom shaft, hits a cone, which in turn drives a side shaft. This in turn pulls a lug strap and picking stick. The picker, connected to the picking stick, is pushed and so the shuttle emerges from the shuttle box and traverses the shed.

Under pick mechanisms

THROW SHUTTLEIn throw shuttle process weft yarn is pas one side to another side completely by hand

FLY SHUTTLE

POSITIVE PICKING In this mechanism, the weft yarn is

inserted through the warp shed directly or positively by air, water, a projectile, a rapier or a needle

ADVANTAGES OF POSITIVE PICKING a small depth of shed Low Warp thread breakage. Pirns are not required. saving in floor space and labour. Produce high quality fabric

HOW TO INCREASE PPM:

1. increasing motor seed. 2. increasing the nose shape of picking tappet. 3. decreasing the length of picking arm. 

1) PROJECTILE(GRIPPER):- The picking action is accomplished by a small Bullet like

Gripper(Projectile), which grips the weft yarn & carries it through the shed.Several gripper are normally used in the loom , while one is crossing the loom with the weft yarn, the others are return to the starting position. The return by conveyer chain.

ADVANTAGES OF PROJECTILE MACHINE

Low power consumption Reduced waste of filling Quick warp and change styleEasy operation ,maintenance and low spare parts

requirements Energy savingDifferent designs and color sequences can

be woven.

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DRAW BACK OF PROJECTILE:-

The dragging of the weft yarn across a loom creates strain on the yarn so projectile loom are not suitable for weak yarn.

2)RAPIER:-A Rapier loom use a Rapier to pull the weft yarn across the loom. RAPIER CAN BE SINGLE OR DOUBLE.

Single Rapier:-For a single Rapier a long rapier device is required to extend across the full width of warp.

Double Rapier:- Two rapier enter the shed from opposite side of loom & transfer the weft yarn from one rapier to another rapier near centre of loom. Double Rapier further divided into two categories 1) Flexible Rapier & 2) Rigid Rapier

3) AIR JET ;-

A loom in which the weft yarn is propelled through the shed by means of a jet of air. Nozzle are used to insert the weft yarn into the shed. The Fabric width of Air Jet loom is normally narrower than Rapier or Projectile loom.

DRAW BACK;- Air jet loom cannot produce great variety of fabrics.

MULTIPHASE LOOM PICKING Multiphase loom continually inserts weft

yarns from yarn carriers.

4) WATER JET LOOM:-

In this water is shoot under high force & with it a weft yarn. The force of water as it propelled across the shed cross the yarn to opposite side ..

DRAW BACK:-In water jet unit use vacuum suction & heat to remove water from the fabrics.

Only use for Hydrophobic fibres.

ADVANTAGES OF WATER JET PICKING High Efficiency Low Maintenance Smooth and Quiet  Total Safety

THANK YOU