TT252 Exam 3 Study Guide

Woven Fabric Construction Parameters

Warp Density, Pick Density, Warp Yarn Number, Filling Yarn Number, Warp Yarn Crimp, Filling Yarn Crimp, Weave Design

Primary Motions

Shedding motion, Filling insertion motion, Beat-up motion, Warp and fabric control (take-up and let off motions)

Shedding motion

Warp threads are separated into two groups to create an opening (called a shed) so the weft yarn can pass through

Filling Insertion Motion

Forces or releases the filling insertion element, which carries the filling yarn through the shed.

Beat-up Motion

The newly added yarn is pushed tightly into place by the reed to form the fabric.

Warp and Fabric Control

As fabric is made, it is rolled up onto a cloth roll. At the same time, new warp yarn is fed into the loom to replace what was used.

Shedding Motion Types

Cam, Dobby, and Jaquard

Filling Insertion Types

Shuttle, Shuttless- Gripper, Rapier, Air jet, and Water jet

Cam

Each cam controls one harness. Warp ends are drawn in from the harnesses, completes simplest weave design

Dobby

Maximum number of harnesses is 40, numerous weave designs.

Jaquard

Most intricate weaving designs, can control every warp end individually, each warp yarn is attached to a harness cord

Filling Insertion Systems

Solid- Shuttle, Rapier, and Gripper, Fluid- Water and Air jet, & Inertia

Let-Off Functions

1) Controls the warp sheet tension at a predetermined level

2) Feeds the warp sheet through the weaving machine

Take-Up Functions

1) Collect the woven fabric on a cloth roll

2) Controls the pick density (weft)

Advantages of off Loom Cloth Roll

1) Produces large cloth rolls, which results in less labor, fewer empty tubes, and less frequent doffing and prep for dyeing and washing.

2) An inspection station can be installed, meaning fabric can be inspected and corrected.

Functions of Warp and Fabric Control Motion

Both Take-Up and Let-Off functions

Loom Timing

how all the parts of a loom are coordinated to work at the right time. As the machine makes one row of fabric, different actions must happen in the correct order.

Secondary Motions

1) Increase weaving productivity

2) Enhance woven fabric quality

3) Produce fancy effects

4) Reduce labor costs

Examples of secondary weaving motions

1) Warp stop motion

2) Filling Stop Motion

3) Filling detection and repair

4) Warp Protector Motion

5. Filling Selection Motion

6. Leno Motion

7. Tuck-in Motion

8. Automatic Weave or Pattern Change

Warp Stop Motion

stops the loom when a warp yarn breaks

Filling stop motion

stops the weaving process when a filling yarn is absent, repair is done manually by weaver

Filling detection and repair

Stops the weaving process when a filling yarn is absent. repair is done automatically w/o weave

Warp protector motion

stops the weaving process if the shuttle did not arrive inside shuttle box

Filling Selection motion

Is needed when more than one filling yarns are used

Automatic weave or pattern change

a) pattern is on a floppy and loaded into the weaving machine, operator has to stop machine for a few minutes to change pattern

b) Weaving machine is interfaced with computer which has several patterns, pattern can be switched without stopping machine

Limitations of shuttle weaving

Shuttle has large dimensions, heavy mass, longer time to open, and longer transit time

Features of Rapier

1) Not commonly used for wide fabric production

2) Can handle any yarn type

3) Used for light to heavy yarns

4) Higher speed than shuttle

Features of Gripper

1) Capable of producing wide fabrics

2) Can handle any yarn type

3) Can’t handle large, flat, continuous, filling yarns

4) Doesn’t need large space to store

5) About same speed as rapier

Features of Airjet

1) Not used for wide fabric production

2) Can’t handle different yarn thickness, heavy yarns, or highly twisted yarns

3) Needs compressed air

4) Higher speed than rapier and gripper

Features of waterjet

1) Can’t handle highly twisted yarns

2) Used for continuous filament yarns

3) special size for the warp

4) Highest speed

Shuttle Looms

1) Higher noise level

2) Higher vibration level

3) Lower production rate

4) Needs quill winding and quills

5) Does not need Leno or Tuckin mechanism (motion)

6) No need for auxiliary selvage

7) Can weave tubular fabrics

8) Not restricted by yarn type

Shuttleless Looms

1) Lower noise level

2) Lower vibration level

3) Higher production rate

4) Does not need quill winding and quills

5) Must have Leno or Tuck-in mechanism (motion)

6) Must have auxiliary selvage (waste)

7) Cannot weave tubular fabric

8) Water jet restricts yarn type

Short term stops

1) Warp breaks

2) Slack warp ends

3) Filling breaks

4) Warp caused filling stops (in case of air jet)

5) Waiting for service

6) Pattern Change (electronic dobby and electronic Jacquard)

Long term stops

1) Style change

2) Pattern change

3) Tying-in

4) Breakdown

5) Scheduled maintenance

Areal Weight

Used to compare different fabrics

Fabric Weight

Used for trade (buying/Selling)